#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <resolv.h>
#include <netinet/in.h>
#include <unistd.h>
#include <arpa/inet.h>
#define MAXLINE 4096
#define SA struct sockaddr
#include <stdarg.h> /* ANSI C header file */
#include <syslog.h> /* for syslog() */
int daemon_proc; /* set nonzero by daemon_init() */
static void
err_doit(int errnoflag, int level, const char *fmt, va_list ap)
{
int errno_save, n;
char buf[MAXLINE + 1];
errno_save = errno; /* value caller might want printed */
#ifdef HAVE_VSNPRINTF
vsnprintf(buf, MAXLINE, fmt, ap); /* safe */
#else
vsprintf(buf, fmt, ap); /* not safe */
#endif
n = strlen(buf);
if (errnoflag)
snprintf(buf + n, MAXLINE - n, ": %s", strerror(errno_save));
strcat(buf, "\n");
if (daemon_proc) {
syslog(level, buf);
} else {
fflush(stdout); /* in case stdout and stderr are the same */
fputs(buf, stderr);
fflush(stderr);
}
return;
}
void
err_sys(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
err_doit(1, LOG_ERR, fmt, ap);
va_end(ap);
exit(1);
}
void
err_quit(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
err_doit(0, LOG_ERR, fmt, ap);
va_end(ap);
exit(1);
}
int
main(int argc, char **argv)
{
int sockfd, n;
char recvline[MAXLINE + 1];
struct sockaddr_in servaddr;
if (argc != 2)
err_quit("usage: a.out <IPaddress>");
if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
err_sys("socket error");
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(13); /* daytime server */
if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0)
err_quit("inet_pton error for %s", argv[1]);
if (connect(sockfd, (SA *) &servaddr, sizeof(servaddr)) < 0)
err_sys("connect error");
while ( (n = read(sockfd, recvline, MAXLINE)) > 0) {
recvline[n] = 0; /* null terminate */
if (fputs(recvline, stdout) == EOF)
err_sys("fputs error");
}
if (n < 0)
err_sys("read error");
exit(0);
}
