/* sv_funcs.c - TCPechod, TCPchargend, TCPdaytimed, TCPtimed */#include <sys/types.h>#include <unistd.h>#include <stdio.h>#include <time.h>#include <string.h>#define	BUFFERSIZE	4096		/* max read buffer size	*/extern	int	errno;void	TCPechod(int), TCPchargend(int), TCPdaytimed(int), TCPtimed(int);int	errexit(const char *format, ...);/*------------------------------------------------------------------------ * TCPecho - do TCP ECHO on the given socket *------------------------------------------------------------------------ */voidTCPechod(int fd){	char	buf[BUFFERSIZE];	int	cc;	while (cc = read(fd, buf, sizeof buf)) {		if (cc < 0)			errexit("echo read: %s\n", strerror(errno));		if (write(fd, buf, cc) < 0)			errexit("echo write: %s\n", strerror(errno));	}}#define	LINELEN		72/*------------------------------------------------------------------------ * TCPchargend - do TCP CHARGEN on the given socket *------------------------------------------------------------------------ */voidTCPchargend(int fd){	char	c, buf[LINELEN+2];	/* print LINELEN chars + \r\n */	c = ' ';	buf[LINELEN] = '\r';	buf[LINELEN+1] = '\n';	while (1) {		int	i;		for (i=0; i<LINELEN; ++i) {			buf[i] = c++;			if (c > '~')				c = ' ';		}		if (write(fd, buf, LINELEN+2) < 0)			break;	}}/*------------------------------------------------------------------------ * TCPdaytimed - do TCP DAYTIME protocol *------------------------------------------------------------------------ */voidTCPdaytimed(int fd){	char	buf[LINELEN], *ctime();	time_t	now;	(void) time(&now);	sprintf(buf, "%s", ctime(&now));	(void) write(fd, buf, strlen(buf));}#define	UNIXEPOCH	2208988800UL	/* UNIX epoch, in UCT secs	*//*------------------------------------------------------------------------ * TCPtimed - do TCP TIME protocol *------------------------------------------------------------------------ */voidTCPtimed(int fd){	time_t	now;	(void) time(&now);	now = htonl((unsigned long)(now + UNIXEPOCH));	(void) write(fd, (char *)&now, sizeof(now));}