sftp.cpp

伯克利做的SFTP安全文件传输协议

// sftp.cpp
// code for sftp.h
// copyright SafeTP Development Group, Inc., 2000  Terms of use are as specified in license.txt

#include "sftp.h"         // this module
#include "xassert.h"      // xfailure
#include "datablok.h"     // DataBlock
#include "sockutil.h"     // recvAll, recvAllToEOF

#include <ctype.h>        // isdigit
#include <stdlib.h>       // strtoul

// parse a reply to a PASV request
void parsePasvArgument(char const *text,
                       IPAddress &addr, int &port)
{
  char const *p = text;

  // scan for the first digit
  while (*p && !isdigit(*p)) {
    p++;
  }
  if (!*p) {
    xfailure(stringb("reply to PASV was malformed (no digits): " <<
                     text));
  }

  // parse the address and port
  string whyFail;
  if (!parsePortArgument(p,
                         addr, port,
                         whyFail)) {
    xfailure(stringb("reply to PASV was malformed, " <<
                     whyFail << ": " << text));
  }
}


// PORT command argument, PASV reply argument
string constructPortArg(IPAddress addr, int port)
{
  return stringb( ((addr >> 24) & 0xff) << "," <<
                  ((addr >> 16) & 0xff) << "," <<
                  ((addr >> 8) & 0xff) << "," <<
                  (addr & 0xff) << "," <<
                  ((port >> 8) & 0xff) << "," <<
                  (port & 0xff) );
}


// parse a PORT command argument, returning false (and setting 'whyFail')
// if there is a problem (also works for PASV replies, as long as 'p'
// is already set to the first digit)
bool parsePortArgument(char const *p,
                       IPAddress &clientAddress, int &clientPort,
                       string &whyFail)
{
  clientAddress = 0;
  clientPort = 0;

  for (int i=0; i<6; i++) {
    if (!isdigit(*p)) {
      if (isprint(*p)) {
        whyFail = stringb("Character '" << *p << "' is not a valid digit.");
      }
      else {
        whyFail = "Unprintable character in input.";
      }
      return false;
    }

    char *endptr;
    unsigned long val = strtoul(p, &endptr, 10 /*decimal*/);
    if (val > 0xFF) {
      whyFail = stringb((i < 4 ? "Address byte " : "Host byte ") <<
                        (i%4) << " (" << val <<
                        "), must be between 0 and 255.");
      return false;
    }

    if (i < 4) {
      clientAddress |= (val << (24 - i*8));
    }
    else {
      clientPort |= (val << (8 - (i-4)*8));
    }

    // advance to next
    while (isdigit(*p))
      { p++; }
    if (*p == ',')
      { p++; }
      // if not, either we're at end (ok) or is bad, and first test
      // at loop start will catch error
  }

  #if 0
  // for testing parsing code
  diagnostic("parsePort: ip address = 0x%lX (%d,%d,%d,%d), "
             "port = 0x%X (%d)\n",
             clientAddress,
             (clientAddress >> 24) & 0xff,
             (clientAddress >> 16) & 0xff,
             (clientAddress >> 8) & 0xff,
             clientAddress & 0xff,
             clientPort, clientPort);
  #endif // 0

  return true;
}


void recvAllBlock(SOCKET s, DataBlock &block, int lenToRead)
{
  xassert(lenToRead <= block.getAllocated());
  recvAll(s, (char*)block.getData(), lenToRead);
  block.setDataLen(lenToRead);
}

int recvAllToEOFBlock(SOCKET s, DataBlock &block, int lenToRead)
{
  xassert(lenToRead <= block.getAllocated());
  int len = recvAllToEOF(s, (char*)block.getData(), lenToRead);
  block.setDataLen(len);
  return len;
}


// ---------------- test code --------------------
#ifdef TEST_SFTP

#include "test.h"      // USUAL_MAIN

void entry()
{
  struct S {
    // input
    char const *text;

    // expected output
    IPAddress addr;
    int port;
    bool ok;
  };

  #define IP(a,b,c,d) ( ((a)<<24)|((b)<<16)|((c)<<8)|(d) )
  #define PORT(a,b) IP(0,0,a,b)

  static S const T[] = {
    { "136,152,99,6,21,179", IP(136,152,99,6), PORT(21,179), true  },
    { "1,2,3,4,5,6",         IP(1,2,3,4),      PORT(5,6),    true  },
    { "1,2,3,4,5,6,7",       IP(1,2,3,4),      PORT(5,6),    true  },
    { "1,2,3,4,5",           0,                0,            false },
    { "1,2,3,4,5,",          0,                0,            false },
    { "256,0,0,0,1,2",       0,                0,            false },
    { " 1,2,3,4,5,6",        0,                0,            false },
    { "1,2,3, 4,5,6",        0,                0,            false },
  };

  #undef PORT
  #undef IP

  loopi(TABLESIZE(T)) {
    // parse entry T[i]
    IPAddress addr;
    int port;
    string whyFail;
    bool result = parsePortArgument(T[i].text, addr, port, whyFail);

    // check for correct return value (will use debugger to see why)
    if (result != T[i].ok) {
      xfailure("entry with wrong return value");
    }

    if (result && (addr != T[i].addr || port != T[i].port)) {
      xfailure("entry with wrong addr/port");
    }
  }
}

USUAL_MAIN

#endif // TEST_SFTP