RFC1034

Overview ¶

Package rfc1034 encompasses portions of:

RFC 1034 - "Domain Names - Concepts and Facilities"

This subpackage implements relevant methods and checks for validating the composition of a candidate RFC 1034 Absolute Name (aka FQDN).

This package's implementation of this RFC is a work-in-progress and may not necessarily be complete!

To see the actual RFC, visit: https://tools.ietf.org/html/rfc1034, or see the documentation for reference on the RFCEntity.URL() method for programmatic URL lookups.

This subpackage is currently maintained by Jesse Coretta (subcon42)

Section 3.1 ¶

This module currently focuses heavily on Section 3.1 of RFC 1034 under the tone of the RFC 2119 Must Imperative. Conditions that are evaluated are as follows:

➡ Total length (253 typed characters)

➡ First absolute name character is total length indicator (1 uint8)

➡ First byte in each label is label length indicator (1 uint8)

➡ Label length(s) for typed characters (1-63 characters each)

➡ Segmentation (label) count is less than, or equal to, 127

➡ Identical brother adjacency (no repeating labels next to one another)

➡ Null terminator presence (last byte of FQDN candidate bytes is the termination character)

➡ Characters present, not including the delimiter periods ("."), are limited to A-Z, a-z, 0-9 and hyphen

➡ TLD label emergency size-offset (Where preceding labels are all large sizes and the absolute name limit is in danger of being breached)

Hostname Bytes ¶

Ultimately, a candidate absolute name is in the following form "under the hood":

[][]uint8{
 []uint8{0x13},                            // 13 is the total *TYPED* length
 []uint8{0x3,119,119,119},                 // 3 length + decimal w,w,w
 []uint8{0x7,101,120,97,109,112,108,101},  // 7 length + decimal e,x,a,m,p,l,e
 []uint8{0x3,99,111,109},                  // 3 length + decimal c,o,m
 []uint8{'\x00'},                          // no length
}

The user is not responsible for input of length bytes, nor the termination character. Specifically, the user is only expected to craft the decimal components shown (the so-called "TYPED" input).