echo客户端-双进程

用于向echo服务端发送字符串，然后接收同样的字符串返回并打印

echo_client.c

#include <stdio.h> //printf、fput
#include <stdlib.h> //atoi
#include <string.h> //memset
#include <unistd.h> //read、close
#include <arpa/inet.h> //sockaddr_in结构、inet_addr
#include <sys/socket.h>
#define BUF_SIZE 100

void write_routine(int sock, char *buf);
void read_routine(int sock, char *buf);

int main(int argc, char *argv[]) {
    char buf[BUF_SIZE];
    if (argc != 3) {
        printf("Usage: %s <IP> <port>\n", argv[0]);
        exit(1);
    }
    
    int sock = socket(PF_INET, SOCK_STREAM, 0);
    if (sock == -1) {
        fputs("socket() error", stderr);
        exit(1);
    }

    struct sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr)); //全部位置0
    serv_addr.sin_family = AF_INET; //
    serv_addr.sin_addr.s_addr = inet_addr(argv[1]); //取1号参数作为目标IP地址
    serv_addr.sin_port = htons(atoi(argv[2])); //取2号参数作为目标端口

    if (connect(sock, (struct sockaddr*) &serv_addr, sizeof(serv_addr)) == -1) {
        fputs("connect() error", stderr);
        exit(1);
    }

    pid_t pid = fork(); //多进程实现读写分割
    if (pid == 0) {
        write_routine(sock, buf);
    } else {
        read_routine(sock, buf);
    }
    close(sock);
    return 0;
}

void write_routine(int sock, char *buf) {
    while(1) {
        fgets(buf, BUF_SIZE, stdin);
        if (!strcmp(buf, "q\n")) {
            shutdown(sock, SHUT_WR);
        }
        write(sock, buf, strlen(buf));
    }
}

void read_routine(int sock, char *buf) {
    while(1) {
        int str_len = read(sock, buf, BUF_SIZE);
        if (str_len == 0) {
            return;
        }
        buf[str_len] = 0;
        printf("Message from server: %s \n", buf);
    }
}

编译
```
gcc echo_client.c -o eclient
```
执行
```
./eclient 127.0.0.1 8100
```

Keyboard shortcuts

echo客户端-双进程

echo_client.c