Socket应用demo 获取IP

服务端的程序，修改权限至777 ，先运行服务端程序，再运行客户端程序，效果为客户端输入字符，服务端将其打印出来，输入end结束

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

#define MAX 10*1024
#define PORT 6666

// Driver function
int main()
{
    char buff[MAX];
    int n;
    int sockfd, connfd, len;
    struct sockaddr_in server, client;

    // socket create and verification
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1) {
        printf("socket creation failed...
");
        exit(0);
    }

    printf("socket successfully created..
");
    bzero(&server, sizeof(server));

    // assign IP, PORT
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = htonl(INADDR_ANY);
    server.sin_port = htons(PORT);

    // binding newly created socket to given IP and verification
    if ((bind(sockfd, (struct sockaddr*)&server, sizeof(server))) != 0) {
        printf("socket bind failed...
");
        exit(0);
    }

    printf("socket successfully binded..
");

    // now server is ready to listen and verification
    if ((listen(sockfd, 5)) != 0) {
        printf("Listen failed...
");
        exit(0);
    }

    printf("server listening...
");

    len = sizeof(client);

    // accept the data packet from client and verification
    connfd = accept(sockfd, (struct sockaddr*)&client, &len);
    if (connfd < 0) {
        printf("server acccept failed...
");
        exit(0);
    }

    printf("server acccept the client...
");

    // infinite loop for chat
    while(1) {
        bzero(buff, MAX);

        // read the messtruct sockaddrge from client and copy it in buffer
        if (read(connfd, buff, sizeof(buff)) <= 0) {
            printf("client close...
");
            close(connfd);
            break;
        }

        // print buffer which contains the client contents
        printf("from client: %s
", buff);

        // if msg contains "Exit" then server exit and chat ended.
        if (strncmp("exit", buff, 4) == 0) {
            printf("server exit...
");
            close(connfd);
            break;
        }
    }

    // After chatting close the socket
    close(sockfd);
    exit(0);
}

　　

客户端：

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

#define HOST "192.168.0.217"        // 根据你服务器的IP地址修改
#define PORT 6666                   // 根据你服务器进程绑定的端口号修改
#define BUFFER_SIZ (4 * 1024)           // 4k的数据区域

int main(void)
{
    int sockfd, ret;
    struct sockaddr_in server;
    char buffer[BUFFER_SIZ];        //用于保存输入的文本

    // 创建套接字描述符
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        printf("create an endpoint for communication fail!
");
        exit(1);
    }

    bzero(&server, sizeof(server));
    server.sin_family = AF_INET;
    server.sin_port = htons(PORT);
    server.sin_addr.s_addr = inet_addr(HOST);

    // 建立TCP连接
    if (connect(sockfd, (struct sockaddr *)&server, sizeof(struct sockaddr)) == -1) {
        printf("connect server fail...
");
        close(sockfd);
        exit(1);
    }

    printf("connect server success...
");

    while (1) {

        printf("please enter some text: ");
        fgets(buffer, BUFFER_SIZ, stdin);

        //输入了end，退出循环（程序）
        if(strncmp(buffer, "end", 3) == 0)
            break;

        write(sockfd, buffer, sizeof(buffer));
    }

    close(sockfd);
    exit(0);
}

服务器IP应当根据实际进行修改。

获取IP地址的函数：

#include <stdio.h>
#include <sys/types.h>
#include <ifaddrs.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
 
int main (int argc, const char * argv[])
{
    struct ifaddrs * ifAddrStruct=NULL;
    struct ifaddrs * ifa=NULL;
    void * tmpAddrPtr=NULL;
 
    getifaddrs(&ifAddrStruct);
 
    for (ifa = ifAddrStruct; ifa != NULL; ifa = ifa->ifa_next)
    {
        if (!ifa->ifa_addr)
        {
            continue;
        }
        if (ifa->ifa_addr->sa_family == AF_INET) // check it is IP4
        {
            // is a valid IP4 Address
            tmpAddrPtr=&((struct sockaddr_in *)ifa->ifa_addr)->sin_addr;
            char addressBuffer[INET_ADDRSTRLEN];
            inet_ntop(AF_INET, tmpAddrPtr, addressBuffer, INET_ADDRSTRLEN);
            printf("%s IP4Func Address %s
", ifa->ifa_name, addressBuffer);
        }
        else if (ifa->ifa_addr->sa_family == AF_INET6) // check it is IP6
        {
            // is a valid IP6 Address
            tmpAddrPtr=&((struct sockaddr_in6 *)ifa->ifa_addr)->sin6_addr;
            char addressBuffer[INET6_ADDRSTRLEN];
            inet_ntop(AF_INET6, tmpAddrPtr, addressBuffer, INET6_ADDRSTRLEN);
            printf("%s IP6Func Address %s
", ifa->ifa_name, addressBuffer);
        }
    }
    if (ifAddrStruct!=NULL)
    {
        freeifaddrs(ifAddrStruct);
    }
 
    return 0;
}