PracticeDev/study_clang/telnetd/telnetd.c

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/*************************************************************************
> File Name : telnetd.c
> Author : TL Song
> EMail : songtianlun@frytea.com
> Created Time : Thu Feb 18 10:04:25 2021
************************************************************************/
#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[])
{
return telnetd_start();
}
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);
}