wip: migrate to mono-repo. SPN has already been moved to spn/

service/network/multicast.go

@@ -0,0 +1,45 @@
+package network
+
+import (
+	"net"
+
+	"github.com/safing/portmaster/service/network/netutils"
+)
+
+// GetMulticastRequestConn searches for and returns the requesting connnection
+// of a possible multicast/broadcast response.
+func GetMulticastRequestConn(responseConn *Connection, responseFromNet *net.IPNet) *Connection {
+	// Calculate the broadcast address the query would have gone to.
+	responseNetBroadcastIP := netutils.GetBroadcastAddress(responseFromNet.IP, responseFromNet.Mask)
+
+	// Find requesting multicast/broadcast connection.
+	for _, conn := range conns.clone() {
+		switch {
+		case !conn.DataIsComplete():
+			// Ignore connection with incomplete data.
+		case conn.Inbound:
+			// Ignore incoming connections.
+		case conn.Ended != 0:
+			// Ignore ended connections.
+		case conn.Entity.Protocol != responseConn.Entity.Protocol:
+			// Ignore on protocol mismatch.
+		case conn.LocalPort != responseConn.LocalPort:
+			// Ignore on local port mismatch.
+		case !conn.LocalIP.Equal(responseConn.LocalIP):
+			// Ignore on local IP mismatch.
+		case !conn.Process().Equal(responseConn.Process()):
+			// Ignore if processes mismatch.
+		case conn.Entity.IPScope == netutils.LocalMulticast &&
+			(responseConn.Entity.IPScope == netutils.LinkLocal ||
+				responseConn.Entity.IPScope == netutils.SiteLocal):
+			// We found a (possibly routed) multicast request that matches the response!
+			return conn
+		case conn.Entity.IP.Equal(responseNetBroadcastIP) &&
+			responseFromNet.Contains(conn.LocalIP):
+			// We found a (link local) broadcast request that matches the response!
+			return conn
+		}
+	}
+
+	return nil
+}