/* * Socket address, internet style. */struct sockaddr_in {    __uint8_t   sin_len;    sa_family_t sin_family;    in_port_t   sin_port;    struct      in_addr sin_addr;    char        sin_zero[8];};

// 地址家族，通常使用AF_INET代表TCP/CP协议族(AF_INET6代表IPV6)sockaddr_in.sin_family// 端口号，必须转化为网络字节序使用htons和ntohssockaddr_in.sin_port// 用于存储ip地址，必须是网络字节序sockaddr_in.sin_addr// 为了让sockaddr与sockaddr_in两个数据结构保持大小相同而保留的空字节sockaddr_in.sin_zero

struct sockaddr_in servaddr;bzero(&servaddr, sizeof(servaddr));servaddr.sin_family = AF_INET;servaddr.sin_port = htons(8090);// 若字符串有效则将字符串转换为32位二进制网络字节序的IPV4地址servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");// 检测转化IP是否出错if (servaddr.sin_addr.s_addr == INADDR_NONE) {    perror("ip");    exit(-1);}

// 将网络字节序转化为主机字节序__uint16_t ntohs(__uint16_t);// 将主机字节序转化为网络字节序__uint16_t htons(__uint16_t);__uint32_t ntohl(__uint32_t);__uint32_t htonl(__uint32_t);// 若字符串有效则将字符串转换为32位二进制网络字节序的IPV4地址，否则为INADDR_NONE  // 其反函数inet_ntoain_addr_t inet_addr(const char* strptr);

// inet_pton能够处理ipv4甚至ipv6(需要改动现在代码)if (inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr) <= 0) {    perror("pton");    exit(-1);}

int socket(int domain, int type, int protocol);

ssize_t recv(int sockfd, void *buff, size_t nbytes, int flags);ssize_t send(int sockfd, const void *buff, size_t nbytes, int flags);ssize_t write (int fd,const void * buf,size_t count);ssize_t read(int fd,void * buf ,size_t count);

int connect (int sockfd,struct sockaddr * serv_addr,int addrlen);

int bind( int sockfd , const struct sockaddr * my_addr, socklen_t addrlen);int listen(int s, int backlog);int accept(int s, struct sockaddr * addr, int * addrlen);

#include <iostream>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#include <sys/wait.h>#include <arpa/inet.h>#include <unistd.h>const int       MAX_LINE    = 512;const ushort    SERV_PORT   = 7890;const char*     SERV_IP     = "127.0.0.1";int main(int argc, const char * argv[]){    int socketfd;    struct sockaddr_in servaddr;    memset(&servaddr, 0, sizeof(servaddr));    servaddr.sin_family = AF_INET;    servaddr.sin_port = htons(SERV_PORT);    // 若字符串有效则将字符串转换为32位二进制网络字节序的IPV4地址//    servaddr.sin_addr.s_addr = inet_addr(SERV_IP);//    if (servaddr.sin_addr.s_addr == INADDR_NONE) {//        perror("ip");//        exit(-1);//    }    // 支持IPV6的新的转换方式，推荐    if (inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr) <= 0) {        perror("pton");        exit(-1);    }    // 创建一个套接字    if ( (socketfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {        perror("socket");        exit(-1);    }    // 连接到主机    if (connect(socketfd, (sockaddr*)&servaddr, sizeof(servaddr)) < 0) {        perror("connect");        exit(-1);    }    // 接收数据    char recvline[MAX_LINE+1];    long bytelen = 0;    while ((bytelen = read(socketfd, recvline, MAX_LINE)) > 0) {        recvline[bytelen] = 0;        printf("recv --> %s\n", recvline);    }    close(socketfd);    return 0;}

#include <iostream>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#include <sys/wait.h>#include <arpa/inet.h>#include <unistd.h>const ushort SERV_PORT   = 7890;int main(int argc, const char * argv[]){    struct sockaddr_in serveraddr;    memset(&serveraddr, 0, sizeof(serveraddr));    serveraddr.sin_family = AF_INET;    serveraddr.sin_port = htons(SERV_PORT);    // 系统自动获取本机IP    serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);    // 创建一个socket    int serverfd = socket(AF_INET,SOCK_STREAM,0);    if (serverfd < 0) {        perror("socket");        exit(-1);    }    // 绑定端口    int bind_ret = bind(serverfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));    if (bind_ret < 0) {        perror("bind");        exit(-1);    }    // 开始监听    // #2: backlog：等待连接队列的最大长度    if (listen(serverfd, 10) < 0) {        perror("listen");        exit(-1);    }    printf("---------- listening (127.0.0.1:%d) ----------\n", SERV_PORT);    // 开始轮询监听请求    bool toggle = true;    while (toggle) {        // 客户端信息结构        int clientfd;        struct sockaddr_in clientaddr;        memset(&serveraddr, 0, sizeof(serveraddr));        socklen_t len = sizeof(clientaddr);        // 接收请求，建立连接        if ( (clientfd = accept(serverfd, (struct sockaddr *)&clientaddr, &len)) < 0 ) {            perror("accept");            exit(-1);        }        // 向客户端发送信息        const char *message = "hello world";        write(clientfd, message, strlen(message)+1);        // 转为点分十进制ip        const char *client_ip = inet_ntoa(clientaddr.sin_addr);        const ushort client_port = ntohs(clientaddr.sin_port);        printf("client(%s:%u) # send -> %s\n", client_ip, client_port, message);        // 关闭与客户端的连接        close(clientfd);    }    // 关闭服务监听    close(serverfd);    return 0;}