b/f: process properly on short SDP

core/AmSdp.cpp

@@ -490,9 +490,11 @@ static bool parse_sdp_line_ex(AmSdp* sdp_msg, char*& s)
 	{
 	  s = is_eql_next(s);
 	  next = get_next_line(s);
-	  string version(s, int(next-s)-2);
-	  str2i(version, sdp_msg->version);
-	  DBG("parse_sdp_line_ex: found version\n");
+	  if (int(next-s)-2 >= 0) {
+	    string version(s, int(next-s)-2);
+	    str2i(version, sdp_msg->version);
+	    DBG("parse_sdp_line_ex: found version\n");
+	  }
 	  s = next;
 	  state = SDP_DESCR;
 	  break;
@@ -510,8 +512,10 @@ static bool parse_sdp_line_ex(AmSdp* sdp_msg, char*& s)
 	  DBG("parse_sdp_line_ex: found session\n");
 	  s = is_eql_next(s);
 	  next = get_next_line(s);
-	  string sessionName(s, int(next-s)-2);
-	  sdp_msg->sessionName = sessionName;
+	  if (int(next-s)-2 >= 0) {
+	    string sessionName(s, int(next-s)-2);
+	    sdp_msg->sessionName = sessionName;
+	  }
 	  s = next;
 	  break;
 	}
@@ -520,7 +524,9 @@ static bool parse_sdp_line_ex(AmSdp* sdp_msg, char*& s)
 	  DBG("parse_sdp_line_ex: found uri\n");
 	  s = is_eql_next(s);
 	  next = get_next_line(s);
-	  sdp_msg->uri = string(s, int(next-s)-2);
+	  if (int(next-s)-2 >= 0) {
+	    sdp_msg->uri = string(s, int(next-s)-2);
+	  }
 	  s = next;
       } break;
 
@@ -560,8 +566,11 @@ static bool parse_sdp_line_ex(AmSdp* sdp_msg, char*& s)
       default:
 	{
 	  next = get_next_line(s);
-	  string line(s, int(next-s)-2);
-	  DBG("parse_sdp_line: skipping unknown Session description %s=\n", (char*)line.c_str());
+	  if (int(next-s)-2 >= 0) {
+	    string line(s, int(next-s)-2);
+	    DBG("parse_sdp_line: skipping unknown Session description %s=\n",
+		(char*)line.c_str());
+	  }
 	  s = next;
 	  break;
 	}
@@ -608,9 +617,11 @@ static bool parse_sdp_line_ex(AmSdp* sdp_msg, char*& s)
       default :
 	{
 	  next = get_next_line(s);
-	  string line(s, int(next-s)-2);
-	  DBG("parse_sdp_line: skipping unknown Media description '%s'\n", 
-	      (char*)line.c_str());
+	  if (int(next-s)-2 >= 0) {
+	    string line(s, int(next-s)-2);
+	    DBG("parse_sdp_line: skipping unknown Media description '%s'\n",
+		(char*)line.c_str());
+	  }
 	  s = next;
 	  break;
 	}