Merge pull request #77 from muxinc/msmith/drop-packets-wrong-source

Add a configuration option to drop packets from an unexpected source address

Author: ioppermann

config.go

@@ -169,6 +169,9 @@ type Config struct {
 
 	// An implementation of the Logger interface
 	Logger Logger
+
+	// if a new IP starts sending data on an existing socket id, allow it
+	AllowPeerIpChange bool
 }
 
 // DefaultConfig is the default configuration for a SRT connection
@@ -209,6 +212,7 @@ var defaultConfig Config = Config{
 	TooLatePacketDrop:     true,
 	TransmissionType:      "live",
 	TSBPDMode:             true,
+	AllowPeerIpChange:     false,
 }
 
 // DefaultConfig returns the default configuration for Dial and Listen.

listen.go

@@ -407,6 +407,14 @@ func (ln *listener) reader(ctx context.Context) {
 				break
 			}
 
+			if !ln.config.AllowPeerIpChange {
+				if p.Header().Addr.String() != conn.RemoteAddr().String() {
+					// ignore the packet, it's not from the expected peer
+					// https://haivision.github.io/srt-rfc/draft-sharabayko-srt.html#name-security-considerations
+					break
+				}
+			}
+
 			conn.push(p)
 		}
 	}