Ticket #326: Add DNS resolver and DNS SRV resolver test in pjlib-util

git-svn-id: http://svn.pjsip.org/repos/pjproject/trunk@1347 74dad513-b988-da41-8d7b-12977e46ad98

4 files changed, 956 insertions, 2 deletions

diff --git a/pjlib-util/src/pjlib-util-test/main.c b/pjlib-util/src/pjlib-util-test/main.c
index 33583e30..35cb6837 100644
--- a/pjlib-util/src/pjlib-util-test/main.c
+++ b/pjlib-util/src/pjlib-util-test/main.c
@@ -17,6 +17,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
  */
 #include "test.h"
+#include <pj/string.h>
 
 #if defined(PJ_SUNOS) && PJ_SUNOS!=0
 #include <signal.h>
@@ -48,6 +49,13 @@ int main(int argc, char *argv[])
 
     rc = test_main();
 
+    if (argc==2 && pj_ansi_strcmp(argv[1], "-i")==0) {
+	char s[10];
+
+	puts("Press ENTER to quit");
+	fgets(s, sizeof(s), stdin);
+    }
+
     return rc;
 }
 
diff --git a/pjlib-util/src/pjlib-util-test/resolver_test.c b/pjlib-util/src/pjlib-util-test/resolver_test.c
new file mode 100644
index 00000000..e045b280
--- /dev/null
+++ b/pjlib-util/src/pjlib-util-test/resolver_test.c
@@ -0,0 +1,936 @@
+/* $Id$ */
+/* 
+ * Copyright (C) 2003-2007 Benny Prijono <benny@prijono.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
+ */
+#include <pjlib-util.h>
+#include <pjlib.h>
+#include "test.h"
+
+
+#define THIS_FILE   "srv_resolver_test.c"
+
+#define ACTION_REPLY	0
+#define ACTION_IGNORE	-1
+#define ACTION_CB	-2
+
+static struct server_t
+{
+    pj_sock_t	     sock;
+    pj_uint16_t	     port;
+    pj_thread_t	    *thread;
+
+    /* Action:
+     *	0:    reply with the response in resp.
+     * -1:    ignore query (to simulate timeout).
+     * other: reply with that error
+     */
+    int		    action;
+
+    pj_dns_parsed_packet    resp;
+    void		  (*action_cb)(const pj_dns_parsed_packet *pkt,
+				       pj_dns_parsed_packet **p_res);
+
+    unsigned	    pkt_count;
+
+} g_server[2];
+
+static pj_pool_t *pool;
+static pj_dns_resolver *resolver;
+static pj_bool_t thread_quit;
+static pj_timer_heap_t *timer_heap;
+static pj_ioqueue_t *ioqueue;
+static pj_thread_t *poll_thread;
+static pj_sem_t *sem;
+static pj_dns_settings set;
+
+static int print_label(char *start, const pj_str_t *name)
+{
+    char *p = (char*) start;
+    const char *startlabel, *endlabel;
+    char *endname;
+
+    /* Tokenize name */
+    startlabel = endlabel = name->ptr;
+    endname = name->ptr + name->slen;
+    while (endlabel != endname) {
+	while (endlabel != endname && *endlabel != '.')
+	    ++endlabel;
+	*p++ = (char)(endlabel - startlabel);
+	pj_memcpy(p, startlabel, endlabel-startlabel);
+	p += (endlabel-startlabel);
+	if (endlabel != endname && *endlabel == '.')
+	    ++endlabel;
+	startlabel = endlabel;
+    }
+    *p++ = '\0';
+
+    return p-start;
+}
+
+static int print_packet(const pj_dns_parsed_packet *rec, char *packet)
+{
+    pj_dns_hdr *hdr;
+    char *p;
+    int i, len;
+
+    /* Initialize header */
+    hdr = (pj_dns_hdr*) packet;
+    pj_bzero(hdr, sizeof(pj_dns_hdr));
+    hdr->id = pj_htons(rec->hdr.id);
+    hdr->flags = pj_htons(rec->hdr.flags);
+    hdr->qdcount = pj_htons(rec->hdr.qdcount);
+    hdr->anscount = pj_htons(rec->hdr.anscount);
+    hdr->nscount = pj_htons(rec->hdr.nscount);
+    hdr->arcount = pj_htons(rec->hdr.arcount);
+
+    p = packet + sizeof(pj_dns_hdr);
+
+    /* Print queries */
+    for (i=0; i<rec->hdr.qdcount; ++i) {
+	pj_uint16_t tmp;
+
+	len = print_label(p, &rec->q[i].name);
+	p += len;
+
+	/* Set type */
+	tmp = pj_htons((pj_uint16_t)rec->q[i].type);
+	pj_memcpy(p, &tmp, 2);
+	p += 2;
+
+	/* Set class (IN=1) */
+	tmp = pj_htons(rec->q[i].dnsclass);
+	pj_memcpy(p, &tmp, 2);
+	p += 2;
+    }
+
+    /* Print answers */
+    for (i=0; i<rec->hdr.anscount; ++i) {
+	const pj_dns_parsed_rr *rr = &rec->ans[i];
+	pj_uint16_t tmp;
+	pj_uint32_t ttl;
+
+	len = print_label(p, &rr->name);
+	p += len;
+
+	/* Set type */
+	tmp = pj_htons((pj_uint16_t)rr->type);
+	pj_memcpy(p, &tmp, 2);
+	p += 2;
+
+	/* Set class */
+	tmp = pj_htons((pj_uint16_t)rr->dnsclass);
+	pj_memcpy(p, &tmp, 2);
+	p += 2;
+
+	/* Set TTL */
+	ttl = pj_htonl(rr->ttl);
+	pj_memcpy(p, &ttl, 4);
+	p += 4;
+
+	if (rr->type == PJ_DNS_TYPE_A) {
+
+	    /* RDLEN is 4 */
+	    tmp = pj_htons(4);
+	    pj_memcpy(p, &tmp, 2);
+	    p += 2;
+
+	    /* Address */
+	    pj_memcpy(p, &rr->rdata.a.ip_addr, 4);
+	    p += 4;
+
+	} else if (rr->type == PJ_DNS_TYPE_CNAME ||
+		   rr->type == PJ_DNS_TYPE_NS) {
+
+	    len = print_label(p+2, &rr->rdata.cname.name);
+
+	    tmp = pj_htons((pj_uint16_t)len);
+	    pj_memcpy(p, &tmp, 2);
+
+	    p += (len + 2);
+
+	} else if (rr->type == PJ_DNS_TYPE_SRV) {
+
+	    /* Skip RDLEN (will write later) */
+	    char *p_rdlen = p;
+
+	    p += 2;
+
+	    /* Priority */
+	    tmp = pj_htons(rr->rdata.srv.prio);
+	    pj_memcpy(p, &tmp, 2);
+	    p += 2;
+
+	    /* Weight */
+	    tmp = pj_htons(rr->rdata.srv.weight);
+	    pj_memcpy(p, &tmp, 2);
+	    p += 2;
+
+	    /* Port */
+	    tmp = pj_htons(rr->rdata.srv.port);
+	    pj_memcpy(p, &tmp, 2);
+	    p += 2;
+
+	    /* Target */
+	    len = print_label(p, &rr->rdata.srv.target);
+
+	    /* Now print RDLEN */
+	    tmp = pj_htons((pj_uint16_t)(len + 6));
+	    pj_memcpy(p_rdlen, &tmp, 2);
+
+	    p += len;
+
+	} else {
+	    pj_assert(!"Not supported");
+	}
+    }
+
+    return p - packet;
+}
+
+
+static int server_thread(void *p)
+{
+    struct server_t *srv = (struct server_t*)p;
+
+    while (!thread_quit) {
+	pj_fd_set_t rset;
+	pj_time_val timeout = {0, 500};
+	pj_sockaddr_in src_addr;
+	pj_dns_parsed_packet *req;
+	char pkt[1024];
+	pj_ssize_t pkt_len;
+	int rc, src_len;
+
+	PJ_FD_ZERO(&rset);
+	PJ_FD_SET(srv->sock, &rset);
+
+	rc = pj_sock_select(srv->sock+1, &rset, NULL, NULL, &timeout);
+	if (rc != 1)
+	    continue;
+
+	src_len = sizeof(src_addr);
+	pkt_len = sizeof(pkt);
+	rc = pj_sock_recvfrom(srv->sock, pkt, &pkt_len, 0, 
+			      &src_addr, &src_len);
+	if (rc != 0) {
+	    app_perror("Server error receiving packet", rc);
+	    continue;
+	}
+
+	PJ_LOG(5,(THIS_FILE, "Server %d processing packet", srv - &g_server[0]));
+	srv->pkt_count++;
+
+	rc = pj_dns_parse_packet(pool, pkt, pkt_len, &req);
+	if (rc != PJ_SUCCESS) {
+	    app_perror("server error parsing packet", rc);
+	    continue;
+	}
+
+	/* Simulate network RTT */
+	pj_thread_sleep(50);
+
+	if (srv->action == ACTION_IGNORE) {
+	    continue;
+	} else if (srv->action == ACTION_REPLY) {
+	    srv->resp.hdr.id = req->hdr.id;
+	    pkt_len = print_packet(&srv->resp, pkt);
+	    pj_sock_sendto(srv->sock, pkt, &pkt_len, 0, &src_addr, src_len);
+	} else if (srv->action == ACTION_CB) {
+	    pj_dns_parsed_packet *resp;
+	    (*srv->action_cb)(req, &resp);
+	    resp->hdr.id = req->hdr.id;
+	    pkt_len = print_packet(resp, pkt);
+	    pj_sock_sendto(srv->sock, pkt, &pkt_len, 0, &src_addr, src_len);
+	} else if (srv->action > 0) {
+	    req->hdr.flags |= PJ_DNS_SET_RCODE(srv->action);
+	    pkt_len = print_packet(req, pkt);
+	    pj_sock_sendto(srv->sock, pkt, &pkt_len, 0, &src_addr, src_len);
+	}
+    }
+
+    return 0;
+}
+
+static int poll_worker_thread(void *p)
+{
+    PJ_UNUSED_ARG(p);
+
+    while (!thread_quit) {
+	pj_time_val delay = {0, 100};
+	pj_timer_heap_poll(timer_heap, NULL);
+	pj_ioqueue_poll(ioqueue, &delay);
+    }
+
+    return 0;
+}
+
+static void destroy(void);
+
+static int init(void)
+{
+    pj_status_t status;
+    pj_str_t nameservers[2];
+    pj_uint16_t ports[2];
+    int i;
+
+    nameservers[0] = pj_str("127.0.0.1");
+    ports[0] = 553;
+    nameservers[1] = pj_str("127.0.0.1");
+    ports[1] = 554;
+
+    g_server[0].port = ports[0];
+    g_server[1].port = ports[1];
+
+    pool = pj_pool_create(mem, NULL, 2000, 2000, NULL);
+
+    status = pj_sem_create(pool, NULL, 0, 2, &sem);
+    pj_assert(status == PJ_SUCCESS);
+
+    for (i=0; i<2; ++i) {
+	pj_sockaddr_in addr;
+
+	status = pj_sock_socket(PJ_AF_INET, PJ_SOCK_DGRAM, 0, &g_server[i].sock);
+	if (status != PJ_SUCCESS)
+	    return -10;
+
+	pj_sockaddr_in_init(&addr, NULL, (pj_uint16_t)g_server[i].port);
+
+	status = pj_sock_bind(g_server[i].sock, &addr, sizeof(addr));
+	if (status != PJ_SUCCESS)
+	    return -20;
+
+	status = pj_thread_create(pool, NULL, &server_thread, &g_server[i],
+				  0, 0, &g_server[i].thread);
+	if (status != PJ_SUCCESS)
+	    return -30;
+    }
+
+    status = pj_timer_heap_create(pool, 16, &timer_heap);
+    pj_assert(status == PJ_SUCCESS);
+
+    status = pj_ioqueue_create(pool, 16, &ioqueue);
+    pj_assert(status == PJ_SUCCESS);
+
+    status = pj_dns_resolver_create(mem, NULL, 0, timer_heap, ioqueue, &resolver);
+    if (status != PJ_SUCCESS)
+	return -40;
+
+    pj_dns_resolver_get_settings(resolver, &set);
+    set.good_ns_ttl = 20;
+    set.bad_ns_ttl = 20;
+    pj_dns_resolver_set_settings(resolver, &set);
+
+    status = pj_dns_resolver_set_ns(resolver, 2, nameservers, ports);
+    pj_assert(status == PJ_SUCCESS);
+
+    status = pj_thread_create(pool, NULL, &poll_worker_thread, NULL, 0, 0, &poll_thread);
+    pj_assert(status == PJ_SUCCESS);
+
+    return 0;
+}
+
+
+static void destroy(void)
+{
+    int i;
+
+    thread_quit = PJ_TRUE;
+
+    for (i=0; i<2; ++i) {
+	pj_thread_join(g_server[i].thread);
+	pj_sock_close(g_server[i].sock);
+    }
+
+    pj_thread_join(poll_thread);
+
+    pj_dns_resolver_destroy(resolver, PJ_FALSE);
+    pj_ioqueue_destroy(ioqueue);
+    pj_timer_heap_destroy(timer_heap);
+
+    pj_sem_destroy(sem);
+    pj_pool_release(pool);
+}
+
+
+////////////////////////////////////////////////////////////////////////////
+/* Simple DNS test */
+#define IP_ADDR0    0x00010203
+
+static void dns_callback(void *user_data,
+			 pj_status_t status,
+			 pj_dns_parsed_packet *resp)
+{
+    PJ_UNUSED_ARG(user_data);
+
+    pj_assert(status == PJ_SUCCESS);
+    pj_assert(resp);
+    pj_assert(resp->hdr.anscount == 1);
+    pj_assert(resp->ans[0].type == PJ_DNS_TYPE_A);
+    pj_assert(resp->ans[0].rdata.a.ip_addr.s_addr == IP_ADDR0);
+
+    pj_sem_post(sem);
+}
+
+
+static int simple_test(void)
+{
+    pj_str_t name = pj_str("helloworld");
+    pj_dns_parsed_packet *r;
+    pj_status_t status;
+
+    PJ_LOG(3,(THIS_FILE, "    simple successful test"));
+
+    g_server[0].pkt_count = 0;
+    g_server[1].pkt_count = 0;
+
+    g_server[0].action = ACTION_REPLY;
+    r = &g_server[0].resp;
+    r->hdr.qdcount = 1;
+    r->hdr.anscount = 1;
+    r->q = PJ_POOL_ZALLOC_T(pool, pj_dns_parsed_query);
+    r->q[0].type = PJ_DNS_TYPE_A;
+    r->q[0].dnsclass = 1;
+    r->q[0].name = name;
+    r->ans = PJ_POOL_ZALLOC_T(pool, pj_dns_parsed_rr);
+    r->ans[0].type = PJ_DNS_TYPE_A;
+    r->ans[0].dnsclass = 1;
+    r->ans[0].name = name;
+    r->ans[0].rdata.a.ip_addr.s_addr = IP_ADDR0;
+
+    g_server[1].action = ACTION_REPLY;
+    r = &g_server[1].resp;
+    r->hdr.qdcount = 1;
+    r->hdr.anscount = 1;
+    r->q = PJ_POOL_ZALLOC_T(pool, pj_dns_parsed_query);
+    r->q[0].type = PJ_DNS_TYPE_A;
+    r->q[0].dnsclass = 1;
+    r->q[0].name = name;
+    r->ans = PJ_POOL_ZALLOC_T(pool, pj_dns_parsed_rr);
+    r->ans[0].type = PJ_DNS_TYPE_A;
+    r->ans[0].dnsclass = 1;
+    r->ans[0].name = name;
+    r->ans[0].rdata.a.ip_addr.s_addr = IP_ADDR0;
+
+    status = pj_dns_resolver_start_query(resolver, &name, PJ_DNS_TYPE_A, 0,
+					 &dns_callback, NULL, NULL);
+    if (status != PJ_SUCCESS)
+	return -1000;
+
+    pj_sem_wait(sem);
+    pj_thread_sleep(1000);
+
+
+    /* Both servers must get packet */
+    pj_assert(g_server[0].pkt_count == 1);
+    pj_assert(g_server[1].pkt_count == 1);
+
+    return 0;
+}
+
+
+////////////////////////////////////////////////////////////////////////////
+/* DNS nameserver fail-over test */
+
+static void dns_callback_1b(void *user_data,
+			    pj_status_t status,
+			    pj_dns_parsed_packet *resp)
+{
+    PJ_UNUSED_ARG(user_data);
+    PJ_UNUSED_ARG(resp);
+
+    pj_assert(status == PJ_STATUS_FROM_DNS_RCODE(PJ_DNS_RCODE_NXDOMAIN));
+
+    pj_sem_post(sem);
+}
+
+
+
+
+/* DNS test */
+static int dns_test(void)
+{
+    pj_str_t name = pj_str("name00");
+    pj_status_t status;
+
+    PJ_LOG(3,(THIS_FILE, "    simple error response test"));
+
+    g_server[0].pkt_count = 0;
+    g_server[1].pkt_count = 0;
+
+    g_server[0].action = PJ_DNS_RCODE_NXDOMAIN;
+    g_server[1].action = PJ_DNS_RCODE_NXDOMAIN;
+
+    status = pj_dns_resolver_start_query(resolver, &name, PJ_DNS_TYPE_A, 0,
+					 &dns_callback_1b, NULL, NULL);
+    if (status != PJ_SUCCESS)
+	return -1000;
+
+    pj_sem_wait(sem);
+    pj_thread_sleep(1000);
+
+    /* Now only server 0 should get packet, since both servers are
+     * in STATE_ACTIVE state
+     */
+    pj_assert(g_server[0].pkt_count == 1);
+    pj_assert(g_server[1].pkt_count == 0);
+
+    /* Wait to allow probing period to complete */
+    PJ_LOG(3,(THIS_FILE, "    waiting for active NS to expire (%d sec)",
+			 set.good_ns_ttl));
+    pj_thread_sleep(set.good_ns_ttl * 1000);
+
+    /* 
+     * Fail-over test 
+     */
+    PJ_LOG(3,(THIS_FILE, "    failing server0"));
+    g_server[0].action = ACTION_IGNORE;
+    g_server[1].action = PJ_DNS_RCODE_NXDOMAIN;
+
+    g_server[0].pkt_count = 0;
+    g_server[1].pkt_count = 0;
+
+    name = pj_str("name01");
+    status = pj_dns_resolver_start_query(resolver, &name, PJ_DNS_TYPE_A, 0,
+					 &dns_callback_1b, NULL, NULL);
+    if (status != PJ_SUCCESS)
+	return -1000;
+
+    pj_sem_wait(sem);
+
+    /*
+     * Check that both servers still receive requests, since they are
+     * in probing state.
+     */
+    PJ_LOG(3,(THIS_FILE, "    checking both NS during probing period"));
+    g_server[0].action = ACTION_IGNORE;
+    g_server[1].action = PJ_DNS_RCODE_NXDOMAIN;
+
+    g_server[0].pkt_count = 0;
+    g_server[1].pkt_count = 0;
+
+    name = pj_str("name02");
+    status = pj_dns_resolver_start_query(resolver, &name, PJ_DNS_TYPE_A, 0,
+					 &dns_callback_1b, NULL, NULL);
+    if (status != PJ_SUCCESS)
+	return -1000;
+
+    pj_sem_wait(sem);
+    pj_thread_sleep(set.qretr_delay *  set.qretr_count);
+
+    /* Both servers must get requests */
+    pj_assert(g_server[0].pkt_count >= 1);
+    pj_assert(g_server[1].pkt_count == 1);
+
+    /* Wait to allow probing period to complete */
+    PJ_LOG(3,(THIS_FILE, "    waiting for probing state to end (%d sec)",
+			 set.qretr_delay * 
+			 (set.qretr_count+2) / 1000));
+    pj_thread_sleep(set.qretr_delay * (set.qretr_count + 2));
+
+
+    /*
+     * Now only server 1 should get requests.
+     */
+    PJ_LOG(3,(THIS_FILE, "    verifying only good NS is used"));
+    g_server[0].action = PJ_DNS_RCODE_NXDOMAIN;
+    g_server[1].action = PJ_DNS_RCODE_NXDOMAIN;
+
+    g_server[0].pkt_count = 0;
+    g_server[1].pkt_count = 0;
+
+    name = pj_str("name03");
+    status = pj_dns_resolver_start_query(resolver, &name, PJ_DNS_TYPE_A, 0,
+					 &dns_callback_1b, NULL, NULL);
+    if (status != PJ_SUCCESS)
+	return -1000;
+
+    pj_sem_wait(sem);
+    pj_thread_sleep(1000);
+
+    /* Both servers must get requests */
+    pj_assert(g_server[0].pkt_count == 0);
+    pj_assert(g_server[1].pkt_count == 1);
+
+    /* Wait to allow probing period to complete */
+    PJ_LOG(3,(THIS_FILE, "    waiting for active NS to expire (%d sec)",
+			 set.good_ns_ttl));
+    pj_thread_sleep(set.good_ns_ttl * 1000);
+
+    /*
+     * Now fail server 1 to switch to server 0
+     */
+    g_server[0].action = PJ_DNS_RCODE_NXDOMAIN;
+    g_server[1].action = ACTION_IGNORE;
+
+    g_server[0].pkt_count = 0;
+    g_server[1].pkt_count = 0;
+
+    name = pj_str("name04");
+    status = pj_dns_resolver_start_query(resolver, &name, PJ_DNS_TYPE_A, 0,
+					 &dns_callback_1b, NULL, NULL);
+    if (status != PJ_SUCCESS)
+	return -1000;
+
+    pj_sem_wait(sem);
+
+    /* Wait to allow probing period to complete */
+    PJ_LOG(3,(THIS_FILE, "    waiting for probing state (%d sec)",
+			 set.qretr_delay * (set.qretr_count+2) / 1000));
+    pj_thread_sleep(set.qretr_delay * (set.qretr_count + 2));
+
+    /*
+     * Now only server 0 should get requests.
+     */
+    PJ_LOG(3,(THIS_FILE, "    verifying good NS"));
+    g_server[0].action = PJ_DNS_RCODE_NXDOMAIN;
+    g_server[1].action = ACTION_IGNORE;
+
+    g_server[0].pkt_count = 0;
+    g_server[1].pkt_count = 0;
+
+    name = pj_str("name05");
+    status = pj_dns_resolver_start_query(resolver, &name, PJ_DNS_TYPE_A, 0,
+					 &dns_callback_1b, NULL, NULL);
+    if (status != PJ_SUCCESS)
+	return -1000;
+
+    pj_sem_wait(sem);
+    pj_thread_sleep(1000);
+
+    /* Both servers must get requests */
+    pj_assert(g_server[0].pkt_count == 1);
+    pj_assert(g_server[1].pkt_count == 0);
+
+
+    return 0;
+}
+
+
+////////////////////////////////////////////////////////////////////////////
+/* Resolver test, normal, with CNAME */
+#define IP_ADDR1    0x02030405
+
+static void action1_1(const pj_dns_parsed_packet *pkt,
+		      pj_dns_parsed_packet **p_res)
+{
+    pj_dns_parsed_packet *res;
+    char *target = "sip.somedomain.com";
+
+    res = PJ_POOL_ZALLOC_T(pool, pj_dns_parsed_packet);
+
+    if (res->q == NULL) {
+	res->q = PJ_POOL_ZALLOC_T(pool, pj_dns_parsed_query);
+    }
+    if (res->ans == NULL) {
+	res->ans = (pj_dns_parsed_rr*) 
+		  pj_pool_calloc(pool, 4, sizeof(pj_dns_parsed_rr));
+    }
+
+    res->hdr.qdcount = 1;
+    res->q[0].type = pkt->q[0].type;
+    res->q[0].dnsclass = pkt->q[0].dnsclass;
+    res->q[0].name = pkt->q[0].name;
+
+    if (pkt->q[0].type == PJ_DNS_TYPE_SRV) {
+
+	pj_assert(pj_strcmp2(&pkt->q[0].name, "_sip._udp.somedomain.com")==0);
+
+	res->hdr.anscount = 1;
+	res->ans[0].type = PJ_DNS_TYPE_SRV;
+	res->ans[0].dnsclass = 1;
+	res->ans[0].name = res->q[0].name;
+	res->ans[0].ttl = 1;
+	res->ans[0].rdata.srv.prio = 1;
+	res->ans[0].rdata.srv.weight = 2;
+	res->ans[0].rdata.srv.port = 5061;
+	res->ans[0].rdata.srv.target = pj_str(target);
+
+    } else if (pkt->q[0].type == PJ_DNS_TYPE_A) {
+	char *alias = "sipalias.somedomain.com";
+
+	pj_assert(pj_strcmp2(&res->q[0].name, target)==0);
+
+	res->hdr.anscount = 2;
+	res->ans[0].type = PJ_DNS_TYPE_CNAME;
+	res->ans[0].dnsclass = 1;
+	res->ans[0].ttl = 1000;	/* resolver should select minimum TTL */
+	res->ans[0].name = res->q[0].name;
+	res->ans[0].rdata.cname.name = pj_str(alias);
+
+	res->ans[1].type = PJ_DNS_TYPE_A;
+	res->ans[1].dnsclass = 1;
+	res->ans[1].ttl = 1;
+	res->ans[1].name = pj_str(alias);
+	res->ans[1].rdata.a.ip_addr.s_addr = IP_ADDR1;
+    }
+
+    *p_res = res;
+}
+
+static void srv_cb_1(void *user_data,
+		     pj_status_t status,
+		     const pj_dns_srv_record *rec)
+{
+    PJ_UNUSED_ARG(user_data);
+
+    pj_assert(status == PJ_SUCCESS);
+    pj_assert(rec->count == 1);
+    pj_assert(rec->entry[0].priority == 1);
+    pj_assert(rec->entry[0].weight == 2);
+    pj_assert(rec->entry[0].addr.ipv4.sin_addr.s_addr == IP_ADDR1);
+    pj_assert(pj_ntohs(rec->entry[0].addr.ipv4.sin_port) == 5061);
+
+    pj_sem_post(sem);
+}
+
+static void srv_cb_1b(void *user_data,
+		      pj_status_t status,
+		      const pj_dns_srv_record *rec)
+{
+    PJ_UNUSED_ARG(user_data);
+
+    pj_assert(status == PJ_STATUS_FROM_DNS_RCODE(PJ_DNS_RCODE_NXDOMAIN));
+    pj_assert(rec->count == 0);
+
+    pj_sem_post(sem);
+}
+
+static int srv_resolver_test(void)
+{
+    pj_status_t status;
+    pj_str_t domain = pj_str("somedomain.com");
+    pj_str_t res_name = pj_str("_sip._udp.");
+
+    /* Successful scenario */
+    PJ_LOG(3,(THIS_FILE, "    srv_resolve(): success scenario"));
+
+    g_server[0].action = ACTION_CB;
+    g_server[0].action_cb = &action1_1;
+    g_server[1].action = ACTION_CB;
+    g_server[1].action_cb = &action1_1;
+
+    g_server[0].pkt_count = 0;
+    g_server[1].pkt_count = 0;
+
+    status = pj_dns_srv_resolve(&domain, &res_name, 5061, pool, resolver, PJ_TRUE,
+				NULL, &srv_cb_1);
+    pj_assert(status == PJ_SUCCESS);
+
+    pj_sem_wait(sem);
+
+    /* Both servers should receive requests since state should be probing */
+    pj_assert(g_server[0].pkt_count == 2);  /* 2 because of SRV and A resolution */
+    pj_assert(g_server[1].pkt_count == 0);
+
+
+    /* Wait until cache expires and nameserver state moves out from STATE_PROBING */
+    PJ_LOG(3,(THIS_FILE, "    waiting for cache to expire (~15 secs).."));
+    pj_thread_sleep(1000 + 
+		    ((set.qretr_count + 2) * set.qretr_delay));
+
+    /* Successful scenario */
+    PJ_LOG(3,(THIS_FILE, "    srv_resolve(): parallel queries"));
+    g_server[0].pkt_count = 0;
+    g_server[1].pkt_count = 0;
+
+    status = pj_dns_srv_resolve(&domain, &res_name, 5061, pool, resolver, PJ_TRUE,
+				NULL, &srv_cb_1);
+    pj_assert(status == PJ_SUCCESS);
+
+
+    status = pj_dns_srv_resolve(&domain, &res_name, 5061, pool, resolver, PJ_TRUE,
+				NULL, &srv_cb_1);
+    pj_assert(status == PJ_SUCCESS);
+
+    pj_sem_wait(sem);
+    pj_sem_wait(sem);
+
+    /* Only server one should get a query */
+    pj_assert(g_server[0].pkt_count == 2);  /* 2 because of SRV and A resolution */
+    pj_assert(g_server[1].pkt_count == 0);
+
+    /* Since TTL is one, subsequent queries should fail */
+    PJ_LOG(3,(THIS_FILE, "    srv_resolve(): cache expires scenario"));
+
+
+    pj_thread_sleep(1000);
+
+    g_server[0].action = PJ_DNS_RCODE_NXDOMAIN;
+    g_server[1].action = PJ_DNS_RCODE_NXDOMAIN;
+
+    status = pj_dns_srv_resolve(&domain, &res_name, 5061, pool, resolver, PJ_TRUE,
+				NULL, &srv_cb_1b);
+    pj_assert(status == PJ_SUCCESS);
+
+    pj_sem_wait(sem);
+
+    return 0;
+}
+
+
+////////////////////////////////////////////////////////////////////////////
+/* Fallback because there's no SRV in answer */
+#define TARGET	    "domain2.com"
+#define IP_ADDR2    0x02030405
+
+static void action2_1(const pj_dns_parsed_packet *pkt,
+		      pj_dns_parsed_packet **p_res)
+{
+    static pj_dns_parsed_packet res;
+
+    if (res.q == NULL) {
+	res.q = PJ_POOL_ZALLOC_T(pool, pj_dns_parsed_query);
+    }
+    if (res.ans == NULL) {
+	res.ans = (pj_dns_parsed_rr*) 
+		  pj_pool_calloc(pool, 4, sizeof(pj_dns_parsed_rr));
+    }
+
+    res.hdr.qdcount = 1;
+    res.q[0].type = pkt->q[0].type;
+    res.q[0].dnsclass = pkt->q[0].dnsclass;
+    res.q[0].name = pkt->q[0].name;
+
+    if (pkt->q[0].type == PJ_DNS_TYPE_SRV) {
+
+	pj_assert(pj_strcmp2(&pkt->q[0].name, "_sip._udp." TARGET)==0);
+
+	res.hdr.anscount = 1;
+	res.ans[0].type = PJ_DNS_TYPE_A;    // <-- this will cause the fallback
+	res.ans[0].dnsclass = 1;
+	res.ans[0].name = res.q[0].name;
+	res.ans[0].ttl = 1;
+	res.ans[0].rdata.srv.prio = 1;
+	res.ans[0].rdata.srv.weight = 2;
+	res.ans[0].rdata.srv.port = 5062;
+	res.ans[0].rdata.srv.target = pj_str("sip01." TARGET);
+
+    } else if (pkt->q[0].type == PJ_DNS_TYPE_A) {
+	char *alias = "sipalias.somedomain.com";
+
+	pj_assert(pj_strcmp2(&res.q[0].name, TARGET)==0);
+
+	res.hdr.anscount = 2;
+	res.ans[0].type = PJ_DNS_TYPE_CNAME;
+	res.ans[0].dnsclass = 1;
+	res.ans[0].name = res.q[0].name;
+	res.ans[0].ttl = 1;
+	res.ans[0].rdata.cname.name = pj_str(alias);
+
+	res.ans[1].type = PJ_DNS_TYPE_A;
+	res.ans[1].dnsclass = 1;
+	res.ans[1].name = pj_str(alias);
+	res.ans[1].ttl = 1;
+	res.ans[1].rdata.a.ip_addr.s_addr = IP_ADDR2;
+    }
+
+    *p_res = &res;
+}
+
+static void srv_cb_2(void *user_data,
+		     pj_status_t status,
+		     const pj_dns_srv_record *rec)
+{
+    PJ_UNUSED_ARG(user_data);
+
+    pj_assert(status == PJ_SUCCESS);
+    pj_assert(rec->count == 1);
+    pj_assert(rec->entry[0].priority == 0);
+    pj_assert(rec->entry[0].weight == 0);
+    pj_assert(rec->entry[0].addr.ipv4.sin_addr.s_addr == IP_ADDR2);
+    pj_assert(pj_ntohs(rec->entry[0].addr.ipv4.sin_port) == 5062);
+
+    pj_sem_post(sem);
+}
+
+static int srv_resolver_fallback_test(void)
+{
+    pj_status_t status;
+    pj_str_t domain = pj_str(TARGET);
+    pj_str_t res_name = pj_str("_sip._udp.");
+
+    PJ_LOG(3,(THIS_FILE, "    srv_resolve(): fallback test"));
+
+    g_server[0].action = ACTION_CB;
+    g_server[0].action_cb = &action2_1;
+    g_server[1].action = ACTION_CB;
+    g_server[1].action_cb = &action2_1;
+
+    status = pj_dns_srv_resolve(&domain, &res_name, 5062, pool, resolver, PJ_TRUE,
+				NULL, &srv_cb_2);
+    if (status != PJ_SUCCESS) {
+	app_perror("     srv_resolve error", status);
+	pj_assert(status == PJ_SUCCESS);
+    }
+
+    pj_sem_wait(sem);
+
+    /* Subsequent query should just get the response from the cache */
+    PJ_LOG(3,(THIS_FILE, "    srv_resolve(): cache test"));
+    g_server[0].pkt_count = 0;
+    g_server[1].pkt_count = 0;
+
+    status = pj_dns_srv_resolve(&domain, &res_name, 5062, pool, resolver, PJ_TRUE,
+				NULL, &srv_cb_2);
+    if (status != PJ_SUCCESS) {
+	app_perror("     srv_resolve error", status);
+	pj_assert(status == PJ_SUCCESS);
+    }
+
+    pj_sem_wait(sem);
+
+    pj_assert(g_server[0].pkt_count == 0);
+    pj_assert(g_server[1].pkt_count == 0);
+
+    return 0;
+}
+
+
+////////////////////////////////////////////////////////////////////////////
+
+
+int resolver_test(void)
+{
+    int rc;
+    
+#ifdef NDEBUG
+    PJ_LOG(3,(THIS_FILE, "    error: NDEBUG is declared"));
+    return -1;
+#endif
+
+    rc = init();
+
+    rc = simple_test();
+    if (rc != 0)
+	goto on_error;
+
+    rc = dns_test();
+    if (rc != 0)
+	goto on_error;
+
+    srv_resolver_test();
+    srv_resolver_fallback_test();
+
+    destroy();
+    return 0;
+
+on_error:
+    destroy();
+    return rc;
+}
+
+
diff --git a/pjlib-util/src/pjlib-util-test/test.c b/pjlib-util/src/pjlib-util-test/test.c
index 599b72e3..cce1f2f2 100644
--- a/pjlib-util/src/pjlib-util-test/test.c
+++ b/pjlib-util/src/pjlib-util-test/test.c
@@ -18,6 +18,7 @@
  */
 #include "test.h"
 #include <pjlib.h>
+#include <pjlib-util.h>
 
 void app_perror(const char *msg, pj_status_t rc)
 {
@@ -49,7 +50,7 @@ static int test_inner(void)
 
     mem = &caching_pool.factory;
 
-    pj_log_set_level(3);
+    pj_log_set_level(5);
     pj_log_set_decor(PJ_LOG_HAS_NEWLINE | PJ_LOG_HAS_TIME | 
                      PJ_LOG_HAS_MICRO_SEC);
 
@@ -58,7 +59,10 @@ static int test_inner(void)
 	app_perror("pj_init() error!!", rc);
 	return rc;
     }
-    
+
+    rc = pjlib_util_init();
+    pj_assert(rc == 0);
+
     pj_dump_config();
     pj_caching_pool_init( &caching_pool, &pj_pool_factory_default_policy, 0 );
 
@@ -75,6 +79,10 @@ static int test_inner(void)
     DO_TEST(stun_test());
 #endif
 
+#if INCLUDE_RESOLVER_TEST
+    DO_TEST(resolver_test());
+#endif
+
 on_return:
     return rc;
 }
diff --git a/pjlib-util/src/pjlib-util-test/test.h b/pjlib-util/src/pjlib-util-test/test.h
index e5e1e24f..10fcb5c8 100644
--- a/pjlib-util/src/pjlib-util-test/test.h
+++ b/pjlib-util/src/pjlib-util-test/test.h
@@ -21,12 +21,14 @@
 #define INCLUDE_XML_TEST	    1
 #define INCLUDE_ENCRYPTION_TEST	    1
 #define INCLUDE_STUN_TEST	    1
+#define INCLUDE_RESOLVER_TEST	    1
 
 extern int xml_test(void);
 extern int encryption_test();
 extern int encryption_benchmark();
 extern int stun_test();
 extern int test_main(void);
+extern int resolver_test(void);
 
 extern void app_perror(const char *title, pj_status_t rc);
 extern pj_pool_factory *mem;