Datatypes - Revision history

Ram: /* Multi-Byte Integers */ Added blurb about variable-length encoding

2014-01-18T16:19:37Z

Multi-Byte Integers: Added blurb about variable-length encoding

← Older revision		Revision as of 16:19, 18 January 2014
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	is the default byte-order; however, big-endian byte order can be selected for		is the default byte-order; however, big-endian byte order can be selected for
	those who want it.		those who want it.

			Some values can also be serialized with spurious zeroes stripped-off, which is called '''variable-length''' encoding. This is suitable for values that are usually small, because it avoids transmitting extra zero bytes over the network.

			A ''variable-length'' encoding of values less than 256 requires 1 single byte, values up to 65536 will require 2 bytes, and so on and so forth. This is the type of encoding used for serializing the length of each G2 packet, for instance.

	== Network/Node Addresses ==		== Network/Node Addresses ==

Dcat: /* Strings */

2009-01-01T04:21:16Z

Strings

← Older revision		Revision as of 04:21, 1 January 2009
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	All applications must be able to parse UTF-8 encoded strings, however, it is up to the		All applications must be able to parse UTF-8 encoded strings, however, it is up to the
	individual application whether to store the string in Unicode, or convert it to the		individual application whether to store the string in Unicode, or convert it to the
	local code page for processing. In situations where a packet must be processed 'and'		local code page for processing. In situations where a packet must be processed ''and''
	forwarded, the original packet must be forwarded rather than a regenerated version.		forwarded, the original packet must be forwarded rather than a regenerated version.
	This ensures that both locally unsupported encodings and packet extensions are		This ensures that both locally unsupported encodings and packet extensions are

Spooky at 22:26, 2 April 2005

2005-04-02T22:26:52Z

← Older revision		Revision as of 22:26, 2 April 2005
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			[[Packet_Structure\|<< Packet Structure]] \| [[Basic_Network_Maintenance\|Basic Network Maintenance >>]] \| [[Main_Page\|Main Page]]


	== Introduction ==		== Introduction ==

Kath: /* Strings */

2005-03-27T17:01:16Z

Strings

← Older revision		Revision as of 17:01, 27 March 2005
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	sequence of 8 bit integers.		sequence of 8 bit integers.

	A zero character (0x00) marks the end of the string, however if the string data meets		A zero character (0x00) marks the end of the string, however, if the string data meets
	the end of the packet (or child packet) payload, the terminator is not required. This		the end of the packet (or child packet) payload, the terminator is not required. This
	means that packets whose payload consists of a string do not need to include a zero		means that packets whose payload consists of a string, do not need to include a zero
	string terminator and their payload length will be the byte length of the encoded		string terminator and their payload length will be the byte length of the encoded
	string exactly.		string exactly.
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	with multi-byte sequences.		with multi-byte sequences.

	All applications must be able to parse UTF-8 encoded strings, however it is up to the		All applications must be able to parse UTF-8 encoded strings, however, it is up to the
	individual application whether to store the string in Unicode or convert it to the a		individual application whether to store the string in Unicode, or convert it to the
	local code page for processing. In situations where a packet must be processed 'and'		local code page for processing. In situations where a packet must be processed 'and'
	forwarded, the original packet must be forwarded rather than a regenerated version.		forwarded, the original packet must be forwarded rather than a regenerated version.

Kath: /* Network/Node Addresses */

2005-03-27T16:52:23Z

Network/Node Addresses

← Older revision		Revision as of 16:52, 27 March 2005
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	A network or node address consists of a physical address and a port number, and are		A network or node address consists of a physical address and a port number, and are
	of variable length depending on the address family.		of variable length, depending on the address family.
	In IPv4, a network/node address is six bytes long: 4 bytes for an IP address and 2		In IPv4, a network/node address is six bytes long: 4 bytes for an IP address and 2
	bytes for a port number as follows:		bytes for a port number as follows:
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	IPv6 addresses are longer and are not yet defined within the scope of Gnutella2,		IPv6 addresses are longer and are not yet defined within the scope of Gnutella2,
	however applications should be aware that if the node address is not 6 bytes it is of		however, applications should be aware that if the node address is not 6 bytes, it is of
	a different address family.		a different address family.

Kath: /* Multi-Byte Integers */

2005-03-27T16:50:52Z

Multi-Byte Integers

← Older revision		Revision as of 16:50, 27 March 2005
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	Multi-byte integers are serialized in the byte-order of the topmost packet. Little endian		Multi-byte integers are serialized in the byte-order of the topmost packet. Little endian
	is the default byte-order; however big-endian byte order can be selected for		is the default byte-order; however, big-endian byte order can be selected for
	those who want it.		those who want it.

Kath: /* Introduction */

2005-03-27T16:50:14Z

Introduction

← Older revision		Revision as of 16:50, 27 March 2005
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	The format of a packet payload is defined by the packet type and can consist of any		The format of a packet payload is defined by the packet type and can consist of any
	binary data; however there are a number of conventions in place for serializing		binary data; however, there are a number of conventions in place for serializing
	common datatypes.		common datatypes.

Dcat at 17:28, 19 March 2005

2005-03-19T17:28:10Z

New page

== Introduction ==

The format of a packet payload is defined by the packet type and can consist of any
binary data; however there are a number of conventions in place for serializing
common datatypes.

== Multi-Byte Integers ==

Multi-byte integers are serialized in the byte-order of the topmost packet. Little endian
is the default byte-order; however big-endian byte order can be selected for
those who want it.

== Network/Node Addresses ==

A network or node address consists of a physical address and a port number, and are
of variable length depending on the address family.
In IPv4, a network/node address is six bytes long: 4 bytes for an IP address and 2
bytes for a port number as follows:

<pre>
<nowiki>
typedef struct
{
BYTE ip[4];
SHORT port;
} IPV4_ENDPOINT;
</nowiki>
</pre>

Note that this is considered an array of 4 8-bit integers (bytes), followed by a 16-bit
integer (short). Byte order does not affect bytes, but it will affect the 16-bit port
number.

IPv6 addresses are longer and are not yet defined within the scope of Gnutella2,
however applications should be aware that if the node address is not 6 bytes it is of
a different address family.

== GUIDs ==

Globally unique identifiers (GUIDs) are used to identify nodes on the network. GUIDs
are serialized as an array of 16 bytes.

== Strings ==

Strings are encoded with UTF-8 encoding and serialized as a zero-terminated
sequence of 8 bit integers.

A zero character (0x00) marks the end of the string, however if the string data meets
the end of the packet (or child packet) payload, the terminator is not required. This
means that packets whose payload consists of a string do not need to include a zero
string terminator and their payload length will be the byte length of the encoded
string exactly.

UTF-8 encoding is required for all strings present in the packet payload. This means
that 7-bit characters may be passed as-is, while extended characters are encoded
with multi-byte sequences.

All applications must be able to parse UTF-8 encoded strings, however it is up to the
individual application whether to store the string in Unicode or convert it to the a
local code page for processing. In situations where a packet must be processed 'and'
forwarded, the original packet must be forwarded rather than a regenerated version.
This ensures that both locally unsupported encodings and packet extensions are
preserved.

Applications should never send ANSI strings directly if they contain extended
characters with the MSB set. These should be encoded with UTF-8. If this is not
done, the decoding process may fail and the packet will be discarded or contain
bogus information.