TCP时间获取程序

一、服务器程序

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

#define MAXLINE 4096
#define LISTENQ 1024
#define SA struct sockaddr

int main(int argc, char *argv[]) {
    int listenfd, connfd;
    struct sockaddr_in servaddr;
    char buff[MAXLINE];
    time_t ticks;

    listenfd = socket(AF_INET, SOCK_STREAM, 0);

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(9999);

    bind(listenfd, (SA *)&servaddr, sizeof(servaddr));

    listen(listenfd, LISTENQ);

    for ( ; ; ) {
        connfd = accept(listenfd, (SA *)NULL, NULL);

        ticks = time(NULL);
        snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));
        write(connfd, buff, strlen(buff));

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

二、显示客户IP地址和端口号的服务器程序

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

#define MAXLINE 4096
#define LISTENQ 1024
#define SA struct sockaddr

int main(int argc, char *argv[]) {
    int listenfd, connfd;
    socklen_t len;
    struct sockaddr_in servaddr, cliaddr;
    char buff[MAXLINE];
    time_t ticks;

    listenfd = socket(AF_INET, SOCK_STREAM, 0);

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(9999);

    bind(listenfd, (SA *)&servaddr, sizeof(servaddr));

    listen(listenfd, LISTENQ);

    for ( ; ; ) {
        len = sizeof(cliaddr);
        connfd = accept(listenfd, (SA *)&cliaddr, &len);
        printf("connection from %s, port %d\n", inet_ntop(AF_INET, 
            &cliaddr.sin_addr, buff, sizeof(buff)), ntohs(cliaddr.sin_port));

        ticks = time(NULL);
        snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));
        write(connfd, buff, strlen(buff));

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

三、并发服务器程序

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

#define MAXLINE 4096
#define LISTENQ 1024
#define SA struct sockaddr

int main(int argc, char *argv[]) {
    int listenfd, connfd;
    pid_t pid;
    struct sockaddr_in servaddr;
    char buff[MAXLINE];
    time_t ticks;

    listenfd = socket(AF_INET, SOCK_STREAM, 0);

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(9999);

    bind(listenfd, (SA *)&servaddr, sizeof(servaddr));

    listen(listenfd, LISTENQ);

    for ( ; ; ) {
        connfd = accept(listenfd, (SA *)NULL, NULL);

        if ( (pid = fork()) == 0) {
            close(listenfd);

            ticks = time(NULL);
            snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));
            write(connfd, buff, strlen(buff));

            close(connfd);
        }

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

四、客户端程序

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

#define SA struct sockaddr
#define MAXLINE 4096

int main(int argc, char *argv[]) {
    int sockfd, n;
    char recvline[MAXLINE + 1];
    struct sockaddr_in servaddr;
    
    if (argc != 2) {
        printf("usage: ./daytimetcpcli <IPaddress>\n");
        return 0;
    }    
    if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket");
        return 0;
    }
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(9999);
    if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0) {
        perror("inet_pton");
        return 0;
    }
    if (connect(sockfd, (SA *) &servaddr, sizeof(servaddr)) < 0) {
        perror("connect");
    }
    while ( (n = read(sockfd, recvline, MAXLINE)) > 0) {
        recvline[n] = 0;
        if (fputs(recvline, stdout) == EOF) {
            perror("fputs");
        }
    }
    if (n < 0) {
        perror("read");
    }
    exit(0);
}