main.py

#!/usr/bin/env python3

import logging
import sys

log = logging.getLogger(__name__)

CONTENT = b'Content-Disposition: form-data; name='
OCTET_STREAM = b'Content-Type: application/octet-stream'
MULTIPART_FORM = 'multipart/form-data'
CRLF = b'\n'
alt_name = dict(normal='url', hiRes='urlHiRes')

# Legacy delimiter for separating the multipart
LEGACY_BOUNDARY = b'--*****2019.04.10.CONRAD*****'


class DecodingError(Exception):
    pass


def extract_content_type_boundary(content_type):
    content_type, semicolon, params = content_type.partition(';')
    if content_type.strip().lower() == 'multipart/form-data':
        for param in params.split(';'):
            name, equal_sign, value = param.strip().partition('=')
            if not equal_sign or name.strip().lower() != 'boundary':
                continue
            stripped = value.strip().strip('"')
            if not stripped:
                raise DecodingError(
                    reason={'debug': {'error': 'Boundary error'}}
                )
            return f'--{stripped}'.encode('ascii')
    # LEGACY! Previously content_type was never passed by acr_client
    # in that case content_type was auto-filled as `application/octet-stream`
    # or other.
    return LEGACY_BOUNDARY


def decode_multipart_form_data(body, content_type):
    fields = {}
    files = {}
    try:
        boundary = extract_content_type_boundary(content_type)
        print("boundary", boundary)
        print("body", body)
        for disp in body.split(boundary)[1:-1]:
            print("disp", disp)
            key, value = disp.split(CONTENT + b'"', 1)[1].split(b'"', 1)
            print("value", value)
            key = key.decode('ascii')
            if OCTET_STREAM in value:
                files[key] = value.split(OCTET_STREAM, 1)[1].split(CRLF)[2]
            else:
                fields[key] = value.split(CRLF)[2].decode('ascii')
        return fields, files
    except IndexError:
        log.info('decode_multipart_form_data error')
        raise DecodingError()


# Read body from stdin.
raw = sys.stdin.read().encode('utf-8')
content_type = "multipart/form-data; boundary=*****2016.05.27.acrcloud.rec.copyright.1712659928.682365*****"
boundary = extract_content_type_boundary(content_type)
print(boundary)
result = decode_multipart_form_data(raw, content_type)
print(result)