网络编程实战：期中大作业与解答剖析

#include "lib/common.h"
#define  MAXLINE     1024

int main(int argc, char **argv) {
    if (argc != 3) {
        error(1, 0, "usage: tcp_client <IPaddress> <port>");
    }
    int port = atoi(argv[2]);
    int socket_fd = tcp_client(argv[1], port);

    char recv_line[MAXLINE], send_line[MAXLINE];
    int n;

    fd_set readmask;
    fd_set allreads;
    FD_ZERO(&allreads);
    FD_SET(0, &allreads);
    FD_SET(socket_fd, &allreads);

    for (;;) {
        readmask = allreads;
        int rc = select(socket_fd + 1, &readmask, NULL, NULL, NULL);

        if (rc <= 0) {
            error(1, errno, "select failed");
        }

        if (FD_ISSET(socket_fd, &readmask)) {
            n = read(socket_fd, recv_line, MAXLINE);
            if (n < 0) {
                error(1, errno, "read error");
            } else if (n == 0) {
                printf("server closed \n");
                break;
            }
            recv_line[n] = 0;
            fputs(recv_line, stdout);
            fputs("\n", stdout);
        }

        if (FD_ISSET(STDIN_FILENO, &readmask)) {
            if (fgets(send_line, MAXLINE, stdin) != NULL) {
                int i = strlen(send_line);
                if (send_line[i - 1] == '\n') {
                    send_line[i - 1] = 0;
                }

                if (strncmp(send_line, "quit", strlen(send_line)) == 0) {
                    if (shutdown(socket_fd, 1)) {
                        error(1, errno, "shutdown failed");
                    }
                }

                size_t rt = write(socket_fd, send_line, strlen(send_line));
                if (rt < 0) {
                    error(1, errno, "write failed ");
                }
            }
        }
    }

    exit(0);
}

#include "lib/common.h"
static int count;

static void sig_int(int signo) {
    printf("\nreceived %d datagrams\n", count);
    exit(0);
}

char *run_cmd(char *cmd) {
    char *data = malloc(16384);
    bzero(data, sizeof(data));
    FILE *fdp;
    const int max_buffer = 256;
    char buffer[max_buffer];
    fdp = popen(cmd, "r");
    char *data_index = data;
    if (fdp) {
        while (!feof(fdp)) {
            if (fgets(buffer, max_buffer, fdp) != NULL) {
                int len = strlen(buffer);
                memcpy(data_index, buffer, len);
                data_index += len;
            }
        }
        pclose(fdp);
    }
    return data;
}

int main(int argc, char **argv) {
    int listenfd;
    listenfd = socket(AF_INET, SOCK_STREAM, 0);

    struct sockaddr_in server_addr;
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(SERV_PORT);

    int on = 1;
    setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

    int rt1 = bind(listenfd, (struct sockaddr *) &server_addr, sizeof(server_addr));
    if (rt1 < 0) {
        error(1, errno, "bind failed ");
    }

    int rt2 = listen(listenfd, LISTENQ);
    if (rt2 < 0) {
        error(1, errno, "listen failed ");
    }

    signal(SIGPIPE, SIG_IGN);

    int connfd;
    struct sockaddr_in client_addr;
    socklen_t client_len = sizeof(client_addr);

    char buf[256];
    count = 0;

    while (1) {
        if ((connfd = accept(listenfd, (struct sockaddr *) &client_addr, &client_len)) < 0) {
            error(1, errno, "bind failed ");
        }

        while (1) {
            bzero(buf, sizeof(buf));
            int n = read(connfd, buf, sizeof(buf));
            if (n < 0) {
                error(1, errno, "error read message");
            } else if (n == 0) {
                printf("client closed \n");
                close(connfd);
                break;
            }
            count++;
            buf[n] = 0;
            if (strncmp(buf, "ls", n) == 0) {
                char *result = run_cmd("ls");
                if (send(connfd, result, strlen(result), 0) < 0)
                    return 1;
                free(result);
            } else if (strncmp(buf, "pwd", n) == 0) {
                char buf[256];
                char *result = getcwd(buf, 256);
                if (send(connfd, result, strlen(result), 0) < 0){
                    return 1;
                 }
            } else if (strncmp(buf, "cd ", 3) == 0) {
                char target[256];
                bzero(target, sizeof(target));
                memcpy(target, buf + 3, strlen(buf) - 3);
                if (chdir(target) == -1) {
                    printf("change dir failed, %s\n", target);
                }
            } else {
                char *error = "error: unknown input type";
                if (send(connfd, error, strlen(error), 0) < 0)
                    return 1;
            }
        }
    }
    exit(0);
}

$ ./telnet-client 127.0.0.1 43211
pwd
/home/vagrant/shared/Code/network/yolanda/build/bin
cd ..
pwd
/home/vagrant/shared/Code/network/yolanda/build
ls
bin  chap-11  lib  CMakeLists.txt  mid-homework  ...
quit

// 再次连接服务器，服务器不退出
$ ./telnet-client 127.0.0.1 43211
pwd
/home/vagrant/shared/Code/network/yolanda/build
quit