一个简单的TCP/IP并发回显C/S(一)

解决问题:
1.并发等待子进程终止(避免出现僵死进程)
2.防止accept,read,write等阻塞函数的中断不能重启
未解决问题
1.服务器非正常终止，崩溃，重启

客户端代码:
vi c2.c

#include <stdio.h>#include <stdlib.h>#include <sys/socket.h>#include <unistd.h>#include <string.h>#include <arpa/inet.h>#include <errno.h>#define OWNPORT 9877#define MAXLINE 4096int main(int argc,char **argv){    if (argc != 2)    {    printf("please add <ipadress>\n");    exit(1);    }    int sockfd;    if ((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0)    {    printf("socket %s\n",strerror(errno));    exit(1);    }    struct sockaddr_in servaddr;    servaddr.sin_family = AF_INET;    servaddr.sin_port = htons(OWNPORT);    if (inet_pton(AF_INET,argv[1],&servaddr.sin_addr) <= 0)    {    printf("inet_pton %s\n",strerror(errno));    exit(1);    }    if (connect(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr)) < 0)    {    printf("connect %s\n",strerror(errno));    exit(1);    }    char buf[MAXLINE + 1];    while (fgets(buf,MAXLINE,stdin) != NULL)    {        /*int pos = strlen(buf);    buf[pos] = '\n';    buf[pos + 1] = '\0';*/    int n = 0;    int size = strlen(buf);    while ((n = write(sockfd,buf + n,size)) >  0 || errno == EINTR)     {        size -= n;        if (size <= 0)        break;    }    if (n < 0)    {        printf("wriet %s\n",strerror(errno));        exit(1);    }       size = 0;    if((n = read(sockfd,buf,MAXLINE)) > 0 || errno == EINTR);    if (n < 0)    {        printf("read %s\n",strerror(errno));        exit(1);    }    buf[n] = '\0';    fputs(buf,stdout);    }    return 0;}

服务器端:

vi s2.c

#include <stdio.h>#include <stdlib.h>#include <sys/socket.h>#include <arpa/inet.h>#include <errno.h>#include <string.h>#include <signal.h>#include <unistd.h>#include <sys/wait.h>#define OWNPORT 9877#define LISTENQ 1024#define MAXLINE 4096#define MAXSIZE 4096void sig_child(int signo){    int pid;    int stat;    while ((pid = waitpid(-1,&stat,WNOHANG)) < 0)    {    printf("waitpid %s\n",strerror(errno));    exit(1);    }}void writeback(int fd){    int n;    char buf[MAXSIZE];    int size = 0;    errno = 0;    while ((n = read(fd,buf,MAXSIZE)) > 0)    {    size += n;    if (n < 0)    {        printf("read %s\n",strerror(errno));        exit(1);    }    n = 0;    while ((n = write(fd,buf + n,size)) > 0 || errno == EINTR)    {        size -= n;        if (size <= 0)        break;    }    if (n < 0)    {        printf("write %s\n",strerror(errno));        exit(1);    }    size = 0;    }}int main(){    int lisfd;    if ((lisfd = socket(AF_INET,SOCK_STREAM,0)) < 0)    {    printf("socket %s\n",strerror(errno));    exit(1);    }    struct sockaddr_in servaddr;    servaddr.sin_family = AF_INET;    servaddr.sin_port = htons(OWNPORT);    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);    if ( bind(lisfd,(struct sockaddr*)&servaddr,sizeof(servaddr)) < 0)    {    printf("bind %s\n",strerror(errno));    exit(1);    }    if (listen(lisfd,LISTENQ) < 0)    {    printf("listen %s\n",strerror(errno));    exit(1);    }    if (signal(SIGCHLD,sig_child) == SIG_ERR)    {    printf("signal %s\n",strerror(errno));    exit(1);    }    int pid,confd;    for (; ;)    {    errno = 0;    if ((confd = accept(lisfd,(struct sockaddr*)NULL,NULL)) < 0)    {        if (errno == EINTR)        continue;        printf("accept %s\n",strerror(errno));        exit(1);    }    if ((pid = fork()) < 0)    {        printf("fork %s\n",strerror(errno));        exit(1);    }else if (pid == 0)    {        close(lisfd);        writeback(confd);        exit(1);    }    close(confd);    }    return 0;}

运行: