cak@Purdue.ARPA (01/12/84)
From: Christopher A Kent <cak@Purdue.ARPA>
Description:
Attempts to use syslog(3) fail in programs that perform other
network functions. Output to the log file is garbled, or correct
network system call invocations fail for no apparent reason.
The syslog supplied with sendmail does, however, function
correctly. Inspection of the two versions shows that the C library
version neglects to bind the datagram socket to any address.
Recompiling the supplied libc source and reinstalling
/lib/libc.a causes the problem to go away(!).
Repeat-By:
Compile and run the following, both with and without an
argument, and inspect the syslog output.
/*
* demonstrate broken syslog
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <syslog.h>
struct sockaddr_in sin = { AF_INET }; /* socket address */
main(argc, argv)
char **argv;
{
int s;
if(fork())
exit(0);
if(argc > 1)
openlog("stest", LOG_PID);
syslog(LOG_INFO, "starting up");
sin.sin_addr.s_addr = INADDR_ANY;
sin.sin_port = htons(77);
s = socket(AF_INET, SOCK_STREAM, 0, 0);
if(s < 0){
perror("socket");
exit(1);
}
if(bind(s, &sin, sizeof(sin)) < 0){
perror("bind");
exit(1);
}
syslog(LOG_INFO, "message1");
syslog(LOG_INFO, "message2");
}
Fix:
While the recompiled version seems to work correctly, the
following diff supplies the "missing" bind, for the conservative-minded:
*** syslog.c.old
--- syslog.c.new
***************
*** 119,124
}
bzero(&SyslogAddr, sizeof SyslogAddr);
SyslogAddr.sin_family = hp->h_addrtype;
bcopy(hp->h_addr, (char *)&SyslogAddr.sin_addr, hp->h_length);
SyslogAddr.sin_port = sp->s_port;
LogStat |= LOG_DGRAM;
--- 119,130 -----
}
bzero(&SyslogAddr, sizeof SyslogAddr);
SyslogAddr.sin_family = hp->h_addrtype;
+ if(bind(LogFile, &SyslogAddr, sizeof SyslogAddr, 0) < 0){
+ perror("syslog: bind");
+ close(LogFile);
+ LogFile = -1;
+ goto bad;
+ }
bcopy(hp->h_addr, (char *)&SyslogAddr.sin_addr, hp->h_length);
SyslogAddr.sin_port = sp->s_port;
LogStat |= LOG_DGRAM;
----------