socket编程之并发回射服务器

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#define MAXLINE 4096
#define LISTENQ 10

void doEcho(int sockfd) {
    char buff[MAXLINE];
    while (true) {
        memset(buff, 0, sizeof(buff));
        int n = read(sockfd, buff, MAXLINE);
        if (n < 0) {
            perror("read error");
            exit(1);
        } else if (n == 0) {
            printf("client closed\n");
            break;
        }
        fputs(buff, stdout);
        write(sockfd, buff, n);
    }
}

int main(int argc, char **argv) {
    
    int listenfd, connfd;
    pid_t childpid;
    socklen_t clilen;
    struct sockaddr_in servaddr, cliaddr;
    
    if ( (listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket error");
        exit(1);
    }
    
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(13);  /* daytime server */
    
    if ( bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0) {
        perror("bind error");
        exit(1);
    }
    
    if ( listen(listenfd, LISTENQ) < 0) {
        perror("listen error");
        exit(1);
    }
    
    for ( ; ; ) {
        clilen = sizeof(cliaddr);
        if ( (connfd = accept(listenfd, (struct sockaddr*)&cliaddr, &clilen)) < 0) {
            perror("accept error");
            exit(1);
        }
        /* 子进程 */
        if ( (childpid = fork()) == 0) {
            close(listenfd);
            // 回射程序
            doEcho(connfd);
            exit(0);
        }
        /* 父进程 */
        close(connfd);
    }
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#define MAXLINE 4096

int main(int argc, char **argv) {
    
    int sockfd;
    struct sockaddr_in servaddr;
    
    if (argc != 2) {
        perror("Usage: a.out <IPaddress>");
        exit(1);
    }
    
    if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket error");
        exit(1);
    }
    
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(13);  /* daytime server */
    if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0) {
        printf("inet_pton error for %s\n", argv[1]);
        exit(1);
    }
    
    if (connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr))) {
        perror("connect error");
        exit(1);
    }
    
    char sendline[MAXLINE], recvline[MAXLINE];
    while (fgets(sendline, MAXLINE, stdin) != NULL) {
        write(sockfd, sendline, strlen(sendline));
        read(sockfd, recvline, MAXLINE);
        fputs(recvline, stdout);
        memset(sendline, 0, sizeof(sendline));
        memset(recvline, 0, sizeof(recvline));
    }
    
    exit(0);
}