drb-signature-magic 1.0.0

DRB Magic Signature

Magic Signature

This signature implementation allows to recognize a drb topic thanks to its magic field. The magic field is a fixed set of bytes in a data file to characterize its format. For example PKzip files always starts with '\x50\x4b\x03\x04'.

Using this module

To include this module into your project, the drb-signature-magic module shall be referenced into requirements.txt file, or the following pip line can be run:

pip install drb-signature-magic

Magic Signature definition

The signature have a type, a pattern and eventually an offset.

Type

Can be

• bytes
• string
• hexa
• regex

offset

It is the offset to skip before test if the signature matches. By default, it is zero, that means that the tes ti made at beginning.

pattern

After apply the offset on the stream of node.

For a string or bytes type the pattern is a value to compare.

For hexa, the pattern is converted to bytes, for example FF FE is converted to b'/xFFE/xFF'. And conversion, the behavior is the same that for bytes.

For a regex the pattern is a string that matches with string if 255 max character read.

Examples

For example to recognize PKzip that starts with '\x50\x4b\x03\x04'

id: 0225053d-4ea2-4046-bf97-af1dbac4e417
label: Test signature hexa for pkzip
category: FORMATTING
factory: pkzip
signatures:
  - magic:
      type: hexa
      pattern: 50 4b 03 04
      offset: 0

Same signature in bytes 'PK\x03\x04' (can be '\x50\x4b\x03\x04' also)

id: 0225053d-4ea2-4046-bf97-af1dbac4e417
label: Test signature bytes for pkzip
category: FORMATTING
factory: pkzip
signatures:
  - magic:
      type: bytes
      pattern: 'PK\x03\x04'
      offset: 0

For example to recognize LAS file sequence ^LAS are in position 0

id: c04f9327-3045-4fc0-93f8-b8dcd6626f64
label: Test signature magic LAS
category: FORMATTING
factory: impl_x
signatures:
  - magic:
      type: bytes
      pattern: ^LAS

For example to recognize a file defined by sequence of 6 decimal are in position 25

id: c04f9327-3045-4fc0-93f8-b8dcd6626f64
label: Test signature magic LAS
category: FORMATTING
factory: impl_x
signatures:
  - magic:
      type: bytes
      pattern: \d\d\d\d\d\d
      offset: 25