Date: Fri, 14 Jun 2002 17:10:21 +0200 From: Sebastien Petit <spe@selectbourse.net> To: freebsd-net@freebsd.org Subject: Problem using ng_ether Message-ID: <20020614150130.56E86BAE9@sbserv0.intra.selectbourse.net>
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Hi,
I've a problem with ng_ether and xl0 driver, when I connect upper <-> lower
directly, packets have ip sum to 0 and a wrong tcp and udp cksum. I try to
use my test code on rl0 driver, and it work fine.
Julian or Archie, can you say me if I must recompute ip/tcp/udp checksum for
all packets read on upper and then writed on lower hook ?
Here is my code:
This code must normally connect upper and lower together and so the packets
flow normally upwards and downwards (like if there is nothing connected to
hooks)
#include <netgraph.h>
#include <netgraph/ng_ether.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <net/ethernet.h>
#include <netinet/tcp.h>
#define HOOKNAME "myhook"
#define HOOKNAME2 "myhook2"
int main(int argc, char **argv)
{
int csock, dsock;
int csock2, dsock2;
struct ngm_connect ngc;
struct ngm_connect ngc2;
int bytesread;
size_t bytesread2;
unsigned char buf[4096];
char buf2[4096];
char hookname[4096];
fd_set fds;
u_short *csum;
int cpt;
struct ether_header *eth = (struct ether_header *)buf;
struct ip *iph = (struct ip *)&buf[sizeof(struct ether_header)];
struct tcphdr *tcph = (struct tcphdr *)&buf[sizeof(struct
ether_header)+sizeof(struct ip)];
NgMkSockNode(NULL, &csock, &dsock);
snprintf(ngc.path, sizeof(ngc.path), "xl0:");
snprintf(ngc.ourhook, sizeof(ngc.ourhook), HOOKNAME);
snprintf(ngc.peerhook, sizeof(ngc.peerhook), "upper");
NgSendMsg(csock, ".", NGM_GENERIC_COOKIE, NGM_CONNECT, &ngc,
sizeof(ngc));
snprintf(ngc.path, sizeof(ngc.path), "xl0:");
snprintf(ngc.ourhook, sizeof(ngc.ourhook), HOOKNAME2);
snprintf(ngc.peerhook, sizeof(ngc.peerhook), "lower");
NgSendMsg(csock, ".", NGM_GENERIC_COOKIE, NGM_CONNECT, &ngc,
sizeof(ngc));
for (;;) {
bzero(buf, sizeof(buf));
bytesread = NgRecvData(dsock, buf, sizeof(buf), hookname);
printf("bytes = %d\n", bytesread);
printf("name = %s\n", hookname);
if (! strcmp(hookname, "myhook")) {
printf("%s !\n", hookname);
NgSendData(dsock, HOOKNAME2, buf, bytesread);
}
else
if (! strcmp(hookname, "myhook2")) {
printf("%s !\n", hookname);
NgSendData(dsock, HOOKNAME, buf, bytesread);
}
}
}
Output of 'ngctl show xl0:':
[root@artik ~]# ngctl show xl0:
Name: xl0 Type: ether ID: 00000001 Num hooks: 2
Local hook Peer name Peer type Peer ID Peer hook
---------- --------- --------- ------- ---------
lower <unnamed> socket 00000055 myhook2
upper <unnamed> socket 00000055 myhook
If now I try to telnet an other host on the same lan on ssh port, here there
is the result of tcpdump on this another host:
16:56:06.971008 172.16.2.3.1218 > 172.16.1.1.22: S [bad tcp cksum ea9c!]
2063189250:2063189250(0) win 65535 <mss 1460> (DF) [tos 0x10] (ttl 64, id
4078, len 44, bad cksum 0!)
0x0000 4510 002c 0fee 4000 4006 0000 ac10 0203 E..,..@.@.......
0x0010 ac10 0101 04c2 0016 7af9 c502 0000 0000 ........z.......
0x0020 6002 ffff 5b43 0000 0204 05b4 0000 `...[C........
16:56:09.965572 172.16.2.3.1218 > 172.16.1.1.22: S [bad tcp cksum ea9c!]
2063189250:2063189250(0) win 65535 <mss 1460> (DF) [tos 0x10] (ttl 64, id
54488, len 44, bad cksum 0!)
0x0000 4510 002c d4d8 4000 4006 0000 ac10 0203 E..,..@.@.......
0x0010 ac10 0101 04c2 0016 7af9 c502 0000 0000 ........z.......
0x0020 6002 ffff 5b43 0000 0204 05b4 0000 `...[C........
16:56:12.964827 172.16.2.3.1218 > 172.16.1.1.22: S [bad tcp cksum ea9c!]
2063189250:2063189250(0) win 65535 <mss 1460> (DF) [tos 0x10] (ttl 64, id
5274, len 44, bad cksum 0!)
0x0000 4510 002c 149a 4000 4006 0000 ac10 0203 E..,..@.@.......
0x0010 ac10 0101 04c2 0016 7af9 c502 0000 0000 ........z.......
0x0020 6002 ffff 5b43 0000 0204 05b4 0000 `...[C........
16:56:15.965646 172.16.2.3.1218 > 172.16.1.1.22: S [bad tcp cksum ea9c!]
2063189250:2063189250(0) win 65535 <mss 1460> (DF) [tos 0x10] (ttl 64, id
58146, len 44, bad cksum 0!)
0x0000 4510 002c e322 4000 4006 0000 ac10 0203 E..,."@.@.......
0x0010 ac10 0101 04c2 0016 7af9 c502 0000 0000 ........z.......
0x0020 6002 ffff 5b43 0000 0204 05b4 0000 `...[C........
16:56:18.965003 172.16.2.3.1218 > 172.16.1.1.22: S [bad tcp cksum ea9c!]
2063189250:2063189250(0) win 65535 <mss 1460> (DF) [tos 0x10] (ttl 64, id
25692, len 44, bad cksum 0!)
0x0000 4510 002c 645c 4000 4006 0000 ac10 0203 E..,d\@.@.......
0x0010 ac10 0101 04c2 0016 7af9 c502 0000 0000 ........z.......
0x0020 6002 ffff 5b43 0000 0204 05b4 0000 `...[C........
As you can see, the ip cksum is 0 and tcp cksum is invalid...
This problem doesn't seem to appear on rl driver (I just replace xl0: with
rl0: on the code) for example and packets flow normally upwards and downwards.
Any ideas ? does my code work perfectly for you or not ?
Thanks
Sebastien.
--
spe@selectbourse.net
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