C语言UDP socket编程

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C语言UDP socket编程

UDP 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,服务器ip和端口)
- 3.等待信息recvfrom(fd,对端地址)

UDP 客户端步骤如下：
- 1.创建待连接套接字fd=scoket()
- 2.发送信息sendto(fd,服务器ip和端口)

UDP服务器

int main(int argc, char const *argv[])
{
    // 创建一个UDP套接字
    int fd = Socket(AF_INET, SOCK_DGRAM, 0);

    struct sockaddr_in srvaddr;
    socklen_t len = sizeof(srvaddr);
    bzero(&srvaddr, len);

    srvaddr.sin_family = AF_INET;
    srvaddr.sin_port = htons(atoi(argv[1]));
    srvaddr.sin_addr.s_addr = htonl(INADDR_ANY);

    // 绑定本地IP和端口
    Bind(fd, &srvaddr, len);

    // 迭代服务器
    char buf[SIZE];
    while(1)
    {
        bzero(buf, SIZE);
        recvfrom(fd, buf, SIZE, 0, NULL, NULL);

        printf("%s", buf);
    }

    return 0;
}

UDP客户端

int main(int argc, char const *argv[])
{
    // 创建一个UDP套接字
    int fd = Socket(AF_INET, SOCK_DGRAM, 0);

    struct sockaddr_in srvaddr;
    socklen_t len = sizeof(srvaddr);
    bzero(&srvaddr, len);

    srvaddr.sin_family = AF_INET;
    //srvaddr.sin_addr.s_addr = inet_addr("192.168.0.166");  
    inet_pton(AF_INET, arg[1], &srvaddr.sin_addr);
    srvaddr.sin_port = htons(atoi(argv[2]));


    char buf[SIZE];
    while(1)
    {
        bzero(buf, SIZE);
        fgets(buf, SIZE, stdin);

        sendto(fd, buf, strlen(buf), 0,
                (struct sockaddr *)&srvaddr, len);
    }

    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;
}