fix(litellm): fix gen_ai.request.messages to be as expected

[constantinius]

Issues

Closes https://linear.app/getsentry/issue/TET-1635/redact-images-litellm

[linear]

TET-1635 Redact images: LiteLLM

[cursor]

Bug: Incorrect mime_type includes data: prefix

The mime_type extraction is incorrect. Using split(";base64,")[0] on a URL like "data:image/jpeg;base64,..." returns "data:image/jpeg" instead of "image/jpeg" as documented in the function's docstring. The "data:" prefix needs to be removed to get the proper MIME type.

 

[cursor]

Bug: Function mutates original kwargs messages corrupting API request

The _convert_message_parts function modifies message dictionaries in-place rather than creating copies. Since messages comes directly from kwargs.get("messages", []), this mutates the original request data that LiteLLM will use for the actual API call to the LLM provider, potentially corrupting the request. A deep copy of the messages should be made before modification.

 

[cursor]

Bug: IndexError when data URL lacks base64 encoding marker

The code assumes all data URLs contain ";base64," after checking only that they start with "data:". Data URLs can omit base64 encoding (e.g., "data:image/jpeg,rawdata"). In such cases, split(";base64,") returns a single-element list, and accessing [1] will raise an IndexError.

 

[cursor]

Bug: Else branch crashes when image_url is None or incomplete

The code on line 78 safely retrieves image_url = item.get("image_url") or {} to handle missing or None values, but the else branch on line 89 directly accesses item["image_url"]["url"] instead of using the safe image_url variable. When item["image_url"] is None, empty, or lacks a "url" key, the safe check on line 79 evaluates to False, routing to this else branch which then crashes with TypeError or KeyError.

 

[sentry]

Bug: The data URI parsing in _convert_message_parts is unsafe. It can cause an IndexError with malformed URIs and incorrectly extracts the mime_type with the "data:" prefix.
_{Severity: HIGH | Confidence: High}

🔍 Detailed Analysis

In the _convert_message_parts function, a data URI from item["image_url"]["url"] is parsed by splitting on ";base64,". This implementation has two flaws. First, if the URI is malformed and does not contain ";base64,", accessing the second element of the split result will raise an IndexError, crashing the callback as it is not wrapped in a try-except block. Second, the first element of the split is assigned to mime_type, which incorrectly includes the "data:" prefix (e.g., "data:image/png" instead of "image/png"), contradicting docstrings and other tests in the codebase.

💡 Suggested Fix

Implement robust parsing for the data URI. First, validate that the url string contains ";base64,". If not, handle the error gracefully. If it is valid, extract the MIME type by taking the part before ";base64," and removing the "data:" prefix. Consider using a regular expression for more reliable parsing.

🤖 Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: sentry_sdk/integrations/litellm.py#L84-L85

Potential issue: In the `_convert_message_parts` function, a data URI from
`item["image_url"]["url"]` is parsed by splitting on ";base64,". This implementation has
two flaws. First, if the URI is malformed and does not contain ";base64,", accessing the
second element of the split result will raise an `IndexError`, crashing the callback as
it is not wrapped in a `try-except` block. Second, the first element of the split is
assigned to `mime_type`, which incorrectly includes the "data:" prefix (e.g.,
"data:image/png" instead of "image/png"), contradicting docstrings and other tests in
the codebase.

_{Did we get this right? 👍 / 👎 to inform future reviews.
Reference ID: 7657057}

[cursor]

Bug: Unsafe direct access bypasses null-safe variable check

Line 78 creates a null-safe image_url variable using item.get("image_url") or {}, but lines 83, 84, and 89 bypass this by directly accessing item["image_url"]["url"]. If item["image_url"] is None, missing, or an empty dict, the code enters the else branch (since empty string doesn't start with data:), and line 89 crashes with TypeError or KeyError. The code should use the safe image_url variable instead of re-accessing item["image_url"].

Additional Locations (1)

• sentry_sdk/integrations/litellm.py#L82-L84