Use different client port if the reserved UDP port is in use.

In case the reserved client port is in use, use different port
instead of assert.

Change-Id: Ie99e3e4a29bd4a809086ae4505ce8498bf40f79a
closes-bug: #1573316

src/dns/bind/bind_resolver.cc

@@ -46,7 +46,11 @@ BindResolver::BindResolver(boost::asio::io_service &io,
     sock_.open(boost::asio::ip::udp::v4(), ec);
     assert(ec.value() == 0);
     sock_.bind(local_ep, ec);
-    assert(ec.value() == 0);
+    if (ec.value() != 0) {
+        local_ep.port(0);
+        sock_.bind(local_ep, ec);
+        assert(ec.value() == 0);
+    }
     AsyncRead();
 }
 

src/dns/test/dns_bind_test.cc

@@ -1061,6 +1061,17 @@ TEST_F(DnsBindTest, DnsUpdateErrorParse) {
 
 int main(int argc, char **argv) {
     Dns::Init();
+
+    // Bind to the client port first so that a new client port is used
+    boost::system::error_code ec;
+    boost::asio::ip::udp::socket sock(*Dns::GetEventManager()->io_service());
+    boost::asio::ip::udp::endpoint ep(boost::asio::ip::address::
+                                      from_string("0.0.0.0", ec),
+                                      ContrailPorts::ContrailDnsClientUdpPort());
+    sock.open(boost::asio::ip::udp::v4(), ec);
+    assert(ec.value() == 0);
+    sock.bind(ep, ec);
+
     ::testing::InitGoogleTest(&argc, argv);
     int error = RUN_ALL_TESTS();
     TaskScheduler::GetInstance()->Terminate();

src/vnsw/agent/oper/mirror_table.cc

@@ -303,7 +303,11 @@ void MirrorTable::MirrorSockInit(void) {
     assert(ec.value() == 0);
 
     udp_sock_->bind(ep, ec);
-    assert(ec.value() == 0);
+    if (ec.value() != 0) {
+        ep.port(0);
+        udp_sock_->bind(ep, ec);
+        assert(ec.value() == 0);
+    }
 
     ip::udp::endpoint sock_ep = udp_sock_->local_endpoint(ec);
     assert(ec.value() == 0);