Add DICOM (Digital Imaging and Communications in Medicine) protocol support

[tmart234]

Summary

DICOM communications is used in medical imaging systems. This PR adds Scapy layers for the DICOM Upper Layer Protocol (DICOM PS3.8).

Features

• Full PDU support: A-ASSOCIATE-RQ/AC/RJ, P-DATA-TF, A-RELEASE-RQ/RP, A-ABORT
• Variable item negotiation: Application Context, Presentation Context, User Information, User Identity, Async Operations, Role Selection
• DIMSE command packets: C-ECHO, C-STORE, C-FIND, C-MOVE, C-GET

Usage

from scapy.contrib.dicom import *

# Build an A-ASSOCIATE-RQ
pkt = DICOM() / A_ASSOCIATE_RQ(
    called_ae_title=_pad_ae_title("SERVER"),
    calling_ae_title=_pad_ae_title("CLIENT"),
    variable_items=[
        DICOMVariableItem() / DICOMApplicationContext(),
        build_presentation_context_rq(1, VERIFICATION_SOP_CLASS_UID, [DEFAULT_TRANSFER_SYNTAX_UID]),
        build_user_information(max_pdu_length=16384),
    ]
)

# Build a C-MOVE-RQ
move_rq = C_MOVE_RQ(message_id=1, move_destination=b"DEST_AE")

Testing

• 59 unit tests in test/contrib/dicom.uts
• All tests pass on Python 3.9+

References

• DICOM PS3.8: https://dicom.nema.org/medical/dicom/current/output/html/part08.html

[codecov]

Codecov Report

❌ Patch coverage is 52.64664% with 331 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.63%. Comparing base (a5bc2bb) to head (29d2131).

Files with missing lines	Patch %	Lines
scapy/contrib/dicom.py	52.64%	331 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4891      +/-   ##
==========================================
- Coverage   80.84%   80.63%   -0.22%     
==========================================
  Files         369      370       +1     
  Lines       90963    91662     +699     
==========================================
+ Hits        73539    73908     +369     
- Misses      17424    17754     +330     

Files with missing lines	Coverage Δ
scapy/contrib/dicom.py	52.64% <52.64%> (ø)

... and 8 files with indirect coverage changes

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[polydroi]

Thanks for the PR. I’ve stared the unit tests. Looks good, however, could you please add type hints to your layer?

[tmart234]

Thanks for the PR. I’ve stared the unit tests. Looks good, however, could you please add type hints to your layer?

Added

[polybassa]

Besides the small Flake8 issues, LGTM.

@gpotter2 do you want to have a final look?

[tmart234]

@polybassa fixed the Flake8 issues