common/telnet.cc

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// -*- C++ -*-

extern "C" {
#include <string.h>
}

#include <iostream>

#include "telnet.h"

#define IAC     0xFF
#define DONT    0xFE
#define DO      0xFD
#define WONT    0xFC
#define WILL    0xFB

//
// XXX - this needs to be made much more efficient...
//
static unsigned char *
find_byte(unsigned char *buf, unsigned int len, unsigned char ch)
{
    for (unsigned char *p = buf ; p < (buf + len) ; p++)
        if (*p == ch)
            return p;

    return(NULL);
}

using std::clog;
using std::endl;

Blob *
Telnet::decode(Blob *b)
{
    b->inc_ref();

    Blob                *b2;
    size_t              newlen = 0;
    size_t              len = b->len();
    unsigned char       *c, *dp = b->data();
    unsigned char       *data = new unsigned char[len];

    clog << "In Telnet::decode(" << b << ")" << endl;

    while ((c = find_byte(dp, len, IAC))) {
        // Copy all previous bytes...
        if (c != dp) {
            memmove(data+newlen, dp, (c - dp));
            newlen += (c - dp);
        }
        // Then, analyze the IAC
        switch (c[1]) {
            // XXX - Should probably actually process these...
          case DO:
            clog << "IAC DO " << short(c[2]) << endl;
            dp += 3; len -= 3;
            break;
          case DONT:
            clog << "IAC DONT " << short(c[2]) << endl;
            dp += 3; len -= 3;
            break;
          case WILL:
            clog << "IAC WILL " << short(c[2]) << endl;
            dp += 3; len -= 3;
            break;
          case WONT:
            clog << "IAC WONT " << short(c[2]) << endl;
            dp += 3; len -= 3;
            break;
          default:
            clog.setf(std::ios::hex, std::ios::dec|std::ios::hex|std::ios::oct);
            clog << "Found unknown IAC: code " << int(c[1]) << endl;
            dp += 2; len -= 2;
            break;
        }
    }

    // And, move the remainder of the data...
    if (len > 0) {
        memmove(data+newlen, dp, len);
        newlen += len;
    }

    // Now, make up a Blob, free 'data' (which Blob has duplicated)
    // and return...
    b->dec_ref();
    b2 = new Blob(data, newlen);
    delete [] data;

    return(b2);
}

Blob *
Telnet::encode(Blob *b)
{
    // Nothing to do here, for now.  At some point, we might want
    // to deal with encoding escapes for telnet protocol...
    return (b);
}

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