access_document.c File Reference

Compact-key CBOR parser for Aliro Access Documents (compact subset of ISO 18013-5 mDoc). More...

#include "access_document.h"
#include <string.h>

Include dependency graph for access_document.c:

Data Structures
struct	item
	Parsed CBOR item: major type, argument value, raw encoded bytes (with length), and payload (contents for strings/arrays after the head). More...

Functions
static int	head (const uint8_t *data, size_t length, size_t *offset, uint8_t *major, uint64_t *value)
	Parse one CBOR head (major type and argument): consume the initial byte (type in bits 7-5, info in bits 4-0), then additional bytes for arguments 24+ (1/2/4/8 bytes).
static int	child_count (uint8_t major, uint64_t value, uint64_t *count)
	Count the number of child elements in a CBOR container by major type: arrays (type 4) → count, maps (type 5) → count*2 (each key-value pair), tags (type 6) → 1 (the tagged value).
static int	parse_at (const uint8_t *data, size_t length, size_t *offset, struct item *out)
	Parse one CBOR-encoded item and all its children iteratively (depth-first traversal), constraining nesting to at most 25 levels to bound the embedded workqueue stack.
static int	root (const uint8_t *data, size_t length, struct item *out)
	Parse the root CBOR item and validate that it consumes the entire input.
static int	child_at (const struct item *container, size_t wanted, struct item *out)
	Extract the child at position wanted (0-indexed) from a CBOR array or map, re-reading the container head and walking wanted+1 items to reach it.
static int	map_find_text (const struct item *map, const char *key, struct item *value)
	Search a CBOR map (major type 5) for an entry with text string key (major type 3).
static int	integer (const struct item *item, int64_t *value)
	Extract a signed integer from a parsed CBOR item: major type 0 (uint) → positive value, type 1 (nint) → -(value + 1).
static int	map_find_int (const struct item *map, int64_t key, struct item *value)
	Search a CBOR map (major type 5) for an entry with integer key.
static int	tagged_embedded (const struct item *tag, struct item *embedded)
	Extract the byte payload from a CBOR tag with tag number 24 (embedded tag for binary data).
static int	timestamp (const struct item *item, uint8_t output[20])
	Extract a 20-byte timestamp from a CBOR item: accept a text string (major type 3) directly, or extract and unwrap a tag-0 wrapper around a text string.

Detailed Description

Compact-key CBOR parser for Aliro Access Documents (compact subset of ISO 18013-5 mDoc).

Parses strictly with iterative depth traversal (no stack recursion), validates CBOR encoding (no floats, no simple values with payloads, minimal representation), and enforces a 25-level nesting bound. Core: parse_at walks encoded items; root validates full-buffer consumption; child_at / map_find_* retrieve nested elements; integer / timestamp extract scalar fields.

Function Documentation

child_at()

static int child_at ( const struct item *  container, size_t  wanted, struct item *  out  )

static

Extract the child at position wanted (0-indexed) from a CBOR array or map, re-reading the container head and walking wanted+1 items to reach it.

Return 0 on success, -1 if the container is not an array/map, the index is out of bounds, or parsing fails.

child_count()

static int child_count ( uint8_t  major, uint64_t  value, uint64_t *  count  )

static

Count the number of child elements in a CBOR container by major type: arrays (type 4) → count, maps (type 5) → count*2 (each key-value pair), tags (type 6) → 1 (the tagged value).

Returns -1 for invalid major types.

head()

static int head ( const uint8_t *  data, size_t  length, size_t *  offset, uint8_t *  major, uint64_t *  value  )

static

Parse one CBOR head (major type and argument): consume the initial byte (type in bits 7-5, info in bits 4-0), then additional bytes for arguments 24+ (1/2/4/8 bytes).

Return 0 on success, -1 on overflow/underrun/non-canonical encoding. Advances offset.

integer()

static int integer ( const struct item *  item, int64_t *  value  )

static

Extract a signed integer from a parsed CBOR item: major type 0 (uint) → positive value, type 1 (nint) → -(value + 1).

Returns 0 on success, -1 if the item is not an integer or overflows int64_t.

map_find_int()

static int map_find_int ( const struct item *  map, int64_t  key, struct item *  value  )

static

Search a CBOR map (major type 5) for an entry with integer key.

Iterate key-value pairs and return 0 when a match is found (value written to result), or -1 if the key is not present or parsing fails.

map_find_text()

static int map_find_text ( const struct item *  map, const char *  key, struct item *  value  )

static

Search a CBOR map (major type 5) for an entry with text string key (major type 3).

Iterate key-value pairs and return 0 when a match is found (value written to result), or -1 if the key is not present or parsing fails.

parse_at()

static int parse_at ( const uint8_t *  data, size_t  length, size_t *  offset, struct item *  out  )

static

Parse one CBOR-encoded item and all its children iteratively (depth-first traversal), constraining nesting to at most 25 levels to bound the embedded workqueue stack.

On success, populate out with the major type, argument value, encoded-byte range, and (for strings) the payload pointer and length. Return 0 on success, -1 on format error, overflow, or underrun.

root()

static int root ( const uint8_t *  data, size_t  length, struct item *  out  )

static

Parse the root CBOR item and validate that it consumes the entire input.

Return 0 on success, -1 if parsing fails or trailing bytes remain.

tagged_embedded()

static int tagged_embedded ( const struct item *  tag, struct item *  embedded  )

static

Extract the byte payload from a CBOR tag with tag number 24 (embedded tag for binary data).

Validate that the tag contains exactly one child of type 2 (byte string) and that it fills the entire tag encoding. Return 0 on success, -1 on format error.

timestamp()

static int timestamp ( const struct item *  item, uint8_t  output[20]  )

static

Extract a 20-byte timestamp from a CBOR item: accept a text string (major type 3) directly, or extract and unwrap a tag-0 wrapper around a text string.

Validate length and copy the payload. Return 0 on success, -1 if format or length is invalid.