Various output fixes:

- Fixed several possible segfaults when selecting non-existing tracks in HLS
- Fixed error when requesting a stream with no compatible HLS tracks
- Fix a possible segfault when playing back an invalid track
- Fixed HLS cache control logic
- Fixed slow lookup of blank hostnames (now skips lookup entirely)
- HLS output replies with 204 rather than 200 for OPTIONS requests
- Removed out-of-the-box compatibility with iOS 10 and lower in the HTML output, in favor of better iOS 11+ support.

lib/socket.cpp

@@ -242,6 +242,7 @@ void Socket::hostBytesToStr(const char *bytes, size_t len, std::string &target){
 /// Returns empty string if no reasonable match could be made.
 std::string Socket::resolveHostToBestExternalAddrGuess(const std::string &host, int family,
                                                        const std::string &hint){
+  if (!host.size()){return "";}
   struct addrinfo *result, *rp, hints;
   std::string newaddr;
 

src/output/output.cpp

@@ -812,6 +812,7 @@ namespace Mist{
     if (!isInitialized){initialize();}
     buffer.clear();
     thisPacket.null();
+    if (!M){return false;}
     if (toKey){
       size_t mainTrack = getMainSelectedTrack();
       if (mainTrack == INVALID_TRACK_ID){
@@ -831,12 +832,14 @@ namespace Mist{
     MEDIUM_MSG("Seeking to %" PRIu64 "ms (%s)", pos, toKey ? "sync" : "direct");
     std::set<size_t> seekTracks;
     for (std::map<size_t, Comms::Users>::iterator it = userSelect.begin(); it != userSelect.end(); it++){
-      seekTracks.insert(it->first);
+      if (M.trackValid(it->first)){seekTracks.insert(it->first);}
     }
     //Seek all seek positions, first
     for (std::set<size_t>::iterator it = seekTracks.begin(); it != seekTracks.end(); it++){
+      if (userSelect[*it]){
         userSelect[*it].setKeyNum(M.getKeyNumForTime(*it, pos));
       }
+    }
     bool ret = seekTracks.size();
     for (std::set<size_t>::iterator it = seekTracks.begin(); it != seekTracks.end(); it++){
       ret &= seek(*it, pos, false);
@@ -1985,6 +1988,10 @@ namespace Mist{
     // depending on whether this is probably bad and the current debug level, print a message
     size_t printLevel = (probablyBad ? DLVL_WARN : DLVL_INFO);
     //The rest of the operations depends on userSelect, so we ignore it if it doesn't exist.
+    if (!M || !M.getValidTracks().count(trackId)){
+      DEBUG_MSG(printLevel, "Dropping invalid track %zu: %s", trackId, reason.c_str());
+      return;
+    }
     if (!userSelect.count(trackId)){
       if (M.hasEmbeddedFrames(trackId)){
         DEBUG_MSG(printLevel, "Dropping %s track %zu (raw): %s", meta.getCodec(trackId).c_str(), trackId, reason.c_str());

src/output/output_hls.cpp

@@ -68,11 +68,18 @@ namespace Mist{
                << "\r\n";
       }
     }
-    if (!vidTracks && audioId != INVALID_TRACK_ID){
+
+    if (!vidTracks){
+      if (audioId != INVALID_TRACK_ID){
+        // Audio only playlist
         result << "#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=" << (M.getBps(audioId) * 8);
         result << ",CODECS=\"" << Util::codecString(M.getCodec(audioId), M.getInit(audioId)) << "\"";
         result << "\r\n";
         result << audioId << "/index.m3u8" << tknStr << "\r\n";
+      }else{
+        // No compatible tracks at all
+        return "";
+      }
     }
     return result.str();
   }
@@ -260,7 +267,12 @@ namespace Mist{
       H.SetHeader("Content-Type", "text/xml");
       H.SetHeader("Server", APPIDENT);
       H.setCORSHeaders();
-      if (method == "OPTIONS" || method == "HEAD"){
+      if (method == "OPTIONS"){
+        H.SendResponse("204", "No content", myConn);
+        responded = true;
+        return;
+      }
+      if (method == "HEAD"){
         H.SendResponse("200", "OK", myConn);
         responded = true;
         return;
@@ -274,19 +286,20 @@ namespace Mist{
       return;
     }// crossdomain.xml
 
-    if (H.method == "OPTIONS"){
+    if (method == "OPTIONS"){
       bool isTS = (HTTP::URL(H.url).getExt().substr(0, 3) != "m3u");
+      H.Clean();
       H.setCORSHeaders();
       if (isTS){
         H.SetHeader("Content-Type", "video/mp2t");
       }else{
         H.SetHeader("Content-Type", "application/vnd.apple.mpegurl");
       }
-      if (isTS && (!(Comms::tknMode & 0x04) || config->getOption("chunkpath"))){
+      if (isTS && !(!(Comms::tknMode & 0x04) || config->getOption("chunkpath"))){
         uint64_t dura = 120000;
         if (M && M.getValidTracks().size()){
           size_t mTrk = M.mainTrack();
-          if (mTrk != INVALID_TRACK_ID){dura = M.getDuration(dura);}
+          if (mTrk != INVALID_TRACK_ID){dura = M.getDuration(mTrk);}
         }
         H.SetHeader("Cache-Control",
                     "public, max-age=" +
@@ -298,7 +311,7 @@ namespace Mist{
         H.SetHeader("Cache-Control", "no-store");
       }
       H.SetBody("");
-      H.SendResponse("200", "OK", myConn);
+      H.SendResponse("204", "No content", myConn);
       responded = true;
       return;
     }
@@ -374,14 +387,14 @@ namespace Mist{
       H.SetHeader("Content-Type", "video/mp2t");
       H.setCORSHeaders();
       if (!(Comms::tknMode & 0x04) || config->getOption("chunkpath")){
-        H.SetHeader("Cache-Control", "no-store");
-      }else{
         H.SetHeader("Cache-Control",
                     "public, max-age=" +
                         JSON::Value(M.getDuration(getMainSelectedTrack()) / 1000).asString() +
                         ", immutable");
         H.SetHeader("Pragma", "");
         H.SetHeader("Expires", "");
+      }else{
+        H.SetHeader("Cache-Control", "no-store");
       }
       if (method == "OPTIONS" || method == "HEAD"){
         H.SendResponse("200", "OK", myConn);
@@ -418,6 +431,10 @@ namespace Mist{
       std::string manifest;
       if (request.find("/") == std::string::npos){
         manifest = liveIndex();
+        if (manifest == ""){
+          onFail("No HLS compatible tracks found");
+          return;
+        }
       }else{
         size_t idx = atoi(request.substr(0, request.find("/")).c_str());
         if (!M.getValidTracks().count(idx)){

src/output/output_http_internal.cpp

@@ -426,17 +426,6 @@ namespace Mist{
               "src=\"player.js\"></script><script>var mv ={reference:false}; mistPlay('" +
               streamName + "',{host:'" + fullURL.getUrl() + "',target:document.getElementById('" + streamName +
               "'),MistVideoObject:mv" + forceType + devSkin + "});" + seekTo + "</script></div></body></html>");
-    if ((uAgent.find("iPad") != std::string::npos) || (uAgent.find("iPod") != std::string::npos) ||
-        (uAgent.find("iPhone") != std::string::npos)){
-      if (uAgent.find("OS 11") == std::string::npos && uAgent.find("OS 12") == std::string::npos &&
-          uAgent.find("OS 13") == std::string::npos && uAgent.find("OS 14") == std::string::npos &&
-          uAgent.find("OS 15") == std::string::npos && uAgent.find("OS 16") == std::string::npos){
-        H.SetHeader("Location", hlsUrl);
-        H.SendResponse("307", "HLS redirect", myConn);
-        responded = true;
-        return;
-      }
-    }
     H.SendResponse("200", "OK", myConn);
     responded = true;
     H.Clean();