echo_client2.c

//
// Created by Administrator on 2018/12/28.
//
#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, recv_len, recv_cnt;
    int idx = 0, read_len = 0;


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

    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]));

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

    while(1) {
        fputs("Input message(Q to quit): ", stdout);
        fgets(message, BUF_SIZE, stdin);

        if (!strcmp(message, "q\n") || !strcmp(message, "Q\n")) {
            break;
        }
        str_len = write(sock, message, strlen(message));

        recv_len=0;
        while (recv_len<str_len) {
            recv_cnt = read(sock, &message[read_len], BUF_SIZE-1);
            if (recv_cnt==-1) {
                error_handling("read() error");
            }
            recv_len+=recv_cnt;
        }

        message[str_len]=0;
        printf("Message from server: %s", message);
    }
    close(sock);
    return 0;
}

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