requestbody: Type-based error handling for MaxBytesError

[rishitashaw]

Replaced the hardcoded error string comparison with a type assertion for http.MaxBytesError to make the code more robust and idiomatic.

Before:

if err != nil && err.Error() == "http: request body too large" {
    err = caddyhttp.Error(http.StatusRequestEntityTooLarge, err)
}

After:

if err != nil {
    if _, ok := err.(*http.MaxBytesError); ok {
        err = caddyhttp.Error(http.StatusRequestEntityTooLarge, err)
    }
}

Related to #6700

[CLAassistant]

All committers have signed the CLA.

[mholt]

Thank you! This is pretty good, but there's a lint failure. I have a suggestion that I think could work but I just did it here in the textbox, so if you want to verify locally that it compiles then I think we'll be all set. :)

[mholt]

Suggested change

	if err != nil {
	if _, ok := err.(*http.MaxBytesError); ok {
	var mbe *http.MaxBytesError
	if errors.As(err, &mbe) {

[rishitashaw]

I'm sorry I didn’t see your comment earlier. I’ve made different changes. Specifically, I removed the redundant nil check and used the type assertion directly for *HTTP.MaxBytesError since the type assertion already guarantees that the error isn’t nil when ok is true.

That said, I really like this project and would love to be more involved. Would it be possible to connect on Slack? I’m eager to contribute more!

[mholt]

Thanks. I still think errors.As() is recommended since the error value can be wrapped, thus failing a type assertion.

And yes! I'm running out the door but when I get back I'll send a Slack invite.

[francislavoie]

I was thinking we'd use https://pkg.go.dev/errors#example-Is errors.Is(err, http.MaxBytesError), then the if wouldn't need to be nested, it could just remain a one-liner condition.

[mholt]

@francislavoie It's a type, not a value.

[francislavoie]

Oh right, they implemented MaxBytesError as a struct type, not as a var error. Gah.

[mholt]

LGTM. Thanks! @rishitashaw What is a good email address for me to invite?

[rishitashaw]

Thanks @mholt
Please send the invite to [email protected]