/** Parse an EXTENDED or EXTENDED2 cell (according to <b>command</b>) from the
* <b>payload_length</b> bytes of <b>payload</b> into <b>cell_out</b>. Return
* 0 on success, -1 on failure. */
int
extended_cell_parse(extended_cell_t *cell_out,
const uint8_t command, const uint8_t *payload,
size_t payload_len)
{
tor_assert(cell_out);
tor_assert(payload);
memset(cell_out, 0, sizeof(*cell_out));
if (payload_len > RELAY_PAYLOAD_SIZE)
return -1;
switch (command) {
case RELAY_COMMAND_EXTENDED:
if (payload_len != TAP_ONIONSKIN_REPLY_LEN)
return -1;
cell_out->cell_type = RELAY_COMMAND_EXTENDED;
cell_out->created_cell.cell_type = CELL_CREATED;
cell_out->created_cell.handshake_len = TAP_ONIONSKIN_REPLY_LEN;
memcpy(cell_out->created_cell.reply, payload, TAP_ONIONSKIN_REPLY_LEN);
break;
case RELAY_COMMAND_EXTENDED2:
{
cell_out->cell_type = RELAY_COMMAND_EXTENDED2;
cell_out->created_cell.cell_type = CELL_CREATED2;
cell_out->created_cell.handshake_len = ntohs(get_uint16(payload));
if (cell_out->created_cell.handshake_len > RELAY_PAYLOAD_SIZE - 2 ||
cell_out->created_cell.handshake_len > payload_len - 2)
return -1;
memcpy(cell_out->created_cell.reply, payload+2,
cell_out->created_cell.handshake_len);
}
break;
default:
return -1;
}
return check_extended_cell(cell_out);
}
/** Format the EXTENDED{,2} cell in <b>cell_in</b>, storing its relay payload
* in <b>payload_out</b>, the number of bytes used in *<b>len_out</b>, and the
* relay command in *<b>command_out</b>. The <b>payload_out</b> must have
* RELAY_PAYLOAD_SIZE bytes available. Return 0 on success, -1 on failure. */
int
extended_cell_format(uint8_t *command_out, uint16_t *len_out,
uint8_t *payload_out, const extended_cell_t *cell_in)
{
uint8_t *p;
if (check_extended_cell(cell_in) < 0)
return -1;
p = payload_out;
memset(p, 0, RELAY_PAYLOAD_SIZE);
switch (cell_in->cell_type) {
case RELAY_COMMAND_EXTENDED:
{
*command_out = RELAY_COMMAND_EXTENDED;
*len_out = TAP_ONIONSKIN_REPLY_LEN;
memcpy(payload_out, cell_in->created_cell.reply,
TAP_ONIONSKIN_REPLY_LEN);
}
break;
case RELAY_COMMAND_EXTENDED2:
{
*command_out = RELAY_COMMAND_EXTENDED2;
*len_out = 2 + cell_in->created_cell.handshake_len;
set_uint16(payload_out, htons(cell_in->created_cell.handshake_len));
if (2+cell_in->created_cell.handshake_len > RELAY_PAYLOAD_SIZE)
return -1;
memcpy(payload_out+2, cell_in->created_cell.reply,
cell_in->created_cell.handshake_len);
}
break;
default:
return -1;
}
return 0;
}
