Experimental support for opportunitic use of jumbograms where only some hosts

on the local network support them.

This adds a new socket option, SO_JUMBO, and a new route flag,
RTF_JUMBO. If _both_ the socket option is set and the route for the host
has RTF_JUMBO set, ip_output will fragment the packet to the largest
possible size for the link, ignoring the card's MTU.

The semantics of this feature will be evolving rapidly; talk to us
if you intend to use it.

ok deraadt@ marius@

1 files changed, 22 insertions, 8 deletions

diff --git a/src/usr.bin/nc/netcat.c b/src/usr.bin/nc/netcat.c
index 36d133a2bb..d39cc0f9bf 100644
--- a/src/usr.bin/nc/netcat.c
+++ b/src/usr.bin/nc/netcat.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: netcat.c,v 1.79 2005/05/24 20:13:28 avsm Exp $ */
+/* $OpenBSD: netcat.c,v 1.80 2005/05/27 04:55:28 mcbride Exp $ */
 /*
  * Copyright (c) 2001 Eric Jackson <ericj@monkey.org>
  *
@@ -63,6 +63,7 @@
 /* Command Line Options */
 int     dflag;                                  /* detached, no stdin */
 int     iflag;                                  /* Interval Flag */
+int     jflag;                                  /* use jumbo frames if we can */
 int     kflag;                                  /* More than one connect */
 int     lflag;                                  /* Bind to local port */
 int     nflag;                                  /* Don't do name look up */
@@ -115,7 +116,8 @@ main(int argc, char *argv[])
         endp = NULL;
         sv = NULL;
 
-        while ((ch = getopt(argc, argv, "46Ddhi:klnp:rSs:tUuvw:X:x:z")) != -1) {
+        while ((ch = getopt(argc, argv,
+            "46Ddhi:jklnp:rSs:tUuvw:X:x:z")) != -1) {
                 switch (ch) {
                 case '4':
                         family = AF_INET;
@@ -147,6 +149,9 @@ main(int argc, char *argv[])
                         if (iflag < 0 || *endp != '\0')
                                 errx(1, "interval cannot be negative");
                         break;
+                case 'j':
+                        jflag = 1;
+                        break;
                 case 'k':
                         kflag = 1;
                         break;
@@ -286,12 +291,13 @@ main(int argc, char *argv[])
                          * functions to talk to the caller.
                          */
                         if (uflag) {
-                                int rv;
-                                char buf[1024];
+                                int rv, plen;
+                                char buf[8192];
                                 struct sockaddr_storage z;
 
                                 len = sizeof(z);
-                                rv = recvfrom(s, buf, sizeof(buf), MSG_PEEK,
+                                plen = jflag ? 8192 : 1024;
+                                rv = recvfrom(s, buf, plen, MSG_PEEK,
                                     (struct sockaddr *)&z, &len);
                                 if (rv < 0)
                                         err(1, "recvfrom");
@@ -501,6 +507,11 @@ remote_connect(const char *host, const char *port, struct addrinfo hints)
                             &x, sizeof(x)) == -1)
                                 err(1, NULL);
                 }
+                if (jflag) {
+                        if (setsockopt(s, SOL_SOCKET, SO_JUMBO,
+                            &x, sizeof(x)) == -1)
+                                err(1, NULL);
+                }
 
                 if (connect(s, res0->ai_addr, res0->ai_addrlen) == 0)
                         break;
@@ -589,9 +600,12 @@ void
 readwrite(int nfd)
 {
         struct pollfd pfd[2];
-        unsigned char buf[BUFSIZ];
+        unsigned char buf[8192];
         int n, wfd = fileno(stdin);
         int lfd = fileno(stdout);
+        int plen;
+
+        plen = jflag ? 8192 : 1024;
 
         /* Setup Network FD */
         pfd[0].fd = nfd;
@@ -614,7 +628,7 @@ readwrite(int nfd)
                         return;
 
                 if (pfd[0].revents & POLLIN) {
-                        if ((n = read(nfd, buf, sizeof(buf))) < 0)
+                        if ((n = read(nfd, buf, plen)) < 0)
                                 return;
                         else if (n == 0) {
                                 shutdown(nfd, SHUT_RD);
@@ -629,7 +643,7 @@ readwrite(int nfd)
                 }
 
                 if (!dflag && pfd[1].revents & POLLIN) {
-                        if ((n = read(wfd, buf, sizeof(buf))) < 0)
+                        if ((n = read(wfd, buf, plen)) < 0)
                                 return;
                         else if (n == 0) {
                                 shutdown(nfd, SHUT_WR);