lib: pass in 'struct Curl_easy *' to most functions

... in most cases instead of 'struct connectdata *' but in some cases in
addition to.

- We mostly operate on transfers and not connections.

- We need the transfer handle to log, store data and more. Everything in
  libcurl is driven by a transfer (the CURL * in the public API).

- This work clarifies and separates the transfers from the connections
  better.

- We should avoid "conn->data". Since individual connections can be used
  by many transfers when multiplexing, making sure that conn->data
  points to the current and correct transfer at all times is difficult
  and has been notoriously error-prone over the years. The goal is to
  ultimately remove the conn->data pointer for this reason.

Closes #6425

1 files changed, 135 insertions, 133 deletions

diff --git a/lib/http.c b/lib/http.c
index 1794f43a2..0d1d0d568 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -94,22 +94,25 @@
  * Forward declarations.
  */
 
-static int http_getsock_do(struct connectdata *conn,
+static int http_getsock_do(struct Curl_easy *data,
+                           struct connectdata *conn,
                            curl_socket_t *socks);
-static bool http_should_fail(struct connectdata *conn);
+static bool http_should_fail(struct Curl_easy *data);
 
 #ifndef CURL_DISABLE_PROXY
-static CURLcode add_haproxy_protocol_header(struct connectdata *conn);
+static CURLcode add_haproxy_protocol_header(struct Curl_easy *data);
 #endif
 
 #ifdef USE_SSL
-static CURLcode https_connecting(struct connectdata *conn, bool *done);
-static int https_getsock(struct connectdata *conn,
+static CURLcode https_connecting(struct Curl_easy *data, bool *done);
+static int https_getsock(struct Curl_easy *data,
+                         struct connectdata *conn,
                          curl_socket_t *socks);
 #else
 #define https_connecting(x,y) CURLE_COULDNT_CONNECT
 #endif
-static CURLcode http_setup_conn(struct connectdata *conn);
+static CURLcode http_setup_conn(struct Curl_easy *data,
+                                struct connectdata *conn);
 
 /*
  * HTTP handler interface.
@@ -165,19 +168,19 @@ const struct Curl_handler Curl_handler_https = {
 };
 #endif
 
-static CURLcode http_setup_conn(struct connectdata *conn)
+static CURLcode http_setup_conn(struct Curl_easy *data,
+                                struct connectdata *conn)
 {
   /* allocate the HTTP-specific struct for the Curl_easy, only to survive
      during this request */
   struct HTTP *http;
-  struct Curl_easy *data = conn->data;
   DEBUGASSERT(data->req.p.http == NULL);
 
   http = calloc(1, sizeof(struct HTTP));
   if(!http)
     return CURLE_OUT_OF_MEMORY;
 
-  Curl_mime_initpart(&http->form, conn->data);
+  Curl_mime_initpart(&http->form, data);
   data->req.p.http = http;
 
   if(data->set.httpversion == CURL_HTTP_VERSION_3) {
@@ -205,16 +208,16 @@ static CURLcode http_setup_conn(struct connectdata *conn)
  * if proxy headers are not available, then it will lookup into http header
  * link list
  *
- * It takes a connectdata struct as input instead of the Curl_easy simply to
- * know if this is a proxy request or not, as it then might check a different
- * header list. Provide the header prefix without colon!.
+ * It takes a connectdata struct as input to see if this is a proxy request or
+ * not, as it then might check a different header list. Provide the header
+ * prefix without colon!
  */
-char *Curl_checkProxyheaders(const struct connectdata *conn,
+char *Curl_checkProxyheaders(struct Curl_easy *data,
+                             const struct connectdata *conn,
                              const char *thisheader)
 {
   struct curl_slist *head;
   size_t thislen = strlen(thisheader);
-  struct Curl_easy *data = conn->data;
 
   for(head = (conn->bits.proxy && data->set.sep_headers) ?
         data->set.proxyheaders : data->set.headers;
@@ -228,7 +231,7 @@ char *Curl_checkProxyheaders(const struct connectdata *conn,
 }
 #else
 /* disabled */
-#define Curl_checkProxyheaders(x,y) NULL
+#define Curl_checkProxyheaders(x,y,z) NULL
 #endif
 
 /*
@@ -291,11 +294,11 @@ char *Curl_copy_header_value(const char *header)
  *
  * Returns CURLcode.
  */
-static CURLcode http_output_basic(struct connectdata *conn, bool proxy)
+static CURLcode http_output_basic(struct Curl_easy *data, bool proxy)
 {
   size_t size = 0;
   char *authorization = NULL;
-  struct Curl_easy *data = conn->data;
+  struct connectdata *conn = data->conn;
   char **userp;
   const char *user;
   const char *pwd;
@@ -351,16 +354,15 @@ static CURLcode http_output_basic(struct connectdata *conn, bool proxy)
  *
  * Returns CURLcode.
  */
-static CURLcode http_output_bearer(struct connectdata *conn)
+static CURLcode http_output_bearer(struct Curl_easy *data)
 {
   char **userp;
   CURLcode result = CURLE_OK;
-  struct Curl_easy *data = conn->data;
 
   userp = &data->state.aptr.userpwd;
   free(*userp);
   *userp = aprintf("Authorization: Bearer %s\r\n",
-                   conn->data->set.str[STRING_BEARER]);
+                   data->set.str[STRING_BEARER]);
 
   if(!*userp) {
     result = CURLE_OUT_OF_MEMORY;
@@ -433,9 +435,9 @@ static bool pickoneauth(struct auth *pick, unsigned long mask)
  *   }
  * }
  */
-static CURLcode http_perhapsrewind(struct connectdata *conn)
+static CURLcode http_perhapsrewind(struct Curl_easy *data,
+                                   struct connectdata *conn)
 {
-  struct Curl_easy *data = conn->data;
   struct HTTP *http = data->req.p.http;
   curl_off_t bytessent;
   curl_off_t expectsend = -1; /* default is unknown */
@@ -565,9 +567,9 @@ static CURLcode http_perhapsrewind(struct connectdata *conn)
  * picked.
  */
 
-CURLcode Curl_http_auth_act(struct connectdata *conn)
+CURLcode Curl_http_auth_act(struct Curl_easy *data)
 {
-  struct Curl_easy *data = conn->data;
+  struct connectdata *conn = data->conn;
   bool pickhost = FALSE;
   bool pickproxy = FALSE;
   CURLcode result = CURLE_OK;
@@ -593,7 +595,7 @@ CURLcode Curl_http_auth_act(struct connectdata *conn)
        conn->httpversion > 11) {
       infof(data, "Forcing HTTP/1.1 for NTLM");
       connclose(conn, "Force HTTP/1.1 connection");
-      conn->data->set.httpversion = CURL_HTTP_VERSION_1_1;
+      data->set.httpversion = CURL_HTTP_VERSION_1_1;
     }
   }
 #ifndef CURL_DISABLE_PROXY
@@ -611,7 +613,7 @@ CURLcode Curl_http_auth_act(struct connectdata *conn)
     if((data->state.httpreq != HTTPREQ_GET) &&
        (data->state.httpreq != HTTPREQ_HEAD) &&
        !conn->bits.rewindaftersend) {
-      result = http_perhapsrewind(conn);
+      result = http_perhapsrewind(data, conn);
       if(result)
         return result;
     }
@@ -638,7 +640,7 @@ CURLcode Curl_http_auth_act(struct connectdata *conn)
       data->state.authhost.done = TRUE;
     }
   }
-  if(http_should_fail(conn)) {
+  if(http_should_fail(data)) {
     failf(data, "The requested URL returned error: %d",
           data->req.httpcode);
     result = CURLE_HTTP_RETURNED_ERROR;
@@ -653,7 +655,8 @@ CURLcode Curl_http_auth_act(struct connectdata *conn)
  * and whether or not it is to a proxy.
  */
 static CURLcode
-output_auth_headers(struct connectdata *conn,
+output_auth_headers(struct Curl_easy *data,
+                    struct connectdata *conn,
                     struct auth *authstatus,
                     const char *request,
                     const char *path,
@@ -661,7 +664,6 @@ output_auth_headers(struct connectdata *conn,
 {
   const char *auth = NULL;
   CURLcode result = CURLE_OK;
-  struct Curl_easy *data = conn->data;
 
 #ifdef CURL_DISABLE_CRYPTO_AUTH
   (void)request;
@@ -720,12 +722,12 @@ output_auth_headers(struct connectdata *conn,
     if(
 #ifndef CURL_DISABLE_PROXY
       (proxy && conn->bits.proxy_user_passwd &&
-       !Curl_checkProxyheaders(conn, "Proxy-authorization")) ||
+       !Curl_checkProxyheaders(data, conn, "Proxy-authorization")) ||
 #endif
       (!proxy && conn->bits.user_passwd &&
-       !Curl_checkheaders(conn, "Authorization"))) {
+       !Curl_checkheaders(data, "Authorization"))) {
       auth = "Basic";
-      result = http_output_basic(conn, proxy);
+      result = http_output_basic(data, proxy);
       if(result)
         return result;
     }
@@ -737,9 +739,9 @@ output_auth_headers(struct connectdata *conn,
   if(authstatus->picked == CURLAUTH_BEARER) {
     /* Bearer */
     if((!proxy && data->set.str[STRING_BEARER] &&
-        !Curl_checkheaders(conn, "Authorization:"))) {
+        !Curl_checkheaders(data, "Authorization:"))) {
       auth = "Bearer";
-      result = http_output_bearer(conn);
+      result = http_output_bearer(data);
       if(result)
         return result;
     }
@@ -770,7 +772,7 @@ output_auth_headers(struct connectdata *conn,
 /**
  * Curl_http_output_auth() setups the authentication headers for the
  * host/proxy and the correct authentication
- * method. conn->data->state.authdone is set to TRUE when authentication is
+ * method. data->state.authdone is set to TRUE when authentication is
  * done.
  *
  * @param conn all information about the current connection
@@ -782,7 +784,8 @@ output_auth_headers(struct connectdata *conn,
  * @returns CURLcode
  */
 CURLcode
-Curl_http_output_auth(struct connectdata *conn,
+Curl_http_output_auth(struct Curl_easy *data,
+                      struct connectdata *conn,
                       const char *request,
                       Curl_HttpReq httpreq,
                       const char *path,
@@ -790,7 +793,6 @@ Curl_http_output_auth(struct connectdata *conn,
                                            up the proxy tunnel */
 {
   CURLcode result = CURLE_OK;
-  struct Curl_easy *data = conn->data;
   struct auth *authhost;
   struct auth *authproxy;
 
@@ -827,7 +829,7 @@ Curl_http_output_auth(struct connectdata *conn,
   /* Send proxy authentication header if needed */
   if(conn->bits.httpproxy &&
      (conn->bits.tunnel_proxy == (bit)proxytunnel)) {
-    result = output_auth_headers(conn, authproxy, request, path, TRUE);
+    result = output_auth_headers(data, conn, authproxy, request, path, TRUE);
     if(result)
       return result;
   }
@@ -846,7 +848,7 @@ Curl_http_output_auth(struct connectdata *conn,
      !data->state.first_host ||
      data->set.allow_auth_to_other_hosts ||
      strcasecompare(data->state.first_host, conn->host.name)) {
-    result = output_auth_headers(conn, authhost, request, path, FALSE);
+    result = output_auth_headers(data, conn, authhost, request, path, FALSE);
   }
   else
     authhost->done = TRUE;
@@ -887,14 +889,13 @@ Curl_http_output_auth(struct connectdata *conn,
  * proxy CONNECT loop.
  */
 
-CURLcode Curl_http_input_auth(struct connectdata *conn, bool proxy,
+CURLcode Curl_http_input_auth(struct Curl_easy *data, bool proxy,
                               const char *auth) /* the first non-space */
 {
   /*
    * This resource requires authentication
    */
-  struct Curl_easy *data = conn->data;
-
+  struct connectdata *conn = data->conn;
 #ifdef USE_SPNEGO
   curlnegotiate *negstate = proxy ? &conn->proxy_negotiate_state :
                                     &conn->http_negotiate_state;
@@ -1062,14 +1063,11 @@ CURLcode Curl_http_input_auth(struct connectdata *conn, bool proxy,
  *
  * @retval TRUE communications should not continue
  */
-static bool http_should_fail(struct connectdata *conn)
+static bool http_should_fail(struct Curl_easy *data)
 {
-  struct Curl_easy *data;
   int httpcode;
-
-  DEBUGASSERT(conn);
-  data = conn->data;
   DEBUGASSERT(data);
+  DEBUGASSERT(data->conn);
 
   httpcode = data->req.httpcode;
 
@@ -1116,10 +1114,10 @@ static bool http_should_fail(struct connectdata *conn)
   ** Either we're not authenticating, or we're supposed to
   ** be authenticating something else.  This is an error.
   */
-  if((httpcode == 401) && !conn->bits.user_passwd)
+  if((httpcode == 401) && !data->conn->bits.user_passwd)
     return TRUE;
 #ifndef CURL_DISABLE_PROXY
-  if((httpcode == 407) && !conn->bits.proxy_user_passwd)
+  if((httpcode == 407) && !data->conn->bits.proxy_user_passwd)
     return TRUE;
 #endif
 
@@ -1140,8 +1138,8 @@ static size_t readmoredata(char *buffer,
                            size_t nitems,
                            void *userp)
 {
-  struct connectdata *conn = (struct connectdata *)userp;
-  struct HTTP *http = conn->data->req.p.http;
+  struct Curl_easy *data = (struct Curl_easy *)userp;
+  struct HTTP *http = data->req.p.http;
   size_t fullsize = size * nitems;
 
   if(!http->postsize)
@@ -1149,7 +1147,7 @@ static size_t readmoredata(char *buffer,
     return 0;
 
   /* make sure that a HTTP request is never sent away chunked! */
-  conn->data->req.forbidchunk = (http->sending == HTTPSEND_REQUEST)?TRUE:FALSE;
+  data->req.forbidchunk = (http->sending == HTTPSEND_REQUEST)?TRUE:FALSE;
 
   if(http->postsize <= (curl_off_t)fullsize) {
     memcpy(buffer, http->postdata, (size_t)http->postsize);
@@ -1159,8 +1157,8 @@ static size_t readmoredata(char *buffer,
       /* move backup data into focus and continue on that */
       http->postdata = http->backup.postdata;
       http->postsize = http->backup.postsize;
-      conn->data->state.fread_func = http->backup.fread_func;
-      conn->data->state.in = http->backup.fread_in;
+      data->state.fread_func = http->backup.fread_func;
+      data->state.in = http->backup.fread_in;
 
       http->sending++; /* move one step up */
 
@@ -1186,7 +1184,7 @@ static size_t readmoredata(char *buffer,
  * Returns CURLcode
  */
 CURLcode Curl_buffer_send(struct dynbuf *in,
-                          struct connectdata *conn,
+                          struct Curl_easy *data,
                           /* add the number of sent bytes to this
                              counter */
                           curl_off_t *bytes_written,
@@ -1198,7 +1196,7 @@ CURLcode Curl_buffer_send(struct dynbuf *in,
   CURLcode result;
   char *ptr;
   size_t size;
-  struct Curl_easy *data = conn->data;
+  struct connectdata *conn = data->conn;
   struct HTTP *http = data->req.p.http;
   size_t sendsize;
   curl_socket_t sockfd;
@@ -1274,7 +1272,7 @@ CURLcode Curl_buffer_send(struct dynbuf *in,
     sendsize = size;
   }
 
-  result = Curl_write(conn, sockfd, ptr, sendsize, &amount);
+  result = Curl_write(data, sockfd, ptr, sendsize, &amount);
 
   if(!result) {
     /*
@@ -1321,7 +1319,7 @@ CURLcode Curl_buffer_send(struct dynbuf *in,
 
         /* set the new pointers for the request-sending */
         data->state.fread_func = (curl_read_callback)readmoredata;
-        data->state.in = (void *)conn;
+        data->state.in = (void *)data;
         http->postdata = ptr;
         http->postsize = (curl_off_t)size;
 
@@ -1421,9 +1419,10 @@ Curl_compareheader(const char *headerline, /* line to check */
  * Curl_http_connect() performs HTTP stuff to do at connect-time, called from
  * the generic Curl_connect().
  */
-CURLcode Curl_http_connect(struct connectdata *conn, bool *done)
+CURLcode Curl_http_connect(struct Curl_easy *data, bool *done)
 {
   CURLcode result;
+  struct connectdata *conn = data->conn;
 
   /* We default to persistent connections. We set this already in this connect
      function to make the re-use checks properly be able to check this bit. */
@@ -1446,9 +1445,9 @@ CURLcode Curl_http_connect(struct connectdata *conn, bool *done)
     /* nothing else to do except wait right now - we're not done here. */
     return CURLE_OK;
 
-  if(conn->data->set.haproxyprotocol) {
+  if(data->set.haproxyprotocol) {
     /* add HAProxy PROXY protocol header */
-    result = add_haproxy_protocol_header(conn);
+    result = add_haproxy_protocol_header(data);
     if(result)
       return result;
   }
@@ -1456,7 +1455,7 @@ CURLcode Curl_http_connect(struct connectdata *conn, bool *done)
 
   if(conn->given->protocol & CURLPROTO_HTTPS) {
     /* perform SSL initialization */
-    result = https_connecting(conn, done);
+    result = https_connecting(data, done);
     if(result)
       return result;
   }
@@ -1469,24 +1468,27 @@ CURLcode Curl_http_connect(struct connectdata *conn, bool *done)
 /* this returns the socket to wait for in the DO and DOING state for the multi
    interface and then we're always _sending_ a request and thus we wait for
    the single socket to become writable only */
-static int http_getsock_do(struct connectdata *conn,
+static int http_getsock_do(struct Curl_easy *data,
+                           struct connectdata *conn,
                            curl_socket_t *socks)
 {
   /* write mode */
+  (void)data;
   socks[0] = conn->sock[FIRSTSOCKET];
   return GETSOCK_WRITESOCK(0);
 }
 
 #ifndef CURL_DISABLE_PROXY
-static CURLcode add_haproxy_protocol_header(struct connectdata *conn)
+static CURLcode add_haproxy_protocol_header(struct Curl_easy *data)
 {
   char proxy_header[128];
   struct dynbuf req;
   CURLcode result;
   char tcp_version[5];
+  DEBUGASSERT(data->conn);
 
   /* Emit the correct prefix for IPv6 */
-  if(conn->bits.ipv6) {
+  if(data->conn->bits.ipv6) {
     strcpy(tcp_version, "TCP6");
   }
   else {
@@ -1497,10 +1499,10 @@ static CURLcode add_haproxy_protocol_header(struct connectdata *conn)
             sizeof(proxy_header),
             "PROXY %s %s %s %li %li\r\n",
             tcp_version,
-            conn->data->info.conn_local_ip,
-            conn->data->info.conn_primary_ip,
-            conn->data->info.conn_local_port,
-            conn->data->info.conn_primary_port);
+            data->info.conn_local_ip,
+            data->info.conn_primary_ip,
+            data->info.conn_local_port,
+            data->info.conn_primary_port);
 
   Curl_dyn_init(&req, DYN_HAXPROXY);
 
@@ -1508,7 +1510,7 @@ static CURLcode add_haproxy_protocol_header(struct connectdata *conn)
   if(result)
     return result;
 
-  result = Curl_buffer_send(&req, conn, &conn->data->info.request_size,
+  result = Curl_buffer_send(&req, data, &data->info.request_size,
                             0, FIRSTSOCKET);
 
   return result;
@@ -1516,10 +1518,11 @@ static CURLcode add_haproxy_protocol_header(struct connectdata *conn)
 #endif
 
 #ifdef USE_SSL
-static CURLcode https_connecting(struct connectdata *conn, bool *done)
+static CURLcode https_connecting(struct Curl_easy *data, bool *done)
 {
   CURLcode result;
-  DEBUGASSERT((conn) && (conn->handler->flags & PROTOPT_SSL));
+  struct connectdata *conn = data->conn;
+  DEBUGASSERT((data) && (data->conn->handler->flags & PROTOPT_SSL));
 
 #ifdef ENABLE_QUIC
   if(conn->transport == TRNSPRT_QUIC) {
@@ -1536,9 +1539,11 @@ static CURLcode https_connecting(struct connectdata *conn, bool *done)
   return result;
 }
 
-static int https_getsock(struct connectdata *conn,
+static int https_getsock(struct Curl_easy *data,
+                         struct connectdata *conn,
                          curl_socket_t *socks)
 {
+  (void)data;
   if(conn->handler->flags & PROTOPT_SSL)
     return Curl_ssl_getsock(conn, socks);
   return GETSOCK_BLANK;
@@ -1550,10 +1555,10 @@ static int https_getsock(struct connectdata *conn,
  * performed.
  */
 
-CURLcode Curl_http_done(struct connectdata *conn,
+CURLcode Curl_http_done(struct Curl_easy *data,
                         CURLcode status, bool premature)
 {
-  struct Curl_easy *data = conn->data;
+  struct connectdata *conn = data->conn;
   struct HTTP *http = data->req.p.http;
 
   /* Clear multipass flag. If authentication isn't done yet, then it will get
@@ -1653,7 +1658,7 @@ static CURLcode expect100(struct Curl_easy *data,
     /* if not doing HTTP 1.0 or version 2, or disabled explicitly, we add an
        Expect: 100-continue to the headers which actually speeds up post
        operations (as there is one packet coming back from the web server) */
-    const char *ptr = Curl_checkheaders(conn, "Expect");
+    const char *ptr = Curl_checkheaders(data, "Expect");
     if(ptr) {
       data->state.expect100header =
         Curl_compareheader(ptr, "Expect:", "100-continue");
@@ -1719,7 +1724,7 @@ CURLcode Curl_http_compile_trailers(struct curl_slist *trailers,
   return result;
 }
 
-CURLcode Curl_add_custom_headers(struct connectdata *conn,
+CURLcode Curl_add_custom_headers(struct Curl_easy *data,
                                  bool is_connect,
 #ifndef USE_HYPER
                                  struct dynbuf *req
@@ -1728,11 +1733,11 @@ CURLcode Curl_add_custom_headers(struct connectdata *conn,
 #endif
   )
 {
+  struct connectdata *conn = data->conn;
   char *ptr;
   struct curl_slist *h[2];
   struct curl_slist *headers;
   int numlists = 1; /* by default */
-  struct Curl_easy *data = conn->data;
   int i;
 
 #ifndef CURL_DISABLE_PROXY
@@ -1876,15 +1881,14 @@ CURLcode Curl_add_custom_headers(struct connectdata *conn,
 }
 
 #ifndef CURL_DISABLE_PARSEDATE
-CURLcode Curl_add_timecondition(const struct connectdata *conn,
+CURLcode Curl_add_timecondition(struct Curl_easy *data,
 #ifndef USE_HYPER
-                                 struct dynbuf *req
+                                struct dynbuf *req
 #else
-                                 void *req
+                                void *req
 #endif
   )
 {
-  struct Curl_easy *data = conn->data;
   const struct tm *tm;
   struct tm keeptime;
   CURLcode result;
@@ -1917,7 +1921,7 @@ CURLcode Curl_add_timecondition(const struct connectdata *conn,
     break;
   }
 
-  if(Curl_checkheaders(conn, condp)) {
+  if(Curl_checkheaders(data, condp)) {
     /* A custom header was specified; it will be sent instead. */
     return CURLE_OK;
   }
@@ -2000,13 +2004,13 @@ void Curl_http_method(struct Curl_easy *data, struct connectdata *conn,
   *reqp = httpreq;
 }
 
-CURLcode Curl_http_useragent(struct Curl_easy *data, struct connectdata *conn)
+CURLcode Curl_http_useragent(struct Curl_easy *data)
 {
   /* The User-Agent string might have been allocated in url.c already, because
      it might have been used in the proxy connect, but if we have got a header
      with the user-agent string specified, we erase the previously made string
      here. */
-  if(Curl_checkheaders(conn, "User-Agent")) {
+  if(Curl_checkheaders(data, "User-Agent")) {
     free(data->state.aptr.uagent);
     data->state.aptr.uagent = NULL;
   }
@@ -2029,7 +2033,7 @@ CURLcode Curl_http_host(struct Curl_easy *data, struct connectdata *conn)
   }
   Curl_safefree(data->state.aptr.host);
 
-  ptr = Curl_checkheaders(conn, "Host");
+  ptr = Curl_checkheaders(data, "Host");
   if(ptr && (!data->state.this_is_a_follow ||
              strcasecompare(data->state.first_host, conn->host.name))) {
 #if !defined(CURL_DISABLE_COOKIES)
@@ -2245,7 +2249,7 @@ CURLcode Curl_http_body(struct Curl_easy *data, struct connectdata *conn,
 
 #ifndef CURL_DISABLE_MIME
   if(http->sendit) {
-    const char *cthdr = Curl_checkheaders(conn, "Content-Type");
+    const char *cthdr = Curl_checkheaders(data, "Content-Type");
 
     /* Read and seek body only. */
     http->sendit->flags |= MIME_BODY_ONLY;
@@ -2270,7 +2274,7 @@ CURLcode Curl_http_body(struct Curl_easy *data, struct connectdata *conn,
   }
 #endif
 
-  ptr = Curl_checkheaders(conn, "Transfer-Encoding");
+  ptr = Curl_checkheaders(data, "Transfer-Encoding");
   if(ptr) {
     /* Some kind of TE is requested, check if 'chunked' is chosen */
     data->req.upload_chunky =
@@ -2331,7 +2335,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
       http->postsize = data->state.infilesize;
 
     if((http->postsize != -1) && !data->req.upload_chunky &&
-       (conn->bits.authneg || !Curl_checkheaders(conn, "Content-Length"))) {
+       (conn->bits.authneg || !Curl_checkheaders(data, "Content-Length"))) {
       /* only add Content-Length if not uploading chunked */
       result = Curl_dyn_addf(r, "Content-Length: %" CURL_FORMAT_CURL_OFF_T
                              "\r\n", http->postsize);
@@ -2354,7 +2358,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
     Curl_pgrsSetUploadSize(data, http->postsize);
 
     /* this sends the buffer and frees all the buffer resources */
-    result = Curl_buffer_send(r, conn, &data->info.request_size, 0,
+    result = Curl_buffer_send(r, data, &data->info.request_size, 0,
                               FIRSTSOCKET);
     if(result)
       failf(data, "Failed sending PUT request");
@@ -2375,7 +2379,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
       if(result)
         return result;
 
-      result = Curl_buffer_send(r, conn, &data->info.request_size, 0,
+      result = Curl_buffer_send(r, data, &data->info.request_size, 0,
                                 FIRSTSOCKET);
       if(result)
         failf(data, "Failed sending POST request");
@@ -2391,7 +2395,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
        we don't upload data chunked, as RFC2616 forbids us to set both
        kinds of headers (Transfer-Encoding: chunked and Content-Length) */
     if(http->postsize != -1 && !data->req.upload_chunky &&
-       (conn->bits.authneg || !Curl_checkheaders(conn, "Content-Length"))) {
+       (conn->bits.authneg || !Curl_checkheaders(data, "Content-Length"))) {
       /* we allow replacing this header if not during auth negotiation,
          although it isn't very wise to actually set your own */
       result = Curl_dyn_addf(r,
@@ -2418,7 +2422,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
        the somewhat bigger ones we allow the app to disable it. Just make
        sure that the expect100header is always set to the preferred value
        here. */
-    ptr = Curl_checkheaders(conn, "Expect");
+    ptr = Curl_checkheaders(data, "Expect");
     if(ptr) {
       data->state.expect100header =
         Curl_compareheader(ptr, "Expect:", "100-continue");
@@ -2445,7 +2449,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
     http->sending = HTTPSEND_BODY;
 
     /* this sends the buffer and frees all the buffer resources */
-    result = Curl_buffer_send(r, conn, &data->info.request_size, 0,
+    result = Curl_buffer_send(r, data, &data->info.request_size, 0,
                               FIRSTSOCKET);
     if(result)
       failf(data, "Failed sending POST request");
@@ -2471,7 +2475,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
        we don't upload data chunked, as RFC2616 forbids us to set both
        kinds of headers (Transfer-Encoding: chunked and Content-Length) */
     if((http->postsize != -1) && !data->req.upload_chunky &&
-       (conn->bits.authneg || !Curl_checkheaders(conn, "Content-Length"))) {
+       (conn->bits.authneg || !Curl_checkheaders(data, "Content-Length"))) {
       /* we allow replacing this header if not during auth negotiation,
          although it isn't very wise to actually set your own */
       result = Curl_dyn_addf(r, "Content-Length: %" CURL_FORMAT_CURL_OFF_T
@@ -2480,7 +2484,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
         return result;
     }
 
-    if(!Curl_checkheaders(conn, "Content-Type")) {
+    if(!Curl_checkheaders(data, "Content-Type")) {
       result = Curl_dyn_add(r, "Content-Type: application/"
                             "x-www-form-urlencoded\r\n");
       if(result)
@@ -2491,7 +2495,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
        the somewhat bigger ones we allow the app to disable it. Just make
        sure that the expect100header is always set to the preferred value
        here. */
-    ptr = Curl_checkheaders(conn, "Expect");
+    ptr = Curl_checkheaders(data, "Expect");
     if(ptr) {
       data->state.expect100header =
         Curl_compareheader(ptr, "Expect:", "100-continue");
@@ -2565,7 +2569,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
         http->sending = HTTPSEND_BODY;
 
         data->state.fread_func = (curl_read_callback)readmoredata;
-        data->state.in = (void *)conn;
+        data->state.in = (void *)data;
 
         /* set the upload size to the progress meter */
         Curl_pgrsSetUploadSize(data, http->postsize);
@@ -2604,7 +2608,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
       }
     }
     /* issue the request */
-    result = Curl_buffer_send(r, conn, &data->info.request_size,
+    result = Curl_buffer_send(r, data, &data->info.request_size,
                               (size_t)included_body, FIRSTSOCKET);
 
     if(result)
@@ -2620,7 +2624,7 @@ CURLcode Curl_http_bodysend(struct Curl_easy *data, struct connectdata *conn,
       return result;
 
     /* issue the request */
-    result = Curl_buffer_send(r, conn, &data->info.request_size, 0,
+    result = Curl_buffer_send(r, data, &data->info.request_size, 0,
                               FIRSTSOCKET);
 
     if(result)
@@ -2640,7 +2644,7 @@ CURLcode Curl_http_cookies(struct Curl_easy *data,
 {
   CURLcode result = CURLE_OK;
   char *addcookies = NULL;
-  if(data->set.str[STRING_COOKIE] && !Curl_checkheaders(conn, "Cookie"))
+  if(data->set.str[STRING_COOKIE] && !Curl_checkheaders(data, "Cookie"))
     addcookies = data->set.str[STRING_COOKIE];
 
   if(data->cookies || addcookies) {
@@ -2697,7 +2701,6 @@ CURLcode Curl_http_cookies(struct Curl_easy *data,
 #endif
 
 CURLcode Curl_http_range(struct Curl_easy *data,
-                         struct connectdata *conn,
                          Curl_HttpReq httpreq)
 {
   if(data->state.use_range) {
@@ -2707,14 +2710,14 @@ CURLcode Curl_http_range(struct Curl_easy *data,
      * ones if any such are specified.
      */
     if(((httpreq == HTTPREQ_GET) || (httpreq == HTTPREQ_HEAD)) &&
-       !Curl_checkheaders(conn, "Range")) {
+       !Curl_checkheaders(data, "Range")) {
       /* if a line like this was already allocated, free the previous one */
       free(data->state.aptr.rangeline);
       data->state.aptr.rangeline = aprintf("Range: bytes=%s\r\n",
                                            data->state.range);
     }
     else if((httpreq == HTTPREQ_POST || httpreq == HTTPREQ_PUT) &&
-            !Curl_checkheaders(conn, "Content-Range")) {
+            !Curl_checkheaders(data, "Content-Range")) {
 
       /* if a line like this was already allocated, free the previous one */
       free(data->state.aptr.rangeline);
@@ -2902,9 +2905,9 @@ CURLcode Curl_http_firstwrite(struct Curl_easy *data,
  * request is to be performed. This creates and sends a properly constructed
  * HTTP request.
  */
-CURLcode Curl_http(struct connectdata *conn, bool *done)
+CURLcode Curl_http(struct Curl_easy *data, bool *done)
 {
-  struct Curl_easy *data = conn->data;
+  struct connectdata *conn = data->conn;
   CURLcode result = CURLE_OK;
   struct HTTP *http;
   Curl_HttpReq httpreq;
@@ -2927,7 +2930,7 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
       case CURL_HTTP_VERSION_2:
         conn->httpversion = 20; /* we know we're on HTTP/2 now */
 
-        result = Curl_http2_switched(conn, NULL, 0);
+        result = Curl_http2_switched(data, NULL, 0);
         if(result)
           return result;
         break;
@@ -2937,8 +2940,7 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
       default:
         /* Check if user wants to use HTTP/2 with clear TCP*/
 #ifdef USE_NGHTTP2
-        if(conn->data->set.httpversion ==
-           CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE) {
+        if(data->set.httpversion == CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE) {
 #ifndef CURL_DISABLE_PROXY
           if(conn->bits.httpproxy && !conn->bits.tunnel_proxy) {
             /* We don't support HTTP/2 proxies yet. Also it's debatable
@@ -2950,7 +2952,7 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
           DEBUGF(infof(data, "HTTP/2 over clean TCP\n"));
           conn->httpversion = 20;
 
-          result = Curl_http2_switched(conn, NULL, 0);
+          result = Curl_http2_switched(data, NULL, 0);
           if(result)
             return result;
         }
@@ -2960,7 +2962,7 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
     }
     else {
       /* prepare for a http2 request */
-      result = Curl_http2_setup(conn);
+      result = Curl_http2_setup(data, conn);
       if(result)
         return result;
     }
@@ -2972,7 +2974,7 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
   if(result)
     return result;
 
-  result = Curl_http_useragent(data, conn);
+  result = Curl_http_useragent(data);
   if(result)
     return result;
 
@@ -2986,7 +2988,7 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
       if(!pq)
         return CURLE_OUT_OF_MEMORY;
     }
-    result = Curl_http_output_auth(conn, request, httpreq,
+    result = Curl_http_output_auth(data, conn, request, httpreq,
                                    (pq ? pq : data->state.up.path), FALSE);
     free(pq);
     if(result)
@@ -2994,13 +2996,13 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
   }
 
   Curl_safefree(data->state.aptr.ref);
-  if(data->change.referer && !Curl_checkheaders(conn, "Referer")) {
+  if(data->change.referer && !Curl_checkheaders(data, "Referer")) {
     data->state.aptr.ref = aprintf("Referer: %s\r\n", data->change.referer);
     if(!data->state.aptr.ref)
       return CURLE_OUT_OF_MEMORY;
   }
 
-  if(!Curl_checkheaders(conn, "Accept-Encoding") &&
+  if(!Curl_checkheaders(data, "Accept-Encoding") &&
      data->set.str[STRING_ENCODING]) {
     Curl_safefree(data->state.aptr.accept_encoding);
     data->state.aptr.accept_encoding =
@@ -3016,14 +3018,14 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
 #ifdef HAVE_LIBZ
   /* we only consider transfer-encoding magic if libz support is built-in */
 
-  if(!Curl_checkheaders(conn, "TE") &&
+  if(!Curl_checkheaders(data, "TE") &&
      data->set.http_transfer_encoding) {
     /* When we are to insert a TE: header in the request, we must also insert
        TE in a Connection: header, so we need to merge the custom provided
        Connection: header and prevent the original to get sent. Note that if
        the user has inserted his/her own TE: header we don't do this magic
        but then assume that the user will handle it all! */
-    char *cptr = Curl_checkheaders(conn, "Connection");
+    char *cptr = Curl_checkheaders(data, "Connection");
 #define TE_HEADER "TE: gzip\r\n"
 
     Curl_safefree(data->state.aptr.te);
@@ -3048,13 +3050,13 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
   if(result)
     return result;
 
-  p_accept = Curl_checkheaders(conn, "Accept")?NULL:"Accept: */*\r\n";
+  p_accept = Curl_checkheaders(data, "Accept")?NULL:"Accept: */*\r\n";
 
   result = Curl_http_resume(data, conn, httpreq);
   if(result)
     return result;
 
-  result = Curl_http_range(data, conn, httpreq);
+  result = Curl_http_range(data, httpreq);
   if(result)
     return result;
 
@@ -3074,7 +3076,7 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
   }
 
 #ifndef CURL_DISABLE_ALTSVC
-  if(conn->bits.altused && !Curl_checkheaders(conn, "Alt-Used")) {
+  if(conn->bits.altused && !Curl_checkheaders(data, "Alt-Used")) {
     altused = aprintf("Alt-Used: %s:%d\r\n",
                       conn->conn_to_host.name, conn->conn_to_port);
     if(!altused) {
@@ -3121,7 +3123,7 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
 #ifndef CURL_DISABLE_PROXY
                   (conn->bits.httpproxy &&
                    !conn->bits.tunnel_proxy &&
-                   !Curl_checkProxyheaders(conn, "Proxy-Connection"))?
+                   !Curl_checkProxyheaders(data, conn, "Proxy-Connection"))?
                   "Proxy-Connection: Keep-Alive\r\n":"",
 #else
                   "",
@@ -3155,9 +3157,9 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
 
   result = Curl_http_cookies(data, conn, &req);
   if(!result)
-    result = Curl_add_timecondition(conn, &req);
+    result = Curl_add_timecondition(data, &req);
   if(!result)
-    result = Curl_add_custom_headers(conn, FALSE, &req);
+    result = Curl_add_custom_headers(data, FALSE, &req);
 
   if(!result) {
     http->postdata = NULL;  /* nothing to post at this point */
@@ -3515,7 +3517,7 @@ CURLcode Curl_http_header(struct Curl_easy *data, struct connectdata *conn,
     if(!auth)
       return CURLE_OUT_OF_MEMORY;
 
-    result = Curl_http_input_auth(conn, proxy, auth);
+    result = Curl_http_input_auth(data, proxy, auth);
 
     free(auth);
 
@@ -3560,7 +3562,7 @@ CURLcode Curl_http_header(struct Curl_easy *data, struct connectdata *conn,
 
         /* some cases of POST and PUT etc needs to rewind the data
            stream at this point */
-        result = http_perhapsrewind(conn);
+        result = http_perhapsrewind(data, conn);
         if(result)
           return result;
       }
@@ -3849,7 +3851,7 @@ CURLcode Curl_http_readwrite_headers(struct Curl_easy *data,
 
             /* switch to http2 now. The bytes after response headers
                are also processed here, otherwise they are lost. */
-            result = Curl_http2_switched(conn, k->str, *nread);
+            result = Curl_http2_switched(data, k->str, *nread);
             if(result)
               return result;
             *nread = 0;
@@ -3923,7 +3925,7 @@ CURLcode Curl_http_readwrite_headers(struct Curl_easy *data,
         writetype |= CLIENTWRITE_BODY;
 
       headerlen = Curl_dyn_len(&data->state.headerb);
-      result = Curl_client_write(conn, writetype,
+      result = Curl_client_write(data, writetype,
                                  Curl_dyn_ptr(&data->state.headerb),
                                  headerlen);
       if(result)
@@ -3936,7 +3938,7 @@ CURLcode Curl_http_readwrite_headers(struct Curl_easy *data,
        * When all the headers have been parsed, see if we should give
        * up and return an error.
        */
-      if(http_should_fail(conn)) {
+      if(http_should_fail(data)) {
         failf(data, "The requested URL returned error: %d",
               k->httpcode);
         return CURLE_HTTP_RETURNED_ERROR;
@@ -3948,7 +3950,7 @@ CURLcode Curl_http_readwrite_headers(struct Curl_easy *data,
       /* Curl_http_auth_act() checks what authentication methods
        * that are available and decides which one (if any) to
        * use. It will set 'newurl' if an auth method was picked. */
-      result = Curl_http_auth_act(conn);
+      result = Curl_http_auth_act(data);
 
       if(result)
         return result;
@@ -3986,8 +3988,8 @@ CURLcode Curl_http_readwrite_headers(struct Curl_easy *data,
                 infof(data, "Got 417 while waiting for a 100\n");
                 data->state.disableexpect = TRUE;
                 DEBUGASSERT(!data->req.newurl);
-                data->req.newurl = strdup(conn->data->change.url);
-                Curl_done_sending(conn, k);
+                data->req.newurl = strdup(data->change.url);
+                Curl_done_sending(data, k);
               }
               else if(data->set.http_keep_sending_on_error) {
                 infof(data, "HTTP error before end of send, keep sending\n");
@@ -3999,7 +4001,7 @@ CURLcode Curl_http_readwrite_headers(struct Curl_easy *data,
               else {
                 infof(data, "HTTP error before end of send, stop sending\n");
                 streamclose(conn, "Stop sending data before everything sent");
-                result = Curl_done_sending(conn, k);
+                result = Curl_done_sending(data, k);
                 if(result)
                   return result;
                 k->upload_done = TRUE;
@@ -4237,7 +4239,7 @@ CURLcode Curl_http_readwrite_headers(struct Curl_easy *data,
     Curl_debug(data, CURLINFO_HEADER_IN, headp,
                Curl_dyn_len(&data->state.headerb));
 
-    result = Curl_client_write(conn, writetype, headp,
+    result = Curl_client_write(data, writetype, headp,
                                Curl_dyn_len(&data->state.headerb));
     if(result)
       return result;