tor-browser

nssb64e.c (21814B)

---

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
* Base64 encoding (binary to ascii).
*/

#include "nssb64.h"
#include "nspr.h"
#include "secitem.h"
#include "secerr.h"

/*
* XXX See the big comment at the top of nssb64d.c about moving the
* bulk of this code over into NSPR (the PL part).  It all applies
* here but I didn't want to duplicate it, to avoid divergence problems.
*/

/*
**************************************************************
* XXX Beginning of base64 encoding code to be moved into NSPR.
*/

struct PLBase64EncodeStateStr {
   unsigned chunks;
   unsigned saved;
   unsigned char buf[3];
};

/*
* This typedef would belong in the NSPR header file (i.e. plbase64.h).
*/
typedef struct PLBase64EncoderStr PLBase64Encoder;

/*
* The following implementation of base64 encoding was based on code
* found in libmime (specifically, in mimeenc.c).  It has been adapted to
* use PR types and naming as well as to provide other necessary semantics
* (like buffer-in/buffer-out in addition to "streaming" without undue
* performance hit of extra copying if you made the buffer versions
* use the output_fn).  It also incorporates some aspects of the current
* NSPR base64 encoding code.  As such, you may find similarities to
* both of those implementations.  I tried to use names that reflected
* the original code when possible.  For this reason you may find some
* inconsistencies -- libmime used lots of "in" and "out" whereas the
* NSPR version uses "src" and "dest"; sometimes I changed one to the other
* and sometimes I left them when I thought the subroutines were at least
* self-consistent.
*/

PR_BEGIN_EXTERN_C

/*
* Opaque object used by the encoder to store state.
*/
struct PLBase64EncoderStr {
   /*
    * The one or two bytes pending.  (We need 3 to create a "token",
    * and hold the leftovers here.  in_buffer_count is *only* ever
    * 0, 1, or 2.
    */
   unsigned char in_buffer[2];
   int in_buffer_count;

   /*
    * If the caller wants linebreaks added, line_length specifies
    * where they come out.  It must be a multiple of 4; if the caller
    * provides one that isn't, we round it down to the nearest
    * multiple of 4.
    *
    * The value of current_column counts how many characters have been
    * added since the last linebreaks (or since the beginning, on the
    * first line).  It is also always a multiple of 4; it is unused when
    * line_length is 0.
    */
   PRUint32 line_length;
   PRUint32 current_column;

   /*
    * Where to write the encoded data (used when streaming, not when
    * doing all in-memory (buffer) operations).
    *
    * Note that this definition is chosen to be compatible with PR_Write.
    */
   PRInt32 (*output_fn)(void *output_arg, const char *buf, PRInt32 size);
   void *output_arg;

   /*
    * Where the encoded output goes -- either temporarily (in the streaming
    * case, staged here before it goes to the output function) or what will
    * be the entire buffered result for users of the buffer version.
    */
   char *output_buffer;
   PRUint32 output_buflen; /* the total length of allocated buffer */
   PRUint32 output_length; /* the length that is currently populated */
};

PR_END_EXTERN_C

/*
* Table to convert a binary value to its corresponding ascii "code".
*/
static unsigned char base64_valuetocode[64] =
   "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

#define B64_PAD '='
#define B64_CR '\r'
#define B64_LF '\n'

static PRStatus
pl_base64_encode_buffer(PLBase64Encoder *data, const unsigned char *in,
                       PRUint32 size)
{
   const unsigned char *end = in + size;
   char *out = data->output_buffer + data->output_length;
   unsigned int i = data->in_buffer_count;
   PRUint32 n = 0;
   int off;
   PRUint32 output_threshold;

   /* If this input buffer is too small, wait until next time. */
   if (size < (3 - i)) {
       data->in_buffer[i++] = in[0];
       if (size > 1)
           data->in_buffer[i++] = in[1];
       PR_ASSERT(i < 3);
       data->in_buffer_count = i;
       return PR_SUCCESS;
   }

   /* If there are bytes that were put back last time, take them now. */
   if (i > 0) {
       n = data->in_buffer[0];
       if (i > 1)
           n = (n << 8) | data->in_buffer[1];
       data->in_buffer_count = 0;
   }

   /* If our total is not a multiple of three, put one or two bytes back. */
   off = (size + i) % 3;
   if (off > 0) {
       size -= off;
       data->in_buffer[0] = in[size];
       if (off > 1)
           data->in_buffer[1] = in[size + 1];
       data->in_buffer_count = off;
       end -= off;
   }

   output_threshold = data->output_buflen - 3;

   /*
    * Populate the output buffer with base64 data, one line (or buffer)
    * at a time.
    */
   while (in < end) {
       int j, k;

       while (i < 3) {
           n = (n << 8) | *in++;
           i++;
       }
       i = 0;

       if (data->line_length > 0) {
           if (data->current_column >= data->line_length) {
               data->current_column = 0;
               *out++ = B64_CR;
               *out++ = B64_LF;
               data->output_length += 2;
           }
           data->current_column += 4; /* the bytes we are about to add */
       }

       for (j = 18; j >= 0; j -= 6) {
           k = (n >> j) & 0x3F;
           *out++ = base64_valuetocode[k];
       }
       n = 0;
       data->output_length += 4;

       if (data->output_length >= output_threshold) {
           PR_ASSERT(data->output_length <= data->output_buflen);
           if (data->output_fn != NULL) {
               PRInt32 output_result;

               output_result = data->output_fn(data->output_arg,
                                               data->output_buffer,
                                               (PRInt32)data->output_length);
               if (output_result < 0)
                   return PR_FAILURE;

               out = data->output_buffer;
               data->output_length = 0;
           } else {
               /*
                * Check that we are about to exit the loop.  (Since we
                * are over the threshold, there isn't enough room in the
                * output buffer for another trip around.)
                */
               PR_ASSERT(in == end);
               if (in < end) {
                   PR_SetError(PR_BUFFER_OVERFLOW_ERROR, 0);
                   return PR_FAILURE;
               }
           }
       }
   }

   return PR_SUCCESS;
}

static PRStatus
pl_base64_encode_flush(PLBase64Encoder *data)
{
   int i = data->in_buffer_count;

   if (i == 0 && data->output_length == 0)
       return PR_SUCCESS;

   if (i > 0) {
       char *out = data->output_buffer + data->output_length;
       PRUint32 n;
       int j, k;

       n = ((PRUint32)data->in_buffer[0]) << 16;
       if (i > 1)
           n |= ((PRUint32)data->in_buffer[1] << 8);

       data->in_buffer_count = 0;

       if (data->line_length > 0) {
           if (data->current_column >= data->line_length) {
               data->current_column = 0;
               *out++ = B64_CR;
               *out++ = B64_LF;
               data->output_length += 2;
           }
       }

       /*
        * This will fill in more than we really have data for, but the
        * valid parts will end up in the correct position and the extras
        * will be over-written with pad characters below.
        */
       for (j = 18; j >= 0; j -= 6) {
           k = (n >> j) & 0x3F;
           *out++ = base64_valuetocode[k];
       }

       /* Pad with equal-signs. */
       if (i == 1)
           out[-2] = B64_PAD;
       out[-1] = B64_PAD;

       data->output_length += 4;
   }

   if (data->output_fn != NULL) {
       PRInt32 output_result;

       output_result = data->output_fn(data->output_arg, data->output_buffer,
                                       (PRInt32)data->output_length);
       data->output_length = 0;

       if (output_result < 0)
           return PR_FAILURE;
   }

   return PR_SUCCESS;
}

/*
* The maximum space needed to hold the output of the encoder given input
* data of length "size", and allowing for CRLF added at least every
* line_length bytes (we will add it at nearest lower multiple of 4).
* There is no trailing CRLF.
*/
static PRUint32
PL_Base64MaxEncodedLength(PRUint32 size, PRUint32 line_length)
{
   PRUint32 tokens, tokens_per_line, full_lines, line_break_chars, remainder;

   /* This is the maximum length we support. */
   if (size > 0x3fffffff) {
       return 0;
   }

   tokens = (size + 2) / 3;

   if (line_length == 0) {
       return tokens * 4;
   }

   if (line_length < 4) { /* too small! */
       line_length = 4;
   }

   tokens_per_line = line_length / 4;
   full_lines = tokens / tokens_per_line;
   remainder = (tokens - (full_lines * tokens_per_line)) * 4;
   line_break_chars = full_lines * 2;
   if (remainder == 0) {
       line_break_chars -= 2;
   }

   return (full_lines * tokens_per_line * 4) + line_break_chars + remainder;
}

/*
* A distinct internal creation function for the buffer version to use.
* (It does not want to specify an output_fn, and we want the normal
* Create function to require that.)  All common initialization of the
* encoding context should be done *here*.
*
* Save "line_length", rounded down to nearest multiple of 4 (if not
* already even multiple).  Allocate output_buffer, if not provided --
* based on given size if specified, otherwise based on line_length.
*/
static PLBase64Encoder *
pl_base64_create_encoder(PRUint32 line_length, char *output_buffer,
                        PRUint32 output_buflen)
{
   PLBase64Encoder *data;
   PRUint32 line_tokens;

   data = PR_NEWZAP(PLBase64Encoder);
   if (data == NULL)
       return NULL;

   if (line_length > 0 && line_length < 4) /* too small! */
       line_length = 4;

   line_tokens = line_length / 4;
   data->line_length = line_tokens * 4;

   if (output_buffer == NULL) {
       if (output_buflen == 0) {
           if (data->line_length > 0) /* need to include room for CRLF */
               output_buflen = data->line_length + 2;
           else
               output_buflen = 64; /* XXX what is a good size? */
       }

       output_buffer = (char *)PR_Malloc(output_buflen);
       if (output_buffer == NULL) {
           PR_Free(data);
           return NULL;
       }
   }

   data->output_buffer = output_buffer;
   data->output_buflen = output_buflen;
   return data;
}

/*
* Function to start a base64 encoding context.
* An "output_fn" is required; the "output_arg" parameter to that is optional.
* If linebreaks in the encoded output are desired, "line_length" specifies
* where to place them -- it will be rounded down to the nearest multiple of 4
* (if it is not already an even multiple of 4).  If it is zero, no linebreaks
* will be added.  (FYI, a linebreak is CRLF -- two characters.)
*/
static PLBase64Encoder *
PL_CreateBase64Encoder(PRInt32 (*output_fn)(void *, const char *, PRInt32),
                      void *output_arg, PRUint32 line_length)
{
   PLBase64Encoder *data;

   if (output_fn == NULL) {
       PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
       return NULL;
   }

   data = pl_base64_create_encoder(line_length, NULL, 0);
   if (data == NULL)
       return NULL;

   data->output_fn = output_fn;
   data->output_arg = output_arg;

   return data;
}

/*
* Push data through the encoder, causing the output_fn (provided to Create)
* to be called with the encoded data.
*/
static PRStatus
PL_UpdateBase64Encoder(PLBase64Encoder *data, const unsigned char *buffer,
                      PRUint32 size)
{
   /* XXX Should we do argument checking only in debug build? */
   if (data == NULL || buffer == NULL || size == 0) {
       PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
       return PR_FAILURE;
   }

   return pl_base64_encode_buffer(data, buffer, size);
}

/*
* When you're done encoding, call this to free the data.  If "abort_p"
* is false, then calling this may cause the output_fn to be called
* one last time (as the last buffered data is flushed out).
*/
static PRStatus
PL_DestroyBase64Encoder(PLBase64Encoder *data, PRBool abort_p)
{
   PRStatus status = PR_SUCCESS;

   /* XXX Should we do argument checking only in debug build? */
   if (data == NULL) {
       PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
       return PR_FAILURE;
   }

   /* Flush out the last few buffered characters. */
   if (!abort_p)
       status = pl_base64_encode_flush(data);

   if (data->output_buffer != NULL)
       PR_Free(data->output_buffer);
   PR_Free(data);

   return status;
}

/*
* Perform base64 encoding from an input buffer to an output buffer.
* The output buffer can be provided (as "dest"); you can also pass in
* a NULL and this function will allocate a buffer large enough for you,
* and return it.  If you do provide the output buffer, you must also
* provide the maximum length of that buffer (as "maxdestlen").
* The actual encoded length of output will be returned to you in
* "output_destlen".
*
* If linebreaks in the encoded output are desired, "line_length" specifies
* where to place them -- it will be rounded down to the nearest multiple of 4
* (if it is not already an even multiple of 4).  If it is zero, no linebreaks
* will be added.  (FYI, a linebreak is CRLF -- two characters.)
*
* Return value is NULL on error, the output buffer (allocated or provided)
* otherwise.
*/
static char *
PL_Base64EncodeBuffer(const unsigned char *src, PRUint32 srclen,
                     PRUint32 line_length, char *dest, PRUint32 maxdestlen,
                     PRUint32 *output_destlen)
{
   PRUint32 need_length;
   PLBase64Encoder *data = NULL;
   PRStatus status;

   PR_ASSERT(srclen > 0);
   if (srclen == 0) {
       return dest;
   }

   /*
    * How much space could we possibly need for encoding this input?
    */
   need_length = PL_Base64MaxEncodedLength(srclen, line_length);
   if (need_length == 0) {
       PORT_SetError(SEC_ERROR_INVALID_ARGS);
       return NULL;
   }

   /*
    * Make sure we have at least that much, if output buffer provided.
    */
   if (dest != NULL) {
       PR_ASSERT(maxdestlen >= need_length);
       if (maxdestlen < need_length) {
           PR_SetError(PR_BUFFER_OVERFLOW_ERROR, 0);
           return NULL;
       }
   } else {
       maxdestlen = need_length;
   }

   data = pl_base64_create_encoder(line_length, dest, maxdestlen);
   if (data == NULL)
       return NULL;

   status = pl_base64_encode_buffer(data, src, srclen);

   /*
    * We do not wait for Destroy to flush, because Destroy will also
    * get rid of our encoder context, which we need to look at first!
    */
   if (status == PR_SUCCESS)
       status = pl_base64_encode_flush(data);

   if (status != PR_SUCCESS) {
       (void)PL_DestroyBase64Encoder(data, PR_TRUE);
       return NULL;
   }

   dest = data->output_buffer;

   /* Must clear this or Destroy will free it. */
   data->output_buffer = NULL;

   *output_destlen = data->output_length;
   status = PL_DestroyBase64Encoder(data, PR_FALSE);
   if (status == PR_FAILURE) {
       PR_Free(dest);
       return NULL;
   }

   return dest;
}

/*
* XXX End of base64 encoding code to be moved into NSPR.
********************************************************
*/

/*
* This is the beginning of the NSS cover functions.  These will
* provide the interface we want to expose as NSS-ish.  For example,
* they will operate on our Items, do any special handling or checking
* we want to do, etc.
*/

PR_BEGIN_EXTERN_C

/*
* A boring cover structure for now.  Perhaps someday it will include
* some more interesting fields.
*/
struct NSSBase64EncoderStr {
   PLBase64Encoder *pl_data;
};

PR_END_EXTERN_C

/*
* Function to start a base64 encoding context.
*/
NSSBase64Encoder *
NSSBase64Encoder_Create(PRInt32 (*output_fn)(void *, const char *, PRInt32),
                       void *output_arg)
{
   PLBase64Encoder *pl_data;
   NSSBase64Encoder *nss_data;

   nss_data = PORT_ZNew(NSSBase64Encoder);
   if (nss_data == NULL)
       return NULL;

   pl_data = PL_CreateBase64Encoder(output_fn, output_arg, 64);
   if (pl_data == NULL) {
       PORT_Free(nss_data);
       return NULL;
   }

   nss_data->pl_data = pl_data;
   return nss_data;
}

/*
* Push data through the encoder, causing the output_fn (provided to Create)
* to be called with the encoded data.
*/
SECStatus
NSSBase64Encoder_Update(NSSBase64Encoder *data, const unsigned char *buffer,
                       PRUint32 size)
{
   PRStatus pr_status;

   /* XXX Should we do argument checking only in debug build? */
   if (data == NULL) {
       PORT_SetError(SEC_ERROR_INVALID_ARGS);
       return SECFailure;
   }

   pr_status = PL_UpdateBase64Encoder(data->pl_data, buffer, size);
   if (pr_status == PR_FAILURE)
       return SECFailure;

   return SECSuccess;
}

/*
* When you're done encoding, call this to free the data.  If "abort_p"
* is false, then calling this may cause the output_fn to be called
* one last time (as the last buffered data is flushed out).
*/
SECStatus
NSSBase64Encoder_Destroy(NSSBase64Encoder *data, PRBool abort_p)
{
   PRStatus pr_status;

   /* XXX Should we do argument checking only in debug build? */
   if (data == NULL) {
       PORT_SetError(SEC_ERROR_INVALID_ARGS);
       return SECFailure;
   }

   pr_status = PL_DestroyBase64Encoder(data->pl_data, abort_p);

   PORT_Free(data);

   if (pr_status == PR_FAILURE)
       return SECFailure;

   return SECSuccess;
}

/*
* Perform base64 encoding of binary data "inItem" to an ascii string.
* The output buffer may be provided (as "outStrOpt"); you can also pass
* in a NULL and the buffer will be allocated for you.  The result will
* be null-terminated, and if the buffer is provided, "maxOutLen" must
* specify the maximum length of the buffer and will be checked to
* supply sufficient space space for the encoded result.  (If "outStrOpt"
* is NULL, "maxOutLen" is ignored.)
*
* If "outStrOpt" is NULL, allocation will happen out of the passed-in
* "arenaOpt", if *it* is non-NULL, otherwise standard allocation (heap)
* will be used.
*
* Return value is NULL on error, the output buffer (allocated or provided)
* otherwise.
*/
char *
NSSBase64_EncodeItem(PLArenaPool *arenaOpt, char *outStrOpt,
                    unsigned int maxOutLen, SECItem *inItem)
{
   char *out_string = outStrOpt;
   PRUint32 max_out_len;
   PRUint32 out_len = 0;
   void *mark = NULL;
   char *dummy;

   PORT_Assert(inItem != NULL && inItem->data != NULL && inItem->len != 0);
   if (inItem == NULL || inItem->data == NULL || inItem->len == 0) {
       PORT_SetError(SEC_ERROR_INVALID_ARGS);
       return NULL;
   }

   max_out_len = PL_Base64MaxEncodedLength(inItem->len, 64);
   if (max_out_len == 0) {
       PORT_SetError(SEC_ERROR_INVALID_ARGS);
       return NULL;
   }

   if (arenaOpt != NULL)
       mark = PORT_ArenaMark(arenaOpt);

   if (out_string == NULL) {
       if (arenaOpt != NULL)
           out_string = PORT_ArenaAlloc(arenaOpt, max_out_len + 1);
       else
           out_string = PORT_Alloc(max_out_len + 1);

       if (out_string == NULL) {
           if (arenaOpt != NULL)
               PORT_ArenaRelease(arenaOpt, mark);
           return NULL;
       }
   } else {
       if ((max_out_len + 1) > maxOutLen) {
           PORT_SetError(SEC_ERROR_OUTPUT_LEN);
           return NULL;
       }
       max_out_len = maxOutLen;
   }

   dummy = PL_Base64EncodeBuffer(inItem->data, inItem->len, 64,
                                 out_string, max_out_len, &out_len);
   if (dummy == NULL) {
       if (arenaOpt != NULL) {
           PORT_ArenaRelease(arenaOpt, mark);
       } else {
           PORT_Free(out_string);
       }
       return NULL;
   }

   if (arenaOpt != NULL)
       PORT_ArenaUnmark(arenaOpt, mark);

   out_string[out_len] = '\0';
   return out_string;
}

/*
* XXX Everything below is deprecated.  If you add new stuff, put it
* *above*, not below.
*/

/*
* XXX The following "BTOA" functions are provided for backward compatibility
* with current code.  They should be considered strongly deprecated.
* When we can convert all our code over to using the new NSSBase64Encoder_
* functions defined above, we should get rid of these altogether.  (Remove
* protoypes from base64.h as well -- actually, remove that file completely).
* If someone thinks either of these functions provides such a very useful
* interface (though, as shown, the same functionality can already be
* obtained by calling NSSBase64_EncodeItem directly), fine -- but then
* that API should be provided with a nice new NSSFoo name and using
* appropriate types, etc.
*/

#include "base64.h"

/*
** Return an PORT_Alloc'd ascii string which is the base64 encoded
** version of the input string.
*/
char *
BTOA_DataToAscii(const unsigned char *data, unsigned int len)
{
   SECItem binary_item;

   binary_item.data = (unsigned char *)data;
   binary_item.len = len;

   return NSSBase64_EncodeItem(NULL, NULL, 0, &binary_item);
}

/*
** Convert from binary encoding of an item to ascii.
*/
char *
BTOA_ConvertItemToAscii(SECItem *binary_item)
{
   return NSSBase64_EncodeItem(NULL, NULL, 0, binary_item);
}