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, 8 insertions, 7 deletions

diff --git a/lib/sendf.h b/lib/sendf.h
index c7e67c745..108a5e934 100644
--- a/lib/sendf.h
+++ b/lib/sendf.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2021, 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
@@ -49,7 +49,7 @@ void Curl_failf(struct Curl_easy *, const char *fmt, ...);
 #define CLIENTWRITE_HEADER (1<<1)
 #define CLIENTWRITE_BOTH   (CLIENTWRITE_BODY|CLIENTWRITE_HEADER)
 
-CURLcode Curl_client_write(struct connectdata *conn, int type, char *ptr,
+CURLcode Curl_client_write(struct Curl_easy *data, int type, char *ptr,
                            size_t len) WARN_UNUSED_RESULT;
 
 bool Curl_recv_has_postponed_data(struct connectdata *conn, int sockindex);
@@ -60,23 +60,24 @@ CURLcode Curl_read_plain(curl_socket_t sockfd,
                          size_t bytesfromsocket,
                          ssize_t *n);
 
-ssize_t Curl_recv_plain(struct connectdata *conn, int num, char *buf,
+ssize_t Curl_recv_plain(struct Curl_easy *data, int num, char *buf,
                         size_t len, CURLcode *code);
-ssize_t Curl_send_plain(struct connectdata *conn, int num,
+ssize_t Curl_send_plain(struct Curl_easy *data, int num,
                         const void *mem, size_t len, CURLcode *code);
 
 /* internal read-function, does plain socket, SSL and krb4 */
-CURLcode Curl_read(struct connectdata *conn, curl_socket_t sockfd,
+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 connectdata *conn,
+CURLcode Curl_write(struct Curl_easy *data,
                     curl_socket_t sockfd,
                     const void *mem, size_t len,
                     ssize_t *written);
 
 /* internal write-function, does plain sockets ONLY */
-CURLcode Curl_write_plain(struct connectdata *conn,
+CURLcode Curl_write_plain(struct Curl_easy *data,
                           curl_socket_t sockfd,
                           const void *mem, size_t len,
                           ssize_t *written);