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 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define SERV_PORT 9877
#define MAXLINE 4096

void 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 \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 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define OWNPORT 9877
#define LISTENQ 1024
#define MAXLINE 4096
#define MAXSIZE 4096

void 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;
}