diff options
| -rw-r--r-- | sys/src/9/ip/tcp.c | 44 |
1 files changed, 24 insertions, 20 deletions
diff --git a/sys/src/9/ip/tcp.c b/sys/src/9/ip/tcp.c index 545cdb42e..050a24a0b 100644 --- a/sys/src/9/ip/tcp.c +++ b/sys/src/9/ip/tcp.c @@ -47,7 +47,7 @@ enum MSL2 = 10, MSPTICK = 50, /* Milliseconds per timer tick */ DEF_MSS = 1460, /* Default maximum segment */ - DEF_MSS6 = 1280, /* Default maximum segment (min) for v6 */ + DEF_MSS6 = 1220, /* Default maximum segment (min) for v6 */ DEF_RTT = 500, /* Default round trip */ DEF_KAT = 120000, /* Default time (ms) between keep alives */ TCP_LISTEN = 0, /* Listen connection */ @@ -846,32 +846,36 @@ localclose(Conv *s, char *reason) /* called with tcb locked */ /* mtu (- TCP + IP hdr len) of 1st hop */ static int -tcpmtu(Proto *tcp, uchar *addr, int version, uint *scale) +tcpmtu(Route *r, int version, uint *scale) { Ipifc *ifc; int mtu; - ifc = findipifc(tcp->f, addr, 0); - switch(version){ - default: - case V4: - mtu = DEF_MSS; - if(ifc != nil) - mtu = ifc->maxtu - ifc->m->hsize - (TCP4_PKT + TCP4_HDRSIZE); - break; - case V6: - mtu = DEF_MSS6; - if(ifc != nil) - mtu = ifc->maxtu - ifc->m->hsize - (TCP6_PKT + TCP6_HDRSIZE); - break; - } /* * set the ws. it doesn't commit us to anything. * ws is the ultimate limit to the bandwidth-delay product. */ *scale = Defadvscale; - return mtu; + /* + * currently we do not implement path MTU discovery + * so use interface MTU *only* if directly reachable + * or when we use V4 which allows routers to fragment. + * otherwise, we use the default MSS which assumes a + * safe minimum MTU of 1280 bytes for V6. + */ + if(r != nil && (version == V4 || (r->type & (Rifc|Runi)) != 0)){ + ifc = r->ifc; + mtu = ifc->maxtu - ifc->m->hsize; + if(version == V6) + return mtu - (TCP6_PKT + TCP6_HDRSIZE); + else + return mtu - (TCP4_PKT + TCP4_HDRSIZE); + } + if(version == V6) + return DEF_MSS6; + else + return DEF_MSS; } static void @@ -1309,7 +1313,7 @@ tcpsndsyn(Conv *s, Tcpctl *tcb) tcb->sndsyntime = NOW; /* set desired mss and scale */ - tcb->mss = tcpmtu(s->p, s->laddr, s->ipversion, &tcb->scale); + tcb->mss = tcpmtu(v6lookup(s->p->f, s->raddr, s), s->ipversion, &tcb->scale); tpriv = s->p->priv; tpriv->stats[Mss] = tcb->mss; } @@ -1487,7 +1491,7 @@ sndsynack(Proto *tcp, Limbo *lp) seg.ack = lp->irs+1; seg.flags = SYN|ACK; seg.urg = 0; - seg.mss = tcpmtu(tcp, lp->laddr, lp->version, &scale); + seg.mss = tcpmtu(v6lookup(tcp->f, lp->raddr, nil), lp->version, &scale); seg.wnd = QMAX; /* if the other side set scale, we should too */ @@ -1763,7 +1767,7 @@ tcpincoming(Conv *s, Tcp *segp, uchar *src, uchar *dst, uchar version) tcb->flags |= SYNACK; /* set desired mss and scale */ - tcb->mss = tcpmtu(s->p, dst, s->ipversion, &tcb->scale); + tcb->mss = tcpmtu(v6lookup(s->p->f, src, s), version, &tcb->scale); /* our sending max segment size cannot be bigger than what he asked for */ if(lp->mss != 0 && lp->mss < tcb->mss) |