Add initrwnd to iproute2

Add initrwnd option parsing to iproute. This option uses the new
rtnetlink init_rcvwnd to set the TCP initial receive window size
advertised by passive and active TCP connections.
Signed-off-by: Laurent Chavey <chavey@google.com>

doc/ip-cref.tex

@@ -1336,6 +1336,13 @@ peers are allowed to send to us.
     MSS (``Maximal Segment Size'') for same connection. The default is
     zero, meaning to use the values specified in~\cite{RFC2414}.
 
++\item \verb|initrwnd NUMBER|
+ 
++--- [2.6.33+ only] Initial receive window size for connections to 
++    this destination. The actual window size is this value multiplied
++    by the MSS (''Maximal Segment Size'') of the connection. The default
++    value is zero, meaning to use Slow Start value.
+ 
 \item \verb|nexthop NEXTHOP|
 
 --- the nexthop of a multipath route. \verb|NEXTHOP| is a complex value

ip/iproute.c

@@ -46,6 +46,7 @@ static const char *mx_names[RTAX_MAX+1] = {
 	[RTAX_INITCWND] = "initcwnd",
 	[RTAX_FEATURES] = "features",
 	[RTAX_RTO_MIN]	= "rto_min",
+	[RTAX_INITRWND]	= "initrwnd",
 };
 static void usage(void) __attribute__((noreturn));
 
@@ -68,7 +69,7 @@ static void usage(void)
 	fprintf(stderr, "           [ rtt TIME ] [ rttvar TIME ] [reordering NUMBER ]\n");
 	fprintf(stderr, "           [ window NUMBER] [ cwnd NUMBER ] [ initcwnd NUMBER ]\n");
 	fprintf(stderr, "           [ ssthresh NUMBER ] [ realms REALM ] [ src ADDRESS ]\n");
-	fprintf(stderr, "           [ rto_min TIME ] [ hoplimit NUMBER ] \n");
+	fprintf(stderr, "           [ rto_min TIME ] [ hoplimit NUMBER ] [ initrwnd NUMBER ]\n");
 	fprintf(stderr, "TYPE := [ unicast | local | broadcast | multicast | throw |\n");
 	fprintf(stderr, "          unreachable | prohibit | blackhole | nat ]\n");
 	fprintf(stderr, "TABLE_ID := [ local | main | default | all | NUMBER ]\n");
@@ -844,6 +845,16 @@ int iproute_modify(int cmd, unsigned flags, int argc, char **argv)
 			if (get_unsigned(&win, *argv, 0))
 				invarg("\"initcwnd\" value is invalid\n", *argv);
 			rta_addattr32(mxrta, sizeof(mxbuf), RTAX_INITCWND, win);
+		} else if (matches(*argv, "initrwnd") == 0) {
+			unsigned win;
+			NEXT_ARG();
+			if (strcmp(*argv, "lock") == 0) {
+				mxlock |= (1<<RTAX_INITRWND);
+				NEXT_ARG();
+			}
+			if (get_unsigned(&win, *argv, 0))
+				invarg("\"initrwnd\" value is invalid\n", *argv);
+			rta_addattr32(mxrta, sizeof(mxbuf), RTAX_INITRWND, win);
 		} else if (matches(*argv, "rttvar") == 0) {
 			unsigned win;
 			NEXT_ARG();