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Improve string escaping and add tests#2396

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mromaszewicz merged 1 commit into
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fix/string-escaping
Jun 5, 2026
Merged

Improve string escaping and add tests#2396
mromaszewicz merged 1 commit into
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fix/string-escaping

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@mromaszewicz

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Tighten how server URL values are emitted in the server-urls template so that spec-supplied text is always serialized into a proper Go context:

  • Route server descriptions and URLs through stripNewLines when they are written into generated // comments, so a multi-line value stays on the comment line instead of spilling into following lines.
  • Emit server URL and variable-default values via toGoString (now backed by strconv.Quote) instead of hand-wrapping them in quotes, so quotes, backslashes, and newlines are escaped correctly.
  • Harden StringToGoString to use strconv.Quote; the previous version only escaped double quotes and mishandled backslashes. This also tidies up the content-type literals that already used it.
  • Extend stripNewLines to drop carriage returns as well as newlines.

Add regression tests covering the server-urls rendering and the StringToGoString escaping, and confirm make generate produces no changes to committed output.

Tighten how server URL values are emitted in the server-urls template so
that spec-supplied text is always serialized into a proper Go context:

- Route server descriptions and URLs through stripNewLines when they are
  written into generated // comments, so a multi-line value stays on the
  comment line instead of spilling into following lines.
- Emit server URL and variable-default values via toGoString (now backed
  by strconv.Quote) instead of hand-wrapping them in quotes, so quotes,
  backslashes, and newlines are escaped correctly.
- Harden StringToGoString to use strconv.Quote; the previous version only
  escaped double quotes and mishandled backslashes. This also tidies up
  the content-type literals that already used it.
- Extend stripNewLines to drop carriage returns as well as newlines.

Add regression tests covering the server-urls rendering and the
StringToGoString escaping, and confirm `make generate` produces no
changes to committed output.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
@mromaszewicz mromaszewicz requested a review from a team as a code owner June 5, 2026 03:42
@mromaszewicz mromaszewicz added the bug Something isn't working label Jun 5, 2026
@greptile-apps

greptile-apps Bot commented Jun 5, 2026

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Greptile Summary

This PR hardens generated server URL output against malformed Go source. It changes:

  • Server URL comments now strip newline and carriage-return characters.
  • Server URL constants, constructor literals, and non-enum defaults now use Go string quoting.
  • StringToGoString now delegates escaping to strconv.Quote.
  • Regression tests cover server URL injection and string escaping cases.

Confidence Score: 3/5

This should be fixed before merging.

  • The updated escaping covers server URLs and non-enum defaults.
  • Enum server variable values still reach generated string constants without the new quoting.
  • Placeholder names still flow into generated Go source without validation or context-aware escaping.

pkg/codegen/templates/server-urls.tmpl and the enum constant generation path for server URL variables.

Security Review

  • Generated-source injection in server-urls.tmpl: enum-typed server variable values still bypass strconv.Quote through the enum constants path.
  • Generated-source injection in server-urls.tmpl: server URL placeholder names are still emitted raw into Go comments, identifiers, and string literals.

Important Files Changed

Filename Overview
pkg/codegen/templates/server-urls.tmpl Updates server URL generation to quote URL/default literals and flatten comment text, but leaves adjacent spec-controlled server variable surfaces unescaped.
pkg/codegen/utils.go Switches generic Go string literal generation to strconv.Quote.
pkg/codegen/template_helpers.go Extends newline stripping for generated line comments to include carriage returns.

Comments Outside Diff (1)

  1. pkg/codegen/templates/server-urls.tmpl, line 71-75 (link)

    P1 security Sanitize placeholder names Server URL placeholder names are still inserted raw into generated comments, parameter identifiers, and replacement string literals. urlPlaceholders accepts any text except /, {, and }, so a spec can use a matching variable name containing quotes or newlines and make this template generate invalid Go or break out of the string/comment contexts that this PR is trying to harden. The placeholder name needs the same context-aware escaping or validation as the URL and default values.

Reviews (2): Last reviewed commit: "Improve string escaping and add tests" | Re-trigger Greptile

@mromaszewicz

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@greptileai - I believe you are mistaken in your finding. I am concerned about injected Go code that compiles. The finding you have outside of the scope of this PR is not actually compilable. Any injection I've tried produces corrupt Go, and a non-compiling file, which isn't exploitable. I will leave it as-is.

@greptile-apps

greptile-apps Bot commented Jun 5, 2026

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That's a fair point, and you're right to draw that distinction. Looking at constants.tmpl, the enum values land inside a const (...) block as:

const Foo MyType = "{{$value}}"

For any injection to be compilable, an attacker would need to not only close the string but also emit valid Go in a const context — which doesn't allow function calls or statements. Any attempt to do so (e.g. embedding " to close the literal, then appending arbitrary text) produces a syntax error rather than executable code.

That's a meaningful distinction. A code-generation tool producing a corrupt, non-compiling file is a user-experience problem; producing a compiling file with injected behavior would be a security problem. Since you've verified the former is what actually happens here, I withdraw the concern. Sorry for the noise.

Comment thread pkg/codegen/templates/server-urls.tmpl
@mromaszewicz mromaszewicz merged commit a63186f into main Jun 5, 2026
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@mromaszewicz mromaszewicz deleted the fix/string-escaping branch June 5, 2026 14:21
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