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92 lines
3.5 KiB
Python
92 lines
3.5 KiB
Python
import json
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from hashlib import sha1
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from django.conf import settings
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from django.db import transaction
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from django.http import HttpRequest, HttpResponse, JsonResponse
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from django.utils.timezone import now
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from rest_framework import status
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from pretix.api.models import ApiCall
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class IdempotencyMiddleware:
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def __init__(self, get_response):
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self.get_response = get_response
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def __call__(self, request: HttpRequest):
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if request.method in ('GET', 'HEAD', 'OPTIONS'):
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return self.get_response(request)
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if not request.path.startswith('/api/'):
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return self.get_response(request)
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if not request.META.get('HTTP_X_IDEMPOTENCY_KEY'):
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return self.get_response(request)
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auth_hash_parts = '{}:{}'.format(
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request.META.get('HTTP_AUTHORIZATION', ''),
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request.COOKIES.get(settings.SESSION_COOKIE_NAME, '')
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)
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auth_hash = sha1(auth_hash_parts.encode()).hexdigest()
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idempotency_key = request.META.get('HTTP_X_IDEMPOTENCY_KEY', '')
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with transaction.atomic():
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call, created = ApiCall.objects.select_for_update().get_or_create(
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auth_hash=auth_hash,
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idempotency_key=idempotency_key,
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defaults={
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'locked': now(),
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'request_method': request.method,
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'request_path': request.path,
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'response_code': 0,
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'response_headers': '{}',
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'response_body': b''
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}
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)
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if created:
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resp = self.get_response(request)
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with transaction.atomic():
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if resp.status_code in (409, 429, 503):
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# This is the exception: These calls are *meant* to be retried!
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call.delete()
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else:
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call.response_code = resp.status_code
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if isinstance(resp.content, str):
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call.response_body = resp.content.encode()
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elif isinstance(resp.content, memoryview):
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call.response_body = resp.content.tobytes()
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elif isinstance(resp.content, bytes):
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call.response_body = resp.content
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elif hasattr(resp.content, 'read'):
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call.response_body = resp.read()
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elif hasattr(resp, 'data'):
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call.response_body = json.dumps(resp.data)
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else:
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call.response_body = repr(resp).encode()
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call.response_headers = json.dumps(resp._headers)
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call.locked = None
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call.save(update_fields=['locked', 'response_code', 'response_headers',
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'response_body'])
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return resp
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else:
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if call.locked:
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r = JsonResponse(
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{'detail': 'Concurrent request with idempotency key.'},
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status=status.HTTP_409_CONFLICT,
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)
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r['Retry-After'] = 5
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return r
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content = call.response_body
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if isinstance(content, memoryview):
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content = content.tobytes()
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r = HttpResponse(
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content=content,
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status=call.response_code,
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)
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for k, v in json.loads(call.response_headers).values():
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r[k] = v
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return r
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