TCP最简单的服务程序

#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <errno.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define MAXSOCKETLEN 1024

static void err_doit(int errnoflag, const char *fmt, va_list ap)
{
char buf[1024];

vsprintf(buf, fmt, ap);
if (errnoflag)
{
if (errno >= 0 && errno <= sys_nerr)
{
sprintf(buf+strlen(buf), ": %s", strerror(errno));
}
}

strcat(buf, " ");
fflush(stdout);
fputs(buf, stderr);
fflush(stderr);
}

void err_print(const char *fmt, ...)
{
va_list ap;

va_start(ap, fmt);
err_doit(1, fmt, ap);
va_end(ap);
exit(1);
}

int main()
{

int sockfd = 0;
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
err_print("socket fd created failed");
}

struct sockaddr_in servaddr;
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(43521);

if (bind(sockfd, (struct sockaddr *)(&servaddr), sizeof(servaddr)) < 0)
{
err_print("bind failed");
}

if (listen(sockfd, MAXSOCKETLEN) < 0)
{
err_print("listen failed");
}

while (1)
{
char buff[1024];
memset(buff, 0,sizeof(buff));

int connfd = -1;
connfd = accept(sockfd, (struct sockaddr *)NULL, NULL);
if (connfd < 0)
{
err_print("accept failed");
}

time_t ticks = time(NULL);
snprintf(buff, sizeof(buff), "%.24s", ctime(&ticks));

size_t size = send(connfd, buff, strlen(buff), 0);
printf("send size:%d, message:%s ", (int)size, buff);
if (size < 0)
{
err_print("write failed");
}

close(connfd);
};

return 0;
}