trial of avoiding 1470 packets

debian/changelog

@@ -1,3 +1,8 @@
+rrqnet (1.5.2) unstable; urgency=medium
+
+  * tpg_patch: avoid UDP payload of 1470 bytes.
+
+ -- Ralph Ronnquist <ralph.ronnquist@gmail.com>  Mon, 01 Nov 2021 01:01:34 +1100
 rrqnet (1.5.1) unstable; urgency=medium
 
   * Bug fix: flip-over limits are microseconds.

rrqnet-ifupdown.sh

@@ -68,6 +68,19 @@ stop_dhclient() {
 ############################################################
 ## The action functions
 
+QUIRK=
+LOGFLAG=
+LOGFILE=
+#function
+process_logoption() {
+    if [ -n "${1##-v*}" ] ; then
+	QUIRK="$1"
+	shift
+    fi
+    LOGFLAG="$1"
+    LOGFILE="$2"
+}
+
 #function
 start_cable_pre_up() {
     local TAP
@@ -81,13 +94,14 @@ start_cable_pre_up() {
     fi
     [ -z "$IF_RRQNET_NICE" ] || \
         RRQDAEMON="/usr/bin/nice -n $IF_RRQNET_NICE $RRQDAEMON"
-    if [ -z "$IF_RRQNET_LOG" ] ; then
+    process_logoption ${IF_RRQNET_LOG}
+    if [ -z "$LOGFILE" ] ; then
 	daemon -U -r -a 10 -n $NAME -- \
-	       $RRQDAEMON $IF_RRQNET_OPTIONS \
+	       $RRQDAEMON $QUIRK $IF_RRQNET_OPTIONS \
 	       $TAP $IF_RRQNET_PORT $IF_RRQNET_REMOTE
     else
-	daemon -U -r -a 10 -n $NAME -E "${IF_RRQNET_LOG#* }" -- \
-	       $RRQDAEMON ${IF_RRQNET_LOG%% *} $IF_RRQNET_OPTIONS \
+	daemon -U -r -a 10 -n $NAME -E "$LOGFILE" -- \
+	       $RRQDAEMON $QUIRK $LOGFLAG $IF_RRQNET_OPTIONS \
 	       $TAP $IF_RRQNET_PORT $IF_RRQNET_REMOTE
     fi
 }

rrqnet.c

@@ -188,6 +188,10 @@ static struct {
 // Flag to signal the UDP socket as being ipv6 or not (forced ipv4)
 static int udp6 = 1;
 
+// Flag to indicate tpg transport patch = avoid UDP payload of 1470
+// bytes by adding 2 tag-along bytes
+static int tpg_quirk = 0;
+
 // Flag whether to make some stderr outputs or not.
 // 1 = normal verbosity, 2 = more output, 3 = source debug level stuff
 static int verbose;
@@ -877,11 +881,16 @@ static void write_remote(unsigned char *buf, int n,struct Remote *r) {
     if ( n < 12 ) {
 	VERBOSE2OUT( "SEND %d bytes to %s\n", n, inet_stoa( &r->uaddr ) );
     } else {
-	VERBOSE2OUT( "SEND %s -> %s to %s\n",
+	VERBOSE2OUT( "SEND %d bytes %s -> %s to %s\n", n,
 		     inet_mtoa( buf+6 ), inet_mtoa( buf ),
 		     inet_stoa( &r->uaddr ) );
     }
     memcpy( output, buf, n ); // Use the private buffer for delivery
+    // Apply the TPG quirk
+    if ( tpg_quirk && ( n == 1470 ) ) {
+	VERBOSE2OUT( "tpg quirk applied\n" );
+	n += 8; // Add 8 "random" tag-along bytes
+    }
     if ( r->spec == 0 ) {
 	if ( r->uaddr.in.sa_family == 0 ) {
 	    // Output to tap/stdio
@@ -1402,6 +1411,11 @@ int main(int argc, char *argv[]) {
     ///// Parse command line arguments
     i = 1;
 #define ENSUREARGS(n) if ( argc < i + n ) usage()
+    ENSUREARGS( 1 );
+    if ( strncmp( "-tpg", argv[i], 4 ) == 0 ) {
+	tpg_quirk = 1;
+	i++;
+    }
     ENSUREARGS( 1 );
     // First: optional -v, -vv or -vvv
     if ( strncmp( "-v", argv[i], 2 ) == 0 ) {