[PATCH 1 of 4] Core: added socket protocol

[Dourov Maxime]

# HG changeset patch
# User maxime <mux99 at live.be>
# Date 1713355365 -7200
#      Wed Apr 17 14:02:45 2024 +0200
# Node ID b7cbe9281f9d6911fd40a894ebc4ac2d701d8fa4
# Parent  49dce50fad40bf09db81ca2a35983ecd7b740e43
Core: added socket protocol.

This patch updates the creation of listening sockets to use a new field
of the `ngx_listening_s` structure. The `protocol` field can be used in
conjunction with the `type` to specify the protocol to be used.

Modules will then be able to specify a different protocol, e.g.
IPPROTO_MPTCP.

diff --git a/src/core/ngx_connection.c b/src/core/ngx_connection.c
--- a/src/core/ngx_connection.c
+++ b/src/core/ngx_connection.c
@@ -487,9 +487,20 @@ ngx_open_listening_sockets(ngx_cycle_t *
                 continue;
             }
 
-            s = ngx_socket(ls[i].sockaddr->sa_family, ls[i].type, 0);
+            s = (ngx_socket_t) -1;
+            if (ls[i].protocol > 0) {
+                s = ngx_socket(ls[i].sockaddr->sa_family, ls[i].type,
+                               ls[i].protocol);
+                /* In case of error, retry with the default protocol */
+                ngx_log_error(NGX_LOG_NOTICE, log, 0,
+                      "socket(%d) failed, trying with 0", ls[i].protocol);
+            }
 
             if (s == (ngx_socket_t) -1) {
+                s = ngx_socket(ls[i].sockaddr->sa_family, ls[i].type, 0);
+            }
+            
+            if (s == (ngx_socket_t) -1) {
                 ngx_log_error(NGX_LOG_EMERG, log, ngx_socket_errno,
                               ngx_socket_n " %V failed", &ls[i].addr_text);
                 return NGX_ERROR;
diff --git a/src/core/ngx_connection.h b/src/core/ngx_connection.h
--- a/src/core/ngx_connection.h
+++ b/src/core/ngx_connection.h
@@ -24,6 +24,7 @@ struct ngx_listening_s {
     ngx_str_t           addr_text;
 
     int                 type;
+    int                 protocol;
 
     int                 backlog;
     int                 rcvbuf;