TCP/IP網絡編程2：UDP迭代連接

服務器端：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <assert.h>
 
#define BUF_SIZE 30
 
int main(int argc, char *argv[]){
    int serv_sock = socket(PF_INET, SOCK_DGRAM, 0);
    assert(serv_sock != -1);

    struct sockaddr_in serv_adr;
    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_adr.sin_port = htons(atoi("8500"));

    assert(bind(serv_sock, (struct sockaddr *)&serv_adr, sizeof(serv_adr)) != -1);

    struct sockaddr_in clnt_adr;
    socklen_t clnt_adr_sz = sizeof(clnt_adr);
    char message[BUF_SIZE];
    while (true){
        int str_len = recvfrom(serv_sock, message, BUF_SIZE, 0, (struct sockaddr *)&clnt_adr, &clnt_adr_sz);
        sendto(serv_sock, message, str_len, 0, (struct sockaddr *)&clnt_adr, clnt_adr_sz);              
    }
    close(serv_sock);
    return 0;
}

客戶端（無連接）：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <assert.h>
 
#define BUF_SIZE 30
 
int main(int argc, char *argv[]){
    int sock = socket(PF_INET, SOCK_DGRAM, 0);
    assert(sock != -1);

    struct sockaddr_in serv_adr;
    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = inet_addr("127.0.0.1");
    serv_adr.sin_port = htons(atoi("8500"));

    struct sockaddr_in from_adr;
    socklen_t adr_sz = sizeof(from_adr);
    char message[BUF_SIZE];
    while (true){
        fputs("Insert message(q to quit):", stdout);
        fgets(message, sizeof(message), stdin);
        if (!strcmp(message, "q\n") || !strcmp(message, "Q\n"))
            break;
        sendto(sock, message, strlen(message), 0, (struct sockaddr *)&serv_adr, sizeof(serv_adr));
        int str_len = recvfrom(sock, message, BUF_SIZE, 0, (struct sockaddr *)&from_adr, &adr_sz);
        message[str_len] = 0;
        printf("Message from server:%s", message);
    }
    close(sock);
    return 0;
}

客戶端（使用connect函數創建連接的UDP）：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <assert.h>
#define BUF_SIZE 30
 
int main(int argc, char *argv[]){
    int sock = socket(PF_INET, SOCK_DGRAM, 0);
    assert(sock != -1);

    struct sockaddr_in serv_adr;
    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = inet_addr("127.0.0.1");
    serv_adr.sin_port = htons(atoi("8500"));

    connect(sock, (struct sockaddr *)&serv_adr, sizeof(serv_adr));

    char message[BUF_SIZE];
    while (true){
        fputs("Insert message(q to quit):", stdout);
        fgets(message, sizeof(message), stdin);
        if (!strcmp(message, "q\n") || !strcmp(message, "Q\n"))
            break;
        write(sock, message, strlen(message));
        int str_len = read(sock, message, sizeof(message) - 1);
        message[str_len] = 0;
        printf("Message from server:%s", message);
    }
    close(sock);
    return 0;
}

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