TCP网络编程实例

server.c

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

#define SERVER_PORT 8003
#define BACKLOG 10

int main(void)
{
    int sockfd, conn_fd;
    struct sockaddr_in my_addr;
    struct sockaddr_in their_addr;
    int sin_size;

    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        fprintf(stderr, "socket error!\n");
        exit(1);
    }

    my_addr.sin_family = AF_INET;
    my_addr.sin_port = htons(SERVER_PORT);
    my_addr.sin_addr.s_addr = INADDR_ANY;
    bzero(&(my_addr.sin_zero), 8);

    if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1)
    {
        fprintf(stderr, "bind error!\n");
        exit(1);
    }

    if (listen(sockfd, BACKLOG) == -1)
    {
        fprintf(stderr, "listen error!\n");
        exit(1);
    }

    while (1)
    {
        sin_size = sizeof(struct sockaddr_in);
        if ((conn_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) == -1)
        {
            fprintf(stderr, "accept error!\n");
            continue;
        }

        printf("server: got connection from %s\n", inet_ntoa(their_addr.sin_addr));

        if (!fork())
        {
            if (send(conn_fd, "Hello, world!\n", 14, 0) == -1)
                fprintf(stderr, "send error!\n");
            close(conn_fd);
            exit(0);
        }
        close(conn_fd);
        while(waitpid(-1, NULL, WNOHANG) > 0);
    }
}


client.c

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

#define SERVER_PORT 8003
#define MAXDATASIZE 100

int main(int argc, char *argv[])
{
    int sockfd, numbytes;
    char buf[MAXDATASIZE];
    struct hostent *he;
    struct sockaddr_in serv_addr;

    if (argc != 2)
    {
        fprintf(stderr, "usage: cilent hostname\n");
        exit(1);
    }

    if ((he = gethostbyname(argv[1])) == NULL)
    {
        fprintf(stderr, "gethostbyname error!\n");
        exit(1);
    }

    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        fprintf(stderr, "socket error!\n");
        exit(1);
    }
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(SERVER_PORT);
    serv_addr.sin_addr = *((struct in_addr *)he->h_addr);
    bzero(&(serv_addr.sin_zero), 8);

    if (connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(struct sockaddr)) == -1)
    {
        fprintf(stderr, "connect error!\n");
        exit(1);
    }

    if ((numbytes = read(sockfd, buf, MAXDATASIZE)) == -1)
    {
        fprintf(stderr, "read error!\n");
        exit(1);
    }

    buf[numbytes] = '\0';
    printf("Received: %s", buf);
    close(sockfd);
}

编译：
gcc server.c -o server
gcc client.c -o client
执行：
打开一终端执行：./server
打开另一终端执行：./client 127.0.0.1