From 3bb14e04405ef918487489abb644949d03d7baa8 Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Wed, 26 Aug 2020 12:32:27 +0200
Subject: Allow multiple Bind directives.

Try all the addresses specified with Bind in order. This is necessary
e.g. for maintaining IPv4+6 connectivity while still being restricted to
one interface.
---
 src/conf.c | 25 ++++++++++++++++++++-----
 src/conf.h |  2 +-
 src/sock.c | 27 ++++++++++++++++++++++++---
 3 files changed, 45 insertions(+), 9 deletions(-)

(limited to 'src')

diff --git a/src/conf.c b/src/conf.c
index e0d6634..7e3c031 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -291,6 +291,7 @@ void free_config (struct config_s *conf)
         safefree (conf->group);
         stringlist_free(conf->basicauth_list);
         stringlist_free(conf->listen_addrs);
+        stringlist_free(conf->bind_addrs);
 #ifdef FILTER_ENABLE
         safefree (conf->filter);
 #endif                          /* FILTER_ENABLE */
@@ -302,7 +303,6 @@ void free_config (struct config_s *conf)
         free_upstream_list (conf->upstream_list);
 #endif                          /* UPSTREAM_SUPPORT */
         safefree (conf->pidpath);
-        safefree (conf->bind_address);
         safefree (conf->via_proxy_name);
         if (conf->errorpages) {
                 it = 0;
@@ -796,12 +796,27 @@ static HANDLE_FUNC (handle_deny)
 
 static HANDLE_FUNC (handle_bind)
 {
-        int r = set_string_arg (&conf->bind_address, line, &match[2]);
+        char *arg = get_string_arg (line, &match[2]);
+
+        if (arg == NULL) {
+                return -1;
+        }
+
+        if (conf->bind_addrs == NULL) {
+               conf->bind_addrs = sblist_new(sizeof(char*), 16);
+               if (conf->bind_addrs == NULL) {
+                       CP_WARN ("Could not create a list "
+                                   "of bind addresses.", "");
+                       safefree(arg);
+                       return -1;
+               }
+        }
+
+        sblist_add (conf->bind_addrs, &arg);
 
-        if (r)
-                return r;
         log_message (LOG_INFO,
-                     "Outgoing connections bound to IP %s", conf->bind_address);
+                     "Added bind address [%s] for outgoing connections.", arg);
+
         return 0;
 }
 
diff --git a/src/conf.h b/src/conf.h
index 9453d66..9914049 100644
--- a/src/conf.h
+++ b/src/conf.h
@@ -68,7 +68,7 @@ struct config_s {
 #endif                          /* UPSTREAM_SUPPORT */
         char *pidpath;
         unsigned int idletimeout;
-        char *bind_address;
+        sblist *bind_addrs;
         unsigned int bindsame;
 
         /*
diff --git a/src/sock.c b/src/sock.c
index 28a7f88..70169a6 100644
--- a/src/sock.c
+++ b/src/sock.c
@@ -34,6 +34,7 @@
 #include "text.h"
 #include "conf.h"
 #include "loop.h"
+#include "sblist.h"
 
 /*
  * Return a human readable error for getaddrinfo() and getnameinfo().
@@ -87,6 +88,26 @@ bind_socket (int sockfd, const char *addr, int family)
         return sockfd;
 }
 
+/**
+ * Try binding the given socket to supplied addresses, stopping when one succeeds.
+ */
+static int
+bind_socket_list (int sockfd, sblist *addresses, int family)
+{
+        size_t nb_addresses = sblist_getsize(addresses);
+        size_t i;
+
+        for (i = 0; i < nb_addresses; i++) {
+                const char *address = *(const char **)sblist_get(addresses, i);
+                if (bind_socket(sockfd, address, family) >= 0) {
+                        log_message(LOG_INFO, "Bound to %s", address);
+                        return 0;
+                }
+        }
+
+        return -1;
+}
+
 /*
  * Open a connection to a remote host.  It's been re-written to use
  * the getaddrinfo() library function, which allows for a protocol
@@ -134,9 +155,9 @@ int opensock (const char *host, int port, const char *bind_to)
                                 close (sockfd);
                                 continue;       /* can't bind, so try again */
                         }
-                } else if (config->bind_address) {
-                        if (bind_socket (sockfd, config->bind_address,
-                                         res->ai_family) < 0) {
+                } else if (config->bind_addrs) {
+                        if (bind_socket_list (sockfd, config->bind_addrs,
+                                              res->ai_family) < 0) {
                                 close (sockfd);
                                 continue;       /* can't bind, so try again */
                         }
-- 
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