Linux 网络编程（UDP）

• 客户端代码

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

#include<sys/socket.h>

#include<sys/types.h>

#include<unistd.h>

#include<netinet/in.h>

#include <errno.h>

int main(int argc, char** argv)

{

    int socketfd = ;

    struct sockaddr_in server_addr;

    char recvbuf[];

    int port = ;

    int nbyte;

    if((socketfd = socket(AF_INET, SOCK_DGRAM, )) == ){

        fprintf(stderr, "socket Error:%s\n\a", strerror(errno));

        exit();

    }

    bzero(&server_addr, sizeof(struct sockaddr_in));

    server_addr.sin_family = AF_INET;

    server_addr.sin_port = htons(port);

    server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");

    int len = sizeof(struct sockaddr_in);

    while(){

        if(sendto(socketfd, "Hello Fredric", strlen("Hello Fredric"), ,

            (struct sockaddr *)&server_addr, len) == -){

            fprintf(stderr, "sendto Error:%s\n\a", strerror(errno));

            close(socketfd);

            exit();

        }

        if((nbyte = recvfrom(socketfd, recvbuf, , , (struct sockaddr *)&server_addr, &len)) == -){

            fprintf(stderr, "recvfrom Error:%s\n\a", strerror(errno));

            close(socketfd);

            exit();

        }

        recvbuf[nbyte] = '\0';

        printf("recv data is:%s\n",recvbuf);

    }

    close(socketfd);

    exit();

}

• 服务器端代码

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

#include<sys/socket.h>

#include<sys/types.h>

#include<unistd.h>

#include<netinet/in.h>

#include <errno.h>

int main(int argc, char** argv){

    int socketfd = ;

    struct sockaddr_in server_addr;

    char recvbuf[];

    char sendbuf[];

    int port = ;

    int nbyte;

    if((socketfd = socket(AF_INET, SOCK_DGRAM, )) == ){

        fprintf(stderr, "socket Error:%s\n\a", strerror(errno));

        exit();

    }

    bzero(&server_addr, sizeof(struct sockaddr_in));

    server_addr.sin_family = AF_INET;

    server_addr.sin_port = htons(port);

    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);

    if((bind(socketfd, &server_addr, sizeof(server_addr))) == -){

        fprintf(stderr, "bind Error:%s\n\a", strerror(errno));

        exit();

    }

    int len = sizeof(struct sockaddr_in);

    while(){

        if((nbyte = recvfrom(socketfd, recvbuf, , , (struct sockaddr*)&server_addr, &len)) == -){

            fprintf(stderr, "recvfrom Error:%s\n\a", strerror(errno));

            close(socketfd);

            exit();

        }

        recvbuf[nbyte] = '\0';

        printf("recv data is:%s\n",recvbuf);

        printf("Input:");

        scanf("%s", sendbuf);

        if((nbyte = sendto(socketfd, sendbuf, sizeof(sendbuf),

        , (struct sockaddr*)&server_addr, len)) == -){

            fprintf(stderr, "sendto Error:%s\n\a", strerror(errno));

            close(socketfd);

            exit();

        }

    }

    close(socketfd);

    exit();

}