fix #750, use specific error code for dns resolve. 2.0.231

@@ -346,6 +346,7 @@ Remark:
 
 ## History
 
+* v2.0, 2017-01-18, fix [#750][bug #750] use specific error code for dns resolve. 2.0.231
 * <strong>v2.0, 2017-01-18, [2.0 beta4(2.0.230)][r2.0b4] released. 86334 lines.</strong>
 * v2.0, 2017-01-18, fix [#749][bug #749], timestamp overflow for ATC. 2.0.230
 * v2.0, 2017-01-11, fix [#740][bug #740], convert ts aac audio private stream 1 to common. 2.0.229

@@ -31,7 +31,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 // current release version
 #define VERSION_MAJOR       2
 #define VERSION_MINOR       0
-#define VERSION_REVISION    230
+#define VERSION_REVISION    231
 
 // generated by configure, only macros.
 #include <srs_auto_headers.hpp>

@@ -97,6 +97,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #define ERROR_SYSTEM_DIR_EXISTS             1056
 #define ERROR_SYSTEM_CREATE_DIR             1057
 #define ERROR_SYSTEM_KILL                   1058
+#define ERROR_SYSTEM_DNS_RESOLVE            1059
 
 ///////////////////////////////////////////////////////
 // RTMP protocol error.

@@ -495,7 +495,7 @@ int srs_librtmp_context_resolve_host(Context* context)
     // connect to server:port
     context->ip = srs_dns_resolve(context->host);
     if (context->ip.empty()) {
-        return -1;
+        return ERROR_SYSTEM_DNS_RESOLVE;
     }
     
     return ret;