kern/50839: icmp time-exceeded causes tcp connect to return success bogusly

[Barney Wolff]

>Number:         50839
>Category:       kern
>Synopsis:       icmp time-exceeded causes tcp connect to return success bogusly
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Apr 11 15:40:05 PDT 2003
>Closed-Date:
>Last-Modified:
>Originator:     Barney Wolff
>Release:        FreeBSD 4.8-STABLE i386
>Organization:
Databus Inc.
>Environment:
System: FreeBSD pit.databus.com 4.8-STABLE FreeBSD 4.8-STABLE #0: Wed Apr 9 15:22:45 EDT 2003 toor at pit.databus.com:/usr/obj/usr/src/sys/PIT i386
and
FreeBSD lab.databus.com 5.0-CURRENT FreeBSD 5.0-CURRENT #1: Fri Apr 11 18:00:56
EDT 2003     toor at lab.databus.com:/usr/obj/usr/src/sys/LAB  i386
>Description:
	TCP connect(2) returns 0 if a routing loop causes an ICMP unreach-time-
	exceeded to be returned.  Problem is that the cmd code is mapped to
	error 0 in in_input.
>How-To-Repeat:
	Set up routing loop (I just added a /32 bogus route on my internal net
	to do this).  Connect to looped destination.  Connect returns 0, but
	socket is of course not writable.  Test prog attached.  This fails on
	both stable and current.
>Fix:
b:/usr/src/sys/netinet $ diff -u ip_input.c.orig ip_input.c
--- ip_input.c.orig     Wed Apr  9 14:07:16 2003
+++ ip_input.c  Fri Apr 11 17:54:11 2003
@@ -1696,7 +1696,7 @@
        0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
        EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
        EMSGSIZE,       EHOSTUNREACH,   0,              0,
-       0,              0,              0,              0,
+       0,              0,              EHOSTUNREACH,   0,
        ENOPROTOOPT,    ECONNREFUSED
 };
  
(This patch is to current.)


Here's the test prog:

/*	conntime.c	Barney Wolff	<barney at databus.com>	*/

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <sys/errno.h>
extern int errno;
#include <sys/time.h>

#ifdef __FreeBSD__
#define sigignore(x) signal(x,SIG_IGN)
#endif

main(int argc,char **argv) {
	int sockfd,lsockfd,i,recv=0,cookie=0,dofork=0;
	struct sockaddr_in skinaddr;
	struct timeval start,end;

	if (argc < 3) {
		fprintf(stderr,"%0 ipaddr port\n");
		exit(1);
	}

	sigignore(SIGPIPE);

	memset(&skinaddr,0,sizeof(skinaddr));
	skinaddr.sin_family = AF_INET;
	skinaddr.sin_addr.s_addr = inet_addr(argv[1]);
	skinaddr.sin_port = htons((short)atoi(argv[2]));

	if ((sockfd=socket(PF_INET,SOCK_STREAM,0)) < 0)
		{perror("socket"); exit(2);}

	i = 1;
	setsockopt(sockfd,SOL_SOCKET,SO_KEEPALIVE,&i,sizeof(i));

	gettimeofday(&start,NULL);
	i = connect(sockfd,(struct sockaddr *)&skinaddr,sizeof(skinaddr));
	gettimeofday(&end,NULL);

	if (i < 0) perror("connection failed");
	fprintf(stderr,"connect returned in %d usec\n",
		1000000*(end.tv_sec-start.tv_sec)+end.tv_usec-start.tv_usec);
	if (i == 0) {
		start = end;
		i = write(sockfd,"GET /\r\n\r\n",9);
		gettimeofday(&end,NULL);
		if (i < 0) perror("write failed");
		fprintf(stderr,"write returned in %d usec\n",
			1000000*(end.tv_sec-start.tv_sec)+end.tv_usec-start.tv_usec);
	}
}
>Release-Note:
>Audit-Trail:
>Unformatted: