《unix网络编程》第五章例子，未处理信号

client.c

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

#define SERV_PORT 8930
#define MAX_LINE 1024

int main(int argc, char** argv)
{
    int sockfd;
    struct sockaddr_in servaddr;
    char sendline[MAX_LINE];
    int sendlen;
    char* ptr;
    int rv;
    int read_cnt;
    char read_buff[MAX_LINE];
    errno = 0;

    if (argc < 2)
    {
        return 0;
    }

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    memset(&servaddr, 0 ,sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(SERV_PORT);
    inet_pton(AF_INET, argv[1], &servaddr.sin_addr);

    rv = connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
    if (rv != 0)
    {
        printf("connect() errno: %d, strerror: %s\n", errno, strerror(errno));
        close(sockfd);
        return 0;
    }

    while (fgets(sendline, MAX_LINE, stdin) != NULL)
    {
        sendlen = strlen(sendline);
        ptr = sendline;
        while (sendlen > 0)
        {
            if ((rv = write(sockfd, ptr, sendlen)) <= 0)
            {
                if (errno == EINTR)
                {
                    rv = 0;
                }
                else
                {
                    printf("write() errno: %d, strerror: %s\n", errno, strerror(errno));
                    close(sockfd);
                    return 0;
                }
            }
            sendlen -= rv;
            ptr = rv;
        }

        memset(read_buff, 0, sizeof(read_buff));
again_read:
        if ((read_cnt = read(sockfd, read_buff, sizeof(read_buff))) < 0)
        {
            if (errno == EINTR)
            {
                goto again_read;
            }
            printf("read() errno: %d, strerror: %s\n", errno, strerror(errno));
            close(sockfd);
            exit(0);
        }
        else if (read_cnt == 0) //close by peer
        {
            printf("close connection by peer\n");
            close(sockfd);
            exit(0);
        }

        printf("receive from server: %s\n", read_buff);
    }
}

server.c

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

#define SERV_PORT 8930
#define MAX_BUFF 1024

int main(int argc, char** argv)
{
    int listenfd;
    int connfd;
    pid_t childpid;
    socklen_t clilen;
    struct sockaddr_in cliaddr;
    struct sockaddr_in servaddr;
    char clientip[16];
    int rv;
    int i;
    char read_buff[MAX_BUFF];
    int read_cnt;
    int write_len;
    char *ptr;
    errno = 0;

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

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

    rv = bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
    if (0 != rv)
    {
        printf("bind() errno: %d, strerror: %s\n", errno, strerror(errno));
        close(listenfd);
        return 0;
    }
    rv = listen(listenfd, 5);
    if (0 != rv)
    {
        printf("listen() errno: %d, strerror: %s\n", errno, strerror(errno));
        close(listenfd);
        return 0;
    }

    while(1)
    {
        clilen = sizeof(cliaddr);
        connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &clilen);
        if ((childpid = fork()) == 0) //child process
        {
            if (connfd < 0)
            {
                printf("accept() errno: %d, strerror: %s\n", errno, strerror(errno));
                close(listenfd);
                return 0;
           }
            close(listenfd);

again_read:
            if ((read_cnt = read(connfd, read_buff, sizeof(read_buff))) < 0)
            {
                if (errno == EINTR)
                {
                    goto again_read;
                }
                printf("read() errno: %d, strerror: %s\n", errno, strerror(errno));
                close(connfd);
                exit(0);
            }
            else if (read_cnt == 0) //close by peer
            {
                printf("close connection by peer\n");
                close(connfd);
                exit(0);
            }

            for (i = 0; i < read_cnt; i )
            {
                if (read_buff[i] == '\n' || read_buff[i] == 0)
                {
                    read_buff[i] = 0;
                    i ;
                    break;
                }
            }
            write_len = i;

            inet_ntop(AF_INET, &(cliaddr.sin_addr.s_addr), clientip, sizeof(clientip));
            printf("client ip: %s, client port: %d, receive mesage: %s\n", clientip, cliaddr.sin_port, read_buff);

            ptr = read_buff;
            while (write_len > 0)
            {
                if ((rv = write(connfd, ptr, write_len)) <= 0)
                {
                    if (errno == EINTR)
                    {
                        rv = 0;
                    }
                    else
                    {
                        printf("write() errno: %d, strerror: %s\n", errno, strerror(errno));
                        close(connfd);
                        exit(0);
                    }
                }
                write_len -= rv;
                ptr = rv;
            }

            exit(0);
        }
        close(connfd);
    }
}