2.2.2.8 LOOKUP

The LOOKUP message is sent by a Resolver to a Publisher to resolve a PNRP ID.

FieldID1 (2 bytes): MUST be set to 0x0045 (LOOKUP_CONTROLS).

Length1 (2 bytes): MUST be set to 0x000C.

Reserved1 (14 bits): Reserved. MUST be set to zero when sent and MUST be ignored on receipt.

A (1 bit): If set, indicates that the sender is willing to accept returned nodes that are not closer to the target ID than the Validate PNRP ID.

0 (1 bit): Reserved. MUST be set to zero when sent and MUST be ignored on receipt.

Precision (2 bytes): Number of significant bits to match. When ResolveCriteria is not set to SEARCH_OPCODE_UPPER_BITS, the Precision field MAY be set to any arbitrary value and MUST be ignored upon receipt.

ResolveCriteria (1 byte): The type of PNRP ID matching that the sender is requesting, which is chosen based on higher-layer requirements. MUST be one of the following (for example, although the values are powers of two, they are not bits that can be combined).

Value	Meaning
SEARCH_OPCODE_NONE 0x00	Compare all 256 bits of the PNRP ID.
SEARCH_OPCODE_ANY_PEERNAME 0x01	Compare only the first 128 bits of the PNRP ID.
SEARCH_OPCODE_NEAREST_PEERNAME 0x02	Compare all 256 bits of the PNRP ID and return the closest possible match.
SEARCH_OPCODE_NEAREST64_PEERNAME 0x04	Compare only the first 192 bits of the PNRP ID and return the closest possible match.
SEARCH_OPCODE_UPPER_BITS 0x08	Compare a number of bits equal to the value in the Precision field.

ResolveReasonCode (1 byte): The reason for the LOOKUP request. This value is ignored by the recipient. MUST be one of the following.

Value	Meaning
REASON_APP_REQUEST 0x00	The LOOKUP was sent in response to an application request.
REASON_REGISTRATION 0x01	The LOOKUP was sent in response to a completed registration that is being announced.
REASON_CACHE_MAINTENANCE 0x02	The LOOKUP was sent because the node is performing cache maintenance.
REASON_SPLIT_DETECTION 0x03	The LOOKUP was sent because the node is testing for a split cloud.

Reserved2 (2 bytes): MUST be set to zero when sent and MUST be ignored on receipt.

FieldID2 (2 bytes): MUST be set to 0x0038 (Target PNRP ID).

Length2 (2 bytes): MUST be set to 0x0024 (36 bytes).

Target PNRP ID (32 bytes): The PNRP ID to look up.

FieldID3 (2 bytes): MUST be set to 0x0039 (Validate PNRP ID).

Length3 (2 bytes): MUST be set to 0x0024 (36 bytes).

Validate PNRP ID (32 bytes): A PNRP ID of the destination machine.

FieldID4 (2 bytes): If present, MUST be set to 0x009A (ROUTING_ENTRY).

Length4 (2 bytes): If present, MUST be set to 4 plus the size in bytes of the Route Entry field.

Route Entry (variable): If present, a ROUTE_ENTRY structure for the best match so far.

Padding4 (variable): A number of bytes between 0 and 3, such that the offset from the start of the message to the end of this field is a multiple of 4. MUST be present if and only if FieldID4 is present. MUST be set to zero when sent and MUST be ignored on receipt.

FieldID5 (2 bytes): MUST be set to 0x009E (IPV6_ENDPOINT_ARRAY).

Length5 (2 bytes): MUST be set to 12+(NumEntries*EntryLength).

NumEntries (2 bytes): Number of entries in the Flagged Path field. MUST be in the range 1 to 22.

ArrayLength (2 bytes): MUST be set to 8+(NumEntries*EntryLength).

ElementFieldType (2 bytes): MUST be set to 0x009D (IPV6_ENDPOINT).

EntryLength (2 bytes): MUST be set to 0x0012 (18 bytes).

Flagged Path (variable): A list of IPV6_ENDPOINT structures for PNRP node that have seen this LOOKUP request so far.