expose if_nametoindex and if_indextoname for overriding

bradh352 · Oct 8, 2024 · 7b987c1 · 7b987c1
1 parent fdc4916
commit 7b987c1
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Showing 12 changed files with 183 additions and 94 deletions.
diff --git a/include/ares.h b/include/ares.h
@@ -759,14 +759,39 @@ struct ares_socket_functions_ex {
    *  \param[in] flags       ares_socket_bind_flags_t flags.
    *  \param[in] address     Buffer containing address.
    *  \param[in] address_len Size of address buffer.
-   *  \param[in]     user_data   Pointer provided to
+   *  \param[in] user_data   Pointer provided to
    * ares_set_socket_functions_ex().
    *  \return 0 on success. -1 on error with an appropriate errno (or
    * WSASetLastError()) set.
    */
   int (*abind)(ares_socket_t sock, unsigned int flags,
                const struct sockaddr *address, socklen_t address_len,
                void *user_data);
+
+  /* Optional. Convert an interface name into the interface index.  If this
+   * callback is not specified, then IPv6 Link-Local DNS servers cannot be used.
+   *
+   * \param[in] ifname  Interface Name as NULL-terminated string.
+   * \param[in] user_data Pointer provided to
+   * ares_set_socket_functions_ex().
+   * \return 0 on failure, otherwise interface index.
+   */
+  unsigned int (*aif_nametoindex)(const char *ifname, void *user_data);
+
+  /* Optional. Convert an interface index into the interface name.  If this
+   * callback is not specified, then IPv6 Link-Local DNS servers cannot be used.
+   *
+   * \param[in] ifindex        Interface index, must be > 0
+   * \param[in] ifname_buf     Buffer to hold interface name. Must be at least
+   *                           IFNAMSIZ in length or 32 bytes if IFNAMSIZ isn't
+   *                           defined.
+   * \param[in] ifname_buf_len Size of ifname_buf for verification.
+   * \param[in] user_data      Pointer provided to
+   * ares_set_socket_functions_ex().
+   * \return NULL on failure, otherwise pointer to provided ifname_buf
+   */
+  const char *(*aif_indextoname)(unsigned int ifindex, char *ifname_buf,
+                                 size_t ifname_buf_len, void *user_data);
 };
 
 /*! Override the native socket functions for the OS with the provided set.
@@ -780,6 +805,8 @@ struct ares_socket_functions_ex {
  *                       past the life of this call.
  *  \param[in] user_data User data thunk which will be passed to each call of
  *                       the registered callbacks.
+ *  \return ARES_SUCCESS on success, or another error code such as ARES_EFORMERR
+ *          on misuse.
  */
 CARES_EXTERN ares_status_t ares_set_socket_functions_ex(
   ares_channel_t *channel, const struct ares_socket_functions_ex *funcs,

diff --git a/src/lib/ares_init.c b/src/lib/ares_init.c
@@ -157,7 +157,7 @@ static ares_status_t init_by_defaults(ares_channel_t *channel)
     addr.family            = AF_INET;
     addr.addr.addr4.s_addr = htonl(INADDR_LOOPBACK);
 
-    rc = ares_sconfig_append(&sconfig, &addr, 0, 0, NULL);
+    rc = ares_sconfig_append(channel, &sconfig, &addr, 0, 0, NULL);
     if (rc != ARES_SUCCESS) {
       goto error; /* LCOV_EXCL_LINE: OutOfMemory */
     }

diff --git a/src/lib/ares_private.h b/src/lib/ares_private.h
@@ -391,10 +391,12 @@ ares_status_t ares_init_by_environment(ares_sysconfig_t *sysconfig);
 ares_status_t ares_init_sysconfig_files(const ares_channel_t *channel,
                                         ares_sysconfig_t     *sysconfig);
 #ifdef __APPLE__
-ares_status_t ares_init_sysconfig_macos(ares_sysconfig_t *sysconfig);
+ares_status_t ares_init_sysconfig_macos(const ares_channel_t *channel,
+                                        ares_sysconfig_t     *sysconfig);
 #endif
 #ifdef USE_WINSOCK
-ares_status_t ares_init_sysconfig_windows(ares_sysconfig_t *sysconfig);
+ares_status_t ares_init_sysconfig_windows(const ares_channel_t *channel,
+                                          ares_sysconfig_t     *sysconfig);
 #endif
 
 ares_status_t ares_parse_sortlist(struct apattern **sortlist, size_t *nsort,
@@ -452,14 +454,14 @@ ares_status_t ares_addrinfo_localhost(const char *name, unsigned short port,
 ares_status_t ares_servers_update(ares_channel_t *channel,
                                   ares_llist_t   *server_list,
                                   ares_bool_t     user_specified);
-ares_status_t ares_sconfig_append(ares_llist_t          **sconfig,
-                                  const struct ares_addr *addr,
-                                  unsigned short          udp_port,
-                                  unsigned short          tcp_port,
-                                  const char             *ll_iface);
-ares_status_t ares_sconfig_append_fromstr(ares_llist_t **sconfig,
-                                          const char    *str,
-                                          ares_bool_t    ignore_invalid);
+ares_status_t
+  ares_sconfig_append(const ares_channel_t *channel, ares_llist_t **sconfig,
+                      const struct ares_addr *addr, unsigned short udp_port,
+                      unsigned short tcp_port, const char *ll_iface);
+ares_status_t ares_sconfig_append_fromstr(const ares_channel_t *channel,
+                                          ares_llist_t        **sconfig,
+                                          const char           *str,
+                                          ares_bool_t           ignore_invalid);
 ares_status_t ares_in_addr_to_sconfig_llist(const struct in_addr *servers,
                                             size_t                nservers,
                                             ares_llist_t        **llist);

diff --git a/src/lib/ares_set_socket_functions.c b/src/lib/ares_set_socket_functions.c
@@ -422,6 +422,21 @@ static int default_abind(ares_socket_t sock, unsigned int flags,
   return bind(sock, address, address_len);
 }
 
+static unsigned int default_aif_nametoindex(const char *ifname, void *user_data)
+{
+  (void)user_data;
+  return ares_os_if_nametoindex(ifname);
+}
+
+static const char *default_aif_indextoname(unsigned int ifindex,
+                                           char        *ifname_buf,
+                                           size_t       ifname_buf_len,
+                                           void        *user_data)
+{
+  (void)user_data;
+  return ares_os_if_indextoname(ifindex, ifname_buf, ifname_buf_len);
+}
+
 static const struct ares_socket_functions_ex default_socket_functions = {
   1,
   ARES_SOCKFUNC_FLAG_NONBLOCKING,
@@ -432,7 +447,9 @@ static const struct ares_socket_functions_ex default_socket_functions = {
   default_arecvfrom,
   default_asendto,
   default_agetsockname,
-  default_abind
+  default_abind,
+  default_aif_nametoindex,
+  default_aif_indextoname
 };
 
 void ares_set_socket_functions_default(ares_channel_t *channel)
@@ -550,7 +567,9 @@ static const struct ares_socket_functions_ex legacy_socket_functions = {
   legacycb_arecvfrom,
   legacycb_asendto,
   NULL, /* agetsockname */
-  NULL  /* abind */
+  NULL, /* abind */
+  NULL, /* aif_nametoindex */
+  NULL  /* aif_indextoname */
 };
 
 void ares_set_socket_functions(ares_channel_t                     *channel,

diff --git a/src/lib/ares_sysconfig.c b/src/lib/ares_sysconfig.c
@@ -59,7 +59,8 @@
 
 
 #if defined(__MVS__)
-static ares_status_t ares_init_sysconfig_mvs(ares_sysconfig_t *sysconfig)
+static ares_status_t ares_init_sysconfig_mvs(const ares_channel_t *channel,
+                                             ares_sysconfig_t     *sysconfig)
 {
   struct __res_state *res = 0;
   size_t              count4;
@@ -98,9 +99,9 @@ static ares_status_t ares_init_sysconfig_mvs(ares_sysconfig_t *sysconfig)
     addr.addr.addr4.s_addr = addr_in->sin_addr.s_addr;
     addr.family            = AF_INET;
 
-    status =
-      ares_sconfig_append(&sysconfig->sconfig, &addr, htons(addr_in->sin_port),
-                          htons(addr_in->sin_port), NULL);
+    status = ares_sconfig_append(channel, &sysconfig->sconfig, &addr,
+                                 htons(addr_in->sin_port),
+                                 htons(addr_in->sin_port), NULL);
 
     if (status != ARES_SUCCESS) {
       return status;
@@ -115,9 +116,9 @@ static ares_status_t ares_init_sysconfig_mvs(ares_sysconfig_t *sysconfig)
     memcpy(&(addr.addr.addr6), &(addr_in->sin6_addr),
            sizeof(addr_in->sin6_addr));
 
-    status =
-      ares_sconfig_append(&sysconfig->sconfig, &addr, htons(addr_in->sin_port),
-                          htons(addr_in->sin_port), NULL);
+    status = ares_sconfig_append(channel, &sysconfig->sconfig, &addr,
+                                 htons(addr_in->sin_port),
+                                 htons(addr_in->sin_port), NULL);
 
     if (status != ARES_SUCCESS) {
       return status;
@@ -129,7 +130,8 @@ static ares_status_t ares_init_sysconfig_mvs(ares_sysconfig_t *sysconfig)
 #endif
 
 #if defined(__riscos__)
-static ares_status_t ares_init_sysconfig_riscos(ares_sysconfig_t *sysconfig)
+static ares_status_t ares_init_sysconfig_riscos(const ares_channel_t *channel,
+                                                ares_sysconfig_t     *sysconfig)
 {
   char         *line;
   ares_status_t status = ARES_SUCCESS;
@@ -152,7 +154,8 @@ static ares_status_t ares_init_sysconfig_riscos(ares_sysconfig_t *sysconfig)
       if (space) {
         *space = '\0';
       }
-      status = ares_sconfig_append_fromstr(&sysconfig->sconfig, pos, ARES_TRUE);
+      status = ares_sconfig_append_fromstr(channel, &sysconfig->sconfig, pos,
+                                           ARES_TRUE);
       if (status != ARES_SUCCESS) {
         break;
       }
@@ -167,7 +170,8 @@ static ares_status_t ares_init_sysconfig_riscos(ares_sysconfig_t *sysconfig)
 #endif
 
 #if defined(WATT32)
-static ares_status_t ares_init_sysconfig_watt32(ares_sysconfig_t *sysconfig)
+static ares_status_t ares_init_sysconfig_watt32(const ares_channel_t *channel,
+                                                ares_sysconfig_t     *sysconfig)
 {
   size_t        i;
   ares_status_t status;
@@ -180,7 +184,8 @@ static ares_status_t ares_init_sysconfig_watt32(ares_sysconfig_t *sysconfig)
     addr.family            = AF_INET;
     addr.addr.addr4.s_addr = htonl(def_nameservers[i]);
 
-    status = ares_sconfig_append(&sysconfig->sconfig, &addr, 0, 0, NULL);
+    status =
+      ares_sconfig_append(channel, &sysconfig->sconfig, &addr, 0, 0, NULL);
 
     if (status != ARES_SUCCESS) {
       return status;
@@ -192,7 +197,8 @@ static ares_status_t ares_init_sysconfig_watt32(ares_sysconfig_t *sysconfig)
 #endif
 
 #if defined(ANDROID) || defined(__ANDROID__)
-static ares_status_t ares_init_sysconfig_android(ares_sysconfig_t *sysconfig)
+static ares_status_t ares_init_sysconfig_android(const ares_channel_t *channel,
+                                                 ares_sysconfig_t *sysconfig)
 {
   size_t        i;
   char        **dns_servers;
@@ -209,8 +215,8 @@ static ares_status_t ares_init_sysconfig_android(ares_sysconfig_t *sysconfig)
   dns_servers = ares_get_android_server_list(MAX_DNS_PROPERTIES, &num_servers);
   if (dns_servers != NULL) {
     for (i = 0; i < num_servers; i++) {
-      status = ares_sconfig_append_fromstr(&sysconfig->sconfig, dns_servers[i],
-                                           ARES_TRUE);
+      status = ares_sconfig_append_fromstr(channel, &sysconfig->sconfig,
+                                           dns_servers[i], ARES_TRUE);
       if (status != ARES_SUCCESS) {
         return status;
       }
@@ -241,8 +247,8 @@ static ares_status_t ares_init_sysconfig_android(ares_sysconfig_t *sysconfig)
       if (__system_property_get(propname, propvalue) < 1) {
         break;
       }
-      status =
-        ares_sconfig_append_fromstr(&sysconfig->sconfig, propvalue, ARES_TRUE);
+      status = ares_sconfig_append_fromstr(channel, &sysconfig->sconfig,
+                                           propvalue, ARES_TRUE);
       if (status != ARES_SUCCESS) {
         return status;
       }
@@ -255,7 +261,9 @@ static ares_status_t ares_init_sysconfig_android(ares_sysconfig_t *sysconfig)
 #endif
 
 #if defined(CARES_USE_LIBRESOLV)
-static ares_status_t ares_init_sysconfig_libresolv(ares_sysconfig_t *sysconfig)
+static ares_status_t
+  ares_init_sysconfig_libresolv(const ares_channel_t *channel,
+                                ares_sysconfig_t     *sysconfig)
 {
   struct __res_state       res;
   ares_status_t            status = ARES_SUCCESS;
@@ -343,7 +351,8 @@ static ares_status_t ares_init_sysconfig_libresolv(ares_sysconfig_t *sysconfig)
       goto done;
     }
 
-    status = ares_sconfig_append_fromstr(&sysconfig->sconfig, ipstr, ARES_TRUE);
+    status = ares_sconfig_append_fromstr(channel, &sysconfig->sconfig, ipstr,
+                                         ARES_TRUE);
 
     ares_free(ipstr);
     if (status != ARES_SUCCESS) {
@@ -494,19 +503,19 @@ ares_status_t ares_init_by_sysconfig(ares_channel_t *channel)
   sysconfig.ndots = 1; /* Default value if not otherwise set */
 
 #if defined(USE_WINSOCK)
-  status = ares_init_sysconfig_windows(&sysconfig);
+  status = ares_init_sysconfig_windows(channel, &sysconfig);
 #elif defined(__MVS__)
-  status = ares_init_sysconfig_mvs(&sysconfig);
+  status = ares_init_sysconfig_mvs(channel, &sysconfig);
 #elif defined(__riscos__)
-  status = ares_init_sysconfig_riscos(&sysconfig);
+  status = ares_init_sysconfig_riscos(channel, &sysconfig);
 #elif defined(WATT32)
-  status = ares_init_sysconfig_watt32(&sysconfig);
+  status = ares_init_sysconfig_watt32(channel, &sysconfig);
 #elif defined(ANDROID) || defined(__ANDROID__)
-  status = ares_init_sysconfig_android(&sysconfig);
+  status = ares_init_sysconfig_android(channel, &sysconfig);
 #elif defined(__APPLE__)
-  status = ares_init_sysconfig_macos(&sysconfig);
+  status = ares_init_sysconfig_macos(channel, &sysconfig);
 #elif defined(CARES_USE_LIBRESOLV)
-  status = ares_init_sysconfig_libresolv(&sysconfig);
+  status = ares_init_sysconfig_libresolv(channel, &sysconfig);
 #else
   status = ares_init_sysconfig_files(channel, &sysconfig);
 #endif