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, 3 insertions, 2 deletions

diff --git a/lib/hostip4.c b/lib/hostip4.c
index df83a2f12..f1acb9093 100644
--- a/lib/hostip4.c
+++ b/lib/hostip4.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * 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
@@ -61,8 +61,9 @@
  * Curl_ipvalid() checks what CURL_IPRESOLVE_* requirements that might've
  * been set and returns TRUE if they are OK.
  */
-bool Curl_ipvalid(struct connectdata *conn)
+bool Curl_ipvalid(struct Curl_easy *data, struct connectdata *conn)
 {
+  (void)data;
   if(conn->ip_version == CURL_IPRESOLVE_V6)
     /* An IPv6 address was requested and we can't get/use one */
     return FALSE;