Changeset 86843 in vbox for trunk/src/VBox/Devices/Network/slirp

Timestamp:

Nov 10, 2020 4:26:48 AM (4 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

141292

Message:

slirp: bugref:9856 - in tcp_input() save optp and optlen in struct
socket for the re-entry on connect dance. Restore them on the second
entry because the options are only parsed at that time.

I'm not sure why - this is code from the original slirp - but nothing
in the options parsing code needs getting the "remote address" as the
comment claims. This bug is pretty corner case and has been
introduced in slirp changes to the BSD stack. Opt for the
conservative fix. The practical consequence is that we should now
respect the MSS that the guest advertises to us (ticketref:15256).

Location:

trunk/src/VBox/Devices/Network/slirp

Files:

• socket.h (modified) (1 diff)
• tcp_input.c (modified) (4 diffs)

trunk/src/VBox/Devices/Network/slirp/socket.h

@@ -60 +60 @@
                                   * so_mconn, for non-blocking connections */
     uint8_t         *so_ohdr;    /* unmolested IP header of the datagram in so_m */
+    caddr_t         so_optp;     /* tcp options in so_m */
+    int             so_optlen;   /* length of options in so_m */
     int             so_urgc;
     struct in_addr  so_faddr;    /* foreign host table entry */

trunk/src/VBox/Devices/Network/slirp/tcp_input.c

@@ -324 +324 @@
         so = inso;
         Log4(("NAT: tcp_input: %R[natsock]\n", so));
+
         /* Re-set a few variables */
         tp = sototcpcb(so);
+
         m = so->so_m;
-        so->so_m = 0;
+        optp = so->so_optp;     /* points into m if set */
+        optlen = so->so_optlen;
+        so->so_m = NULL;
+        so->so_optp = 0;
+        so->so_optlen = 0;
 
         if (RT_LIKELY(so->so_ohdr != NULL))
@@ -826 +832 @@
                 so->so_ti = ti;
                 so->so_ohdr = RTMemDup(ohdr, ohdrlen);
+                so->so_optp = optp;
+                so->so_optlen = optlen;
                 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
                 TCP_STATE_SWITCH_TO(tp, TCPS_SYN_RECEIVED);
@@ -2015 +2023 @@
     int mss;
 
-    LogFlowFunc(("ENTER: tcp_mss: tp = %R[tcpcb793], offer = %d\n", tp, offer));
+    LogFlowFunc(("ENTER: tcp_mss: offer=%u, t_maxseg=%u; tp=%R[natsock]\n",
+                 offer, (unsigned int)tp->t_maxseg, so));
 
     mss = min(if_mtu, if_mru) - sizeof(struct tcpiphdr);
@@ -2029 +2038 @@
     sbreserve(pData, &so->so_rcv, tcp_rcvspace+((tcp_rcvspace%mss)?(mss-(tcp_rcvspace%mss)):0));
 
-    Log2((" returning mss = %d\n", mss));
-
+    LogFlowFunc(("LEAVE: mss=%d\n", mss));
     return mss;
 }