（unix网络编程）tcp回射程序二：避免僵尸进程

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/wait.h>

#define MAXLINE 4096
#define SERV_PORT 5000
#define LISTENQ 5

void str_echo(int sockfd) {
ssize_t n;
char buf[MAXLINE];
const char *quit_code = "QUIT\n";

for(;;) {
if ((n = read(sockfd, buf, MAXLINE)) > 0) {
if (strcmp(buf, quit_code) == 0) {
printf("client quit\n");
break;
}

if (write(sockfd, buf, n) < 0) {
printf("write error:%s\n", strerror(errno));
}
memset(buf, 0x00, MAXLINE);
}

if (n < 0 && errno != EINTR) {
printf("str_echo: read error:%s\n", strerror(errno));
}
}
}

void sig_chld(int signo) {
pid_t pid;
int stat;

printf("SIGCHLD handled\n");
while ((pid = waitpid(-1, &stat, WNOHANG)) > 0) {
printf("child %d terminated\n", pid);
}
}

int main(int argc, char **argv)
{
int listenfd, connfd;
pid_t childpid;
socklen_t clilen;
struct sockaddr_in cliaddr, servaddr;

if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
printf("socket error:%s\n", strerror(errno));
return -1;
}

memset(&servaddr, 0x00, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);

if (bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0) {
printf("bind error:%s\n", strerror(errno));
return -1;
}

if (listen(listenfd, LISTENQ) < 0) {
printf("listen error:%s\n", strerror(errno));
return -1;
}

signal(SIGCHLD, sig_chld);

for(;;) {
clilen = sizeof(cliaddr);
if ((connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &clilen)) < 0) {
printf("listen error:%s\n", strerror(errno));
return -1;
}

if ((childpid = fork()) == 0) {
if (close(listenfd) < 0) {
printf("close listenfd error:%s\n", strerror(errno));
}
str_echo(connfd);
exit(0);
}

if (close(connfd) < 0) {
printf("close connfd error:%s\n", strerror(errno));
}
}

}

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <errno.h>
#include <arpa/inet.h>
#include <stdlib.h>

#define SERV_PORT 5000
#define MAXLINE 4096

void str_cli(FILE *fp, int sockfd) {
const char *quit_code = "QUIT\n";
char sendline[MAXLINE], recvline[MAXLINE];

while (fgets(sendline, MAXLINE, fp) != NULL) {
if (strcmp(sendline, quit_code) == 0) {
printf("client quit\n");
break;
}

if (write(sockfd, sendline, strlen(sendline)) < 0) {
printf("write error:%s\n", strerror(errno));
}

if (read(sockfd, recvline, MAXLINE) == 0) {
printf("server terminated:%s\n", strerror(errno));
}

if (fputs(recvline, stdout) == EOF) {
printf("fputs over\n");
}
memset(sendline, 0x00, MAXLINE);
memset(recvline, 0x00, MAXLINE);
}

if ((write(sockfd, quit_code, strlen(quit_code))) < 0) {
printf("tell server quit error\n");
}
}

int main(int argc, char **argv)
{
int sockfd;
struct sockaddr_in servaddr;

if (argc != 2) {
printf("tcpcli1 <IPaddres>\n");
return -1;
}

if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
printf("socket error:%s\n", strerror(errno));
return -1;
}

memset(&servaddr, 0x00, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(SERV_PORT);
if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) < 0) {
printf("inet_pton error:%s\n", strerror(errno));
return -1;
}

if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0) {
printf("connect error:%s\n", strerror(errno));
return -1;
}

str_cli(stdin, sockfd);
exit(0);
}