Added STUN DNS-SRV functionality to stun module. A simple test app is also...

Added STUN DNS-SRV functionality to stun module. A simple test app is also provided. This code is not yet used by other parts of the stun module.

darcs-hash:20060322010119-7659e-d025815b4b0b813b9b41b052c30efc9e380b1cf1.gz

RELEASE

@@ -18,6 +18,7 @@ API/ABI changes and versioning
    other important information to developers; 
  - and should be updated _continuously_! />
 
+- Added the stun_dns_lookup.*() interface to sofia-sip/stun.h.
 
 Contributors to this release
 ----------------------------

libsofia-sip-ua/stun/Makefile.am

@@ -10,18 +10,13 @@ AUTOMAKE_OPTIONS = 	foreign
 # ----------------------------------------------------------------------
 # Header paths
 
-INCLUDES = 		-I$(srcdir)/../su -I../su
+INCLUDES = 		-I$(srcdir)/../su -I../su -I$(srcdir)/../sresolv
 
 # ----------------------------------------------------------------------
 # Build targets
 
-# if HAVE_TLS
-stun_lib_sources = 	stun.c stun_common.c
-stun_prog_targets =     stunc torture_stun
-#else
-#stun_lib_targets = 
-#stun_prog_targets =
-#endif
+stun_lib_sources = 	stun.c stun_common.c stun_dns.c
+stun_prog_targets =     stunc torture_stun lookup_stun_server
 
 noinst_LTLIBRARIES = 	libstun.la
 
@@ -45,6 +40,8 @@ LDADD =			libstun.la \
 
 torture_stun_LDFLAGS = 	-static
 
+lookup_stun_server_LDADD = libstun.la ../sresolv/libsresolv.la ../su/libsu.la
+
 # ----------------------------------------------------------------------
 # tests
 # XXX: torture_stun cannot be used as a automake test as is

libsofia-sip-ua/stun/lookup_stun_server.c

+/*
+ * This file is part of the Sofia-SIP package
+ *
+ * Copyright (C) 2006 Nokia Corporation.
+ *
+ * Contact: Pekka Pessi <pekka.pessi@nokia.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ *
+ */
+
+/**
+ * @file lookup_stun_server.c 
+ * @brief Test app for STUN DNS-SRV lookups.
+ *
+ * @author Kai Vehmanen <Kai.Vehmanen@nokia.com>
+ *
+ * @todo TODO
+ * - picks one UDP and TLS target:port
+ * - does not pick up A/AAAA records that might be delivered
+ *   in 'Additional Data' section as defined in RFC2782
+ */
+
+#include <stdio.h>
+
+#include <sofia-sip/su.h>
+#include <sofia-sip/su_alloc.h>
+#include <sofia-sip/su_wait.h>
+#define STUN_MAGIC_T su_root_t
+#include <sofia-sip/stun.h>
+
+
+static void lookup_cb(stun_dns_lookup_t *self,
+		      su_root_t *root)
+{
+  const char *tls_target = NULL, *udp_target = NULL;
+  uint16_t tls_port = 0, udp_port = 0;
+  int res;
+
+  res = stun_dns_lookup_get_results(self, 
+				    &tls_target, &tls_port, 
+				    &udp_target, &udp_port);
+  if (res == 0) {
+    printf("STUN DNS-SRV: stun-tls at %s:%u.\n", tls_target, tls_port); 
+    printf("STUN DNS-SRV: stun (udp) at %s:%u.\n", udp_target, udp_port); 
+  }
+  
+  su_root_break(root);
+}
+
+int main(int argc, char *argv[])
+{
+  su_root_t *root;
+  stun_dns_lookup_t *lookup;
+
+  if (argc < 2) {
+    printf("usage: ./lookup_stun_server <domain>\n");
+    return -1;
+  }
+
+  /* step: initialize sofia su OS abstraction layer */
+  su_init();
+
+  /* step: create a su event loop and connect it to glib */
+  root = su_root_create(NULL);
+
+  /* step: initiate the DNS-SRV lookup */
+  lookup = stun_dns_lookup(root, root, lookup_cb, argv[1]);
+ 
+  /* step: enter the main loop (break fro lookup_cb()) */
+  su_root_run(root);
+
+  /* step: free any allocated resources */
+  stun_dns_lookup_destroy(lookup);
+  su_root_destroy(root);
+  su_deinit();
+
+  return 0;
+}

libsofia-sip-ua/stun/sofia-sip/stun.h

@@ -45,9 +45,10 @@
 
 SOFIA_BEGIN_DECLS
 
-typedef struct stun_handle_s    stun_handle_t;
-typedef struct stun_request_s   stun_request_t;
-typedef struct stun_discovery_s stun_discovery_t;
+typedef struct stun_handle_s     stun_handle_t;
+typedef struct stun_request_s    stun_request_t;
+typedef struct stun_discovery_s  stun_discovery_t;
+typedef struct stun_dns_lookup_s stun_dns_lookup_t;
 
 #ifndef STUN_MAGIC_T 
 #define STUN_MAGIC_T            struct stun_magic_t
@@ -120,6 +121,9 @@ typedef enum stun_state_e {
 
 } stun_state_t;
 
+/* -------------------------------------------------------------------
+ * Calback function prototypes (signals emitted by the stack) */
+
 /* Per discovery */
 typedef void (*stun_discovery_f)(stun_discovery_magic_t *magic,
 				 stun_handle_t *sh,
@@ -144,6 +148,10 @@ typedef int (*stun_send_callback)(stun_magic_t *magic,
 				  unsigned len,
 				  int only_a_keepalive);
 
+/** Callback for delivering DNS lookup results */
+typedef void (*stun_dns_lookup_f)(stun_dns_lookup_t *self,
+				  stun_magic_t *magic);
+
 /* -------------------------------------------------------------------
  * Functions for managing STUN handles. */
 
@@ -215,6 +223,19 @@ int stun_handle_set_uname_pwd(stun_handle_t *sh,
 			      const char *pwd,
 			      int len_pwd);
 
+/* -------------------------------------------------------------------
+ * Functions for STUN server discovery using DNS (RFC3489/3489bis) */
+
+stun_dns_lookup_t *stun_dns_lookup(stun_magic_t *magic, 
+				   su_root_t *root,
+				   stun_dns_lookup_f func, 
+				   const char *domain);
+int stun_dns_lookup_get_results(stun_dns_lookup_t *self, 
+				const char **tls_target,
+				uint16_t *tls_port,
+				const char **udp_target,
+				uint16_t *udp_port);
+void stun_dns_lookup_destroy(stun_dns_lookup_t *self);
 
 SOFIA_END_DECLS
 

libsofia-sip-ua/stun/stun_dns.c

+/*
+ * This file is part of the Sofia-SIP package
+ *
+ * Copyright (C) 2006 Nokia Corporation.
+ *
+ * Contact: Pekka Pessi <pekka.pessi@nokia.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ *
+ */
+
+/**
+ * @file stun_dns.c 
+ * @brief Functins to discover STUN server address using DNS-SRV.
+ *
+ * Refs: 
+ *   - RFC3489/3489bis
+ *   - RFC2782
+ * 
+ * @author Kai Vehmanen <kai.vehmanen@nokia.com>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#define STUN_SRV_SERVICE_TLS "_stun-tls._tcp"
+#define STUN_SRV_SERVICE_UDP "_stun._udp"
+
+#include <sofia-sip/stun.h>
+#include <sofia-sip/su.h>
+#include <sofia-sip/su_alloc.h>
+#include <sofia-sip/su_wait.h>
+#define HAVE_SU_WAIT_H 1 /* workaround for bug in sresolv.h */
+#define SRES_CONTEXT_T stun_dns_lookup_t
+#include <sofia-sip/sresolv.h>
+
+#include "stun_internal.h"
+
+struct stun_dns_lookup_s {
+  su_home_t          stun_home[1];
+  su_root_t         *stun_root;
+  stun_magic_t      *stun_magic;
+  sres_resolver_t   *stun_sres;
+  stun_dns_lookup_f  stun_cb;
+  char              *stun_tls_target;
+  char              *stun_udp_target;
+  uint16_t           stun_tls_port;
+  uint16_t           stun_udp_port;
+  unsigned           stun_state:2;       /**< bit0:udp, bit1:stun-tls */
+};
+
+enum stun_dns_state {
+  stun_dns_udp = 1,
+  stun_dns_tls = 2,
+  stun_dns_done = stun_dns_udp | stun_dns_tls
+};
+
+/**
+ * Internal callback used for gathering DNS replies.
+ */
+static void priv_sres_cb(stun_dns_lookup_t *self,
+			 sres_query_t *q,
+			 sres_record_t **answer)
+{
+  int i;
+
+  sres_sort_answers(self->stun_sres, answer);
+
+  /* note: picks the first ones (sort puts records with most
+   *       weight at start */
+
+  for (i = 0; answer[i] != NULL; i++) {
+    sres_srv_record_t *rr = (sres_srv_record_t *) answer[i]->sr_srv;
+    if (rr && rr->srv_record && rr->srv_record->r_type == sres_type_srv) {
+      const char *tls_name = STUN_SRV_SERVICE_TLS;
+      const char *udp_name = STUN_SRV_SERVICE_UDP;
+      if ((self->stun_state & stun_dns_tls) == 0 &&
+	  strncmp(rr->srv_record->r_name, tls_name, strlen(tls_name)) == 0) {
+	self->stun_tls_target = su_strdup(self->stun_home, rr->srv_target);
+	self->stun_tls_port = rr->srv_port;
+	self->stun_state |= stun_dns_tls;
+	SU_DEBUG_5(("%s: stun-tls for domain %s is at %s:%u.\n", 
+		    __func__, rr->srv_record->r_name, self->stun_tls_target, self->stun_tls_port)); 
+      }
+      else if ((self->stun_state & stun_dns_udp) == 0 &&
+	       strncmp(rr->srv_record->r_name, udp_name, strlen(udp_name)) == 0) {
+	self->stun_udp_target = su_strdup(self->stun_home, rr->srv_target);
+	self->stun_udp_port = rr->srv_port;
+	self->stun_state |= stun_dns_udp;
+	SU_DEBUG_5(("%s: stun for domain %s is at %s:%u.\n", 
+		    __func__, rr->srv_record->r_name, self->stun_udp_target, self->stun_udp_port)); 
+      }
+    }
+  }
+
+  if (self->stun_state == stun_dns_done) {
+    self->stun_cb(self, self->stun_magic);
+  }
+
+  sres_free_answers(self->stun_sres, answer);
+}
+
+/**
+ * Performs a DNS-SRV check for STUN 'stun-tls' and
+ * 'stun' (udp) services for 'domain'.
+ *
+ * The result will be delivered asynchronously in the
+ * 'func' callback. 'root' will be used as the event loop.
+ */
+stun_dns_lookup_t *stun_dns_lookup(stun_magic_t *magic, 
+				   su_root_t *root,
+				   stun_dns_lookup_f func, 
+				   const char *domain)
+{
+  stun_dns_lookup_t *self = su_zalloc(NULL, sizeof(stun_dns_lookup_t));
+  sres_query_t *query;
+  int socket;
+  
+  /* see nta.c:outgoing_answer_srv() */
+
+  su_home_init(self->stun_home);
+  self->stun_magic = magic;
+  self->stun_cb = func;
+  self->stun_root = root;
+  self->stun_sres = sres_resolver_create(root, NULL, TAG_END());
+  if (self->stun_sres) {
+    socket = sres_resolver_root_socket(self->stun_sres);
+    if (socket > 0) {
+      char *query_udp = su_sprintf(self->stun_home, "%s.%s", STUN_SRV_SERVICE_UDP, domain);
+      char *query_tcp = su_sprintf(self->stun_home, "%s.%s", STUN_SRV_SERVICE_TLS, domain);
+      
+      query = sres_query_make(self->stun_sres, priv_sres_cb, self, socket, sres_type_srv, query_udp);
+      query = sres_query_make(self->stun_sres, priv_sres_cb, self, socket, sres_type_srv, query_tcp);
+    }
+    else {
+      sres_resolver_destroy(self->stun_sres);
+      su_free(NULL, self), self = NULL;
+    }
+  }
+  else {
+    su_free(NULL, self), self = NULL;
+  }
+  
+  return self;
+}
+
+/**
+ * Fetches the results of a completed STUN DNS-SRV lookup.
+ *
+ * @param self context pointer
+ * @param tls_target location where to stored the 'target'
+ *        SRV field for stun-tls service
+ * @param tls_port location where to store port number
+ * @param udp_target location where to stored the 'target'
+ *        SRV field for stun service (udp)
+ * @param udp_port location where to store port number
+ *
+ * @return 0 on success, non-zero otherwise
+ */ 
+int stun_dns_lookup_get_results(stun_dns_lookup_t *self, 
+				const char **tls_target,
+				uint16_t *tls_port,
+				const char **udp_target,
+				uint16_t *udp_port)
+{
+  int result = -1;
+  if (self->stun_state == stun_dns_done) {
+    if (tls_target) *tls_target = self->stun_tls_target;
+    if (tls_port) *tls_port = self->stun_tls_port;
+    if (udp_target) *udp_target = self->stun_udp_target;
+    if (udp_port) *udp_port = self->stun_udp_port;
+    result = 0;
+  }
+
+  return result;
+}
+
+/**
+ * Destroys the 'self' object created by stun_dns_lookup_destroy().
+ */
+void stun_dns_lookup_destroy(stun_dns_lookup_t *self)
+{
+  if (self->stun_sres)
+    sres_resolver_destroy(self->stun_sres);
+  su_home_destroy(self->stun_home);
+  su_free(NULL, self);
+}
+