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, 125 insertions, 0 deletions

diff --git a/ares_options.c b/ares_options.c
index d00368a..bb1d5d5 100644
--- a/ares_options.c
+++ b/ares_options.c
@@ -21,6 +21,7 @@
 #include "ares.h"
 #include "ares_data.h"
 #include "ares_private.h"
+#include "inet_net_pton.h"
 
 
 int ares_get_servers(ares_channel channel,
@@ -125,3 +126,127 @@ int ares_set_servers(ares_channel channel,
 
   return ARES_SUCCESS;
 }
+
+/* Incomming string format: host[:port][,host[:port]]... */
+int ares_set_servers_csv(ares_channel channel,
+                         const char* _csv)
+{
+  struct ares_addr_node *srvr;
+  int num_srvrs = 0;
+  int i;
+  char* csv = NULL;
+  char* ptr;
+  char* start_host;
+  int port;
+  bool found_port;
+  int rv = ARES_SUCCESS;
+  struct ares_addr_node *servers = NULL;
+  struct ares_addr_node *last = NULL;
+
+  if (ares_library_initialized() != ARES_SUCCESS)
+    return ARES_ENOTINITIALIZED;
+
+  if (!channel)
+    return ARES_ENODATA;
+
+  ares__destroy_servers_state(channel);
+
+  i = strlen(_csv);
+  if (i == 0)
+     return ARES_SUCCESS; /* blank all servers */
+
+  csv = malloc(i + 2);
+  strcpy(csv, _csv);
+  if (csv[i-1] != ',') { /* make parsing easier by ensuring ending ',' */
+    csv[i] = ',';
+    csv[i+1] = 0;
+  }
+
+  ptr = csv;
+  start_host = csv;
+  found_port = false;
+  for (ptr; *ptr; ptr++) {
+    if (*ptr == ',') {
+      char* pp = ptr - 1;
+      struct in_addr in4;
+      struct ares_in6_addr in6;
+      struct ares_addr_node *s = NULL;
+
+      *ptr = 0; /* null terminate host:port string */
+      /* Got an entry..see if port was specified. */
+      while (pp > start_host) {
+        if (*pp == ':')
+          break; /* yes */
+        if (!isdigit(*pp)) {
+          /* Found end of digits before we found :, so wasn't a port */
+          pp = ptr;
+          break;
+        }
+        pp--;
+      }
+      if ((pp != start_host) && ((pp + 1) < ptr)) {
+        /* Found it. */
+        found_port = true;
+        port = atoi(pp + 1);
+        *pp = 0; /* null terminate host */
+      }
+      /* resolve host, try ipv4 first, rslt is in network byte order */
+      rv = ares_inet_pton(AF_INET, start_host, &in4);
+      if (!rv) {
+        /* Ok, try IPv6 then */
+        rv = ares_inet_pton(AF_INET6, start_host, &in6);
+        if (!rv) {
+          rv = ARES_EBADSTR;
+          goto out;
+        }
+        /* was ipv6, add new server */
+        s = malloc(sizeof(*s));
+        if (!s) {
+          rv = ARES_ENOMEM;
+          goto out;
+        }
+        s->family = AF_INET6;
+        memcpy(&s->addr, &in6, sizeof(struct ares_in6_addr));
+      }
+      else {
+        /* was ipv4, add new server */
+        s = malloc(sizeof(*s));
+        if (!s) {
+          rv = ARES_ENOMEM;
+          goto out;
+        }
+        s->family = AF_INET;
+        memcpy(&s->addr, &in4, sizeof(struct in_addr));
+      }
+      if (s) {
+        /* TODO:  Add port to ares_addr_node and assign it here. */
+
+        s->next = NULL;
+        if (last) {
+          last->next = s;
+        }
+        else {
+          servers = s;
+          last = s;
+        }
+      }
+
+      /* Set up for next one */
+      found_port = false;
+      start_host = ptr + 1;
+    }
+  }
+
+  rv = ares_set_servers(channel, servers);
+
+  out:
+  if (csv)
+    free(csv);
+  while (servers) {
+    struct ares_addr_node *s = servers;
+    servers = servers->next;
+    free(s);
+  }
+
+  return rv;
+}