aboutgitcodebugslistschat
diff options
context:
space:
mode:
-rw-r--r--tcp.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/tcp.c b/tcp.c
index 7de8fa9..d5e47c9 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1187,10 +1187,23 @@ static int tcp_send_to_tap(struct ctx *c, struct tcp_tap_conn *conn, int flags,
th->doff = sizeof(*th) / 4;
if (flags & SYN) {
+ uint16_t mss;
+
/* Options: MSS, NOP and window scale if allowed (4-8 bytes) */
*data++ = OPT_MSS;
*data++ = OPT_MSS_LEN;
- *(uint16_t *)data = htons(info.tcpi_snd_mss);
+
+ if (c->mtu == -1) {
+ mss = info.tcpi_snd_mss;
+ } else {
+ mss = c->mtu - sizeof(sizeof *th);
+ if (IN6_IS_ADDR_V4MAPPED(&conn->a.a6))
+ mss -= sizeof(struct iphdr);
+ else
+ mss -= sizeof(struct ipv6hdr);
+ }
+ *(uint16_t *)data = htons(mss);
+
data += OPT_MSS_LEN - 2;
th->doff += OPT_MSS_LEN / 4;