🐛 Raises meaningful exception when IPv6 URL is malformed #1512

MaelPic · 2025-05-22T18:23:08Z

What do these changes do?

For IPv6 URL, if brackets are set in reversed order (closing bracket before open bracket), the raised exception is now ValueError("Invalid IPv6 URL"), which is more convenient that the reported one (IndexError: string index out of range).

Are there changes in behavior for the user?

If url contains brackets in opposite order:
Previous behavior: exception IndexError is raised
New behavior: exception ValueError is raised

Related issue number

Fixes #1485

Checklist

I think the code is well written
Unit tests for the changes exist
Documentation reflects the changes

codspeed-hq · 2025-05-22T18:37:50Z

CodSpeed Performance Report

Merging #1512 will not alter performance

_{Comparing MaelPic:bugfix-ipv6-parsing (63ba8c5) with master (07d0ba3)}

Summary

✅ 101 untouched benchmarks

codecov · 2025-05-22T18:39:19Z

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.37%. Comparing base (07d0ba3) to head (63ba8c5).

❌ Your project check has failed because the head coverage (98.06%) is below the target coverage (100.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1512   +/-   ##
=======================================
  Coverage   99.37%   99.37%           
=======================================
  Files          30       30           
  Lines        6068     6079   +11     
  Branches      265      265           
=======================================
+ Hits         6030     6041   +11     
  Misses         35       35           
  Partials        3        3

Flag	Coverage Δ
CI-GHA	`99.37% <100.00%> (+<0.01%)`	⬆️
MyPy	`98.06% <100.00%> (+<0.01%)`	⬆️
OS-Linux	`99.44% <100.00%> (+<0.01%)`	⬆️
OS-Windows	`99.48% <100.00%> (+<0.01%)`	⬆️
OS-macOS	`99.33% <100.00%> (+<0.01%)`	⬆️
Py-3.10.11	`99.12% <100.00%> (+<0.01%)`	⬆️
Py-3.10.17	`99.35% <100.00%> (+<0.01%)`	⬆️
Py-3.11.12	`99.35% <100.00%> (+<0.01%)`	⬆️
Py-3.11.9	`99.12% <100.00%> (+<0.01%)`	⬆️
Py-3.12.10	`99.35% <100.00%> (+<0.01%)`	⬆️
Py-3.13.3	`99.12% <100.00%> (-0.23%)`	⬇️
Py-3.13.3t	`99.75% <100.00%> (+<0.01%)`	⬆️
Py-3.9.13	`99.08% <100.00%> (+<0.01%)`	⬆️
Py-3.9.22	`99.31% <100.00%> (+<0.01%)`	⬆️
Py-pypy7.3.16	`99.33% <100.00%> (+<0.01%)`	⬆️
Py-pypy7.3.19	`99.36% <100.00%> (+<0.01%)`	⬆️
VM-macos-latest	`99.33% <100.00%> (+<0.01%)`	⬆️
VM-ubuntu-latest	`99.44% <100.00%> (+<0.01%)`	⬆️
VM-windows-latest	`99.48% <100.00%> (+<0.01%)`	⬆️
pytest	`99.44% <100.00%> (+<0.01%)`	⬆️

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webknjaz · 2025-05-22T21:58:38Z

tests/test_url.py

-    with pytest.raises(ValueError, match="An IPv4 address cannot be in brackets"):
-        URL("http://[127.0.0.1]/")
+@pytest.mark.parametrize(
+    ("url"),


Suggested change

("url"),

"url",

webknjaz · 2025-05-22T22:01:24Z

note: we agreed with Mael that he'll add a change note later on, while traveling

webknjaz

@MaelPic thanks for your contribution during the PyCon US Sprints last week!

Would you me able to make the following cosmetic changes? Or do you need us to pick up the PR and complete it instead?

webknjaz · 2025-05-28T16:33:26Z

CHANGES/1512.bugfix.rst

+It fixes the issue where exception `IndexError` was raised in the
+following conditions: empty IPv6 URL, brackets in reverse order.
+
+-- by :user:` MaelPic`.


Suggested change

-- by :user:` MaelPic`.

-- by :user:`MaelPic`

webknjaz · 2025-05-28T16:33:49Z

CHANGES/1512.bugfix.rst

+It fixes the issue where exception `IndexError` was raised in the
+following conditions: empty IPv6 URL, brackets in reverse order.


Suggested change

It fixes the issue where exception `IndexError` was raised in the

following conditions: empty IPv6 URL, brackets in reverse order.

These fixes the issue where exception :exc:`IndexError` was

leaking from the internal code because of not being handled and

transformed into a user-facing error. The problem was happening

under the following conditions: empty IPv6 URL, brackets in

reverse order.

webknjaz · 2025-05-28T16:37:39Z

CHANGES/1512.bugfix.rst

+Aligned the type of exception raised for improper IPv6 URL values,
+which should be `ValueError`.


Suggested change

Aligned the type of exception raised for improper IPv6 URL values,

which should be `ValueError`.

Started raising a :exc:`ValueError` exception raised for corrupted

IPv6 URL values.

webknjaz · 2025-05-28T16:45:44Z

tests/test_url.py

+    "url",
+    [
+        "http://[]/",  # Empty IPv6 URL
+        "http://[1]/",  # No semicolon


(you probably meant “no colon” in there)

webknjaz · 2025-05-28T16:47:18Z

tests/test_url.py

+    [
+        "http://[]/",  # Empty IPv6 URL
+        "http://[1]/",  # No semicolon
+        "http://[127.0.0.1]/",  # IPv4 inside brackets
+        "http://]1dec:0:0:0::1[/",  # Brackets in reversed order
+    ],


Instead of having code comments, it's best to set explicit param ids. They will show up in the test report, and will make it easier to both reason about the testing semantics, plus can be used to select and run one of the test params with pytest:

Suggested change

[

"http://[]/", # Empty IPv6 URL

"http://[1]/", # No semicolon

"http://[127.0.0.1]/", # IPv4 inside brackets

"http://]1dec:0:0:0::1[/", # Brackets in reversed order

],

(

"http://[]/",

"http://[1]/",

"http://[127.0.0.1]/",

"http://]1dec:0:0:0::1[/",

),

ids=(

"empty-IPv6-like-URL",

"no-colons-in-IPv6",

"IPv4-inside-brackets",

"brackets-in-reversed-order",

),

I agree, it is better

bdraco · 2025-05-28T16:51:04Z

yarl/_parse.py

@@ -69,11 +69,11 @@ def split_url(url: str) -> SplitURLType:
            # Valid bracketed hosts are defined in
            # https://www.rfc-editor.org/rfc/rfc3986#page-49
            # https://url.spec.whatwg.org/
-            if bracketed_host[0] == "v":
+            if bracketed_host.startswith("v"):


Suggested change

if bracketed_host.startswith("v"):

if bracketed_host and bracketed_host[0] == "v":

This is faster since there is no function call

…ersed Problem: If brackets are reversed or content inside brackets is empty, `bracketed_host` will be an empty string. In consequence, reaching the first element of `bracketed_host` returns an `IndexError`. Solution: Use `startswith` because it does not raise anything if the string is empty and then it fallbacks into the following check verifying the presence of `:`. Also, the raised message was made more generic but still keeps its meaning.

webknjaz added the bug label May 22, 2025

MaelPic force-pushed the bugfix-ipv6-parsing branch from e3af387 to 5001d56 Compare May 22, 2025 21:49

MaelPic changed the title ~~🐛 more meaningful exception if reversed brackets in ipv6 URL~~ 🐛 Raises meaningful exception when IPv6 URL is malformed May 22, 2025

webknjaz reviewed May 22, 2025

View reviewed changes

MaelPic force-pushed the bugfix-ipv6-parsing branch from 5001d56 to f89d97b Compare May 23, 2025 00:47

psf-chronographer bot added the bot:chronographer:provided There is a change note present in this PR label May 23, 2025

webknjaz reviewed May 28, 2025

View reviewed changes

webknjaz requested review from bdraco and Dreamsorcerer May 28, 2025 16:49

bdraco reviewed May 28, 2025

View reviewed changes

webknjaz mentioned this pull request May 28, 2025

Unhandled exception (IndexError) in URL parsing #1485

Open

5 tasks

Dreamsorcerer approved these changes May 28, 2025

View reviewed changes

MaelPic force-pushed the bugfix-ipv6-parsing branch from f89d97b to 63ba8c5 Compare May 29, 2025 14:52

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		It fixes the issue where exception `IndexError` was raised in the
		following conditions: empty IPv6 URL, brackets in reverse order.

-It fixes the issue where exception `IndexError` was raised in the
-following conditions: empty IPv6 URL, brackets in reverse order.
+These fixes the issue where exception :exc:`IndexError` was
+leaking from the internal code because of not being handled and
+transformed into a user-facing error. The problem was happening
+under the following conditions: empty IPv6 URL, brackets in
+reverse order.

		Aligned the type of exception raised for improper IPv6 URL values,
		which should be `ValueError`.

	if bracketed_host.startswith("v"):
	if bracketed_host and bracketed_host[0] == "v":

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🐛 Raises meaningful exception when IPv6 URL is malformed #1512

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🐛 Raises meaningful exception when IPv6 URL is malformed #1512

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What do these changes do?

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Related issue number

Checklist

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codspeed-hq bot commented May 22, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Merging #1512 will not alter performance

Summary

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MaelPic commented May 22, 2025 •

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