Add message_id parameter (#63)

* Add message_id parameter

* Validate length of message id when user provided

* Formatting

AUTHORS.md

@@ -1,4 +1,5 @@
-* Abhishek Ram <[email protected]> @abhishek-ram
-* Chad Gates @chadgates
-* Bruno Ribeiro da Silva <[email protected]> @loop0 
-* Robin C Samuel @robincsamuel
+- Abhishek Ram <[email protected]> @abhishek-ram
+- Chad Gates @chadgates
+- Bruno Ribeiro da Silva <[email protected]> @loop0
+- Robin C Samuel @robincsamuel
+- Brandon Joyce @brandonjoyce

pyas2lib/as2.py

@@ -330,6 +330,7 @@ def build(
         content_type="application/edi-consent",
         additional_headers=None,
         disposition_notification_to="[email protected]",
+        message_id=None,
     ):
 
         """Function builds the AS2 message. Compresses, signs and encrypts
@@ -354,6 +355,10 @@ def build(
         :param disposition_notification_to:
             Email address for disposition-notification-to header entry.
             (default "[email protected]")
+
+        :param message_id:
+            A value to be used for the left side of the message id. If not provided a
+              unique id is generated. (default None)
         """
 
         # Validations
@@ -372,10 +377,22 @@ def build(
                 "Encryption of messages is enabled but encrypt key is not set for the receiver."
             )
 
-        # Generate message id using UUID 1 as it uses both hostname and time
-        self.message_id = (
-            email_utils.make_msgid(domain=self.sender.domain).lstrip("<").rstrip(">")
-        )
+        if message_id:
+            self.message_id = f"{message_id}@{self.sender.domain}"
+        else:
+            self.message_id = (
+                email_utils.make_msgid(domain=self.sender.domain)
+                .lstrip("<")
+                .rstrip(">")
+            )
+
+        # ensure the total length of the message id is no more than 255 characters
+        if len(self.message_id) > 255:
+            raise ValueError(
+                "Message ID must be no more than 255 characters for "
+                "compatibility with some AS2 servers. "
+                f"Current message ID length is {len(self.message_id)}."
+            )
 
         # Set up the message headers
         as2_headers = {

pyas2lib/tests/test_basic.py

@@ -1,4 +1,5 @@
 """Module for testing the basic features of pyas2."""
+import pytest
 import socket
 from pyas2lib import as2
 from . import Pyas2TestCase
@@ -200,6 +201,29 @@ def test_plain_message_without_domain(self):
         out_message.build(self.test_data)
         self.assertEqual(out_message.message_id.split("@")[1], socket.getfqdn())
 
+    def test_plain_message_with_custom_message_id(self):
+        """Test Message building with a custom message id"""
+
+        # Build an As2 message to be transmitted to partner
+        self.org.domain = "example.com"
+        out_message = as2.Message(self.org, self.partner)
+        out_message.build(self.test_data, message_id="some_custom_id")
+        self.assertEqual(out_message.message_id, "[email protected]")
+
+    def test_invalid_message_id_length_raises_error(self):
+        """Test Message building with a custom message id that's invalid"""
+
+        # Build an As2 message to be transmitted to partner
+        self.org.domain = "example.com"
+        out_message = as2.Message(self.org, self.partner)
+        very_long_message_id = "a" * 1000
+        with pytest.raises(ValueError) as excinfo:
+            out_message.build(self.test_data, message_id=very_long_message_id)
+        assert (
+            "Message ID must be no more than 255 characters for compatibility"
+            in str(excinfo.value)
+        )
+
     def find_org(self, as2_id):
         return self.org