From 5929822114ac19debd3d18e3146942b401c31740 Mon Sep 17 00:00:00 2001
From: Stefan Eissing <stefan@eissing.org>
Date: Wed, 14 Feb 2024 12:09:32 +0100
Subject: [PATCH] lib: send rework

Curl_read/Curl_write clarifications

- replace `Curl_read()`, `Curl_write()` and `Curl_nwrite()` to 1clarify
  when and at what level they operate

- send/recv of transfer related data is now done via
  `Curl_xfer_send()/Curl_xfer_recv()` which no longer has
  socket/socketindex as parameter. It decides on the transfer setup of
  `conn->sockfd` and `conn->writesockfd` on which connection filter
  chain to operate.

- send/recv on a specific connection filter chain is done via
  `Curl_conn_send()/Curl_conn_recv()` which get the socket index as
  parameter.

- rename `Curl_setup_transfer()` to `Curl_xfer_setup()` for naming
  consistency

- clarify that the special CURLE_AGAIN handling to return `CURLE_OK`
  with length 0 only applies to `Curl_xfer_send()` and CURLE_AGAIN is
  returned by all other send() variants.

SingleRequest reshuffling

- move functions into request.[ch]
- differentiate between reset and free
- add Curl_req_done() to perform last actions
- add a send `bufq` to SingleRequest for future use in keeping upload data

Closes #12963
---
 lib/Makefile.inc      |   2 +
 lib/c-hyper.c         |  24 +++---
 lib/c-hyper.h         |   6 ++
 lib/cf-h1-proxy.c     |   9 +-
 lib/cf-haproxy.c      |  14 ++-
 lib/cfilters.c        |  72 ++++++++++++++--
 lib/cfilters.h        |  32 ++++++-
 lib/curl_rtmp.c       |   4 +-
 lib/dict.c            |  23 +++--
 lib/easy.c            |  35 +++-----
 lib/ftp.c             |  25 +++---
 lib/gopher.c          |   6 +-
 lib/http.c            |  24 +++---
 lib/imap.c            |  11 ++-
 lib/krb5.c            |  17 ++--
 lib/ldap.c            |   2 +-
 lib/mqtt.c            |  13 ++-
 lib/multi.c           |   7 +-
 lib/openldap.c        |   2 +-
 lib/pingpong.c        |  27 ++++--
 lib/pingpong.h        |   2 +-
 lib/pop3.c            |   5 +-
 lib/request.c         | 108 ++++++++++++++++++++++++
 lib/request.h         | 192 ++++++++++++++++++++++++++++++++++++++++++
 lib/rtsp.c            |   4 +-
 lib/sendf.c           | 112 +-----------------------
 lib/sendf.h           |  20 +----
 lib/smb.c             |  11 +--
 lib/smtp.c            |   9 +-
 lib/telnet.c          |  10 +--
 lib/tftp.c            |   4 +-
 lib/transfer.c        |  68 +++++++++++++--
 lib/transfer.h        |  21 ++++-
 lib/url.c             |  60 +++++--------
 lib/url.h             |   1 -
 lib/urldata.h         | 122 +--------------------------
 lib/vssh/libssh.c     |  20 ++---
 lib/vssh/libssh2.c    |  26 +++---
 lib/vssh/wolfssh.c    |  10 +--
 lib/ws.c              |  13 +--
 tests/unit/unit1620.c |   2 -
 41 files changed, 687 insertions(+), 488 deletions(-)
 create mode 100644 lib/request.c
 create mode 100644 lib/request.h

diff --git a/lib/Makefile.inc b/lib/Makefile.inc
index ef3f8a0add..400e2b1ac5 100644
--- a/lib/Makefile.inc
+++ b/lib/Makefile.inc
@@ -201,6 +201,7 @@ LIB_CFILES =         \
   psl.c              \
   rand.c             \
   rename.c           \
+  request.c          \
   rtsp.c             \
   select.c           \
   sendf.c            \
@@ -337,6 +338,7 @@ LIB_HFILES =         \
   psl.h              \
   rand.h             \
   rename.h           \
+  request.h          \
   rtsp.h             \
   select.h           \
   sendf.h            \
diff --git a/lib/c-hyper.c b/lib/c-hyper.c
index f07dd6c0b1..f8e36e909d 100644
--- a/lib/c-hyper.c
+++ b/lib/c-hyper.c
@@ -53,6 +53,7 @@
 
 #include <hyper.h>
 #include "urldata.h"
+#include "cfilters.h"
 #include "sendf.h"
 #include "headers.h"
 #include "transfer.h"
@@ -74,7 +75,8 @@ typedef enum {
 size_t Curl_hyper_recv(void *userp, hyper_context *ctx,
                        uint8_t *buf, size_t buflen)
 {
-  struct Curl_easy *data = userp;
+  struct hyp_io_ctx *io_ctx = userp;
+  struct Curl_easy *data = io_ctx->data;
   struct connectdata *conn = data->conn;
   CURLcode result;
   ssize_t nread;
@@ -82,7 +84,8 @@ size_t Curl_hyper_recv(void *userp, hyper_context *ctx,
   (void)ctx;
 
   DEBUGF(infof(data, "Curl_hyper_recv(%zu)", buflen));
-  result = Curl_read(data, conn->sockfd, (char *)buf, buflen, &nread);
+  result = Curl_conn_recv(data, io_ctx->sockindex,
+                          (char *)buf, buflen, &nread);
   if(result == CURLE_AGAIN) {
     /* would block, register interest */
     DEBUGF(infof(data, "Curl_hyper_recv(%zu) -> EAGAIN", buflen));
@@ -106,15 +109,14 @@ size_t Curl_hyper_recv(void *userp, hyper_context *ctx,
 size_t Curl_hyper_send(void *userp, hyper_context *ctx,
                        const uint8_t *buf, size_t buflen)
 {
-  struct Curl_easy *data = userp;
-  struct connectdata *conn = data->conn;
+  struct hyp_io_ctx *io_ctx = userp;
+  struct Curl_easy *data = io_ctx->data;
   CURLcode result;
   ssize_t nwrote;
 
   DEBUGF(infof(data, "Curl_hyper_send(%zu)", buflen));
-  result = Curl_write(data, conn->sockfd, (void *)buf, buflen, &nwrote);
-  if(!result && !nwrote)
-    result = CURLE_AGAIN;
+  result = Curl_conn_send(data, io_ctx->sockindex,
+                          (void *)buf, buflen, &nwrote);
   if(result == CURLE_AGAIN) {
     DEBUGF(infof(data, "Curl_hyper_send(%zu) -> EAGAIN", buflen));
     /* would block, register interest */
@@ -885,7 +887,7 @@ CURLcode Curl_http(struct Curl_easy *data, bool *done)
      may be parts of the request that is not yet sent, since we can deal with
      the rest of the request in the PERFORM phase. */
   *done = TRUE;
-  Curl_client_cleanup(data);
+  Curl_cw_reset(data);
 
   /* Add collecting of headers written to client. For a new connection,
    * we might have done that already, but reuse
@@ -939,7 +941,9 @@ CURLcode Curl_http(struct Curl_easy *data, bool *done)
     goto error;
   }
   /* tell Hyper how to read/write network data */
-  hyper_io_set_userdata(io, data);
+  h->io_ctx.data = data;
+  h->io_ctx.sockindex = FIRSTSOCKET;
+  hyper_io_set_userdata(io, &h->io_ctx);
   hyper_io_set_read(io, Curl_hyper_recv);
   hyper_io_set_write(io, Curl_hyper_send);
 
@@ -1200,7 +1204,7 @@ CURLcode Curl_http(struct Curl_easy *data, bool *done)
   if((httpreq == HTTPREQ_GET) || (httpreq == HTTPREQ_HEAD)) {
     /* HTTP GET/HEAD download */
     Curl_pgrsSetUploadSize(data, 0); /* nothing */
-    Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE, -1);
+    Curl_xfer_setup(data, FIRSTSOCKET, -1, TRUE, -1);
   }
   conn->datastream = Curl_hyper_stream;
   if(data->state.expect100header)
diff --git a/lib/c-hyper.h b/lib/c-hyper.h
index 0c7de90b70..4a07233078 100644
--- a/lib/c-hyper.h
+++ b/lib/c-hyper.h
@@ -29,6 +29,11 @@
 
 #include <hyper.h>
 
+struct hyp_io_ctx {
+  struct Curl_easy *data;
+  int sockindex;
+};
+
 /* per-transfer data for the Hyper backend */
 struct hyptransfer {
   hyper_waker *write_waker;
@@ -36,6 +41,7 @@ struct hyptransfer {
   const hyper_executor *exec;
   hyper_waker *exp100_waker;
   hyper_waker *send_body_waker;
+  struct hyp_io_ctx io_ctx;
 };
 
 size_t Curl_hyper_recv(void *userp, hyper_context *ctx,
diff --git a/lib/cf-h1-proxy.c b/lib/cf-h1-proxy.c
index 167e5315a8..b7afe27a3f 100644
--- a/lib/cf-h1-proxy.c
+++ b/lib/cf-h1-proxy.c
@@ -366,7 +366,6 @@ static CURLcode recv_CONNECT_resp(struct Curl_cfilter *cf,
 {
   CURLcode result = CURLE_OK;
   struct SingleRequest *k = &data->req;
-  curl_socket_t tunnelsocket = Curl_conn_cf_get_socket(cf, data);
   char *linep;
   size_t line_len;
   int error, writetype;
@@ -386,7 +385,7 @@ static CURLcode recv_CONNECT_resp(struct Curl_cfilter *cf,
 
     /* Read one byte at a time to avoid a race condition. Wait at most one
        second before looping to ensure continuous pgrsUpdates. */
-    result = Curl_read(data, tunnelsocket, &byte, 1, &nread);
+    result = Curl_conn_recv(data, cf->sockindex, &byte, 1, &nread);
     if(result == CURLE_AGAIN)
       /* socket buffer drained, return */
       return CURLE_OK;
@@ -593,7 +592,9 @@ static CURLcode start_CONNECT(struct Curl_cfilter *cf,
     goto error;
   }
   /* tell Hyper how to read/write network data */
-  hyper_io_set_userdata(io, data);
+  h->io_ctx.data = data;
+  h->io_ctx.sockindex = cf->sockindex;
+  hyper_io_set_userdata(io, &h->io_ctx);
   hyper_io_set_read(io, Curl_hyper_recv);
   hyper_io_set_write(io, Curl_hyper_send);
   conn->sockfd = tunnelsocket;
@@ -1007,7 +1008,7 @@ out:
     data->req.header = TRUE; /* assume header */
     data->req.bytecount = 0;
     data->req.ignorebody = FALSE;
-    Curl_client_cleanup(data);
+    Curl_cw_reset(data);
     Curl_pgrsSetUploadCounter(data, 0);
     Curl_pgrsSetDownloadCounter(data, 0);
 
diff --git a/lib/cf-haproxy.c b/lib/cf-haproxy.c
index c062887bf3..652070e12d 100644
--- a/lib/cf-haproxy.c
+++ b/lib/cf-haproxy.c
@@ -129,11 +129,17 @@ static CURLcode cf_haproxy_connect(struct Curl_cfilter *cf,
   case HAPROXY_SEND:
     len = Curl_dyn_len(&ctx->data_out);
     if(len > 0) {
-      ssize_t written = Curl_conn_send(data, cf->sockindex,
-                                       Curl_dyn_ptr(&ctx->data_out),
-                                       len, &result);
-      if(written < 0)
+      ssize_t written;
+      result = Curl_conn_send(data, cf->sockindex,
+                              Curl_dyn_ptr(&ctx->data_out),
+                              len, &written);
+      if(result == CURLE_AGAIN) {
+        result = CURLE_OK;
+        written = 0;
+      }
+      else if(result)
         goto out;
+      DEBUGASSERT(written >= 0);
       Curl_dyn_tail(&ctx->data_out, len - (size_t)written);
       if(Curl_dyn_len(&ctx->data_out) > 0) {
         result = CURLE_OK;
diff --git a/lib/cfilters.c b/lib/cfilters.c
index 823e90c3f2..2bf1dd844f 100644
--- a/lib/cfilters.c
+++ b/lib/cfilters.c
@@ -168,38 +168,46 @@ void Curl_conn_close(struct Curl_easy *data, int index)
   }
 }
 
-ssize_t Curl_conn_recv(struct Curl_easy *data, int num, char *buf,
-                       size_t len, CURLcode *code)
+ssize_t Curl_cf_recv(struct Curl_easy *data, int num, char *buf,
+                     size_t len, CURLcode *code)
 {
   struct Curl_cfilter *cf;
 
   DEBUGASSERT(data);
   DEBUGASSERT(data->conn);
+  *code = CURLE_OK;
   cf = data->conn->cfilter[num];
   while(cf && !cf->connected) {
     cf = cf->next;
   }
   if(cf) {
-    return cf->cft->do_recv(cf, data, buf, len, code);
+    ssize_t nread = cf->cft->do_recv(cf, data, buf, len, code);
+    DEBUGASSERT(nread >= 0 || *code);
+    DEBUGASSERT(nread < 0 || !*code);
+    return nread;
   }
   failf(data, "recv: no filter connected");
   *code = CURLE_FAILED_INIT;
   return -1;
 }
 
-ssize_t Curl_conn_send(struct Curl_easy *data, int num,
-                       const void *mem, size_t len, CURLcode *code)
+ssize_t Curl_cf_send(struct Curl_easy *data, int num,
+                     const void *mem, size_t len, CURLcode *code)
 {
   struct Curl_cfilter *cf;
 
   DEBUGASSERT(data);
   DEBUGASSERT(data->conn);
+  *code = CURLE_OK;
   cf = data->conn->cfilter[num];
   while(cf && !cf->connected) {
     cf = cf->next;
   }
   if(cf) {
-    return cf->cft->do_send(cf, data, mem, len, code);
+    ssize_t nwritten = cf->cft->do_send(cf, data, mem, len, code);
+    DEBUGASSERT(nwritten >= 0 || *code);
+    DEBUGASSERT(nwritten < 0 || !*code || !len);
+    return nwritten;
   }
   failf(data, "send: no filter connected");
   DEBUGASSERT(0);
@@ -662,6 +670,58 @@ size_t Curl_conn_get_max_concurrent(struct Curl_easy *data,
   return (result || n <= 0)? 1 : (size_t)n;
 }
 
+int Curl_conn_sockindex(struct Curl_easy *data, curl_socket_t sockfd)
+{
+  if(data && data->conn &&
+     sockfd != CURL_SOCKET_BAD && sockfd == data->conn->sock[SECONDARYSOCKET])
+    return SECONDARYSOCKET;
+  return FIRSTSOCKET;
+}
+
+CURLcode Curl_conn_recv(struct Curl_easy *data, int sockindex,
+                        char *buf, size_t blen, ssize_t *n)
+{
+  CURLcode result = CURLE_OK;
+  ssize_t nread;
+
+  DEBUGASSERT(data->conn);
+  nread = data->conn->recv[sockindex](data, sockindex, buf, blen, &result);
+  DEBUGASSERT(nread >= 0 || result);
+  DEBUGASSERT(nread < 0 || !result);
+  *n = (nread >= 0)? (size_t)nread : 0;
+  return result;
+}
+
+CURLcode Curl_conn_send(struct Curl_easy *data, int sockindex,
+                        const void *buf, size_t blen,
+                        ssize_t *pnwritten)
+{
+  ssize_t nwritten;
+  CURLcode result = CURLE_OK;
+  struct connectdata *conn;
+
+  DEBUGASSERT(sockindex >= 0 && sockindex < 2);
+  DEBUGASSERT(pnwritten);
+  DEBUGASSERT(data);
+  DEBUGASSERT(data->conn);
+  conn = data->conn;
+#ifdef CURLDEBUG
+  {
+    /* Allow debug builds to override this logic to force short sends
+    */
+    char *p = getenv("CURL_SMALLSENDS");
+    if(p) {
+      size_t altsize = (size_t)strtoul(p, NULL, 10);
+      if(altsize)
+        blen = CURLMIN(blen, altsize);
+    }
+  }
+#endif
+  nwritten = conn->send[sockindex](data, sockindex, buf, blen, &result);
+  DEBUGASSERT((nwritten >= 0) || result);
+  *pnwritten = nwritten;
+  return result;
+}
 
 void Curl_pollset_reset(struct Curl_easy *data,
                         struct easy_pollset *ps)
diff --git a/lib/cfilters.h b/lib/cfilters.h
index f83842920b..65ae3d4cbb 100644
--- a/lib/cfilters.h
+++ b/lib/cfilters.h
@@ -405,8 +405,8 @@ void Curl_conn_adjust_pollset(struct Curl_easy *data,
  * actuel number of bytes copied or a negative value on error.
  * The error code is placed into `*code`.
  */
-ssize_t Curl_conn_recv(struct Curl_easy *data, int sockindex, char *buf,
-                       size_t len, CURLcode *code);
+ssize_t Curl_cf_recv(struct Curl_easy *data, int sockindex, char *buf,
+                     size_t len, CURLcode *code);
 
 /**
  * Send `len` bytes of data from `buf` through the filter chain `sockindex`
@@ -414,8 +414,8 @@ ssize_t Curl_conn_recv(struct Curl_easy *data, int sockindex, char *buf,
  * or a negative value on error.
  * The error code is placed into `*code`.
  */
-ssize_t Curl_conn_send(struct Curl_easy *data, int sockindex,
-                       const void *buf, size_t len, CURLcode *code);
+ssize_t Curl_cf_send(struct Curl_easy *data, int sockindex,
+                     const void *buf, size_t len, CURLcode *code);
 
 /**
  * The easy handle `data` is being attached to `conn`. This does
@@ -497,6 +497,30 @@ size_t Curl_conn_get_max_concurrent(struct Curl_easy *data,
                                     int sockindex);
 
 
+/**
+ * Get the index of the given socket in the connection's sockets.
+ * Useful in calling `Curl_conn_send()/Curl_conn_recv()` with the
+ * correct socket index.
+ */
+int Curl_conn_sockindex(struct Curl_easy *data, curl_socket_t sockfd);
+
+/*
+ * Receive data on the connection, using FIRSTSOCKET/SECONDARYSOCKET.
+ * Will return CURLE_AGAIN iff blocked on receiving.
+ */
+CURLcode Curl_conn_recv(struct Curl_easy *data, int sockindex,
+                        char *buf, size_t buffersize,
+                        ssize_t *pnread);
+
+/*
+ * Send data on the connection, using FIRSTSOCKET/SECONDARYSOCKET.
+ * Will return CURLE_AGAIN iff blocked on sending.
+ */
+CURLcode Curl_conn_send(struct Curl_easy *data, int sockindex,
+                        const void *buf, size_t blen,
+                        ssize_t *pnwritten);
+
+
 void Curl_pollset_reset(struct Curl_easy *data,
                         struct easy_pollset *ps);
 
diff --git a/lib/curl_rtmp.c b/lib/curl_rtmp.c
index 147b12a3ff..b2f2adad8b 100644
--- a/lib/curl_rtmp.c
+++ b/lib/curl_rtmp.c
@@ -265,10 +265,10 @@ static CURLcode rtmp_do(struct Curl_easy *data, bool *done)
 
   if(data->state.upload) {
     Curl_pgrsSetUploadSize(data, data->state.infilesize);
-    Curl_setup_transfer(data, -1, -1, FALSE, FIRSTSOCKET);
+    Curl_xfer_setup(data, -1, -1, FALSE, FIRSTSOCKET);
   }
   else
-    Curl_setup_transfer(data, FIRSTSOCKET, -1, FALSE, -1);
+    Curl_xfer_setup(data, FIRSTSOCKET, -1, FALSE, -1);
   *done = TRUE;
   return CURLE_OK;
 }
diff --git a/lib/dict.c b/lib/dict.c
index 323984822d..955290f4da 100644
--- a/lib/dict.c
+++ b/lib/dict.c
@@ -122,11 +122,10 @@ static char *unescape_word(const char *input)
 }
 
 /* sendf() sends formatted data to the server */
-static CURLcode sendf(curl_socket_t sockfd, struct Curl_easy *data,
-                      const char *fmt, ...) CURL_PRINTF(3, 4);
+static CURLcode sendf(struct Curl_easy *data,
+                      const char *fmt, ...) CURL_PRINTF(2, 3);
 
-static CURLcode sendf(curl_socket_t sockfd, struct Curl_easy *data,
-                      const char *fmt, ...)
+static CURLcode sendf(struct Curl_easy *data, const char *fmt, ...)
 {
   ssize_t bytes_written;
   size_t write_len;
@@ -146,7 +145,7 @@ static CURLcode sendf(curl_socket_t sockfd, struct Curl_easy *data,
 
   for(;;) {
     /* Write the buffer to the socket */
-    result = Curl_write(data, sockfd, sptr, write_len, &bytes_written);
+    result = Curl_xfer_send(data, sptr, write_len, &bytes_written);
 
     if(result)
       break;
@@ -178,8 +177,6 @@ static CURLcode dict_do(struct Curl_easy *data, bool *done)
   char *nthdef = NULL; /* This is not part of the protocol, but required
                           by RFC 2229 */
   CURLcode result;
-  struct connectdata *conn = data->conn;
-  curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
 
   char *path;
 
@@ -228,7 +225,7 @@ static CURLcode dict_do(struct Curl_easy *data, bool *done)
       goto error;
     }
 
-    result = sendf(sockfd, data,
+    result = sendf(data,
                    "CLIENT " LIBCURL_NAME " " LIBCURL_VERSION "\r\n"
                    "MATCH "
                    "%s "    /* database */
@@ -243,7 +240,7 @@ static CURLcode dict_do(struct Curl_easy *data, bool *done)
       failf(data, "Failed sending DICT request");
       goto error;
     }
-    Curl_setup_transfer(data, FIRSTSOCKET, -1, FALSE, -1); /* no upload */
+    Curl_xfer_setup(data, FIRSTSOCKET, -1, FALSE, -1); /* no upload */
   }
   else if(strncasecompare(path, DICT_DEFINE, sizeof(DICT_DEFINE)-1) ||
           strncasecompare(path, DICT_DEFINE2, sizeof(DICT_DEFINE2)-1) ||
@@ -276,7 +273,7 @@ static CURLcode dict_do(struct Curl_easy *data, bool *done)
       goto error;
     }
 
-    result = sendf(sockfd, data,
+    result = sendf(data,
                    "CLIENT " LIBCURL_NAME " " LIBCURL_VERSION "\r\n"
                    "DEFINE "
                    "%s "     /* database */
@@ -289,7 +286,7 @@ static CURLcode dict_do(struct Curl_easy *data, bool *done)
       failf(data, "Failed sending DICT request");
       goto error;
     }
-    Curl_setup_transfer(data, FIRSTSOCKET, -1, FALSE, -1);
+    Curl_xfer_setup(data, FIRSTSOCKET, -1, FALSE, -1);
   }
   else {
 
@@ -302,7 +299,7 @@ static CURLcode dict_do(struct Curl_easy *data, bool *done)
         if(ppath[i] == ':')
           ppath[i] = ' ';
       }
-      result = sendf(sockfd, data,
+      result = sendf(data,
                      "CLIENT " LIBCURL_NAME " " LIBCURL_VERSION "\r\n"
                      "%s\r\n"
                      "QUIT\r\n", ppath);
@@ -311,7 +308,7 @@ static CURLcode dict_do(struct Curl_easy *data, bool *done)
         goto error;
       }
 
-      Curl_setup_transfer(data, FIRSTSOCKET, -1, FALSE, -1);
+      Curl_xfer_setup(data, FIRSTSOCKET, -1, FALSE, -1);
     }
   }
 
diff --git a/lib/easy.c b/lib/easy.c
index b2a66ad0fa..7ea1ce1f63 100644
--- a/lib/easy.c
+++ b/lib/easy.c
@@ -1038,7 +1038,7 @@ fail:
  */
 void curl_easy_reset(struct Curl_easy *data)
 {
-  Curl_free_request_state(data);
+  Curl_req_reset(&data->req, data);
 
   /* zero out UserDefined data: */
   Curl_freeset(data);
@@ -1166,9 +1166,11 @@ CURLcode curl_easy_pause(struct Curl_easy *data, int action)
 }
 
 
-static CURLcode easy_connection(struct Curl_easy *data, curl_socket_t *sfd,
+static CURLcode easy_connection(struct Curl_easy *data,
                                 struct connectdata **connp)
 {
+  curl_socket_t sfd;
+
   if(!data)
     return CURLE_BAD_FUNCTION_ARGUMENT;
 
@@ -1178,9 +1180,9 @@ static CURLcode easy_connection(struct Curl_easy *data, curl_socket_t *sfd,
     return CURLE_UNSUPPORTED_PROTOCOL;
   }
 
-  *sfd = Curl_getconnectinfo(data, connp);
+  sfd = Curl_getconnectinfo(data, connp);
 
-  if(*sfd == CURL_SOCKET_BAD) {
+  if(sfd == CURL_SOCKET_BAD) {
     failf(data, "Failed to get recent socket");
     return CURLE_UNSUPPORTED_PROTOCOL;
   }
@@ -1196,7 +1198,6 @@ static CURLcode easy_connection(struct Curl_easy *data, curl_socket_t *sfd,
 CURLcode curl_easy_recv(struct Curl_easy *data, void *buffer, size_t buflen,
                         size_t *n)
 {
-  curl_socket_t sfd;
   CURLcode result;
   ssize_t n1;
   struct connectdata *c;
@@ -1204,7 +1205,7 @@ CURLcode curl_easy_recv(struct Curl_easy *data, void *buffer, size_t buflen,
   if(Curl_is_in_callback(data))
     return CURLE_RECURSIVE_API_CALL;
 
-  result = easy_connection(data, &sfd, &c);
+  result = easy_connection(data, &c);
   if(result)
     return result;
 
@@ -1214,7 +1215,7 @@ CURLcode curl_easy_recv(struct Curl_easy *data, void *buffer, size_t buflen,
     Curl_attach_connection(data, c);
 
   *n = 0;
-  result = Curl_read(data, sfd, buffer, buflen, &n1);
+  result = Curl_conn_recv(data, FIRSTSOCKET, buffer, buflen, &n1);
 
   if(result)
     return result;
@@ -1226,11 +1227,10 @@ CURLcode curl_easy_recv(struct Curl_easy *data, void *buffer, size_t buflen,
 #ifdef USE_WEBSOCKETS
 CURLcode Curl_connect_only_attach(struct Curl_easy *data)
 {
-  curl_socket_t sfd;
   CURLcode result;
   struct connectdata *c = NULL;
 
-  result = easy_connection(data, &sfd, &c);
+  result = easy_connection(data, &c);
   if(result)
     return result;
 
@@ -1251,13 +1251,12 @@ CURLcode Curl_connect_only_attach(struct Curl_easy *data)
 CURLcode Curl_senddata(struct Curl_easy *data, const void *buffer,
                        size_t buflen, ssize_t *n)
 {
-  curl_socket_t sfd;
   CURLcode result;
-  ssize_t n1;
   struct connectdata *c = NULL;
   SIGPIPE_VARIABLE(pipe_st);
 
-  result = easy_connection(data, &sfd, &c);
+  *n = 0;
+  result = easy_connection(data, &c);
   if(result)
     return result;
 
@@ -1266,20 +1265,12 @@ CURLcode Curl_senddata(struct Curl_easy *data, const void *buffer,
        needs to be reattached */
     Curl_attach_connection(data, c);
 
-  *n = 0;
   sigpipe_ignore(data, &pipe_st);
-  result = Curl_write(data, sfd, buffer, buflen, &n1);
+  result = Curl_conn_send(data, FIRSTSOCKET, buffer, buflen, n);
   sigpipe_restore(&pipe_st);
 
-  if(n1 == -1)
+  if(result && result != CURLE_AGAIN)
     return CURLE_SEND_ERROR;
-
-  /* detect EAGAIN */
-  if(!result && !n1)
-    return CURLE_AGAIN;
-
-  *n = n1;
-
   return result;
 }
 
diff --git a/lib/ftp.c b/lib/ftp.c
index 53445b3d5a..4deb841b3a 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -151,7 +151,7 @@ static CURLcode wc_statemach(struct Curl_easy *data);
 static void wc_data_dtor(void *ptr);
 static CURLcode ftp_state_retr(struct Curl_easy *data, curl_off_t filesize);
 static CURLcode ftp_readresp(struct Curl_easy *data,
-                             curl_socket_t sockfd,
+                             int sockindex,
                              struct pingpong *pp,
                              int *ftpcode,
                              size_t *size);
@@ -581,12 +581,12 @@ static CURLcode InitiateTransfer(struct Curl_easy *data)
     /* set the SO_SNDBUF for the secondary socket for those who need it */
     Curl_sndbufset(conn->sock[SECONDARYSOCKET]);
 
-    Curl_setup_transfer(data, -1, -1, FALSE, SECONDARYSOCKET);
+    Curl_xfer_setup(data, -1, -1, FALSE, SECONDARYSOCKET);
   }
   else {
     /* FTP download: */
-    Curl_setup_transfer(data, SECONDARYSOCKET,
-                        conn->proto.ftpc.retr_size_saved, FALSE, -1);
+    Curl_xfer_setup(data, SECONDARYSOCKET,
+                    conn->proto.ftpc.retr_size_saved, FALSE, -1);
   }
 
   conn->proto.ftpc.pp.pending_resp = TRUE; /* expect server response */
@@ -664,13 +664,13 @@ static bool ftp_endofresp(struct Curl_easy *data, struct connectdata *conn,
 }
 
 static CURLcode ftp_readresp(struct Curl_easy *data,
-                             curl_socket_t sockfd,
+                             int sockindex,
                              struct pingpong *pp,
                              int *ftpcode, /* return the ftp-code if done */
                              size_t *size) /* size of the response */
 {
   int code;
-  CURLcode result = Curl_pp_readresp(data, sockfd, pp, &code, size);
+  CURLcode result = Curl_pp_readresp(data, sockindex, pp, &code, size);
 
 #ifdef HAVE_GSSAPI
   {
@@ -805,7 +805,7 @@ CURLcode Curl_GetFTPResponse(struct Curl_easy *data,
         break;
       }
     }
-    result = ftp_readresp(data, sockfd, pp, ftpcode, &nread);
+    result = ftp_readresp(data, FIRSTSOCKET, pp, ftpcode, &nread);
     if(result)
       break;
 
@@ -1725,7 +1725,7 @@ static CURLcode ftp_state_ul_setup(struct Curl_easy *data,
         infof(data, "File already completely uploaded");
 
         /* no data to transfer */
-        Curl_setup_transfer(data, -1, -1, FALSE, -1);
+        Curl_xfer_setup(data, -1, -1, FALSE, -1);
 
         /* Set ->transfer so that we won't get any error in
          * ftp_done() because we didn't transfer anything! */
@@ -2396,7 +2396,7 @@ static CURLcode ftp_state_retr(struct Curl_easy *data,
 
     if(ftp->downloadsize == 0) {
       /* no data to transfer */
-      Curl_setup_transfer(data, -1, -1, FALSE, -1);
+      Curl_xfer_setup(data, -1, -1, FALSE, -1);
       infof(data, "File already completely downloaded");
 
       /* Set ->transfer so that we won't get any error in ftp_done()
@@ -2803,7 +2803,6 @@ static CURLcode ftp_statemachine(struct Curl_easy *data,
                                  struct connectdata *conn)
 {
   CURLcode result;
-  curl_socket_t sock = conn->sock[FIRSTSOCKET];
   int ftpcode;
   struct ftp_conn *ftpc = &conn->proto.ftpc;
   struct pingpong *pp = &ftpc->pp;
@@ -2813,7 +2812,7 @@ static CURLcode ftp_statemachine(struct Curl_easy *data,
   if(pp->sendleft)
     return Curl_pp_flushsend(data, pp);
 
-  result = ftp_readresp(data, sock, pp, &ftpcode, &nread);
+  result = ftp_readresp(data, FIRSTSOCKET, pp, &ftpcode, &nread);
   if(result)
     return result;
 
@@ -3813,7 +3812,7 @@ static CURLcode ftp_do_more(struct Curl_easy *data, int *completep)
   }
 
   /* no data to transfer */
-  Curl_setup_transfer(data, -1, -1, FALSE, -1);
+  Curl_xfer_setup(data, -1, -1, FALSE, -1);
 
   if(!ftpc->wait_data_conn) {
     /* no waiting for the data connection so this is now complete */
@@ -4415,7 +4414,7 @@ static CURLcode ftp_dophase_done(struct Curl_easy *data, bool connected)
 
   if(ftp->transfer != PPTRANSFER_BODY)
     /* no data to transfer */
-    Curl_setup_transfer(data, -1, -1, FALSE, -1);
+    Curl_xfer_setup(data, -1, -1, FALSE, -1);
   else if(!connected)
     /* since we didn't connect now, we want do_more to get called */
     conn->bits.do_more = TRUE;
diff --git a/lib/gopher.c b/lib/gopher.c
index 9ca08289eb..e49da8147c 100644
--- a/lib/gopher.c
+++ b/lib/gopher.c
@@ -185,7 +185,7 @@ static CURLcode gopher_do(struct Curl_easy *data, bool *done)
     if(strlen(sel) < 1)
       break;
 
-    result = Curl_nwrite(data, FIRSTSOCKET, sel, k, &amount);
+    result = Curl_xfer_send(data, sel, k, &amount);
     if(!result) { /* Which may not have written it all! */
       result = Curl_client_write(data, CLIENTWRITE_HEADER, sel, amount);
       if(result)
@@ -227,7 +227,7 @@ static CURLcode gopher_do(struct Curl_easy *data, bool *done)
   free(sel_org);
 
   if(!result)
-    result = Curl_nwrite(data, FIRSTSOCKET, "\r\n", 2, &amount);
+    result = Curl_xfer_send(data, "\r\n", 2, &amount);
   if(result) {
     failf(data, "Failed sending Gopher request");
     return result;
@@ -236,7 +236,7 @@ static CURLcode gopher_do(struct Curl_easy *data, bool *done)
   if(result)
     return result;
 
-  Curl_setup_transfer(data, FIRSTSOCKET, -1, FALSE, -1);
+  Curl_xfer_setup(data, FIRSTSOCKET, -1, FALSE, -1);
   return CURLE_OK;
 }
 #endif /* CURL_DISABLE_GOPHER */
diff --git a/lib/http.c b/lib/http.c
index dd1fc4ffa0..97ef4550f5 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -1356,7 +1356,11 @@ CURLcode Curl_buffer_send(struct dynbuf *in,
       sendsize = (size_t)data->set.upload_buffer_size;
   }
 
-  result = Curl_nwrite(data, sockindex, ptr, sendsize, &amount);
+  result = Curl_conn_send(data, sockindex, ptr, sendsize, &amount);
+  if(result == CURLE_AGAIN) {
+    result = CURLE_OK;
+    amount = 0;
+  }
 
   if(!result) {
     /*
@@ -2511,8 +2515,8 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
       failf(data, "Failed sending PUT request");
     else
       /* prepare for transfer */
-      Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE,
-                          http->postsize?FIRSTSOCKET:-1);
+      Curl_xfer_setup(data, FIRSTSOCKET, -1, TRUE,
+                      http->postsize?FIRSTSOCKET:-1);
     if(result)
       return result;
     break;
@@ -2534,7 +2538,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
         failf(data, "Failed sending POST request");
       else
         /* setup variables for the upcoming transfer */
-        Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE, -1);
+        Curl_xfer_setup(data, FIRSTSOCKET, -1, TRUE, -1);
       break;
     }
 
@@ -2592,8 +2596,8 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
       failf(data, "Failed sending POST request");
     else
       /* prepare for transfer */
-      Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE,
-                          http->postsize?FIRSTSOCKET:-1);
+      Curl_xfer_setup(data, FIRSTSOCKET, -1, TRUE,
+                      http->postsize?FIRSTSOCKET:-1);
     if(result)
       return result;
 
@@ -2735,8 +2739,8 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
     if(result)
       failf(data, "Failed sending HTTP POST request");
     else
-      Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE,
-                          http->postdata?FIRSTSOCKET:-1);
+      Curl_xfer_setup(data, FIRSTSOCKET, -1, TRUE,
+                      http->postdata?FIRSTSOCKET:-1);
     break;
 
   default:
@@ -2755,11 +2759,11 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
             !(data->set.connect_only))
       /* Set up the transfer for two-way since without CONNECT_ONLY set, this
          request probably wants to send data too post upgrade */
-      Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE, FIRSTSOCKET);
+      Curl_xfer_setup(data, FIRSTSOCKET, -1, TRUE, FIRSTSOCKET);
 #endif
     else
       /* HTTP GET/HEAD download: */
-      Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE, -1);
+      Curl_xfer_setup(data, FIRSTSOCKET, -1, TRUE, -1);
   }
 
   return result;
diff --git a/lib/imap.c b/lib/imap.c
index 50849eefc2..43ec83d09c 100644
--- a/lib/imap.c
+++ b/lib/imap.c
@@ -1213,14 +1213,14 @@ static CURLcode imap_state_fetch_resp(struct Curl_easy *data,
 
     if(data->req.bytecount == size)
       /* The entire data is already transferred! */
-      Curl_setup_transfer(data, -1, -1, FALSE, -1);
+      Curl_xfer_setup(data, -1, -1, FALSE, -1);
     else {
       /* IMAP download */
       data->req.maxdownload = size;
       /* force a recv/send check of this connection, as the data might've been
        read off the socket already */
       data->state.select_bits = CURL_CSELECT_IN;
-      Curl_setup_transfer(data, FIRSTSOCKET, size, FALSE, -1);
+      Curl_xfer_setup(data, FIRSTSOCKET, size, FALSE, -1);
     }
   }
   else {
@@ -1268,7 +1268,7 @@ static CURLcode imap_state_append_resp(struct Curl_easy *data, int imapcode,
     Curl_pgrsSetUploadSize(data, data->state.infilesize);
 
     /* IMAP upload */
-    Curl_setup_transfer(data, -1, -1, FALSE, FIRSTSOCKET);
+    Curl_xfer_setup(data, -1, -1, FALSE, FIRSTSOCKET);
 
     /* End of DO phase */
     imap_state(data, IMAP_STOP);
@@ -1299,7 +1299,6 @@ static CURLcode imap_statemachine(struct Curl_easy *data,
                                   struct connectdata *conn)
 {
   CURLcode result = CURLE_OK;
-  curl_socket_t sock = conn->sock[FIRSTSOCKET];
   int imapcode;
   struct imap_conn *imapc = &conn->proto.imapc;
   struct pingpong *pp = &imapc->pp;
@@ -1316,7 +1315,7 @@ static CURLcode imap_statemachine(struct Curl_easy *data,
 
   do {
     /* Read the response from the server */
-    result = Curl_pp_readresp(data, sock, pp, &imapcode, &nread);
+    result = Curl_pp_readresp(data, FIRSTSOCKET, pp, &imapcode, &nread);
     if(result)
       return result;
 
@@ -1694,7 +1693,7 @@ static CURLcode imap_dophase_done(struct Curl_easy *data, bool connected)
 
   if(imap->transfer != PPTRANSFER_BODY)
     /* no data to transfer */
-    Curl_setup_transfer(data, -1, -1, FALSE, -1);
+    Curl_xfer_setup(data, -1, -1, FALSE, -1);
 
   return CURLE_OK;
 }
diff --git a/lib/krb5.c b/lib/krb5.c
index 4db19fb27f..885319e00f 100644
--- a/lib/krb5.c
+++ b/lib/krb5.c
@@ -52,6 +52,7 @@
 #include "ftp.h"
 #include "curl_gssapi.h"
 #include "sendf.h"
+#include "transfer.h"
 #include "curl_krb5.h"
 #include "warnless.h"
 #include "strcase.h"
@@ -90,8 +91,7 @@ static CURLcode ftpsend(struct Curl_easy *data, struct connectdata *conn,
 #ifdef HAVE_GSSAPI
     conn->data_prot = PROT_CMD;
 #endif
-    result = Curl_nwrite(data, FIRSTSOCKET, sptr, write_len,
-                        &bytes_written);
+    result = Curl_xfer_send(data, sptr, write_len, &bytes_written);
 #ifdef HAVE_GSSAPI
     DEBUGASSERT(data_sec > PROT_NONE && data_sec < PROT_LAST);
     conn->data_prot = data_sec;
@@ -470,7 +470,7 @@ socket_read(struct Curl_easy *data, int sockindex, void *to, size_t len)
   ssize_t nread = 0;
 
   while(len > 0) {
-    nread = Curl_conn_recv(data, sockindex, to_p, len, &result);
+    result = Curl_conn_recv(data, sockindex, to_p, len, &nread);
     if(nread > 0) {
       len -= nread;
       to_p += nread;
@@ -497,8 +497,8 @@ socket_write(struct Curl_easy *data, int sockindex, const void *to,
   ssize_t written;
 
   while(len > 0) {
-    written = Curl_conn_send(data, sockindex, to_p, len, &result);
-    if(written > 0) {
+    result = Curl_conn_send(data, sockindex, to_p, len, &written);
+    if(!result && written > 0) {
       len -= written;
       to_p += written;
     }
@@ -567,8 +567,11 @@ static ssize_t sec_recv(struct Curl_easy *data, int sockindex,
   *err = CURLE_OK;
 
   /* Handle clear text response. */
-  if(conn->sec_complete == 0 || conn->data_prot == PROT_CLEAR)
-    return Curl_conn_recv(data, sockindex, buffer, len, err);
+  if(conn->sec_complete == 0 || conn->data_prot == PROT_CLEAR) {
+    ssize_t nread;
+    *err = Curl_conn_recv(data, sockindex, buffer, len, &nread);
+    return nread;
+  }
 
   if(conn->in_buffer.eof_flag) {
     conn->in_buffer.eof_flag = 0;
diff --git a/lib/ldap.c b/lib/ldap.c
index 4c04647f4f..53497a5c41 100644
--- a/lib/ldap.c
+++ b/lib/ldap.c
@@ -749,7 +749,7 @@ quit:
   FREE_ON_WINLDAP(host);
 
   /* no data to transfer */
-  Curl_setup_transfer(data, -1, -1, FALSE, -1);
+  Curl_xfer_setup(data, -1, -1, FALSE, -1);
   connclose(conn, "LDAP connection always disable reuse");
 
   return result;
diff --git a/lib/mqtt.c b/lib/mqtt.c
index 5a9d6d0f10..b0aafc7970 100644
--- a/lib/mqtt.c
+++ b/lib/mqtt.c
@@ -120,7 +120,7 @@ static CURLcode mqtt_send(struct Curl_easy *data,
   CURLcode result = CURLE_OK;
   struct MQTT *mq = data->req.p.mqtt;
   ssize_t n;
-  result = Curl_nwrite(data, FIRSTSOCKET, buf, len, &n);
+  result = Curl_xfer_send(data, buf, len, &n);
   if(result)
     return result;
   Curl_debug(data, CURLINFO_HEADER_OUT, buf, (size_t)n);
@@ -366,8 +366,7 @@ static CURLcode mqtt_recv_atleast(struct Curl_easy *data, size_t nbytes)
     ssize_t nread;
 
     DEBUGASSERT(nbytes - rlen < sizeof(readbuf));
-    result = Curl_read(data, data->conn->sock[FIRSTSOCKET],
-                       (char *)readbuf, nbytes - rlen, &nread);
+    result = Curl_xfer_recv(data, (char *)readbuf, nbytes - rlen, &nread);
     if(result)
       return result;
     DEBUGASSERT(nread >= 0);
@@ -622,7 +621,6 @@ static CURLcode mqtt_read_publish(struct Curl_easy *data, bool *done)
 {
   CURLcode result = CURLE_OK;
   struct connectdata *conn = data->conn;
-  curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
   ssize_t nread;
   size_t remlen;
   struct mqtt_conn *mqtt = &conn->proto.mqtt;
@@ -679,7 +677,7 @@ MQTT_SUBACK_COMING:
     size_t rest = mq->npacket;
     if(rest > sizeof(buffer))
       rest = sizeof(buffer);
-    result = Curl_read(data, sockfd, buffer, rest, &nread);
+    result = Curl_xfer_recv(data, buffer, rest, &nread);
     if(result) {
       if(CURLE_AGAIN == result) {
         infof(data, "EEEE AAAAGAIN");
@@ -744,7 +742,6 @@ static CURLcode mqtt_doing(struct Curl_easy *data, bool *done)
   struct mqtt_conn *mqtt = &conn->proto.mqtt;
   struct MQTT *mq = data->req.p.mqtt;
   ssize_t nread;
-  curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
   unsigned char byte;
 
   *done = FALSE;
@@ -762,7 +759,7 @@ static CURLcode mqtt_doing(struct Curl_easy *data, bool *done)
   switch(mqtt->state) {
   case MQTT_FIRST:
     /* Read the initial byte only */
-    result = Curl_read(data, sockfd, (char *)&mq->firstbyte, 1, &nread);
+    result = Curl_xfer_recv(data, (char *)&mq->firstbyte, 1, &nread);
     if(result)
       break;
     else if(!nread) {
@@ -778,7 +775,7 @@ static CURLcode mqtt_doing(struct Curl_easy *data, bool *done)
     FALLTHROUGH();
   case MQTT_REMAINING_LENGTH:
     do {
-      result = Curl_read(data, sockfd, (char *)&byte, 1, &nread);
+      result = Curl_xfer_recv(data, (char *)&byte, 1, &nread);
       if(!nread)
         break;
       Curl_debug(data, CURLINFO_HEADER_IN, (char *)&byte, 1);
diff --git a/lib/multi.c b/lib/multi.c
index 1c8c362f18..c6869a3155 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -706,9 +706,10 @@ static CURLcode multi_done(struct Curl_easy *data,
 
   process_pending_handles(data->multi); /* connection / multiplex */
 
-  Curl_safefree(data->state.ulbuf);
+  if(!result)
+    result = Curl_req_done(&data->req, data, premature);
 
-  Curl_client_cleanup(data);
+  Curl_safefree(data->state.ulbuf);
 
   CONNCACHE_LOCK(data);
   Curl_detach_connection(data);
@@ -1007,7 +1008,7 @@ static int connecting_getsock(struct Curl_easy *data, curl_socket_t *socks)
 {
   struct connectdata *conn = data->conn;
   (void)socks;
-  /* Not using `conn->sockfd` as `Curl_setup_transfer()` initializes
+  /* Not using `conn->sockfd` as `Curl_xfer_setup()` initializes
    * that *after* the connect. */
   if(conn && conn->sock[FIRSTSOCKET] != CURL_SOCKET_BAD) {
     /* Default is to wait to something from the server */
diff --git a/lib/openldap.c b/lib/openldap.c
index 1e60ff7387..47266f64e4 100644
--- a/lib/openldap.c
+++ b/lib/openldap.c
@@ -916,7 +916,7 @@ static CURLcode oldap_do(struct Curl_easy *data, bool *done)
       else {
         lr->msgid = msgid;
         data->req.p.ldap = lr;
-        Curl_setup_transfer(data, FIRSTSOCKET, -1, FALSE, -1);
+        Curl_xfer_setup(data, FIRSTSOCKET, -1, FALSE, -1);
         *done = TRUE;
       }
     }
diff --git a/lib/pingpong.c b/lib/pingpong.c
index b976ffbeac..c12f7cd7b6 100644
--- a/lib/pingpong.c
+++ b/lib/pingpong.c
@@ -199,8 +199,11 @@ CURLcode Curl_pp_vsendf(struct Curl_easy *data,
 #ifdef HAVE_GSSAPI
   conn->data_prot = PROT_CMD;
 #endif
-  result = Curl_nwrite(data, FIRSTSOCKET, s, write_len, &bytes_written);
-  if(result)
+  result = Curl_conn_send(data, FIRSTSOCKET, s, write_len, &bytes_written);
+  if(result == CURLE_AGAIN) {
+    bytes_written = 0;
+  }
+  else if(result)
     return result;
 #ifdef HAVE_GSSAPI
   data_sec = conn->data_prot;
@@ -251,7 +254,7 @@ CURLcode Curl_pp_sendf(struct Curl_easy *data, struct pingpong *pp,
 }
 
 static CURLcode pingpong_read(struct Curl_easy *data,
-                              curl_socket_t sockfd,
+                              int sockindex,
                               char *buffer,
                               size_t buflen,
                               ssize_t *nread)
@@ -261,7 +264,7 @@ static CURLcode pingpong_read(struct Curl_easy *data,
   enum protection_level prot = data->conn->data_prot;
   data->conn->data_prot = PROT_CLEAR;
 #endif
-  result = Curl_read(data, sockfd, buffer, buflen, nread);
+  result = Curl_conn_recv(data, sockindex, buffer, buflen, nread);
 #ifdef HAVE_GSSAPI
   DEBUGASSERT(prot  > PROT_NONE && prot < PROT_LAST);
   data->conn->data_prot = (unsigned char)prot;
@@ -275,7 +278,7 @@ static CURLcode pingpong_read(struct Curl_easy *data,
  * Reads a piece of a server response.
  */
 CURLcode Curl_pp_readresp(struct Curl_easy *data,
-                          curl_socket_t sockfd,
+                          int sockindex,
                           struct pingpong *pp,
                           int *code, /* return the server code if done */
                           size_t *size) /* size of the response */
@@ -300,7 +303,7 @@ CURLcode Curl_pp_readresp(struct Curl_easy *data,
     ssize_t gotbytes = 0;
     char buffer[900];
 
-    result = pingpong_read(data, sockfd, buffer, sizeof(buffer), &gotbytes);
+    result = pingpong_read(data, sockindex, buffer, sizeof(buffer), &gotbytes);
     if(result == CURLE_AGAIN)
       return CURLE_OK;
 
@@ -396,9 +399,15 @@ CURLcode Curl_pp_flushsend(struct Curl_easy *data,
 {
   /* we have a piece of a command still left to send */
   ssize_t written;
-  CURLcode result = Curl_nwrite(data, FIRSTSOCKET,
-                                pp->sendthis + pp->sendsize - pp->sendleft,
-                                pp->sendleft, &written);
+  CURLcode result;
+
+  result = Curl_conn_send(data, FIRSTSOCKET,
+                          pp->sendthis + pp->sendsize - pp->sendleft,
+                          pp->sendleft, &written);
+  if(result == CURLE_AGAIN) {
+    result = CURLE_OK;
+    written = 0;
+  }
   if(result)
     return result;
 
diff --git a/lib/pingpong.h b/lib/pingpong.h
index 006b9c5388..28172c7284 100644
--- a/lib/pingpong.h
+++ b/lib/pingpong.h
@@ -132,7 +132,7 @@ CURLcode Curl_pp_vsendf(struct Curl_easy *data,
  * Reads a piece of a server response.
  */
 CURLcode Curl_pp_readresp(struct Curl_easy *data,
-                          curl_socket_t sockfd,
+                          int sockindex,
                           struct pingpong *pp,
                           int *code, /* return the server code if done */
                           size_t *size); /* size of the response */
diff --git a/lib/pop3.c b/lib/pop3.c
index cf25192828..993b2e1c7f 100644
--- a/lib/pop3.c
+++ b/lib/pop3.c
@@ -934,7 +934,7 @@ static CURLcode pop3_state_command_resp(struct Curl_easy *data,
 
   if(pop3->transfer == PPTRANSFER_BODY) {
     /* POP3 download */
-    Curl_setup_transfer(data, FIRSTSOCKET, -1, FALSE, -1);
+    Curl_xfer_setup(data, FIRSTSOCKET, -1, FALSE, -1);
 
     if(pp->overflow) {
       /* The recv buffer contains data that is actually body content so send
@@ -970,7 +970,6 @@ static CURLcode pop3_statemachine(struct Curl_easy *data,
                                   struct connectdata *conn)
 {
   CURLcode result = CURLE_OK;
-  curl_socket_t sock = conn->sock[FIRSTSOCKET];
   int pop3code;
   struct pop3_conn *pop3c = &conn->proto.pop3c;
   struct pingpong *pp = &pop3c->pp;
@@ -987,7 +986,7 @@ static CURLcode pop3_statemachine(struct Curl_easy *data,
 
  do {
     /* Read the response from the server */
-   result = Curl_pp_readresp(data, sock, pp, &pop3code, &nread);
+   result = Curl_pp_readresp(data, FIRSTSOCKET, pp, &pop3code, &nread);
    if(result)
      return result;
 
diff --git a/lib/request.c b/lib/request.c
new file mode 100644
index 0000000000..933f8850c3
--- /dev/null
+++ b/lib/request.c
@@ -0,0 +1,108 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ * SPDX-License-Identifier: curl
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#include "urldata.h"
+#include "dynbuf.h"
+#include "doh.h"
+#include "request.h"
+#include "sendf.h"
+#include "url.h"
+
+/* The last 3 #include files should be in this order */
+#include "curl_printf.h"
+#include "curl_memory.h"
+#include "memdebug.h"
+
+CURLcode Curl_req_init(struct SingleRequest *req)
+{
+  memset(req, 0, sizeof(*req));
+  Curl_bufq_init2(&req->sendbuf, UPLOADBUFFER_DEFAULT, 1,
+                  BUFQ_OPT_SOFT_LIMIT);
+  return CURLE_OK;
+}
+
+CURLcode Curl_req_start(struct SingleRequest *req,
+                        struct Curl_easy *data)
+{
+  req->start = Curl_now();
+  Curl_cw_reset(data);
+  return CURLE_OK;
+}
+
+CURLcode Curl_req_done(struct SingleRequest *req,
+                       struct Curl_easy *data, bool aborted)
+{
+  (void)req;
+  /* TODO: add flush handling for client output */
+  (void)aborted;
+  Curl_cw_reset(data);
+  return CURLE_OK;
+}
+
+void Curl_req_reset(struct SingleRequest *req, struct Curl_easy *data)
+{
+  /* This is a bit ugly. `req->p` is a union and we assume we can
+   * free this safely without leaks. */
+  Curl_safefree(req->p.http);
+  Curl_safefree(req->newurl);
+  Curl_cw_reset(data);
+
+  Curl_bufq_reset(&req->sendbuf);
+  if(data->set.upload_buffer_size != req->sendbuf.chunk_size) {
+    Curl_bufq_free(&req->sendbuf);
+    Curl_bufq_init2(&req->sendbuf, data->set.upload_buffer_size, 1,
+                    BUFQ_OPT_SOFT_LIMIT);
+  }
+
+#ifndef CURL_DISABLE_DOH
+  if(req->doh) {
+    Curl_close(&req->doh->probe[0].easy);
+    Curl_close(&req->doh->probe[1].easy);
+  }
+#endif
+}
+
+void Curl_req_free(struct SingleRequest *req, struct Curl_easy *data)
+{
+  /* This is a bit ugly. `req->p` is a union and we assume we can
+   * free this safely without leaks. */
+  Curl_safefree(req->p.http);
+  Curl_safefree(req->newurl);
+  Curl_bufq_free(&req->sendbuf);
+  Curl_cw_reset(data);
+
+#ifndef CURL_DISABLE_DOH
+  if(req->doh) {
+    Curl_close(&req->doh->probe[0].easy);
+    Curl_close(&req->doh->probe[1].easy);
+    Curl_dyn_free(&req->doh->probe[0].serverdoh);
+    Curl_dyn_free(&req->doh->probe[1].serverdoh);
+    curl_slist_free_all(req->doh->headers);
+    Curl_safefree(req->doh);
+  }
+#endif
+}
+
diff --git a/lib/request.h b/lib/request.h
new file mode 100644
index 0000000000..c769e0e1ff
--- /dev/null
+++ b/lib/request.h
@@ -0,0 +1,192 @@
+#ifndef HEADER_CURL_REQUEST_H
+#define HEADER_CURL_REQUEST_H
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ * SPDX-License-Identifier: curl
+ *
+ ***************************************************************************/
+
+/* This file is for lib internal stuff */
+
+#include "curl_setup.h"
+
+#include "bufq.h"
+
+/* forward declarations */
+struct UserDefined;
+
+enum expect100 {
+  EXP100_SEND_DATA,           /* enough waiting, just send the body now */
+  EXP100_AWAITING_CONTINUE,   /* waiting for the 100 Continue header */
+  EXP100_SENDING_REQUEST,     /* still sending the request but will wait for
+                                 the 100 header once done with the request */
+  EXP100_FAILED               /* used on 417 Expectation Failed */
+};
+
+enum upgrade101 {
+  UPGR101_INIT,               /* default state */
+  UPGR101_WS,                 /* upgrade to WebSockets requested */
+  UPGR101_H2,                 /* upgrade to HTTP/2 requested */
+  UPGR101_RECEIVED,           /* 101 response received */
+  UPGR101_WORKING             /* talking upgraded protocol */
+};
+
+
+/*
+ * Request specific data in the easy handle (Curl_easy).  Previously,
+ * these members were on the connectdata struct but since a conn struct may
+ * now be shared between different Curl_easys, we store connection-specific
+ * data here. This struct only keeps stuff that's interesting for *this*
+ * request, as it will be cleared between multiple ones
+ */
+struct SingleRequest {
+  curl_off_t size;        /* -1 if unknown at this point */
+  curl_off_t maxdownload; /* in bytes, the maximum amount of data to fetch,
+                             -1 means unlimited */
+  curl_off_t bytecount;         /* total number of bytes read */
+  curl_off_t writebytecount;    /* number of bytes written */
+
+  curl_off_t pendingheader;      /* this many bytes left to send is actually
+                                    header and not body */
+  struct curltime start;         /* transfer started at this time */
+  unsigned int headerbytecount;  /* received server headers (not CONNECT
+                                    headers) */
+  unsigned int allheadercount;   /* all received headers (server + CONNECT) */
+  unsigned int deductheadercount; /* this amount of bytes doesn't count when
+                                     we check if anything has been transferred
+                                     at the end of a connection. We use this
+                                     counter to make only a 100 reply (without
+                                     a following second response code) result
+                                     in a CURLE_GOT_NOTHING error code */
+  int headerline;               /* counts header lines to better track the
+                                   first one */
+  curl_off_t offset;            /* possible resume offset read from the
+                                   Content-Range: header */
+  int httpcode;                 /* error code from the 'HTTP/1.? XXX' or
+                                   'RTSP/1.? XXX' line */
+  int keepon;
+  struct curltime start100;      /* time stamp to wait for the 100 code from */
+  enum expect100 exp100;        /* expect 100 continue state */
+  enum upgrade101 upgr101;      /* 101 upgrade state */
+
+  /* Client Writer stack, handles trasnfer- and content-encodings, protocol
+   * checks, pausing by client callbacks. */
+  struct Curl_cwriter *writer_stack;
+  struct bufq sendbuf; /* data which needs to be send to the server */
+  time_t timeofdoc;
+  long bodywrites;
+  char *location;   /* This points to an allocated version of the Location:
+                       header data */
+  char *newurl;     /* Set to the new URL to use when a redirect or a retry is
+                       wanted */
+
+  /* 'upload_present' is used to keep a byte counter of how much data there is
+     still left in the buffer, aimed for upload. */
+  ssize_t upload_present;
+
+  /* 'upload_fromhere' is used as a read-pointer when we uploaded parts of a
+     buffer, so the next read should read from where this pointer points to,
+     and the 'upload_present' contains the number of bytes available at this
+     position */
+  char *upload_fromhere;
+
+  /* Allocated protocol-specific data. Each protocol handler makes sure this
+     points to data it needs. */
+  union {
+    struct FILEPROTO *file;
+    struct FTP *ftp;
+    struct HTTP *http;
+    struct IMAP *imap;
+    struct ldapreqinfo *ldap;
+    struct MQTT *mqtt;
+    struct POP3 *pop3;
+    struct RTSP *rtsp;
+    struct smb_request *smb;
+    struct SMTP *smtp;
+    struct SSHPROTO *ssh;
+    struct TELNET *telnet;
+  } p;
+#ifndef CURL_DISABLE_DOH
+  struct dohdata *doh; /* DoH specific data for this request */
+#endif
+  char fread_eof[2]; /* the body read callback (index 0) returned EOF or
+                        the trailer read callback (index 1) returned EOF */
+#ifndef CURL_DISABLE_COOKIES
+  unsigned char setcookies;
+#endif
+  BIT(header);        /* incoming data has HTTP header */
+  BIT(content_range); /* set TRUE if Content-Range: was found */
+  BIT(download_done); /* set to TRUE when download is complete */
+  BIT(eos_written);   /* iff EOS has been written to client */
+  BIT(upload_done);   /* set to TRUE when doing chunked transfer-encoding
+                         upload and we're uploading the last chunk */
+  BIT(ignorebody);    /* we read a response-body but we ignore it! */
+  BIT(http_bodyless); /* HTTP response status code is between 100 and 199,
+                         204 or 304 */
+  BIT(chunk);         /* if set, this is a chunked transfer-encoding */
+  BIT(ignore_cl);     /* ignore content-length */
+  BIT(upload_chunky); /* set TRUE if we are doing chunked transfer-encoding
+                         on upload */
+  BIT(getheader);    /* TRUE if header parsing is wanted */
+  BIT(forbidchunk);  /* used only to explicitly forbid chunk-upload for
+                        specific upload buffers. See readmoredata() in http.c
+                        for details. */
+  BIT(no_body);      /* the response has no body */
+  BIT(authneg);      /* TRUE when the auth phase has started, which means
+                        that we are creating a request with an auth header,
+                        but it is not the final request in the auth
+                        negotiation. */
+};
+
+/**
+ * Initialize the state of the request for first use.
+ */
+CURLcode Curl_req_init(struct SingleRequest *req);
+
+/**
+ * The request is about to start.
+ */
+CURLcode Curl_req_start(struct SingleRequest *req,
+                        struct Curl_easy *data);
+
+/**
+ * The request is done. If not aborted, make sure that buffers are
+ * flushed to the client.
+ * @param req        the request
+ * @param data       the transfer
+ * @param aborted    TRUE iff the request was aborted/errored
+ */
+CURLcode Curl_req_done(struct SingleRequest *req,
+                       struct Curl_easy *data, bool aborted);
+
+/**
+ * Free the state of the request, not usable afterwards.
+ */
+void Curl_req_free(struct SingleRequest *req, struct Curl_easy *data);
+
+/**
+ * Reset the state of the request for new use, given the
+ * settings.
+ */
+void Curl_req_reset(struct SingleRequest *req, struct Curl_easy *data);
+
+
+#endif /* HEADER_CURL_REQUEST_H */
diff --git a/lib/rtsp.c b/lib/rtsp.c
index 26f4735344..b4290246ac 100644
--- a/lib/rtsp.c
+++ b/lib/rtsp.c
@@ -310,7 +310,7 @@ static CURLcode rtsp_do(struct Curl_easy *data, bool *done)
   }
 
   if(rtspreq == RTSPREQ_RECEIVE) {
-    Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE, -1);
+    Curl_xfer_setup(data, FIRSTSOCKET, -1, TRUE, -1);
 
     return result;
   }
@@ -573,7 +573,7 @@ static CURLcode rtsp_do(struct Curl_easy *data, bool *done)
     return result;
   }
 
-  Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE, putsize?FIRSTSOCKET:-1);
+  Curl_xfer_setup(data, FIRSTSOCKET, -1, TRUE, putsize?FIRSTSOCKET:-1);
 
   /* Increment the CSeq on success */
   data->state.rtsp_next_client_CSeq++;
diff --git a/lib/sendf.c b/lib/sendf.c
index 053d74a10c..54ed6fb295 100644
--- a/lib/sendf.c
+++ b/lib/sendf.c
@@ -61,79 +61,6 @@
 
 static CURLcode do_init_stack(struct Curl_easy *data);
 
-/*
- * Curl_nwrite() is an internal write function that sends data to the
- * server. Works with a socket index for the connection.
- *
- * If the write would block (CURLE_AGAIN), it returns CURLE_OK and
- * (*nwritten == 0). Otherwise we return regular CURLcode value.
- */
-CURLcode Curl_nwrite(struct Curl_easy *data,
-                     int sockindex,
-                     const void *buf,
-                     size_t blen,
-                     ssize_t *pnwritten)
-{
-  ssize_t nwritten;
-  CURLcode result = CURLE_OK;
-  struct connectdata *conn;
-
-  DEBUGASSERT(sockindex >= 0 && sockindex < 2);
-  DEBUGASSERT(pnwritten);
-  DEBUGASSERT(data);
-  DEBUGASSERT(data->conn);
-  conn = data->conn;
-#ifdef CURLDEBUG
-  {
-    /* Allow debug builds to override this logic to force short sends
-    */
-    char *p = getenv("CURL_SMALLSENDS");
-    if(p) {
-      size_t altsize = (size_t)strtoul(p, NULL, 10);
-      if(altsize)
-        blen = CURLMIN(blen, altsize);
-    }
-  }
-#endif
-  nwritten = conn->send[sockindex](data, sockindex, buf, blen, &result);
-  if(result == CURLE_AGAIN) {
-    nwritten = 0;
-    result = CURLE_OK;
-  }
-  else if(result) {
-    nwritten = -1; /* make sure */
-  }
-  else {
-    DEBUGASSERT(nwritten >= 0);
-  }
-
-  *pnwritten = nwritten;
-  return result;
-}
-
-/*
- * Curl_write() is an internal write function that sends data to the
- * server. Works with plain sockets, SCP, SSL or kerberos.
- *
- * If the write would block (CURLE_AGAIN), we return CURLE_OK and
- * (*written == 0). Otherwise we return regular CURLcode value.
- */
-CURLcode Curl_write(struct Curl_easy *data,
-                    curl_socket_t sockfd,
-                    const void *mem,
-                    size_t len,
-                    ssize_t *written)
-{
-  struct connectdata *conn;
-  int num;
-
-  DEBUGASSERT(data);
-  DEBUGASSERT(data->conn);
-  conn = data->conn;
-  num = (sockfd != CURL_SOCKET_BAD && sockfd == conn->sock[SECONDARYSOCKET]);
-  return Curl_nwrite(data, num, mem, len, written);
-}
-
 /* Curl_client_write() sends data to the write callback(s)
 
    The bit pattern defines to what "streams" to write to. Body and/or header.
@@ -163,7 +90,7 @@ CURLcode Curl_client_write(struct Curl_easy *data,
   return Curl_cwriter_write(data, data->req.writer_stack, type, buf, blen);
 }
 
-void Curl_client_cleanup(struct Curl_easy *data)
+void Curl_cw_reset(struct Curl_easy *data)
 {
   struct Curl_cwriter *writer = data->req.writer_stack;
 
@@ -499,40 +426,3 @@ void Curl_cwriter_remove_by_name(struct Curl_easy *data,
   }
 }
 
-/*
- * Internal read-from-socket function. This is meant to deal with plain
- * sockets, SSL sockets and kerberos sockets.
- *
- * Returns a regular CURLcode value.
- */
-CURLcode Curl_read(struct Curl_easy *data,   /* transfer */
-                   curl_socket_t sockfd,     /* read from this socket */
-                   char *buf,                /* store read data here */
-                   size_t sizerequested,     /* max amount to read */
-                   ssize_t *n)               /* amount bytes read */
-{
-  CURLcode result = CURLE_RECV_ERROR;
-  ssize_t nread = 0;
-  size_t bytesfromsocket = 0;
-  char *buffertofill = NULL;
-  struct connectdata *conn = data->conn;
-
-  /* Set 'num' to 0 or 1, depending on which socket that has been sent here.
-     If it is the second socket, we set num to 1. Otherwise to 0. This lets
-     us use the correct ssl handle. */
-  int num = (sockfd == conn->sock[SECONDARYSOCKET]);
-
-  *n = 0; /* reset amount to zero */
-
-  bytesfromsocket = CURLMIN(sizerequested, (size_t)data->set.buffer_size);
-  buffertofill = buf;
-
-  nread = conn->recv[num](data, num, buffertofill, bytesfromsocket, &result);
-  if(nread < 0)
-    goto out;
-
-  *n += nread;
-  result = CURLE_OK;
-out:
-  return result;
-}
diff --git a/lib/sendf.h b/lib/sendf.h
index e4dba9d78b..9d3d5946ab 100644
--- a/lib/sendf.h
+++ b/lib/sendf.h
@@ -61,7 +61,7 @@ CURLcode Curl_client_write(struct Curl_easy *data, int type, const char *ptr,
 /**
  * Free all resources related to client writing.
  */
-void Curl_client_cleanup(struct Curl_easy *data);
+void Curl_cw_reset(struct Curl_easy *data);
 
 /**
  * Client Writers - a chain passing transfer BODY data to the client.
@@ -175,22 +175,4 @@ void Curl_cwriter_def_close(struct Curl_easy *data,
                             struct Curl_cwriter *writer);
 
 
-/* internal read-function, does plain socket, SSL and krb4 */
-CURLcode Curl_read(struct Curl_easy *data, curl_socket_t sockfd,
-                   char *buf, size_t buffersize,
-                   ssize_t *n);
-
-/* internal write-function, does plain socket, SSL, SCP, SFTP and krb4 */
-CURLcode Curl_write(struct Curl_easy *data,
-                    curl_socket_t sockfd,
-                    const void *mem, size_t len,
-                    ssize_t *written);
-
-/* internal write-function, using sockindex for connection destination */
-CURLcode Curl_nwrite(struct Curl_easy *data,
-                     int sockindex,
-                     const void *buf,
-                     size_t blen,
-                     ssize_t *pnwritten);
-
 #endif /* HEADER_CURL_SENDF_H */
diff --git a/lib/smb.c b/lib/smb.c
index 1d1867cc27..ae585b4c1a 100644
--- a/lib/smb.c
+++ b/lib/smb.c
@@ -485,7 +485,6 @@ static CURLcode smb_connect(struct Curl_easy *data, bool *done)
 static CURLcode smb_recv_message(struct Curl_easy *data, void **msg)
 {
   struct connectdata *conn = data->conn;
-  curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
   struct smb_conn *smbc = &conn->proto.smbc;
   char *buf = smbc->recv_buf;
   ssize_t bytes_read;
@@ -494,7 +493,7 @@ static CURLcode smb_recv_message(struct Curl_easy *data, void **msg)
   size_t len = MAX_MESSAGE_SIZE - smbc->got;
   CURLcode result;
 
-  result = Curl_read(data, sockfd, buf + smbc->got, len, &bytes_read);
+  result = Curl_xfer_recv(data, buf + smbc->got, len, &bytes_read);
   if(result)
     return result;
 
@@ -568,8 +567,7 @@ static CURLcode smb_send(struct Curl_easy *data, ssize_t len,
   ssize_t bytes_written;
   CURLcode result;
 
-  result = Curl_nwrite(data, FIRSTSOCKET, data->state.ulbuf,
-                      len, &bytes_written);
+  result = Curl_xfer_send(data, data->state.ulbuf, len, &bytes_written);
   if(result)
     return result;
 
@@ -594,9 +592,8 @@ static CURLcode smb_flush(struct Curl_easy *data)
   if(!smbc->send_size)
     return CURLE_OK;
 
-  result = Curl_nwrite(data, FIRSTSOCKET,
-                       data->state.ulbuf + smbc->sent,
-                       len, &bytes_written);
+  result = Curl_xfer_send(data, data->state.ulbuf + smbc->sent, len,
+                          &bytes_written);
   if(result)
     return result;
 
diff --git a/lib/smtp.c b/lib/smtp.c
index 0d18afc1c5..e10a00477b 100644
--- a/lib/smtp.c
+++ b/lib/smtp.c
@@ -1164,7 +1164,7 @@ static CURLcode smtp_state_data_resp(struct Curl_easy *data, int smtpcode,
     Curl_pgrsSetUploadSize(data, data->state.infilesize);
 
     /* SMTP upload */
-    Curl_setup_transfer(data, -1, -1, FALSE, FIRSTSOCKET);
+    Curl_xfer_setup(data, -1, -1, FALSE, FIRSTSOCKET);
 
     /* End of DO phase */
     smtp_state(data, SMTP_STOP);
@@ -1196,7 +1196,6 @@ static CURLcode smtp_statemachine(struct Curl_easy *data,
                                   struct connectdata *conn)
 {
   CURLcode result = CURLE_OK;
-  curl_socket_t sock = conn->sock[FIRSTSOCKET];
   int smtpcode;
   struct smtp_conn *smtpc = &conn->proto.smtpc;
   struct pingpong *pp = &smtpc->pp;
@@ -1212,7 +1211,7 @@ static CURLcode smtp_statemachine(struct Curl_easy *data,
 
   do {
     /* Read the response from the server */
-    result = Curl_pp_readresp(data, sock, pp, &smtpcode, &nread);
+    result = Curl_pp_readresp(data, FIRSTSOCKET, pp, &smtpcode, &nread);
     if(result)
       return result;
 
@@ -1434,7 +1433,7 @@ static CURLcode smtp_done(struct Curl_easy *data, CURLcode status,
       return CURLE_OUT_OF_MEMORY;
 
     /* Send the end of block data */
-    result = Curl_write(data, conn->writesockfd, eob, len, &bytes_written);
+    result = Curl_xfer_send(data, eob, len, &bytes_written);
     if(result) {
       free(eob);
       return result;
@@ -1595,7 +1594,7 @@ static CURLcode smtp_dophase_done(struct Curl_easy *data, bool connected)
 
   if(smtp->transfer != PPTRANSFER_BODY)
     /* no data to transfer */
-    Curl_setup_transfer(data, -1, -1, FALSE, -1);
+    Curl_xfer_setup(data, -1, -1, FALSE, -1);
 
   return CURLE_OK;
 }
diff --git a/lib/telnet.c b/lib/telnet.c
index 34dc5e8067..9b6ae3c611 100644
--- a/lib/telnet.c
+++ b/lib/telnet.c
@@ -1270,8 +1270,8 @@ static CURLcode send_telnet_data(struct Curl_easy *data,
         break;
       default:                    /* write! */
         bytes_written = 0;
-        result = Curl_nwrite(data, FIRSTSOCKET, outbuf + total_written,
-                             outlen - total_written, &bytes_written);
+        result = Curl_xfer_send(data, outbuf + total_written,
+                                outlen - total_written, &bytes_written);
         total_written += bytes_written;
         break;
     }
@@ -1464,7 +1464,7 @@ static CURLcode telnet_do(struct Curl_easy *data, bool *done)
       }
       if(events.lNetworkEvents & FD_READ) {
         /* read data from network */
-        result = Curl_read(data, sockfd, buffer, sizeof(buffer), &nread);
+        result = Curl_xfer_recv(data, buffer, sizeof(buffer), &nread);
         /* read would've blocked. Loop again */
         if(result == CURLE_AGAIN)
           break;
@@ -1545,7 +1545,7 @@ static CURLcode telnet_do(struct Curl_easy *data, bool *done)
     default:                    /* read! */
       if(pfd[0].revents & POLLIN) {
         /* read data from network */
-        result = Curl_read(data, sockfd, buffer, sizeof(buffer), &nread);
+        result = Curl_xfer_recv(data, buffer, sizeof(buffer), &nread);
         /* read would've blocked. Loop again */
         if(result == CURLE_AGAIN)
           break;
@@ -1635,7 +1635,7 @@ static CURLcode telnet_do(struct Curl_easy *data, bool *done)
   }
 #endif
   /* mark this as "no further transfer wanted" */
-  Curl_setup_transfer(data, -1, -1, FALSE, -1);
+  Curl_xfer_setup(data, -1, -1, FALSE, -1);
 
   return result;
 }
diff --git a/lib/tftp.c b/lib/tftp.c
index 4288110da6..1b48779605 100644
--- a/lib/tftp.c
+++ b/lib/tftp.c
@@ -1240,7 +1240,7 @@ static CURLcode tftp_multi_statemach(struct Curl_easy *data, bool *done)
     *done = (state->state == TFTP_STATE_FIN) ? TRUE : FALSE;
     if(*done)
       /* Tell curl we're done */
-      Curl_setup_transfer(data, -1, -1, FALSE, -1);
+      Curl_xfer_setup(data, -1, -1, FALSE, -1);
   }
   else {
     /* no timeouts to handle, check our socket */
@@ -1263,7 +1263,7 @@ static CURLcode tftp_multi_statemach(struct Curl_easy *data, bool *done)
       *done = (state->state == TFTP_STATE_FIN) ? TRUE : FALSE;
       if(*done)
         /* Tell curl we're done */
-        Curl_setup_transfer(data, -1, -1, FALSE, -1);
+        Curl_xfer_setup(data, -1, -1, FALSE, -1);
     }
     /* if rc == 0, then select() timed out */
   }
diff --git a/lib/transfer.c b/lib/transfer.c
index 36ca444b19..1935909b91 100644
--- a/lib/transfer.c
+++ b/lib/transfer.c
@@ -448,7 +448,7 @@ static ssize_t Curl_xfer_recv_resp(struct Curl_easy *data,
     return 0;
   }
 
-  *err = Curl_read(data, data->conn->sockfd, buf, blen, &nread);
+  *err = Curl_xfer_recv(data, buf, blen, &nread);
   if(*err)
     return -1;
   DEBUGASSERT(nread >= 0);
@@ -770,12 +770,14 @@ static CURLcode readwrite_upload(struct Curl_easy *data,
          that instead of reading more data */
     }
 
+    if(!Curl_bufq_is_empty(&k->sendbuf)) {
+      DEBUGASSERT(0);
+    }
     /* write to socket (send away data) */
-    result = Curl_write(data,
-                        conn->writesockfd,  /* socket to send to */
-                        k->upload_fromhere, /* buffer pointer */
-                        k->upload_present,  /* buffer size */
-                        &bytes_written);    /* actually sent */
+    result = Curl_xfer_send(data,
+                            k->upload_fromhere, /* buffer pointer */
+                            k->upload_present,  /* buffer size */
+                            &bytes_written);    /* actually sent */
     if(result)
       return result;
 
@@ -1590,11 +1592,10 @@ CURLcode Curl_retry_request(struct Curl_easy *data, char **url)
 }
 
 /*
- * Curl_setup_transfer() is called to setup some basic properties for the
+ * Curl_xfer_setup() is called to setup some basic properties for the
  * upcoming transfer.
  */
-void
-Curl_setup_transfer(
+void Curl_xfer_setup(
   struct Curl_easy *data,   /* transfer */
   int sockindex,            /* socket index to read from or -1 */
   curl_off_t size,          /* -1 if unknown at this point */
@@ -1610,6 +1611,7 @@ Curl_setup_transfer(
 
   DEBUGASSERT(conn != NULL);
   DEBUGASSERT((sockindex <= 1) && (sockindex >= -1));
+  DEBUGASSERT((writesockindex <= 1) && (writesockindex >= -1));
 
   httpsending = ((conn->handler->protocol&PROTO_FAMILY_HTTP) &&
                  (http->sending == HTTPSEND_REQUEST));
@@ -1727,3 +1729,51 @@ CURLcode Curl_xfer_write_done(struct Curl_easy *data, bool premature)
   (void)premature;
   return Curl_cw_out_done(data);
 }
+
+CURLcode Curl_xfer_send(struct Curl_easy *data,
+                        const void *buf, size_t blen,
+                        ssize_t *pnwritten)
+{
+  CURLcode result;
+  int sockindex;
+
+  if(!data || !data->conn)
+    return CURLE_FAILED_INIT;
+  /* FIXME: would like to enable this, but some protocols (MQTT) do not
+   * setup the transfer correctly, it seems
+  if(data->conn->writesockfd == CURL_SOCKET_BAD) {
+    failf(data, "transfer not setup for sending");
+    DEBUGASSERT(0);
+    return CURLE_SEND_ERROR;
+  } */
+  sockindex = ((data->conn->writesockfd != CURL_SOCKET_BAD) &&
+               (data->conn->writesockfd == data->conn->sock[SECONDARYSOCKET]));
+  result = Curl_conn_send(data, sockindex, buf, blen, pnwritten);
+  if(result == CURLE_AGAIN) {
+    result = CURLE_OK;
+    *pnwritten = 0;
+  }
+  return result;
+}
+
+CURLcode Curl_xfer_recv(struct Curl_easy *data,
+                        char *buf, size_t blen,
+                        ssize_t *pnrcvd)
+{
+  int sockindex;
+
+  if(!data || !data->conn)
+    return CURLE_FAILED_INIT;
+  /* FIXME: would like to enable this, but some protocols (MQTT) do not
+   * setup the transfer correctly, it seems
+  if(data->conn->sockfd == CURL_SOCKET_BAD) {
+    failf(data, "transfer not setup for receiving");
+    DEBUGASSERT(0);
+    return CURLE_RECV_ERROR;
+  } */
+  sockindex = ((data->conn->sockfd != CURL_SOCKET_BAD) &&
+               (data->conn->sockfd == data->conn->sock[SECONDARYSOCKET]));
+  if(data->set.buffer_size > 0 && (size_t)data->set.buffer_size < blen)
+    blen = (size_t)data->set.buffer_size;
+  return Curl_conn_recv(data, sockindex, buf, blen, pnrcvd);
+}
diff --git a/lib/transfer.h b/lib/transfer.h
index 6de418c564..917a3d23e4 100644
--- a/lib/transfer.h
+++ b/lib/transfer.h
@@ -75,8 +75,7 @@ CURLcode Curl_xfer_write_resp(struct Curl_easy *data,
                               bool is_eos, bool *done);
 
 /* This sets up a forthcoming transfer */
-void
-Curl_setup_transfer (struct Curl_easy *data,
+void Curl_xfer_setup(struct Curl_easy *data,
                      int sockindex,     /* socket index to read from or -1 */
                      curl_off_t size,   /* -1 if unknown at this point */
                      bool getheader,    /* TRUE if header parsing is wanted */
@@ -91,4 +90,22 @@ Curl_setup_transfer (struct Curl_easy *data,
  */
 CURLcode Curl_xfer_write_done(struct Curl_easy *data, bool premature);
 
+/**
+ * Send data on the socket/connection filter designated
+ * for transfer's outgoing data.
+ * Will return CURLE_OK on blocking with (*pnwritten == 0).
+ */
+CURLcode Curl_xfer_send(struct Curl_easy *data,
+                        const void *buf, size_t blen,
+                        ssize_t *pnwritten);
+
+/**
+ * Receive data on the socket/connection filter designated
+ * for transfer's incoming data.
+ * Will return CURLE_AGAIN on blocking with (*pnrcvd == 0).
+ */
+CURLcode Curl_xfer_recv(struct Curl_easy *data,
+                        char *buf, size_t blen,
+                        ssize_t *pnrcvd);
+
 #endif /* HEADER_CURL_TRANSFER_H */
diff --git a/lib/url.c b/lib/url.c
index 21bd66b45e..ae976d7b11 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -261,7 +261,7 @@ CURLcode Curl_close(struct Curl_easy **datap)
     free(data->state.range);
 
   /* freed here just in case DONE wasn't called */
-  Curl_free_request_state(data);
+  Curl_req_free(&data->req, data);
 
   /* Close down all open SSL info and sessions */
   Curl_ssl_close_all(data);
@@ -269,10 +269,6 @@ CURLcode Curl_close(struct Curl_easy **datap)
   Curl_safefree(data->state.scratch);
   Curl_ssl_free_certinfo(data);
 
-  /* Cleanup possible redirect junk */
-  free(data->req.newurl);
-  data->req.newurl = NULL;
-
   if(data->state.referer_alloc) {
     Curl_safefree(data->state.referer);
     data->state.referer_alloc = FALSE;
@@ -325,15 +321,6 @@ CURLcode Curl_close(struct Curl_easy **datap)
   Curl_safefree(data->state.aptr.proxyuser);
   Curl_safefree(data->state.aptr.proxypasswd);
 
-#ifndef CURL_DISABLE_DOH
-  if(data->req.doh) {
-    Curl_dyn_free(&data->req.doh->probe[0].serverdoh);
-    Curl_dyn_free(&data->req.doh->probe[1].serverdoh);
-    curl_slist_free_all(data->req.doh->headers);
-    Curl_safefree(data->req.doh);
-  }
-#endif
-
 #if !defined(CURL_DISABLE_HTTP) && !defined(CURL_DISABLE_FORM_API)
   Curl_mime_cleanpart(data->state.formp);
   Curl_safefree(data->state.formp);
@@ -519,9 +506,17 @@ CURLcode Curl_open(struct Curl_easy **curl)
 
   data->magic = CURLEASY_MAGIC_NUMBER;
 
+  result = Curl_req_init(&data->req);
+  if(result) {
+    DEBUGF(fprintf(stderr, "Error: request init failed\n"));
+    free(data);
+    return result;
+  }
+
   result = Curl_resolver_init(data, &data->state.async.resolver);
   if(result) {
     DEBUGF(fprintf(stderr, "Error: resolver_init failed\n"));
+    Curl_req_free(&data->req, data);
     free(data);
     return result;
   }
@@ -545,6 +540,7 @@ CURLcode Curl_open(struct Curl_easy **curl)
     Curl_resolver_cleanup(data->state.async.resolver);
     Curl_dyn_free(&data->state.headerb);
     Curl_freeset(data);
+    Curl_req_free(&data->req, data);
     free(data);
     data = NULL;
   }
@@ -2054,24 +2050,6 @@ static CURLcode setup_connection_internals(struct Curl_easy *data,
   return CURLE_OK;
 }
 
-/*
- * Curl_free_request_state() should free temp data that was allocated in the
- * Curl_easy for this single request.
- */
-
-void Curl_free_request_state(struct Curl_easy *data)
-{
-  Curl_safefree(data->req.p.http);
-  Curl_safefree(data->req.newurl);
-#ifndef CURL_DISABLE_DOH
-  if(data->req.doh) {
-    Curl_close(&data->req.doh->probe[0].easy);
-    Curl_close(&data->req.doh->probe[1].easy);
-  }
-#endif
-  Curl_client_cleanup(data);
-}
-
 
 #ifndef CURL_DISABLE_PROXY
 
@@ -3609,7 +3587,7 @@ static CURLcode create_conn(struct Curl_easy *data,
         (void)conn->handler->done(data, result, FALSE);
         goto out;
       }
-      Curl_setup_transfer(data, -1, -1, FALSE, -1);
+      Curl_xfer_setup(data, -1, -1, FALSE, -1);
     }
 
     /* since we skip do_init() */
@@ -3620,10 +3598,10 @@ static CURLcode create_conn(struct Curl_easy *data,
 #endif
 
   /* Setup filter for network connections */
-  conn->recv[FIRSTSOCKET] = Curl_conn_recv;
-  conn->send[FIRSTSOCKET] = Curl_conn_send;
-  conn->recv[SECONDARYSOCKET] = Curl_conn_recv;
-  conn->send[SECONDARYSOCKET] = Curl_conn_send;
+  conn->recv[FIRSTSOCKET] = Curl_cf_recv;
+  conn->send[FIRSTSOCKET] = Curl_cf_send;
+  conn->recv[SECONDARYSOCKET] = Curl_cf_recv;
+  conn->send[SECONDARYSOCKET] = Curl_cf_send;
   conn->bits.tcp_fastopen = data->set.tcp_fastopen;
 
   /* Complete the easy's SSL configuration for connection cache matching */
@@ -3866,7 +3844,7 @@ CURLcode Curl_connect(struct Curl_easy *data,
   *asyncp = FALSE; /* assume synchronous resolves by default */
 
   /* init the single-transfer specific data */
-  Curl_free_request_state(data);
+  Curl_req_reset(&data->req, data);
   memset(&data->req, 0, sizeof(struct SingleRequest));
   data->req.size = data->req.maxdownload = -1;
   data->req.no_body = data->set.opt_no_body;
@@ -3935,12 +3913,14 @@ CURLcode Curl_init_do(struct Curl_easy *data, struct connectdata *conn)
     /* in HTTP lingo, no body means using the HEAD request... */
     data->state.httpreq = HTTPREQ_HEAD;
 
-  k->start = Curl_now(); /* start time */
+  result = Curl_req_start(&data->req, data);
+  if(result)
+    return result;
+
   k->header = TRUE; /* assume header */
   k->bytecount = 0;
   k->ignorebody = FALSE;
 
-  Curl_client_cleanup(data);
   Curl_speedinit(data);
   Curl_pgrsSetUploadCounter(data, 0);
   Curl_pgrsSetDownloadCounter(data, 0);
diff --git a/lib/url.h b/lib/url.h
index 7c1a29bc3c..6d36950833 100644
--- a/lib/url.h
+++ b/lib/url.h
@@ -41,7 +41,6 @@ void Curl_disconnect(struct Curl_easy *data,
                      struct connectdata *, bool dead_connection);
 CURLcode Curl_setup_conn(struct Curl_easy *data,
                          bool *protocol_done);
-void Curl_free_request_state(struct Curl_easy *data);
 CURLcode Curl_parse_login_details(const char *login, const size_t len,
                                   char **userptr, char **passwdptr,
                                   char **optionsptr);
diff --git a/lib/urldata.h b/lib/urldata.h
index 59f290b727..3d68a60563 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -143,6 +143,7 @@ typedef unsigned int curl_prot_t;
 #include "splay.h"
 #include "dynbuf.h"
 #include "dynhds.h"
+#include "request.h"
 
 /* return the count of bytes sent, or -1 on error */
 typedef ssize_t (Curl_send)(struct Curl_easy *data,   /* transfer */
@@ -616,22 +617,6 @@ struct easy_pollset {
   unsigned char actions[MAX_SOCKSPEREASYHANDLE];
 };
 
-enum expect100 {
-  EXP100_SEND_DATA,           /* enough waiting, just send the body now */
-  EXP100_AWAITING_CONTINUE,   /* waiting for the 100 Continue header */
-  EXP100_SENDING_REQUEST,     /* still sending the request but will wait for
-                                 the 100 header once done with the request */
-  EXP100_FAILED               /* used on 417 Expectation Failed */
-};
-
-enum upgrade101 {
-  UPGR101_INIT,               /* default state */
-  UPGR101_WS,                 /* upgrade to WebSockets requested */
-  UPGR101_H2,                 /* upgrade to HTTP/2 requested */
-  UPGR101_RECEIVED,           /* 101 response received */
-  UPGR101_WORKING             /* talking upgraded protocol */
-};
-
 enum doh_slots {
   /* Explicit values for first two symbols so as to match hard-coded
    * constants in existing code
@@ -650,111 +635,6 @@ enum doh_slots {
   DOH_PROBE_SLOTS
 };
 
-/*
- * Request specific data in the easy handle (Curl_easy).  Previously,
- * these members were on the connectdata struct but since a conn struct may
- * now be shared between different Curl_easys, we store connection-specific
- * data here. This struct only keeps stuff that's interesting for *this*
- * request, as it will be cleared between multiple ones
- */
-struct SingleRequest {
-  curl_off_t size;        /* -1 if unknown at this point */
-  curl_off_t maxdownload; /* in bytes, the maximum amount of data to fetch,
-                             -1 means unlimited */
-  curl_off_t bytecount;         /* total number of bytes read */
-  curl_off_t writebytecount;    /* number of bytes written */
-
-  curl_off_t pendingheader;      /* this many bytes left to send is actually
-                                    header and not body */
-  struct curltime start;         /* transfer started at this time */
-  unsigned int headerbytecount;  /* received server headers (not CONNECT
-                                    headers) */
-  unsigned int allheadercount;   /* all received headers (server + CONNECT) */
-  unsigned int deductheadercount; /* this amount of bytes doesn't count when
-                                     we check if anything has been transferred
-                                     at the end of a connection. We use this
-                                     counter to make only a 100 reply (without
-                                     a following second response code) result
-                                     in a CURLE_GOT_NOTHING error code */
-  int headerline;               /* counts header lines to better track the
-                                   first one */
-  curl_off_t offset;            /* possible resume offset read from the
-                                   Content-Range: header */
-  int httpcode;                 /* error code from the 'HTTP/1.? XXX' or
-                                   'RTSP/1.? XXX' line */
-  int keepon;
-  struct curltime start100;      /* time stamp to wait for the 100 code from */
-  enum expect100 exp100;        /* expect 100 continue state */
-  enum upgrade101 upgr101;      /* 101 upgrade state */
-
-  /* Client Writer stack, handles trasnfer- and content-encodings, protocol
-   * checks, pausing by client callbacks. */
-  struct Curl_cwriter *writer_stack;
-  time_t timeofdoc;
-  long bodywrites;
-  char *location;   /* This points to an allocated version of the Location:
-                       header data */
-  char *newurl;     /* Set to the new URL to use when a redirect or a retry is
-                       wanted */
-
-  /* 'upload_present' is used to keep a byte counter of how much data there is
-     still left in the buffer, aimed for upload. */
-  ssize_t upload_present;
-
-  /* 'upload_fromhere' is used as a read-pointer when we uploaded parts of a
-     buffer, so the next read should read from where this pointer points to,
-     and the 'upload_present' contains the number of bytes available at this
-     position */
-  char *upload_fromhere;
-
-  /* Allocated protocol-specific data. Each protocol handler makes sure this
-     points to data it needs. */
-  union {
-    struct FILEPROTO *file;
-    struct FTP *ftp;
-    struct HTTP *http;
-    struct IMAP *imap;
-    struct ldapreqinfo *ldap;
-    struct MQTT *mqtt;
-    struct POP3 *pop3;
-    struct RTSP *rtsp;
-    struct smb_request *smb;
-    struct SMTP *smtp;
-    struct SSHPROTO *ssh;
-    struct TELNET *telnet;
-  } p;
-#ifndef CURL_DISABLE_DOH
-  struct dohdata *doh; /* DoH specific data for this request */
-#endif
-  char fread_eof[2]; /* the body read callback (index 0) returned EOF or
-                        the trailer read callback (index 1) returned EOF */
-#ifndef CURL_DISABLE_COOKIES
-  unsigned char setcookies;
-#endif
-  BIT(header);        /* incoming data has HTTP header */
-  BIT(content_range); /* set TRUE if Content-Range: was found */
-  BIT(download_done); /* set to TRUE when download is complete */
-  BIT(eos_written);   /* iff EOS has been written to client */
-  BIT(upload_done);   /* set to TRUE when doing chunked transfer-encoding
-                         upload and we're uploading the last chunk */
-  BIT(ignorebody);    /* we read a response-body but we ignore it! */
-  BIT(http_bodyless); /* HTTP response status code is between 100 and 199,
-                         204 or 304 */
-  BIT(chunk);         /* if set, this is a chunked transfer-encoding */
-  BIT(ignore_cl);     /* ignore content-length */
-  BIT(upload_chunky); /* set TRUE if we are doing chunked transfer-encoding
-                         on upload */
-  BIT(getheader);    /* TRUE if header parsing is wanted */
-  BIT(forbidchunk);  /* used only to explicitly forbid chunk-upload for
-                        specific upload buffers. See readmoredata() in http.c
-                        for details. */
-  BIT(no_body);      /* the response has no body */
-  BIT(authneg);      /* TRUE when the auth phase has started, which means
-                        that we are creating a request with an auth header,
-                        but it is not the final request in the auth
-                        negotiation. */
-};
-
 /*
  * Specific protocol handler.
  */
diff --git a/lib/vssh/libssh.c b/lib/vssh/libssh.c
index 02148d0c18..7cfc950216 100644
--- a/lib/vssh/libssh.c
+++ b/lib/vssh/libssh.c
@@ -1349,9 +1349,9 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
         Curl_pgrsSetUploadSize(data, data->state.infilesize);
       }
       /* upload data */
-      Curl_setup_transfer(data, -1, -1, FALSE, FIRSTSOCKET);
+      Curl_xfer_setup(data, -1, -1, FALSE, FIRSTSOCKET);
 
-      /* not set by Curl_setup_transfer to preserve keepon bits */
+      /* not set by Curl_xfer_setup to preserve keepon bits */
       conn->sockfd = conn->writesockfd;
 
       /* store this original bitmask setup to use later on if we can't
@@ -1575,7 +1575,7 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
       sshc->sftp_dir = NULL;
 
       /* no data to transfer */
-      Curl_setup_transfer(data, -1, -1, FALSE, -1);
+      Curl_xfer_setup(data, -1, -1, FALSE, -1);
       state(data, SSH_STOP);
       break;
 
@@ -1720,14 +1720,14 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
     /* Setup the actual download */
     if(data->req.size == 0) {
       /* no data to transfer */
-      Curl_setup_transfer(data, -1, -1, FALSE, -1);
+      Curl_xfer_setup(data, -1, -1, FALSE, -1);
       infof(data, "File already completely downloaded");
       state(data, SSH_STOP);
       break;
     }
-    Curl_setup_transfer(data, FIRSTSOCKET, data->req.size, FALSE, -1);
+    Curl_xfer_setup(data, FIRSTSOCKET, data->req.size, FALSE, -1);
 
-    /* not set by Curl_setup_transfer to preserve keepon bits */
+    /* not set by Curl_xfer_setup to preserve keepon bits */
     conn->writesockfd = conn->sockfd;
 
     /* we want to use the _receiving_ function even when the socket turns
@@ -1849,9 +1849,9 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
       }
 
       /* upload data */
-      Curl_setup_transfer(data, -1, data->req.size, FALSE, FIRSTSOCKET);
+      Curl_xfer_setup(data, -1, data->req.size, FALSE, FIRSTSOCKET);
 
-      /* not set by Curl_setup_transfer to preserve keepon bits */
+      /* not set by Curl_xfer_setup to preserve keepon bits */
       conn->sockfd = conn->writesockfd;
 
       /* store this original bitmask setup to use later on if we can't
@@ -1893,9 +1893,9 @@ static CURLcode myssh_statemach_act(struct Curl_easy *data, bool *block)
         /* download data */
         bytecount = ssh_scp_request_get_size(sshc->scp_session);
         data->req.maxdownload = (curl_off_t) bytecount;
-        Curl_setup_transfer(data, FIRSTSOCKET, bytecount, FALSE, -1);
+        Curl_xfer_setup(data, FIRSTSOCKET, bytecount, FALSE, -1);
 
-        /* not set by Curl_setup_transfer to preserve keepon bits */
+        /* not set by Curl_xfer_setup to preserve keepon bits */
         conn->writesockfd = conn->sockfd;
 
         /* we want to use the _receiving_ function even when the socket turns
diff --git a/lib/vssh/libssh2.c b/lib/vssh/libssh2.c
index 3a661f81eb..33dbe1c920 100644
--- a/lib/vssh/libssh2.c
+++ b/lib/vssh/libssh2.c
@@ -2195,9 +2195,9 @@ static CURLcode ssh_statemach_act(struct Curl_easy *data, bool *block)
         Curl_pgrsSetUploadSize(data, data->state.infilesize);
       }
       /* upload data */
-      Curl_setup_transfer(data, -1, -1, FALSE, FIRSTSOCKET);
+      Curl_xfer_setup(data, -1, -1, FALSE, FIRSTSOCKET);
 
-      /* not set by Curl_setup_transfer to preserve keepon bits */
+      /* not set by Curl_xfer_setup to preserve keepon bits */
       conn->sockfd = conn->writesockfd;
 
       if(result) {
@@ -2448,7 +2448,7 @@ static CURLcode ssh_statemach_act(struct Curl_easy *data, bool *block)
       Curl_safefree(sshp->readdir_longentry);
 
       /* no data to transfer */
-      Curl_setup_transfer(data, -1, -1, FALSE, -1);
+      Curl_xfer_setup(data, -1, -1, FALSE, -1);
       state(data, SSH_STOP);
       break;
 
@@ -2590,14 +2590,14 @@ static CURLcode ssh_statemach_act(struct Curl_easy *data, bool *block)
     /* Setup the actual download */
     if(data->req.size == 0) {
       /* no data to transfer */
-      Curl_setup_transfer(data, -1, -1, FALSE, -1);
+      Curl_xfer_setup(data, -1, -1, FALSE, -1);
       infof(data, "File already completely downloaded");
       state(data, SSH_STOP);
       break;
     }
-    Curl_setup_transfer(data, FIRSTSOCKET, data->req.size, FALSE, -1);
+    Curl_xfer_setup(data, FIRSTSOCKET, data->req.size, FALSE, -1);
 
-    /* not set by Curl_setup_transfer to preserve keepon bits */
+    /* not set by Curl_xfer_setup to preserve keepon bits */
     conn->writesockfd = conn->sockfd;
 
     /* we want to use the _receiving_ function even when the socket turns
@@ -2741,9 +2741,9 @@ static CURLcode ssh_statemach_act(struct Curl_easy *data, bool *block)
       /* upload data */
       data->req.size = data->state.infilesize;
       Curl_pgrsSetUploadSize(data, data->state.infilesize);
-      Curl_setup_transfer(data, -1, -1, FALSE, FIRSTSOCKET);
+      Curl_xfer_setup(data, -1, -1, FALSE, FIRSTSOCKET);
 
-      /* not set by Curl_setup_transfer to preserve keepon bits */
+      /* not set by Curl_xfer_setup to preserve keepon bits */
       conn->sockfd = conn->writesockfd;
 
       if(result) {
@@ -2812,9 +2812,9 @@ static CURLcode ssh_statemach_act(struct Curl_easy *data, bool *block)
       /* download data */
       bytecount = (curl_off_t)sb.st_size;
       data->req.maxdownload = (curl_off_t)sb.st_size;
-      Curl_setup_transfer(data, FIRSTSOCKET, bytecount, FALSE, -1);
+      Curl_xfer_setup(data, FIRSTSOCKET, bytecount, FALSE, -1);
 
-      /* not set by Curl_setup_transfer to preserve keepon bits */
+      /* not set by Curl_xfer_setup to preserve keepon bits */
       conn->writesockfd = conn->sockfd;
 
       /* we want to use the _receiving_ function even when the socket turns
@@ -3193,12 +3193,13 @@ static ssize_t ssh_tls_recv(libssh2_socket_t sock, void *buffer,
   struct connectdata *conn = data->conn;
   Curl_recv *backup = conn->recv[0];
   struct ssh_conn *ssh = &conn->proto.sshc;
+  int socknum = Curl_conn_sockindex(data, sock);
   (void)flags;
 
   /* swap in the TLS reader function for this call only, and then swap back
      the SSH one again */
   conn->recv[0] = ssh->tls_recv;
-  result = Curl_read(data, sock, buffer, length, &nread);
+  result = Curl_conn_recv(data, socknum, buffer, length, &nread);
   conn->recv[0] = backup;
   if(result == CURLE_AGAIN)
     return -EAGAIN; /* magic return code for libssh2 */
@@ -3217,12 +3218,13 @@ static ssize_t ssh_tls_send(libssh2_socket_t sock, const void *buffer,
   struct connectdata *conn = data->conn;
   Curl_send *backup = conn->send[0];
   struct ssh_conn *ssh = &conn->proto.sshc;
+  int socknum = Curl_conn_sockindex(data, sock);
   (void)flags;
 
   /* swap in the TLS writer function for this call only, and then swap back
      the SSH one again */
   conn->send[0] = ssh->tls_send;
-  result = Curl_write(data, sock, buffer, length, &nwrite);
+  result = Curl_conn_send(data, socknum, buffer, length, &nwrite);
   conn->send[0] = backup;
   if(result == CURLE_AGAIN)
     return -EAGAIN; /* magic return code for libssh2 */
diff --git a/lib/vssh/wolfssh.c b/lib/vssh/wolfssh.c
index 7396791cec..c6b94fd50d 100644
--- a/lib/vssh/wolfssh.c
+++ b/lib/vssh/wolfssh.c
@@ -678,9 +678,9 @@ static CURLcode wssh_statemach_act(struct Curl_easy *data, bool *block)
         Curl_pgrsSetUploadSize(data, data->state.infilesize);
       }
       /* upload data */
-      Curl_setup_transfer(data, -1, -1, FALSE, FIRSTSOCKET);
+      Curl_xfer_setup(data, -1, -1, FALSE, FIRSTSOCKET);
 
-      /* not set by Curl_setup_transfer to preserve keepon bits */
+      /* not set by Curl_xfer_setup to preserve keepon bits */
       conn->sockfd = conn->writesockfd;
 
       if(result) {
@@ -778,14 +778,14 @@ static CURLcode wssh_statemach_act(struct Curl_easy *data, bool *block)
       /* Setup the actual download */
       if(data->req.size == 0) {
         /* no data to transfer */
-        Curl_setup_transfer(data, -1, -1, FALSE, -1);
+        Curl_xfer_setup(data, -1, -1, FALSE, -1);
         infof(data, "File already completely downloaded");
         state(data, SSH_STOP);
         break;
       }
-      Curl_setup_transfer(data, FIRSTSOCKET, data->req.size, FALSE, -1);
+      Curl_xfer_setup(data, FIRSTSOCKET, data->req.size, FALSE, -1);
 
-      /* not set by Curl_setup_transfer to preserve keepon bits */
+      /* not set by Curl_xfer_setup to preserve keepon bits */
       conn->writesockfd = conn->sockfd;
 
       /* we want to use the _receiving_ function even when the socket turns
diff --git a/lib/ws.c b/lib/ws.c
index f4675cec47..b2305932ac 100644
--- a/lib/ws.c
+++ b/lib/ws.c
@@ -1020,8 +1020,12 @@ static CURLcode ws_flush(struct Curl_easy *data, struct websocket *ws,
     while(Curl_bufq_peek(&ws->sendbuf, &out, &outlen)) {
       if(data->set.connect_only)
         result = Curl_senddata(data, out, outlen, &n);
-      else
-        result = Curl_write(data, data->conn->writesockfd, out, outlen, &n);
+      else {
+        result = Curl_xfer_send(data, out, outlen, &n);
+        if(!result && !n && outlen)
+          result = CURLE_AGAIN;
+      }
+
       if(result) {
         if(result == CURLE_AGAIN) {
           if(!complete) {
@@ -1086,8 +1090,7 @@ CURL_EXTERN CURLcode curl_ws_send(CURL *data, const void *buffer,
     /* raw mode sends exactly what was requested, and this is from within
        the write callback */
     if(Curl_is_in_callback(data)) {
-      result = Curl_write(data, data->conn->writesockfd, buffer, buflen,
-                          &nwritten);
+      result = Curl_xfer_send(data, buffer, buflen, &nwritten);
     }
     else
       result = Curl_senddata(data, buffer, buflen, &nwritten);
@@ -1104,7 +1107,7 @@ CURL_EXTERN CURLcode curl_ws_send(CURL *data, const void *buffer,
     return result;
 
   /* TODO: the current design does not allow partial writes, afaict.
-   * It is not clear who the application is supposed to react. */
+   * It is not clear how the application is supposed to react. */
   space = Curl_bufq_space(&ws->sendbuf);
   DEBUGF(infof(data, "curl_ws_send(len=%zu), sendbuf len=%zu space %zu",
                buflen, Curl_bufq_len(&ws->sendbuf), space));
diff --git a/tests/unit/unit1620.c b/tests/unit/unit1620.c
index 8b6f34ca7d..dc3b3455af 100644
--- a/tests/unit/unit1620.c
+++ b/tests/unit/unit1620.c
@@ -84,8 +84,6 @@ UNITTEST_START
                 "Curl_free() did not set to NULL");
   }
 
-  Curl_free_request_state(empty);
-
   rc = Curl_close(&empty);
   fail_unless(rc == CURLE_OK, "Curl_close() failed");