sktsrvr.cpp

伯克利做的SFTP安全文件传输协议

// sktsrvr.cpp
// listen to a socket, and then forward data between it and the tty

#include <iostream.h>      // cout
#include <stdio.h>         // printf
#include <stdlib.h>        // atoi
#include <syslog.h>        // syslog

#include "sockutil.h"      // socket funcs
#include "datablok.h"      // DataBlock
#include "str.h"           // stringb


#define STDIN 0
#define STDOUT 1

int doit(int argc, char *argv[])
{
  // positional arguments
  int listenPort;
  if (argc < 2) {
    printf("usage: %s listen-port\n"
           "  once an incoming connection happens, socket data is send to\n"
           "  and received from the terminal\n", argv[0]);
    return 0;
  }

  listenPort = atoi(argv[1]);


  // wait for an incoming connection
  fprintf(stderr, "waiting for connection on port %d\n", listenPort);
  SOCKET listener = listen_socket(listenPort);
  SOCKET socket = accept_socket(listener);
  close_socket(listener);

  fprintf(stderr, "connection received: %s\n", sockInfo(socket).pcharc());


  // create a forwarding buffer
  DataBlock buffer(1024);
  buffer.setDataLen(1024);

  // enter forwarding loop
  for(;;) {
    SocketSet sockset;
    sockset.add(socket);
    sockset.add(STDIN);
    sockset.blockUntilReadable();

    if (sockset.contains(socket)) {
      // socket -> STDOUT
      int len = recv(socket, buffer.getData(), buffer.getDataLen(), 0);
      if (len < 0) {
        perror("recv");
        exit(2);
      }
      else if (len == 0) {
        fprintf(stderr, "connection closed\n");
        break;
      }

      len = write(STDOUT, buffer.getData(), len);
      if (len < 0) {
        perror("write");
        exit(2);
      }
    }
    else if (sockset.contains(STDIN)) {
      // STDIN -> socket
      int len = read(STDIN, buffer.getData(), buffer.getDataLen());
      if (len < 0) {
        perror("read");
        exit(2);
      }
      else if (len == 0) {
        fprintf(stderr, "user typed EOF\n");
        break;
      }

      len = send(socket, buffer.getData(), len, 0);
      if (len < 0) {
        perror("send");
        exit(2);
      }
    }
    else {
      fprintf(stderr, "select() screwed up!\n");
    }
  }

  close_socket(socket);
  return 0;
}


int main(int argc, char *argv[])
{
  xBase::logExceptions = false;       // generally I'm handling them myself
  socket_lib_init();
  try {
    return doit(argc, argv);
  }
  catch (xBase &x) {
    fprintf(stderr, "unhandled exception: %s\n", x.why());
    return 4;
  }
}