filkeydb.cpp

伯克利做的SFTP安全文件传输协议

// filkeydb.cpp
// code for filkeydb.h

#include "filkeydb.h"      // this module
#include "keyutils.h"      // sm_{load,save,test}Key
#include "usercfg.h"       // userConfigDir
#include "sockutil.h"      // formatAddress
#include "nonport.h"       // isDirectory, applyToCwdContents

#include <iostream.h>      // cout

#ifdef WIN32
  #define DIRSLASH '\\'
#else
  #define DIRSLASH '/'
#endif


// slightly reduce redundancy
#define DSAPublicKey_str "DSAPublicKey"


// name for a given ip addr's key
string keyName(IPAddress addr)
{
  return stringb("keys" << DIRSLASH <<
                 formatAddress(addr) << DIRSLASH <<
                 DSAPublicKey_str);
}


bool FileKeyDB::containsKey(IPAddress addr)
{
  return sm_testKey(keyName(addr));
}


DataBlock FileKeyDB::getKey(IPAddress addr)
{
  return sm_loadKey(keyName(addr));
}


void FileKeyDB::setKey(IPAddress addr, DataBlock const &key)
{
  sm_saveKey(keyName(addr), key);
}


// context (i.e. closure) for the getMatchingAddrs fn
struct GetMatchingCtx {
public:
  int count;                 // # of matching addrs
  int next;                  // index of next addr to add
  IPAddress *addrs;          // array into which addrs are added

  DataBlock const &key;      // key to match

public:
  GetMatchingCtx(DataBlock const &k)
    : count(0),
      next(0),
      addrs(NULL),
      key(k)
  {}
};


// when ctx->arr is NULL, we're just counting the # of matching entries
//   "     "     is not NULL, we're adding addrs to the array
bool getMatchingAddrsHelper(char const *name, void *extra)
{
  GetMatchingCtx *ctx = (GetMatchingCtx*)extra;
  if (name[0] != '.') {     // don't look at '.' or '..'
    // get key stored there
    try {
      IPAddress addr = resolveHostName(name);
        // doesn't really do DNS because name is dotted decimal

      DataBlock stored = sm_loadKey(keyName(addr));
      if (stored == ctx->key) {
        if (ctx->addrs == NULL) {
          // just counting
          ctx->count++;
        }
        else {
          // add it to array
          xassert(ctx->next < ctx->count);    // bounds check
          ctx->addrs[ctx->next] = addr;
          ctx->next++;
        }
      }
    }
    catch (...)
      {}     // malformed directory structure; don't care
  }
  return true;     // continue
}


IPAddress *FileKeyDB::getMatchingAddrs(int &numMatching, DataBlock const &key)
{
  GetMatchingCtx ctx(key);

  // count # of matching addrs
  string dir = stringb(userConfigDir() << DIRSLASH << "keys");
  ensurePath(dir, true /*isDirectory*/);
  applyToDirContents(dir, getMatchingAddrsHelper, &ctx);

  // check for no matches
  if (ctx.count == 0) {
    numMatching = 0;
    return NULL;
  }

  // put matching addrs into an array
  ctx.addrs = new IPAddress[ctx.count];
  applyToDirContents(dir, getMatchingAddrsHelper, &ctx);
  xassert(ctx.count == ctx.next);

  // there is a subtle possibility for error here, if the contents of the
  // directory change between passes.. but we'll assume that that is rare
  // (worst case is an xassert failure)

  // return them
  numMatching = ctx.count;
  return ctx.addrs;
}


// ------------------ test code -----------------------------
#ifdef TEST_FILKEYDB

#include "test.h"       // misc.
#include "strtokp.h"    // StrtokParse
#include "syserr.h"     // xSysError::xsyserror


void entry()
{
  char buf[80];
  DataBlock block;
  FileKeyDB db;

  // setup error handling
  nonportFail = xSysError::xsyserror;

  for(;;) {
    cout << "filkeydb> ";
    cout.flush();
    gets(buf);
    StrtokParse tok(buf, " ");
    if (tok == 0) {
      continue;
    }

    if (tok==2 && 0==strcmp(tok[0], "contains")) {
      cout << db.containsKey(resolveHostName(tok[1])) << endl;
    }
    else if (tok==2 && 0==strcmp(tok[0], "get")) {
      block = db.getKey(resolveHostName(tok[1]));
      block.print();
    }
    else if (tok==3 && 0==strcmp(tok[0], "set")) {
      block.readFromFile(tok[2]);
      db.setKey(resolveHostName(tok[1]), block);
    }
    else if (tok==2 && 0==strcmp(tok[0], "getMatching")) {
      block.readFromFile(tok[1]);
      int count;
      IPAddress *addrs = db.getMatchingAddrs(count, block);
      for (int i=0; i<count; i++) {
        cout << formatAddress(addrs[i]) << endl;
      }
      delete[] addrs;
    }
    else if (0==strcmp(tok[0], "quit")) {
      break;
    }
    else {
      cout << "bad command: " << buf << endl;
    }
  }
}

USUAL_MAIN


#endif // TEST_FILKEYDB