C语言TCP socket编程

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C语言TCP socket编程

TCP 服务器步骤如下：
- 1.创建等链接套接字fd=socket()
- 2.绑定待链接套接字bind(fd,地址和端口)
- 3.监听套接字listen(fd)
- 4.等待客户端连接connfd=accept(fd) 3次握手
- 5.与客户端传输数据read(connfd)/write(connfd)
- 6.与客户端断开连接close(fd)、close(connfd) 4次挥手
TCP 客户端步骤如下：
- 1.创建待连接套接字fd=scoket()
- 2.连接服务器connect(fd) 3次握手
- 3.与服务器传输数据read(fd)/write(fd)
- 3.与服务器断开连接close(fd) 4次挥手

TCP服务器

int main(int argc, char const *argv[])
{
    if(argc != 2)
    {
        printf("Usage: %s <PORT>\n", argv[0]);
        exit(0);
    }

    // 创建一个TCP套接字
    int fd = Socket(AF_INET, SOCK_STREAM, 0);

    // 绑定地址（IP:PORT）
    struct sockaddr_in srvaddr, cliaddr;
    bzero(&srvaddr, sizeof(struct sockaddr_in));

    srvaddr.sin_family = AF_INET;
    srvaddr.sin_port = htons(atoi(argv[1]));
    // inet_pton(AF_INET, "192.168.1.166", &srvaddr.sin_addr);
    srvaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    Bind(fd, (struct sockaddr *)&srvaddr, sizeof(struct sockaddr_in));

    // 设置监听套接字 根据你等待连接队列的最大长度
    Listen(fd, BACKLOG);

    // 等待对方的连接请求
    len = sizeof(cliaddr);  
    int connfd = Accept(fd, (struct sockaddr *)&cliaddr, &len); 

    char peeraddr[50];
    bzero(peeraddr, 50);
    printf("new connection: %s:%hu\n",
                inet_ntop(AF_INET, &cliaddr.sin_addr, peeraddr, 50),
                ntohs(cliaddr.sin_port));

    char buf[SIZE];
    while(1)
    {
        bzero(buf, SIZE);
        if(Read(connfd, buf, SIZE) == 0)
            break;

        printf("from Jack: %s", buf);
    }

    close(fd);
    close(connfd);

    return 0;
}

TCP客户端

int main(int argc, char const *argv[])
{
    if(argc != 3)
    {
        printf("Usage: %s <IP> <PORT>\n", argv[0]);
        exit(0);
    }

    // 创建一个TCP套接字
    int fd = Socket(AF_INET, SOCK_STREAM, 0);

    // 准备好对端的地址信息
    struct sockaddr_in srvaddr;
    bzero(&srvaddr, sizeof(srvaddr));

    srvaddr.sin_family = AF_INET;
    //srvaddr.sin_addr.s_addr=inet_addr("192.168.1.166");   
    inet_pton(AF_INET, argv[1], &srvaddr.sin_addr);
    srvaddr.sin_port = htons(atoi(argv[2]));

    // 连接服务端
    Connect(fd, (struct sockaddr *)&srvaddr, sizeof(srvaddr));

    char buf[SIZE];
    while(1)
    {
        bzero(buf, SIZE);
        if(fgets(buf, SIZE, stdin) == NULL)
            break;

        Write(fd, buf, strlen(buf));
    }

    close(fd);
    return 0;
}

socket API做了如下封装

ssize_t Write(int fildes, const void *buf, size_t nbyte)
{
    ssize_t retval = write(fildes, buf, nbyte);
    if(retval == -1)
    {
        perror("write() error");
    }

    return retval;
}

ssize_t Read(int fildes, void *buf, size_t nbyte)
{
    int ret = read(fildes, buf, nbyte);
    if(ret == -1)
    {
        perror("read() failed");
    }
    return ret;
}

int Bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen)
{
    int ret = bind(sockfd, addr, addrlen);
    if(ret == -1)
    {
        perror("bind() failed");
    }
    return ret;
}

int Listen(int sockfd, int backlog)
{
    int ret = listen(sockfd, backlog);
    if(ret == -1)
    {
        perror("listen() failed");
    }
    return ret;
}

int Accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen)
{
    int ret = accept(sockfd, addr, addrlen);
    if(ret == -1)
    {
        perror("accept() failed");
    }
    return ret;
}

int Connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen)
{
    int ret = connect(sockfd, addr, addrlen);
    if(ret == -1)
    {
        perror("connect() failed");
    }
    return ret;
}

int Socket(int domain, int type, int protocol)
{
    int sockfd = socket(domain, type, protocol);
    if(sockfd == -1)
    {
        perror("socket() error");
    }

    return sockfd;
}

int Setsockopt(int sockfd, int level, int optname,
           const void *optval, socklen_t optlen)
{
    int retval = setsockopt(sockfd, level, optname, optval, optlen);
    if(retval == -1)
    {
        perror("setsockopt() error");
    }

    return retval;
}

int Select(int nfds, fd_set *readfds, fd_set *writefds,
       fd_set *exceptfds, struct timeval *timeout)
{
    int ret = select(nfds, readfds, writefds, exceptfds, timeout);
    if(ret == -1)
    {
        perror("select() failed");
    }
    return ret;
}