自己实现telnet程序

来源：互联网发布：js淘宝购物车脚本之家编辑：程序博客网时间：2024/04/30 18:03
转自：http://blog.csdn.net/gujintong1110/article/details/44278535
#include <stdio.h>  #include <unistd.h>#include <stdlib.h>#include <string.h>#include <sys/types.h>  #include <sys/socket.h>  #include <netinet/in.h>  #include <arpa/inet.h>  #include <sys/types.h>#include <sys/wait.h>#include <pthread.h>int save_fd;#define BUFSIZE 1024/*telnet_cmd:ff fb 01 ff fb 03 ff fc 1f*/const unsigned char cmd_telnet[9] = {0xff, 0xfb, 0x01, 0xff, 0xfb, 0x03, 0xff, 0xfc, 0x1f};char cmdLine[1024] = {0};void task_process(int sockfd);int telnetd(void);void *telnetd_pthread(void * arg);void *task_process_pthread(void *arg) ;/*启动telnet服务*/int telnetd_start(){#if 1    pthread_t id;    int i,ret;    ret=pthread_create(&id,NULL,(void *) telnetd_pthread,NULL);    if(ret!=0){        printf ("Telnet: telnet_starting.......err!\n");        return -1;    }#else     int pid;    int status;    if(pid=fork()) {        //exit(0);        //是父进程，结束父进程        waitpid(-1, &status, WNOHANG | WUNTRACED | WCONTINUED);        return 0;    } else if(pid < 0) {        return -1;//exit(1);        //fork失败，退出    }    printf("Telnet: telnet_starting.......\n");    telnetd();#endif  }/*telnet 主服务任务*///int main(int argc, char *argv[])int telnetd(void)  {      pid_t fpid;    int status;    int server_sockfd;//服务器端套接字      int client_sockfd;//客户端套接字      int len;      struct sockaddr_in server_addr;   //服务器网络地址结构体      struct sockaddr_in remote_addr; //客户端网络地址结构体      int sin_size;      memset(&server_addr,0,sizeof(server_addr)); //数据初始化--清零      server_addr.sin_family=AF_INET; //设置为IP通信      server_addr.sin_addr.s_addr=htonl(INADDR_ANY);//服务器IP地址--允许连接到所有本地地址上      server_addr.sin_port=htons(23); //服务器telnet端口号      //init_telnetd();    /*创建服务器端套接字--IPv4协议，面向连接通信，TCP协议*/      if((server_sockfd=socket(AF_INET,SOCK_STREAM,0))<0)      {            perror("socket");          return -1;      }          /*将套接字绑定到服务器的网络地址上*/      if (bind(server_sockfd,(struct sockaddr *)&server_addr,sizeof(struct sockaddr))<0)      {          perror("bind");          return -1;      }      /*监听连接请求*/      listen(server_sockfd,1);      printf("Telnet: listening for telnet requests....\n");    sin_size=sizeof(struct sockaddr_in);      while(1) {              /*等待客户端连接请求到达*/          if((client_sockfd=accept(server_sockfd,(struct sockaddr *)&remote_addr,&sin_size))<0)          {              perror("accept");              return 1;          }          //printf("accept client %s\n",inet_ntoa(remote_addr.sin_addr));  #if 0               fpid = fork();        if (fpid < 0) {               perror("call fork() err!\n");               exit(1);        } else if (fpid == 0) {               task_process(client_sockfd);               close(client_sockfd);               exit(0);        } else {            waitpid(-1, &status, WNOHANG | WUNTRACED | WCONTINUED);        }#else         pthread_t id;        int i,ret;        ret=pthread_create(&id,NULL,(void *) task_process_pthread,(void *)client_sockfd);        if(ret!=0){            printf ("Telnet: telnet_starting.......err!\n");            return -1;        }        pthread_join(id,NULL);#endif          }       close(client_sockfd);      close(server_sockfd);      return 0;   } void * telnetd_pthread(void *arg){    telnetd();  }/*发送telnet协议命令*/int send_telnet_cmd(int fd){    return write(fd, cmd_telnet, sizeof(cmd_telnet));}/*读取命令字符串*/int read_cmdline(int sockfd, char *cmdLine, int size){    int ret, rev_count = 0;    char *buf = NULL;    buf = cmdLine;    while(1 == (ret = read(sockfd, buf, 1))) {        rev_count++;        if(rev_count > BUFSIZE - 2) {            return rev_count;        }        if(*buf == '\n') {            return rev_count;        }        buf++;    }    return ret;} /*输出重定向*/int ioStdSet(int src_fd, int dest_fd, int *save_fd) {    *save_fd = dup(dest_fd);    dup2(src_fd, dest_fd);    //close(src_fd);    return *save_fd;}/*恢复输出重定向*/void recoverIoStdSet(int src_fd, int dest_fd) {    dup2(src_fd, dest_fd);    close(src_fd);}/*解析字符串*/int cmd_analyze(char *cmd){    unsigned char *ptr = NULL;    unsigned char *ptr_tmp;    if(strlen(cmd) < 12 || strlen(cmd) > 48) {        return -1;    }    /*去除多余的换行符及其他多余字符*/    while((ptr = strstr(cmd, "\r")) != 0 ) {        while(*ptr != 0) {            *ptr = *(ptr+1);            ptr++;        }    }    while((ptr = strstr(cmd, "\n")) != 0 ) {        while(*ptr != 0) {            *ptr = *(ptr+1);            ptr++;        }    }#if 1    ptr = cmd;    while((!((*ptr > 'a' && *ptr < 'z') || (*ptr > 'A' && *ptr < 'Z') || (*ptr > '0' && *ptr < '9'))) && (*ptr != 0)) {        ptr_tmp = ptr;        while(*ptr_tmp != 0) {            *ptr_tmp = *(ptr_tmp+1);            ptr_tmp++;        }    }#endif      if(strlen(cmd) < 12 || strlen(cmd) > 48) {        return -1;    }    return 0;}/*执行命令并回显到telnet终端*/int cmd_process(int fd, char *cmdLine){    ioStdSet(fd, 1, &save_fd); /*标准输出重定向*/    /*这里添加命令处理函数*/    /*示例*/    printf("Welcome to Telnet server.[%s]\n",cmdLine);    recoverIoStdSet(save_fd, 1); /*恢复输出重定向*/    return 0;}/*telnet交互处理函数*/void task_process(int sockfd){    char cmdLine[BUFSIZE]={0};    int count = 0;    int i=0,tmp = 0;    int ret;    while(1) {        send_telnet_cmd(sockfd);        ioStdSet(sockfd, 1, &save_fd);        printf("\r\r\nlinux>");        recoverIoStdSet(save_fd, 1);        memset(cmdLine, 0, sizeof(cmdLine));        count = read_cmdline(sockfd, cmdLine, BUFSIZE);        if(count <= 0) {            //perror("read err");            //exit(1);对方断开连接，返回            return ;        }        ret = cmd_analyze(cmdLine);        //printf("[%s,%d]rev count:%d,buf:%s\n",__FUNCTION__,__LINE__,count, cmdLine);        if(ret == 0) {            cmd_process(sockfd, cmdLine);        }    }}void *task_process_pthread(void *arg) {    int sockfd;    sockfd = (int) arg;    task_process(sockfd);     pthread_exit((void *)1);}
阅读全文
1 0