local-bind: Support binding to local interface/IPs

Add 3 new functions to set the local binding for the out-going
socket connection, and add ares_set_servers_csv() to set a
list of servers at once as a comma-separated string.

Signed-off-by: Ben Greear <greearb@candelatech.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/ares_init.c b/ares_init.c
index a812b2d..718d552 100644
--- a/ares_init.c
+++ b/ares_init.c
@@ -172,6 +172,10 @@ int ares_init_options(ares_channel *channelptr, struct ares_options *options,
   channel->last_server = 0;
   channel->last_timeout_processed = (time_t)now.tv_sec;
 
+  memset(&channel->local_dev_name, 0, sizeof(channel->local_dev_name));
+  channel->local_ip4 = 0;
+  memset(&channel->local_ip6, 0, sizeof(channel->local_ip6));
+
   /* Initialize our lists of queries */
   ares__init_list_head(&(channel->all_queries));
   for (i = 0; i < ARES_QID_TABLE_SIZE; i++)
@@ -286,6 +290,10 @@ int ares_dup(ares_channel *dest, ares_channel src)
   (*dest)->sock_create_cb      = src->sock_create_cb;
   (*dest)->sock_create_cb_data = src->sock_create_cb_data;
 
+  strncpy((*dest)->local_dev_name, src->local_dev_name, sizeof(src->local_dev_name));
+  (*dest)->local_ip4 = src->local_ip4;
+  memcpy((*dest)->local_ip6, src->local_ip6, sizeof(src->local_ip6));
+
   /* Full name server cloning required when not all are IPv4 */
   for (i = 0; i < src->nservers; i++)
     {
@@ -1604,6 +1612,28 @@ unsigned short ares__generate_new_id(rc4_key* key)
   return r;
 }
 
+void ares_set_local_ip4(ares_channel channel, uint32_t local_ip)
+{
+  channel->local_ip4 = local_ip;
+}
+
+/* local_ip6 should be 16 bytes in length */
+void ares_set_local_ip6(ares_channel channel,
+                        const unsigned char* local_ip6)
+{
+  memcpy(&channel->local_ip6, local_ip6, sizeof(channel->local_ip6));
+}
+
+/* local_dev_name should be null terminated. */
+void ares_set_local_dev(ares_channel channel,
+                        const char* local_dev_name)
+{
+  strncpy(channel->local_dev_name, local_dev_name,
+          sizeof(channel->local_dev_name));
+  channel->local_dev_name[sizeof(channel->local_dev_name) - 1] = 0;
+}
+
+
 void ares_set_socket_callback(ares_channel channel,
                               ares_sock_create_callback cb,
                               void *data)