Error thrown when escaping front slashes in regex patterns that have already been escaped

[Nick Taylor]

Describe the bug

There is logic in the edge bundler that escapes front slashes for regexes, but doesn’t take into account if they are already escaped.

See

edge-bundler/node/declaration.ts

Line 134 in 9d798de

 const normalizedPattern = pattern.replace(/\//g, '\\/') 

So basically

edge-bundler/node/manifest.ts

Lines 183 to 197 in 9d798de

     try { 
       return parsePattern(declaration.pattern) 
     } catch (error: unknown) { 
       // eslint-disable-next-line max-depth 
       if (failUnsupportedRegex) { 
         throw new Error( 
           `Could not parse path declaration of function '${declaration.function}': ${(error as Error).message}`, 
         ) 
       } 
  
       console.warn( 
         `Function '${declaration.function}' uses an unsupported regular expression and will not be invoked: ${ 
           (error as Error).message 
         }`, 
       ) 

runs and parsePattern converts

"^(?:\\/(_next\\/data\\/[^/]{1,}))?(?:\\/([^/.]{1,}))\\/api(?:\\/((?:[^\\/#\\?]+?)(?:\\/(?:[^\\/#\\?]+?))*))?(.json)?[\\/#\\?]?$"

to

"^(?:\\\\/(_next\\\\/data\\\\/[^\\/]{1,}))?(?:\\\\/([^\\/.]{1,}))\\\\/api(?:\\\\/((?:[^\\\\/#\\?]+?)(?:\\\\/(?:[^\\\\/#\\?]+?))*))?(.json)?[\\\\/#\\?]?$"

which results in the following error

Unexpected token: "/" at 1:7.
◈ Rewrote URL to /static/chunks/pages/shows/static/[id]-52e80ca069ee1610.js
Function 'next_middleware' uses an unsupported regular expression and will not be invoked: 

/^(?:\\/(_next\\/data\\/[^\/]{1,}))?(?:\\/([^\/.]{1,}))?\\/api(?:\\/((?:[^\\/#\?]+?)(?:\\/(?:[^\\/#\?]+?))*))?(.json)?[\\/#\?]?$/ 

because there is an extra escaped backslash added.

In our scenario on the frameworks team, the failing regular expressions are typicially generated from the Next.js framework.

The first question I have is do we need to normalize these regex patterns at the edge bundler level?

const normalizedPattern = pattern.replace(/\//g, '\\/')

In user and framework land, if they weren't escaped properly, I would expect it to fail if I did not escape things properly. Is there a use case on the edge functions team for this? I would assume so given the code was added. 😎

For more context see https://netlify.slack.com/archives/C01TKAEBP3Q/p1682545091365449

Configuration

Please enter the following command in a terminal and copy/paste its output:

npx envinfo --system --binaries

System:
OS: macOS 13.3.1
CPU: (10) arm64 Apple M1 Pro
Memory: 139.58 MB / 32.00 GB
Shell: 5.9 - /bin/zsh
Binaries:
Node: 18.15.0 - ~/.n/bin/node
Yarn: 1.22.19 - ~/.n/bin/yarn
npm: 9.5.0 - ~/.n/bin/npm

Pull requests

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contributions guidelines.

[Rob Stanford]

Hey @nickytonline, this appears to be done - do you mind confirming and closing if so? Thanks!

[Nick Taylor]

Work on this is complete.