text: /* 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).
   *
   * $Id: nssb64e.c,v 1.4 2012/04/25 14:50:16 gerv%gerv.net Exp $
   */
  
  #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;
  
      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);
  
      /*
       * 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 (PRArenaPool *arenaOpt, char *outStrOpt,
  		      unsigned int maxOutLen, SECItem *inItem)
  {
      char *out_string = outStrOpt;
      PRUint32 max_out_len;
      PRUint32 out_len;
      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 (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);
  }
  