blob: 6a8900a94c3bc1d2dfa053bf582b34951403fb45 [file] [log] [blame]
/*
* Author: Jeff Thompson
*
* BSD license, See the LICENSE file for more information.
*/
#include "BinaryXML.h"
#include "BinaryXMLDecoder.h"
/**
* Return the octet at self->offset, converting to unsigned int. Increment self->offset.
* This does not check for reading past the end of the input, so this is called "unsafe".
*/
static inline unsigned int unsafeReadOctet(struct ndn_BinaryXMLDecoder *self)
{
return (unsigned int)(self->input[self->offset++] & 0xff);
}
/**
* Return the octet at self->offset, converting to unsigned int. Do not increment self->offset.
* This does not check for reading past the end of the input, so this is called "unsafe".
*/
static inline unsigned int unsafeGetOctet(struct ndn_BinaryXMLDecoder *self)
{
return (unsigned int)(self->input[self->offset] & 0xff);
}
char *ndn_BinaryXMLDecoder_decodeTypeAndValue(struct ndn_BinaryXMLDecoder *self, unsigned int *type, unsigned int *valueOut)
{
unsigned int value = 0;
int gotFirstOctet = 0;
while (1) {
if (self->offset >= self->inputLength)
return "ndn_BinaryXMLDecoder_decodeTypeAndVal: read past the end of the input";
unsigned int octet = unsafeReadOctet(self);
if (!gotFirstOctet) {
if (octet == 0)
return "ndn_BinaryXMLDecoder_decodeTypeAndVal: the first header octet may not be zero";
gotFirstOctet = 1;
}
if (octet & ndn_BinaryXML_TT_FINAL) {
// Finished.
*type = octet & ndn_BinaryXML_TT_MASK;
value = (value << ndn_BinaryXML_TT_VALUE_BITS) | ((octet >> ndn_BinaryXML_TT_BITS) & ndn_BinaryXML_TT_VALUE_MASK);
break;
}
value = (value << ndn_BinaryXML_REGULAR_VALUE_BITS) | (octet & ndn_BinaryXML_REGULAR_VALUE_MASK);
}
*valueOut = value;
return 0;
}
char *ndn_BinaryXMLDecoder_readDTag(struct ndn_BinaryXMLDecoder *self, unsigned int expectedTag)
{
char *error;
unsigned int type;
unsigned int value;
if (error = ndn_BinaryXMLDecoder_decodeTypeAndValue(self, &type, &value))
return error;
if (type != ndn_BinaryXML_DTAG)
return "ndn_BinaryXMLDecoder_readDTag: header type is not a DTAG";
if (value != expectedTag)
return "ndn_BinaryXMLDecoder_readDTag: did not get the expected DTAG";
return 0;
}
char *ndn_BinaryXMLDecoder_readElementClose(struct ndn_BinaryXMLDecoder *self)
{
if (self->offset >= self->inputLength)
return "ndn_BinaryXMLDecoder_readElementClose: read past the end of the input";
if (unsafeReadOctet(self) != ndn_BinaryXML_CLOSE)
return "ndn_BinaryXMLDecoder_readDTag: did not get the expected element close";
return 0;
}
char *ndn_BinaryXMLDecoder_peekDTag(struct ndn_BinaryXMLDecoder *self, unsigned int expectedTag, int *gotExpectedTag)
{
// Default to 0.
*gotExpectedTag = 0;
// First check if it is an element close (which cannot be the expected tag).
if (self->offset >= self->inputLength)
return "ndn_BinaryXMLDecoder_readElementClose: read past the end of the input";
if (unsafeGetOctet(self) == 0)
return 0;
unsigned int type;
unsigned int value;
unsigned int saveOffset = self->offset;
char *error = ndn_BinaryXMLDecoder_decodeTypeAndValue(self, &type, &value);
// Restore offset.
self->offset = saveOffset;
if (error)
return error;
if (type == ndn_BinaryXML_DTAG && value == expectedTag)
*gotExpectedTag = 1;
return 0;
}
char *ndn_BinaryXMLDecoder_readBinaryDTagElement
(struct ndn_BinaryXMLDecoder *self, unsigned int expectedTag, int allowNull, unsigned char **value, unsigned int *valueLen)
{
char *error;
if (error = ndn_BinaryXMLDecoder_readDTag(self, expectedTag))
return error;
if (allowNull) {
if (self->offset >= self->inputLength)
return "ndn_BinaryXMLDecoder_readBinaryDTagElement: read past the end of the input";
if (unsafeGetOctet(self) == ndn_BinaryXML_CLOSE) {
// The binary item is missing, and this is allowed, so read the element close and return a null value.
++self->offset;
*value = 0;
*valueLen = 0;
return 0;
}
}
unsigned int itemType;
if (error = ndn_BinaryXMLDecoder_decodeTypeAndValue(self, &itemType, valueLen))
return error;
// Ignore itemType.
*value = self->input + self->offset;
self->offset += *valueLen;
if (error = ndn_BinaryXMLDecoder_readElementClose(self))
return error;
return 0;
}