2.6.2 客户端

#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#define MAX_LINE (1024)
#define SERVER_PORT (7778)
void setnoblocking(int fd)
{
    int opts = 0;
    opts = fcntl(fd, F_GETFL);
    opts = opts | O_NONBLOCK;
    fcntl(fd, F_SETFL);
}
int main(int argc, char **argv)
{
    int  sockfd;
    char recvline[MAX_LINE + 1] = {0};
    struct sockaddr_in server_addr;
    if (argc != 2) {
        fprintf(stderr, "usage ./client <SERVER_IP>\n");
        exit(0);
    }
    if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        fprintf(stderr, "socket error");
        exit(0);
    }
    // server addr 赋值
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    if (inet_pton(AF_INET, argv[1], &server_addr.sin_addr) <= 0) {
        fprintf(stderr, "inet_pton error for %s", argv[1]);
        exit(0);
    }
    // 链接服务端
    if (connect(sockfd, (struct sockaddr*) &server_addr, sizeof(server_addr)) < 0) {
        perror("connect");
        fprintf(stderr, "connect error\n"); 
        exit(0);
    }
    setnoblocking(sockfd);
    char input[100];
    int n = 0;
    int count = 0;
    // 不断的从标准输入字符串
        printf("[send] %s\n", input);
        n = 0;
        // 把输入的字符串发送 到 服务器中去
        n = send(sockfd, input, strlen(input), 0);
        if (n < 0) {
            perror("send");
        }
        n = 0;
        count = 0;
        // 读取 服务器返回的数据
        while (1)
        {
            n = read(sockfd, recvline + count, MAX_LINE);
            if (n == MAX_LINE)
            {
                count += n;
                continue;
            }
            else if (n < 0){
                perror("recv");
                break;
            }
            else {
                count += n;
                recvline[count] = '\0';
                printf("[recv] %s\n", recvline);
                break;
            }
        }
    }
}