tcp程序——回聲客戶端

服務器端

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUF_SIZE 1024

void error_handling(char *message);

int main(int argc, char *argv[])
{
    int serv_sock;
    int clnt_sock;

    struct sockaddr_in serv_addr;
    struct sockaddr_in clnt_addr;
    socklen_t clnt_addr_size;
    int str_len;

    char message[BUF_SIZE];

    if(argc!=2){
        printf("Usage: %s <port>\n", argv[0]);
        exit(1);
    }

    puts("socket()...");
    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if(serv_sock==-1)
        error_handling("socket() error");


    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(atoi(argv[1]));

    puts("bind()...");
    if(bind(serv_sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr))==-1)
        error_handling("bind() error");

    puts("listen()...");
    if(listen(serv_sock, 5)==-1)
        error_handling("listen() error");

    //同一個時刻只能連接一個客戶端
    while(1){
        //連接客戶端
        puts("wait accept()...");
        clnt_addr_size = sizeof(clnt_addr);
        clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_addr, &clnt_addr_size);
        if(clnt_sock==-1)
            error_handling("accept() error");
        else
            puts("accepted");

        //從客戶端讀取信息，並返回給客戶端
        while((str_len=read(clnt_sock,message,BUF_SIZE))!=0){
            puts("read() and write() message");
            write(clnt_sock, message, str_len);
        }

        //關閉客戶端
        close(clnt_sock);
        puts("closed");
    }

    close(serv_sock);
    return 0;
}

void error_handling(char *message)
{
    fputs(message, stderr);
    fputc('\n',stderr);
    perror("[error]");
    exit(1);
}

客戶端

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUF_SIZE 1024

void error_handling(char *message);

int main(int argc, char *argv[])
{
    int sock;
    struct sockaddr_in serv_addr;
    char message[BUF_SIZE];
    int str_len;

    if(argc!=3){
        printf("Usage: %s <host> <port>\n",argv[0]);
        exit(1);
    }

    puts("socket()...");
    sock = socket(PF_INET, SOCK_STREAM, 0);
    if(sock==-1)
        error_handling("socket() error");

    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
    serv_addr.sin_port = htons(atoi(argv[2]));

    puts("connect()...");
    if(connect(sock, (struct sockaddr*) &serv_addr, sizeof(serv_addr))==-1)
        error_handling("bind() error");
    else
        puts("connected...");


    while(1){
        fputs("Input message(Q to quit): ",stdout);
        fgets(message, BUF_SIZE, stdin);
        if(strcmp(message,"q\n")==0 || strcmp(message,"Q\n")==0)
            break;

        puts("write() and read() message");
        write(sock,message,strlen(message));
        str_len = read(sock, message, BUF_SIZE-1);
        if(str_len==-1)
            error_handling("read() error");

        message[str_len] = 0;
        printf("Message from server: %s\n",message);
    }


    close(sock);
    return 0;
}


void error_handling(char *message)
{
    fputs(message, stderr);
    fputc('\n',stderr);
    exit(1);
}

運行

./server 54321

./client 127.0.0.1 54321

參考

• TCP/IP網絡編程，尹聖雨