Date: Fri, 6 Dec 1996 17:54:48 -0700 (MST) From: Ade Barkah <mbarkah@hemi.com> To: hackers@freebsd.org Subject: bug in 2.2-alpha loopback (?) Message-ID: <199612070054.RAA12233@hemi.com>
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[Sorry if you got this twice, this is a resend, seems that the first
one didn't get through]
Hi,
It seems that read() on a socket via the loopback interface does not
return 0 ("EOF") when the socket is broken. Instead, it returns 1,
with the data returned being '\004' (ctrl-D).
This breaks various code which check return values with:
if ((ret = read (....)) <= 0)
/* error processing here */
since ret gets set to 1. (In my case, lex gets really confused.)
For convenience, sample test code appended. It simply binds to port
2000 and waits for a connection. Telnet to localhost port 2000, hit
ctrl-] and quit, and read the result (should return 0). Works fine
in 2.1.x, breaks on 2.2-Alpha.
Thanks,
-Ade
ps. sorry I don't know enough to make a bug-fix patch.
-------------------------------------------------------------------
Inet: mbarkah@hemi.com - HEMISPHERE ONLINE - <http://www.hemi.com/>;
-------------------------------------------------------------------
--CUT HERE--
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
int
main(void)
{
int c, s, fd, alen=1, ret, port = 2000, opval = 1;
char buf[1024];
struct sockaddr_in sin, cin;
bzero(&sin, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = INADDR_ANY;
sin.sin_port = htons((unsigned short) port);
if ((s = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
perror("ERROR: Can't get socket");
exit(-1);
}
if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (int *) &opval,
sizeof(opval)) == -1) {
perror("ERROR: Cannot set SO_REUSEADDR");
exit(-1);
}
if (setsockopt(s, SOL_SOCKET, SO_KEEPALIVE, (int *) &opval,
sizeof(opval)) == -1) {
perror("ERROR: Cannot set SO_KEEPALIVE");
exit(-1);
}
if (bind(s, (struct sockaddr *) & sin, sizeof(sin)) == -1) {
perror("ERROR: Failed to bind");
return (-1);
}
if (listen(s, 3) == -1) {
perror("ERROR: Can't listen()");
return (-1);
}
printf("Waiting for client on port %d\n", port);
alen = sizeof(cin);
fd = accept (s, (struct sockaddr *)&cin, &alen);
ret = read(fd, buf, sizeof(buf)-1);
printf("Attention, read() returned %d.\n", ret);
if (ret > 10)
ret = 10;
for (c = 0; c < ret; c++)
printf("[%d]", buf[c]);
printf("\n");
}
--CUT HERE--
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