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devbridge: fix mss clamping

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- use protocol constants from ip/ip.h and ip/ipv6.h
- support mss clamping for ipv6
- fix padding bug on 64 bit machines (can't use sizeof(Tcphdr))
This commit is contained in:
cinap_lenrek 2017-12-17 20:30:24 +01:00
parent 0affe02b61
commit 520c938f0b
2 changed files with 43 additions and 52 deletions
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94
sys/src/9/port/devbridge.c
View file

@ -1,5 +1,5 @@
/* /*
* IPv4 Ethernet bridge * IP Ethernet bridge
*/ */
#include "u.h" #include "u.h"
#include "../port/lib.h" #include "../port/lib.h"
@ -7,13 +7,13 @@
#include "dat.h" #include "dat.h"
#include "fns.h" #include "fns.h"
#include "../ip/ip.h" #include "../ip/ip.h"
#include "../ip/ipv6.h"
#include "../port/netif.h" #include "../port/netif.h"
#include "../port/error.h" #include "../port/error.h"
typedef struct Bridge Bridge; typedef struct Bridge Bridge;
typedef struct Port Port; typedef struct Port Port;
typedef struct Centry Centry; typedef struct Centry Centry;
typedef struct Iphdr Iphdr;
typedef struct Tcphdr Tcphdr; typedef struct Tcphdr Tcphdr;
enum enum
@ -138,27 +138,12 @@ struct Port
}; };
enum { enum {
IP_TCPPROTO = 6,
EOLOPT = 0, EOLOPT = 0,
NOOPOPT = 1, NOOPOPT = 1,
MSSOPT = 2, MSSOPT = 2,
MSS_LENGTH = 4, /* Mean segment size */ MSS_LENGTH = 4, /* Mean segment size */
SYN = 0x02, /* Pkt. is synchronise */ SYN = 0x02, /* Pkt. is synchronise */
IPHDR = 20, /* sizeof(Iphdr) */ TCPHDR = 20,
};
struct Iphdr
{
uchar vihl; /* Version and header length */
uchar tos; /* Type of service */
uchar length[2]; /* packet length */
uchar id[2]; /* ip->identification */
uchar frag[2]; /* Fragment information */
uchar ttl; /* Time to live */
uchar proto; /* Protocol */
uchar cksum[2]; /* Header checksum */
uchar src[4]; /* IP source */
uchar dst[4]; /* IP destination */
}; };
struct Tcphdr struct Tcphdr
@ -864,34 +849,38 @@ static void
tcpmsshack(Etherpkt *epkt, int n) tcpmsshack(Etherpkt *epkt, int n)
{ {
int hl, optlen; int hl, optlen;
Iphdr *iphdr;
Tcphdr *tcphdr; Tcphdr *tcphdr;
ulong mss, cksum; ulong mss, cksum;
uchar *optr; uchar *optr;
/* ignore non-ipv4 packets */ /* ignore non-ipv4 packets */
if(nhgets(epkt->type) != ETIP4) switch(nhgets(epkt->type)){
case ETIP4:
case ETIP6:
break;
default:
return; return;
iphdr = (Iphdr*)(epkt->data); }
n -= ETHERHDRSIZE; n -= ETHERHDRSIZE;
if(n < IPHDR) if(n < 1)
return; return;
switch(epkt->data[0]&0xF0){
/* ignore bad packets */ case IP_VER4:
if(iphdr->vihl != (IP_VER4|IP_HLEN4)) { hl = (epkt->data[0]&15)<<2;
hl = (iphdr->vihl&0xF)<<2; if(n < hl+TCPHDR || hl < IP4HDR || epkt->data[9] != TCP)
if((iphdr->vihl&0xF0) != IP_VER4 || hl < (IP_HLEN4<<2))
return; return;
} else n -= hl;
hl = IP_HLEN4<<2; tcphdr = (Tcphdr*)(epkt->data + hl);
break;
/* ignore non-tcp packets */ case IP_VER6:
if(iphdr->proto != IP_TCPPROTO) if(n < IP6HDR+TCPHDR || epkt->data[6] != TCP)
return;
n -= IP6HDR;
tcphdr = (Tcphdr*)(epkt->data + IP6HDR);
break;
default:
return; return;
n -= hl; }
if(n < sizeof(Tcphdr))
return;
tcphdr = (Tcphdr*)((uchar*)(iphdr) + hl);
// MSS can only appear in SYN packet // MSS can only appear in SYN packet
if(!(tcphdr->flag[1] & SYN)) if(!(tcphdr->flag[1] & SYN))
return; return;
@ -900,8 +889,8 @@ tcpmsshack(Etherpkt *epkt, int n)
return; return;
// check for MSS option // check for MSS option
optr = (uchar*)tcphdr + sizeof(Tcphdr); optr = (uchar*)tcphdr + TCPHDR;
n = hl - sizeof(Tcphdr); n = hl - TCPHDR;
for(;;) { for(;;) {
if(n <= 0 || *optr == EOLOPT) if(n <= 0 || *optr == EOLOPT)
return; return;
@ -922,10 +911,11 @@ tcpmsshack(Etherpkt *epkt, int n)
mss = nhgets(optr+2); mss = nhgets(optr+2);
if(mss <= TcpMssMax) if(mss <= TcpMssMax)
return; return;
// fit checksum // fit checksum
cksum = nhgets(tcphdr->cksum); cksum = nhgets(tcphdr->cksum);
if(optr-(uchar*)tcphdr & 1) { if(optr-(uchar*)tcphdr & 1) {
print("tcpmsshack: odd alignment!\n"); // print("tcpmsshack: odd alignment!\n");
// odd alignments are a pain // odd alignments are a pain
cksum += nhgets(optr+1); cksum += nhgets(optr+1);
cksum -= (optr[1]<<8)|(TcpMssMax>>8); cksum -= (optr[1]<<8)|(TcpMssMax>>8);
@ -1028,7 +1018,7 @@ etherread(void *a)
static int static int
fragment(Etherpkt *epkt, int n) fragment(Etherpkt *epkt, int n)
{ {
Iphdr *iphdr; Ip4hdr *iphdr;
if(n <= TunnelMtu) if(n <= TunnelMtu)
return 0; return 0;
@ -1036,14 +1026,14 @@ fragment(Etherpkt *epkt, int n)
/* ignore non-ipv4 packets */ /* ignore non-ipv4 packets */
if(nhgets(epkt->type) != ETIP4) if(nhgets(epkt->type) != ETIP4)
return 0; return 0;
iphdr = (Iphdr*)(epkt->data); iphdr = (Ip4hdr*)(epkt->data);
n -= ETHERHDRSIZE; n -= ETHERHDRSIZE;
/* /*
* ignore: IP runt packets, bad packets (I don't handle IP * ignore: IP runt packets, bad packets (I don't handle IP
* options for the moment), packets with don't-fragment set, * options for the moment), packets with don't-fragment set,
* and short blocks. * and short blocks.
*/ */
if(n < IPHDR || iphdr->vihl != (IP_VER4|IP_HLEN4) || if(n < IP4HDR || iphdr->vihl != (IP_VER4|IP_HLEN4) ||
iphdr->frag[0] & (IP_DF>>8) || nhgets(iphdr->length) > n) iphdr->frag[0] & (IP_DF>>8) || nhgets(iphdr->length) > n)
return 0; return 0;
@ -1053,7 +1043,7 @@ fragment(Etherpkt *epkt, int n)
static void static void
etherwrite(Port *port, Block *bp) etherwrite(Port *port, Block *bp)
{ {
Iphdr *eh, *feh; Ip4hdr *eh, *feh;
Etherpkt *epkt; Etherpkt *epkt;
int n, lid, len, seglen, dlen, blklen, mf; int n, lid, len, seglen, dlen, blklen, mf;
Block *nb; Block *nb;
@ -1075,26 +1065,26 @@ etherwrite(Port *port, Block *bp)
return; return;
} }
seglen = (TunnelMtu - ETHERHDRSIZE - IPHDR) & ~7; seglen = (TunnelMtu - ETHERHDRSIZE - IP4HDR) & ~7;
eh = (Iphdr*)(epkt->data); eh = (Ip4hdr*)(epkt->data);
len = nhgets(eh->length); len = nhgets(eh->length);
frag = nhgets(eh->frag); frag = nhgets(eh->frag);
mf = frag & IP_MF; mf = frag & IP_MF;
frag <<= 3; frag <<= 3;
dlen = len - IPHDR; dlen = len - IP4HDR;
lid = nhgets(eh->id); lid = nhgets(eh->id);
bp->rp += ETHERHDRSIZE+IPHDR; bp->rp += ETHERHDRSIZE+IP4HDR;
if(0) if(0)
print("seglen=%d, dlen=%d, mf=%x, frag=%d\n", print("seglen=%d, dlen=%d, mf=%x, frag=%d\n",
seglen, dlen, mf, frag); seglen, dlen, mf, frag);
for(fragoff = 0; fragoff < dlen; fragoff += seglen) { for(fragoff = 0; fragoff < dlen; fragoff += seglen) {
nb = allocb(ETHERHDRSIZE+IPHDR+seglen); nb = allocb(ETHERHDRSIZE+IP4HDR+seglen);
feh = (Iphdr*)(nb->wp+ETHERHDRSIZE); feh = (Ip4hdr*)(nb->wp+ETHERHDRSIZE);
memmove(nb->wp, epkt, ETHERHDRSIZE+IPHDR); memmove(nb->wp, epkt, ETHERHDRSIZE+IP4HDR);
nb->wp += ETHERHDRSIZE+IPHDR; nb->wp += ETHERHDRSIZE+IP4HDR;
if((fragoff + seglen) >= dlen) { if((fragoff + seglen) >= dlen) {
seglen = dlen - fragoff; seglen = dlen - fragoff;
@ -1103,7 +1093,7 @@ etherwrite(Port *port, Block *bp)
else else
hnputs(feh->frag, (frag+fragoff>>3) | IP_MF); hnputs(feh->frag, (frag+fragoff>>3) | IP_MF);
hnputs(feh->length, seglen + IPHDR); hnputs(feh->length, seglen + IP4HDR);
hnputs(feh->id, lid); hnputs(feh->id, lid);
if(seglen){ if(seglen){

1
sys/src/9/port/portmkfile
View file

@ -79,6 +79,7 @@ trap.$O: ../port/systab.h
devpipe.$O: ../port/netif.h devpipe.$O: ../port/netif.h
netif.$O: ../port/netif.h netif.$O: ../port/netif.h
devuart.$O: ../port/netif.h devuart.$O: ../port/netif.h
devbridge.$O: ../port/netif.h ../ip/ip.h ../ip/ipv6.h
devdraw.$O: screen.h /sys/include/draw.h /sys/include/memdraw.h /sys/include/memlayer.h /sys/include/cursor.h devdraw.$O: screen.h /sys/include/draw.h /sys/include/memdraw.h /sys/include/memlayer.h /sys/include/cursor.h
devmouse.$O: screen.h /sys/include/draw.h /sys/include/memdraw.h /sys/include/cursor.h devmouse.$O: screen.h /sys/include/draw.h /sys/include/memdraw.h /sys/include/cursor.h
swcursor.$O: screen.h /sys/include/draw.h /sys/include/memdraw.h /sys/include/cursor.h swcursor.$O: screen.h /sys/include/draw.h /sys/include/memdraw.h /sys/include/cursor.h