Developers.GnutellaHandshakeHeaders

Handshake Headers

These are the Gnutella handshake headers that Shareaza uses. See the complete list at: [1]

First Line

The computer that makes the connection sends

GNUTELLA CONNECT/0.6

to tell the receiving computer that it wants to communicate with Gnutella. This begins the handshake. The remote computer responds with the line

GNUTELLA/0.6 200 OK

to connect, or

GNUTELLA/0.6 503 Need an Ultrapeer

to say that it can't connect. The only two status codes in use are 200 for OK and 503 for refused. Text after the 503 describes why the remote computer can't connect, and can be anything.

User Agent

User-Agent: Shareaza 2.1.0.97

Each computer tells the other the name and version number of the Gnutella software it is running.

Internet Addresses

Listen-IP: 67.176.34.172:6346 Remote-IP: 81.103.192.245

If we sent these two headers, Listen-IP is our IP address and port number. In place of Listen-IP, some clients use X-My-Address or Node. We have a socket listening for new connections on that port. We tell the remote computer what IP address it seems to have from here with the Remote-IP header.

X-Try-Ultrapeers: 24.98.97.155:6348 2004-12-18T23:47Z,

This header lists IP addresess and port numbers of more computers running Gnutella. Like a Web cache of Gnutella computers, this lets us try more addresses until we find a few that are online. Commas separate each record, and the date and time at the end of each is the last time we connected to that computer.

Compression

All popular Gnutella programs support compression, and Gnutella connections are almost always compressed. To setup compression, the initiating computer says

Accept-Encoding: deflate

to say we can accept compressed data. The receiving computer responds with

Accept-Encoding: deflate Content-Encoding: deflate

which means it also accepts compressed data, and will be sending compressed data right after this handshake is over. The initiating computer confirms compression with

Content-Encoding: deflate

which means it also will be sending compressed data.

Gnutella2 Packets

Setting up Gnutella2 communication in place of regular Gnutella packets is similar to setting up compression. The computer that made the connection says

Accept: application/x-gnutella2

to advertise it accepts Gnutella2 packets. If the contacted computer can speak Gnutella2, it responds with

Accept: application/x-gnutella2 Content-Type: application/x-gnutella2

meaning it can also accept Gnutella2 packets, and will be sending them. The first computer then says

Content-Type: application/x-gnutella2

to annonce it also will be sending Gnutella2 packets. Some clients use x-shareaza in place of x-gnutella2 in these headers, and Shareaza can understand both.

Ultrapeers

In Gnutella and Gnutella2, there are two roles for a computer on the network. Gnutella calls them ultrapeer and leaf, while Gnutella2 calls them hub and leaf. In the handshake, each computer tells the other what role it is currently playing.

X-Ultrapeer: True

or

X-Ultrapeer: False

Computers also express whether they need more ultrapeer or hub connections with the header

X-Ultrapeer-Needed: True

or

X-Ultrapeer-Needed: False

Some clients use Hub in place of Ultrapeer in these headers, and Shareaza can understand both.

Gnutella Features

These headers advertise that the computer that sends them is capable of advanced Gnutella features.

GGEP: 0.5 Pong-Caching: 0.1 Vendor-Message: 0.1 X-Query-Routing: 0.1