一个简单的TCP/IP并发回显C/S(二)

解决问题:
服务器进程或主机意外崩溃或重启
输出重定向
客户端代码:

vi c3.c

#include <unistd.h>#include <stdlib.h>#include <sys/socket.h>#include <arpa/inet.h>#include <stdio.h>#include <errno.h>#include <string.h>#include <sys/select.h>#define SERV_PORT 9877#define MAXLINE 4096void client_echo(FILE *fp,int sockfd){    int fd = fileno(fp);    int maxfd = fd > sockfd ? fd : sockfd;    fd_set fs;    FD_ZERO(&fs);    int n;    char buf[MAXLINE];    int ioeof = 0;    for (; ;)    {    if (ioeof == 0)        FD_SET(fd,&fs);    FD_SET(sockfd,&fs);    if (select(maxfd + 1,&fs,NULL,NULL,NULL) < 0)    {        printf("select: %s\n",strerror(errno));        exit(1);    }    if (FD_ISSET(sockfd,&fs))    {        if ((n = read(sockfd,buf,MAXLINE)) ==  0)        {        if (ioeof == 1)            return;        else            printf("server is broke\n");        }else if (n < 0)        {           printf("read: %s\n",strerror(errno));        exit(1);        }        if (write(fd,buf,n) != n)        {        printf("write %s\n",strerror(errno));        exit(1);        }    }    if (FD_ISSET(fd,&fs))    {        if ((n = read(fd,buf,MAXLINE)) == 0)        {        ioeof = 1;        if(shutdown(sockfd,SHUT_WR) < 0)        {            printf("shutdown error\n");            exit(1);        }        FD_CLR(fileno(fp),&fs);        continue;        }else if (n < 0)        {           printf("read: %s\n",strerror(errno));        exit(1);        }        if (write(sockfd,buf,n) != n)        {        printf("write: %s\n",strerror(errno));        exit(1);        }    }    }}int 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(SERV_PORT);    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);    }    client_echo(stdout,sockfd);   }

服务器代码:

vi s3.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;}