Translated from Yoram kulbak and Danny Bickson the eMule Protocol Specification
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6.1
General message encoding highlights
This chapter describes the general message encoding methods for TCP/UDP listeners.
6.1.1
Byte orderAll messages are encoded with little-Endian instead of big-Endian and big-Endian.
Is the agreed network byte order. This is easy to explain. In fact, the client/server is based on Microsoft Windows and runs on Intel processors.
6.1.2
Message HeaderAll messages have a 6-byte header with the following structure: 1. Protocol-one byte, protocol id-0xe3 is eDonkey, and 0xc5 is emule2. size-4 bytes message size-
The message size, in bytes, does not contain the header. For example, if the message does not contain any payload, for example, in section 6.4.11, the message length is zero. 3. Type-one byte, type-unique message ID
6.1.3
Message tagThe label is similar to the TLV (type, length, value) structure, used to add optional data to the eMule message. There are several types of labels. This chapter lists all the labels. When it comes to a specific tag in a protocol message, only the tag type is specified. Readers should take this chapter as a reference to determine the accurate structure of the protocol message. Each tag has four fields, and they are not continuous in the message: 1. type-1 byte integer 2. name-it can be one of the following l Variable Length string L 1 byte integer 3. value-it can be one of the following L 4-byte integer L 4-byte floating point number l Variable Length string 4. the special-1-byte Integer type is used. The label that is used to specify a specific value is called an integer tag. Similarly, we have a string tag and a floating point tag. The type value of the string tag is 2, the type value of the integer tag is 3, and the type value of the floating point tag is 4. When a tag is encoded for sending, It is encoded in the above order, for example, type, name, and value. Type is encoded into one byte. The name is encoded into two byte length values, which can be a string name or an integer name. For example, the integer name 0x15 is encoded in the order of 0x01.
0x00 0x15. Fixed value ranges (like integer and floating-point numbers) are written as they do, and string values are encoded in the same length value format. Note: The name provided by the tag has no specific protocol meaning, but is easy to reference in later protocol message descriptions.
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