Expected Behavior

When using cloudevents.http.from_http(headers, body), an event that is missing any of the required fields should result in a cloud_exceptions.MissingRequiredFields exception with a message that indicates which field is missing.

Actual Behavior

When given a Binary Cloud Event that is missing a required field ce-id, ce-source, or ce-type, it will return a MissingRequiredFields error with the incorrect error message Failed to find specversion in HTTP request.

Steps to Reproduce the Problem

from cloudevents.http import from_http
from cloudevents.exceptions import MissingRequiredFields

# Correctly does not result in an error if all required fields are present
def test_from_http():
    event = from_http({"ce-specversion": "1.0", "ce-id":"123", "ce-type": "test-type", "ce-source": "test-source"}, "{}")
    assert event["id"] == "123"

# Returns an incorrect error message
def test_from_http_missing_id_binary():
    try:
        event = from_http({"ce-specversion": "1.0", "ce-type": "test-type", "ce-source": "test-source"}, "{}")
        assert 1 == 2
    except MissingRequiredFields as e:
        assert "Failed to find specversion in HTTP request" == str(e)

# Returns the appropriate message
def test_from_http_missing_id_structured():
    try:
        event = from_http({}, "{\"specversion\": \"1.0\", \"type\": \"test-type\", \"source\": \"test-source\"}")
        assert 1 == 2
    except MissingRequiredFields as e:
        assert "Missing required attributes: {'id'}" == str(e)

The code flow is as follows:

1. it checks is_binary(headers)

   sdk-python/cloudevents/http/http_methods.py

   Line 46 in b83bfc5

   if is_binary(headers):

2. It calls binary_parser.can_read

   sdk-python/cloudevents/http/event_type.py

   Lines 6 to 16 in b83bfc5

   	def is_binary(headers: typing.Dict[str, str]) -> bool:
   	"""Uses internal marshallers to determine whether this event is binary
   	:param headers: the HTTP headers
   	:type headers: typing.Dict[str, str]
   	:returns bool: returns a bool indicating whether the headers indicate
   	a binary event type
   	"""
   	headers = {key.lower(): value for key, value in headers.items()}
   	content_type = headers.get("content-type", "")
   	binary_parser = binary.BinaryHTTPCloudEventConverter()
   	return binary_parser.can_read(content_type=content_type, headers=headers)

3. it calls has_binary_headers

   sdk-python/cloudevents/sdk/converters/binary.py

   Lines 29 to 35 in b83bfc5

   	def can_read(
   	self,
   	content_type: str = None,
   	headers: typing.Dict[str, str] = {"ce-specversion": None},
   	) -> bool:
   	return has_binary_headers(headers)

4. has_binary_headers checks for the presence of all required fields, which in this test case is false because it is missing ce-id

   sdk-python/cloudevents/sdk/converters/util.py

   Lines 4 to 10 in b83bfc5

   	def has_binary_headers(headers: typing.Dict[str, str]) -> bool:
   	return (
   	"ce-specversion" in headers
   	and "ce-source" in headers
   	and "ce-type" in headers
   	and "ce-id" in headers
   	)

5. it then falls through and tries to get the specversion here

   sdk-python/cloudevents/http/http_methods.py

   Line 57 in b83bfc5

   specversion = raw_ce.get("specversion", None)

6. specversion is never set and the error gets thrown here

   sdk-python/cloudevents/http/http_methods.py

   Lines 64 to 67 in b83bfc5

   	if specversion is None:
   	raise cloud_exceptions.MissingRequiredFields(
   	"Failed to find specversion in HTTP request"
   	)

I think that the solution might be as simple as changing all of the ands to ors in the has_binary_headers method in step 4.

Specifications

• Platform: Mac OS
• Python Version: 3.9.4