Packets/Login/Vanilla

 (1.1.2.4125)

It's worth noting that, for this build, the client automatically disconnect after a successful login challenge and proof exchange and sends a reconnect packet right away instead of asking for the realm list.

Some enums first:

Opcodes

Name	Value
LOGIN_CHALL	0x00
LOGIN_PROOF	0x01
RECON_CHALL	0x02
RECON_PROOF	0x03
REALMLIST	0x10
XFER_INITIATE	0x30
XFER_DATA	0x31

Error codes

Name	Value
LOGIN_OK	0x00
LOGIN_FAILED	0x01
LOGIN_FAILED2	0x02
LOGIN_BANNED	0x03
LOGIN_UNKNOWN_ACCOUNT	0x04
LOGIN_UNKNOWN_ACCOUNT3	0x05
LOGIN_ALREADYONLINE	0x06
LOGIN_NOTIME	0x07
LOGIN_DBBUSY	0x08
LOGIN_BADVERSION	0x09
LOGIN_DOWNLOAD_FILE	0x0A
LOGIN_FAILED3	0x0B
LOGIN_SUSPENDED	0x0C
LOGIN_FAILED4	0x0D
LOGIN_CONNECTED	0x0E
LOGIN_PARENTALCONTROL	0x0F
LOGIN_LOCKED_ENFORCED	0x10

Challenge packets

AuthLogonChallenge_Client

Offset	Type	Name	Description
0x0	uint8	command	LOGIN_CHALL (0x0)
0x1	uint8	protocol_version	3 for 1.12, unknown for 1.1.
0x2	uint16	size	length of package minus the size of the command, protocol_version and size fields (4 bytes).
0x4	char[4]	gamename	'WoW'
0x8	uint8[3]	version	0x01 0x01 0x02
0xB	uint16	build	4125, aka Revision
0xD	char[4]	platform	eg 'x86'
0x11	char[4]	os	eg 'Win'
0x15	char[4]	country	eg 'enUS'
0x19	uint32	worldregion_bias	offset in minutes from UTC time , eg. 180 means 180 minutes
0x1D	uint32	ip	client_ip
0x21	uint8	account_name_len	Length of the account_name field in bytes. The client can only send 16 characters, but this can still be more than 16 bytes if non-ASCII characters are used.
0x22	char[account_name_len]	account_name	UTF-8 encoded uppercase string of the username. Not all unicode characters are uppercased correctly.

AuthLogonChallenge_Server

Offset	Type	Name	Description
0x1	uint8	command	LOGIN_CHALL (0x0)
0x2	uint8	protocol_version	Must be 0.
0x3	uint8	result
0x4	char[32]	B	SRP public server ephemeral
0x24	uint8	g_len	SRP generator length
0x25	uint8	g	SRP generator
0x26	uint8	n_len	SRP modulus length
0x27	char[32]	n	SRP modulus
0x47	char[32]	srp_salt	SRP user's salt
0x47	char[16]	crc_salt	A salt to be used in AuthLogonProof_Client.crc_hash

Proof packets

AuthLogonProof_Client

Offset	Type	Name	Description
0x0	uint8	command	0x1
0x1	uint8[32]	a
0x21	uint8[20]	m1
0x35	uint8[20]	crc_hash
0x49	uint8	num_keys

AuthLogonProof_Server

Offset	Type	Name	Description
0x0	uint8	command	0x1
0x1	uint8	error
0x2	uint8[20]	m2
0x16	uint32	unk

Reconnection challenge packets

AuthReconnectionChallenge_Client has the same structure as AuthLogonChallenge_Client, except that the command is 0x2.

AuthReconnectionChallenge_Server

Offset	Type	Name	Description
0x0	uint8	command	0x2
0x1	uint8	error
0x2	char[16]	challenge_data	random data, used as a challenge
0x12	uint64	unk1
0x1A	uint64	unk2

Reconnection proof packets

AuthReconnectionProof_Client

Offset	Type	Name	Description
0x0	uint8	command	0x3
0x1	char[16]	proof_data
0x11	char[20]	client_proof
0x25	char[20]	unk_hash
0x39	uint8	unk

To check if the client proof is correct, the server must calculate SHA1(account_name | proof_data | challenge_data | session_key) and compare it to client_proof.

AuthReconnectionProof_Server

Offset	Type	Name	Description
0x0	uint8	command	0x3
0x1	uint8	error

Realm list packets

RealmList_Client

Offset	Type	Name	Description
0x0	uint8	cmd	REALMLIST
0x1	uint32	unknown	null

The server answers with a packet composed of a RealmHeader_Server, as many RealmInfo_Server as specified and a RealmFooter_Server.

RealmHeader_Server

Offset	Type	Name	Description
0x0	uint8	cmd	REALMLIST
0x1	uint16	size	size of the rest of packet, without these 3 first bytes
0x3	uint32	unknown	null
0x7	uint8	num_realms	Number of RealmInfo_Server

The size value can be computed with the part of the header taken into account plus the footer (5+2 bytes) and the size of every RealmInfo_Server which is variable.

RealmInfo_Server

Offset	Type	Name	Description
0x0	uint32	type	realm type? 0 is normal, 1 is PVP
0x4	uint8	flags	see below
0x5	char[]	name	Zero terminated string; name of the Realm
	char[]	addr_port	Zero terminated string; address of the Realm ("ip:port")
	float	population	Population value. 0 is low, 1 is medium, 2 is high.
	uint8	num_chars	The number of chars you have on that server
	uint8	time_zone	really?
	uint8	unknown

Flags     Meaning
0x01     Color the realm name in red (can't create char?)
0x02     Realm is offline

RealmFooter_Server

Offset	Type	Name	Description
0x0	uint16	unk

 (1.12.1.5875)

Challenge Packets

The AuthLogonChallenge_Server packet has added the two_factor_authentication field and will hang waiting for it to be sent.

AuthLogonChallenge_Server

Offset	Type	Name	Description
0x1	uint8	command	LOGIN_CHALL (0x0)
0x2	uint8	protocol_version	Must be 0.
0x3	uint8	result
0x4	char[32]	B	SRP public server ephemeral
0x24	uint8	g_len	SRP generator length
0x25	uint8	g	SRP generator
0x26	uint8	n_len	SRP modulus length
0x27	char[32]	n	SRP modulus
0x47	char[32]	srp_salt	SRP user's salt
0x47	char[16]	crc_salt	A salt to be used in AuthLogonProof_Client.crc_hash
0x57	bool	two_factor_authentication	0 for disabled.

Proof packets changed during Vanilla:

AuthLogonProof_Client

Offset	Type	Name	Description
0x0	uint8	command	0x1
0x1	uint8[32]	a
0x21	uint8[20]	m1
0x35	uint8[20]	crc_hash
0x49	uint8	num_keys
0x4A	uint8	unk	Added in 1.12.x client branch

AuthLogonProof_Server

Offset	Type	Name	Description
0x0	uint8	command	0x1
0x1	uint8	error
0x2	uint8[20]	m2
0x16	uint32	unk1
0x1A	uint32	unk2
0x1E	uint32	unk3