curl_global_sslset.3: clarify the openssl situation

and add rustls

Closes #10188

diff --git a/docs/libcurl/curl_global_sslset.3 b/docs/libcurl/curl_global_sslset.3
index c1e791afe6e76eff27a6a099b4592c9635c6c0de..abd674b09b3f07c25a763a169408d254a7e793b3 100644 (file)
--- a/docs/libcurl/curl_global_sslset.3
+++ b/docs/libcurl/curl_global_sslset.3
@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2023, 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
@@ -35,7 +35,7 @@ typedef struct {
 
 typedef enum {
   CURLSSLBACKEND_NONE = 0,
-  CURLSSLBACKEND_OPENSSL = 1,
+  CURLSSLBACKEND_OPENSSL = 1, /* or one of its forks */
   CURLSSLBACKEND_GNUTLS = 2,
   CURLSSLBACKEND_NSS = 3,
   CURLSSLBACKEND_GSKIT = 5,
@@ -45,8 +45,9 @@ typedef enum {
   CURLSSLBACKEND_SECURETRANSPORT = 9,
   CURLSSLBACKEND_AXTLS = 10, /* deprecated */
   CURLSSLBACKEND_MBEDTLS = 11,
-  CURLSSLBACKEND_MESALINK = 12,
-  CURLSSLBACKEND_BEARSSL = 13
+  CURLSSLBACKEND_MESALINK = 12, /* deprecated */
+  CURLSSLBACKEND_BEARSSL = 13,
+  CURLSSLBACKEND_RUSTLS = 14
 } curl_sslbackend;
 
 CURLsslset curl_global_sslset(curl_sslbackend id,
@@ -88,6 +89,15 @@ This function is thread-safe since libcurl 7.84.0 if
 If this is not thread-safe, you must not call this function when any other
 thread in the program (i.e. a thread sharing the same memory) is running.
 This does not just mean no other thread that is using libcurl.
+.SH OpenSSL
+The name "OpenSSL" is used for all versions of OpenSSL and its associated
+forks/flavors in this function. OpenSSL, BoringSSL, libressl, quictls and
+AmiSSL are all supported by libcurl, but in the eyes of
+\fIcurl_global_sslset(3)\fP they are all just "OpenSSL". They all mostly
+provide the same API.
+
+\fIcurl_version_info(3)\fP can return more specific info about the exact
+OpenSSL flavor and version number is use.
 .SH EXAMPLE
 .nf
   /* choose a specific backend */