bird/lib/cbor.c

#include <stdint.h>
#include <string.h>

#include "lib/cbor.h"

/* String versions of type constants */
static const char *cbor_type_str_a[] = {
  "POSINT",
  "NEGINT",
  "BYTES",
  "TEXT",
  "ARRAY",
  "MAP",
  "TAG",
  "SPECIAL",
};

const char *
cbor_type_str(enum cbor_basic_type t)
{
  return (t < ARRAY_SIZE(cbor_type_str_a)) ?
    cbor_type_str_a[t] :
    tmp_sprintf("(unknown: %u)", t);
}

/* Raw data writing */

bool cbor_put_check(struct cbor_writer *w, u64 amount)
{
  return w->data.pos + amount <= w->data.end;
}

#define CBOR_PUT(amount) ({					\
    byte *put = w->data.pos;					\
    if ((w->data.pos += (amount)) >= w->data.end) return false;	\
    put; })

bool cbor_put_raw_u8(struct cbor_writer *w, byte b)
{
  *(CBOR_PUT(1)) = b;
  return true;
}

bool cbor_put_raw_u16(struct cbor_writer *w, u16 val)
{
  put_u16(CBOR_PUT(2), val);
  return true;
}

bool cbor_put_raw_u32(struct cbor_writer *w, u32 val)
{
  put_u32(CBOR_PUT(4), val);
  return true;
}

bool cbor_put_raw_u64(struct cbor_writer *w, u64 val)
{
  put_u64(CBOR_PUT(8), val);
  return true;
}

bool cbor_put_raw_data(struct cbor_writer *w, const byte *block, u64 size)
{
  memcpy(CBOR_PUT(size), block, size);
  return true;
}

/* Basic value putting */
bool cbor_put(struct cbor_writer *w, enum cbor_basic_type type, u64 value)
{
  ASSERT_DIE((type >= 0) && (type <= 8));
  w->stack[w->stack_pos].items++;
  byte tt = type << 5;
  if (value < 0x18)
    return
      cbor_put_raw_u8(w, tt | value);
  else if (value < 0x100)
    return
      cbor_put_raw_u8(w, tt | 0x18) &&
      cbor_put_raw_u8(w, value);
  else if (value < 0x10000)
    return
      cbor_put_raw_u8(w, tt | 0x19) &&
      cbor_put_raw_u16(w, value);
  else if (value < 0x100000000)
    return
      cbor_put_raw_u8(w, tt | 0x1a) &&
      cbor_put_raw_u32(w, value);
  else
    return
      cbor_put_raw_u8(w, tt | 0x1b) &&
      cbor_put_raw_u64(w, value);
}

bool cbor_put_int(struct cbor_writer *w, int64_t value)
{
  if (value >= 0)
    return cbor_put(w, CBOR_POSINT, value);
  else
    return cbor_put(w, CBOR_NEGINT, -1-value);
}

/* Strings */
bool cbor_put_raw_bytes(struct cbor_writer *w, enum cbor_basic_type type, const byte *block, u64 size)
{
  return
    cbor_put(w, type, size) &&
    cbor_put_raw_data(w, block, size);
}

/* Arrays and maps */
bool cbor_put_open(struct cbor_writer *w, enum cbor_basic_type type)
{
  if (++w->stack_pos >= w->stack_max)
    return false;

  w->stack[w->stack_pos].head = w->data.pos;
  w->stack[w->stack_pos].items = 0;

  return cbor_put(w, type, ~0ULL);
}

bool cbor_put_close(struct cbor_writer *w, u64 actual_size, bool strict)
{
  ASSERT_DIE(w->stack_pos > 0);

  /* Pop the stack */
  byte *head = w->stack[w->stack_pos].head;
  u64 items = w->stack[w->stack_pos].items;

  w->stack_pos--;

  /* The open mark puts its item counter one level
   * too deep; fixing this. */
  items--;
  w->stack[w->stack_pos].items++;

  /* Check the original head position */
  ASSERT_DIE((head[0] & 0x1f) == 0x1b);
  ASSERT_DIE(w->data.pos >= w->data.start + 9);
  switch (head[0] >> 5)
  {
    case CBOR_ARRAY:
      if (strict && (items != actual_size))
	bug("Inconsistent array item count");
      break;

    case CBOR_MAP:
      if (strict && (items != actual_size * 2))
	bug("Inconsistent map item count");
      else if (items & 1)
	bug("Trailing map key");
      else
	items /= 2;
      break;

    default:
      bug("Head points to something other than array or map");
  }

  /* Move the data back */

  if (items < 0x18)
  {
    memmove(head+1, head+9, w->data.pos - (head+9));
    head[0] &= (0xe0 | items);
    w->data.pos -= 8;
  }
  else if (items < 0x100)
  {
    memmove(head+2, head+9, w->data.pos - (head+9));
    head[0] &= 0xf8;
    head[1] = items;
    w->data.pos -= 7;
  }
  else if (items < 0x10000)
  {
    memmove(head+3, head+9, w->data.pos - (head+9));
    head[0] &= 0xf9;
    put_u16(head+1, items);
    w->data.pos -= 6;
  }
  else if (items < 0x100000000)
  {
    memmove(head+5, head+9, w->data.pos - (head+9));
    head[0] &= 0xfa;
    put_u32(head+1, items);
    w->data.pos -= 4;
  }
  else
  {
    head[0] &= 0xfb;
    put_u64(head+1, items);
  }

  return true;
}

/* Tags: TODO! */


/* Writer contexts */
struct cbor_writer *
cbor_reply_init(struct cbor_channel *cch)
{
  ASSERT_DIE(cch->stream->s->tbsize > 16);
  ASSERT_DIE(cch->stream->s->tbuf);
  struct cbor_writer *cw = &cch->writer;
  if (cch->stream->s->tbuf != cch->stream->s->tpos)
    bug("Not implemented reply to not-fully-flushed buffer");

  cbor_writer_init(cw, cch->stream->writer_depth, cch->stream->s->tbuf, cch->stream->s->tbsize);

  ASSERT_DIE(cbor_open_array(cw));
  ASSERT_DIE(cbor_put_posint(cw, cch->id));
  return cw;
}

void
cbor_reply_send(struct cbor_channel *cch, struct cbor_writer *cw)
{
  ASSERT_DIE(cw == &cch->writer);
  ASSERT_DIE(cbor_close_array(cw));
  sk_send(cch->stream->s, cw->data.pos - cw->data.start);
}

#if 0

void cbor_epoch_time(struct cbor_writer *writer, int64_t time, int shift)
{
  write_item(writer, 6, 1); // 6 is TAG, 1 is tag number for epoch time
  cbor_relativ_time(writer, time, shift);
}

void cbor_relativ_time(struct cbor_writer *writer, int64_t time, int shift)
{
  write_item(writer, 6, 4); // 6 is TAG, 4 is tag number for decimal fraction
  cbor_open_list_with_length(writer, 2);
  cbor_add_int(writer, shift);
  cbor_add_int(writer, time);
}

void cbor_add_ipv4(struct cbor_writer *writer, ip4_addr addr)
{
  write_item(writer, 6, 52); // 6 is TAG, 52 is tag number for ipv4
  write_item(writer, 2, 4); // bytestring of length 4
  put_ip4(&writer->cbor[writer->pt], addr);
  writer->pt += 4;
}

void cbor_add_ipv6(struct cbor_writer *writer, ip6_addr addr)
{
  write_item(writer, 6, 54); // 6 is TAG, 54 is tag number for ipv6
  write_item(writer, 2, 16); // bytestring of length 16
  put_ip6(&writer->cbor[writer->pt], addr);
  writer->pt += 16;
}


void cbor_add_ipv4_prefix(struct cbor_writer *writer, net_addr_ip4 *n)
{
  write_item(writer, 6, 52); // 6 is TAG, 52 is tag number for ipv4
  cbor_open_block_with_length(writer, 2);
  cbor_add_int(writer, n->pxlen);
  write_item(writer, 2, 4); // bytestring of length 4
  put_ip4(&writer->cbor[writer->pt], n->prefix);
  writer->pt += 4;
}


void cbor_add_ipv6_prefix(struct cbor_writer *writer, net_addr_ip6 *n)
{
  write_item(writer, 6, 54); // 6 is TAG, 54 is tag number for ipv6
  cbor_open_block_with_length(writer, 2);
  cbor_add_int(writer, n->pxlen);

  write_item(writer, 2, 16);
  put_ip6(&writer->cbor[writer->pt], n->prefix);
  writer->pt += 16;
}


void cbor_add_uint(struct cbor_writer *writer, uint64_t item)
{
  write_item(writer, 0, item);
}

void cbor_add_tag(struct cbor_writer *writer, int item)
{
  write_item(writer, 6, item);
}

void cbor_add_string(struct cbor_writer *writer, const char *string)
{
  int length = strlen(string);
  write_item(writer, 3, length);  // 3 is major, then goes length of string and string
  check_memory(writer, length);
  memcpy(writer->cbor+writer->pt, string, length);
  writer->pt+=length;
}

void cbor_nonterminated_string(struct cbor_writer *writer, const char *string, uint32_t length)
{
  write_item(writer, 3, length);  // 3 is major, then goes length of string and string
  check_memory(writer, length);
  memcpy(writer->cbor+writer->pt, string, length);
  writer->pt+=length;
}

void write_item(struct cbor_writer *writer, uint8_t major, uint64_t num)
{
  //log("write major %i %li", major, num);
  major = major<<5;
  check_memory(writer, 10);
  if (num > ((uint64_t)1<<(4*8))-1)
  { // We need 8 bytes to encode the num
    major += 0x1b; // reserving those bytes
    writer->cbor[writer->pt] = major;
    writer->pt++;
    for (int i = 7; i>=0; i--)
    { // write n-th byte of num
      uint8_t to_write = (num>>(i*8)) & 0xff;
      writer->cbor[writer->pt] = to_write;
      writer->pt++;
    }
    return;
  }
  if (num > (1<<(2*8))-1)
  { // We need 4 bytes to encode the num
    major += 0x1a; // reserving those bytes
    writer->cbor[writer->pt] = major;
    writer->pt++;
    for (int i = 3; i>=0; i--)
    { // write n-th byte of num
      uint8_t to_write = (num>>(i*8)) & 0xff;
      writer->cbor[writer->pt] = to_write;
      writer->pt++;
    }
    return;
  }
  if (num > (1<<(8))-1)
  { // We need 2 bytes to encode the num
    major += 0x19; // reserving those bytes
    writer->cbor[writer->pt] = major;
    writer->pt++;
    for (int i = 1; i>=0; i--)
    { // write n-th byte of num
      uint8_t to_write = (num>>(i*8)) & 0xff;
      writer->cbor[writer->pt] = to_write;
      writer->pt++;
    }
    return;
  }
  if (num > 23)
  { // byte is enough, but aditional value would be too big
    major += 0x18; // reserving that byte
    writer->cbor[writer->pt] = major;
    writer->pt++;
    uint8_t to_write = num & 0xff;
    writer->cbor[writer->pt] = to_write;
    writer->pt++;
    return;
  }
  //log("write item major %i num %i writer->pt %i writer->capacity %i writer %i", major, num, writer->pt, writer->capacity, writer);
  major += num;  // we can store the num as additional value
  writer->cbor[writer->pt] = major;
  writer->pt++;
}

void cbor_write_item_with_constant_val_length_4(struct cbor_writer *writer, uint8_t major, uint64_t num)
{
// this is only for headers which should be constantly long.
  major = major<<5;
  check_memory(writer, 10);
  major += 0x1a; // reserving those bytes
  writer->cbor[writer->pt] = major;
  writer->pt++;
  for (int i = 3; i>=0; i--)
  { // write n-th byte of num
    uint8_t to_write = (num>>(i*8)) & 0xff;
    writer->cbor[writer->pt] = to_write;
    writer->pt++;
  }
}


void rewrite_4bytes_int(struct cbor_writer *writer, int pt, int num)
{
  for (int i = 3; i>=0; i--)
  {
    uint8_t to_write = (num>>(i*8)) & 0xff;
    writer->cbor[pt] = to_write;
    pt++;
  }
}

void check_memory(struct cbor_writer *writer, int add_size)
{
  if (writer->capacity - writer->pt-add_size < 0)
  {
    bug("There is not enough space for cbor response in given buffer");
  }
}
#endif