Allow configuring query string max length

[elct9620]

Description

Please describe your pull request. Thank you for contributing! You're the best.

According to #2273 discussion, I add an optional cflags to configure query string max length when we compile puma.

This change is reference @maleksiuk version (maleksiuk@1c56e5f) to keep source code clean, but I didn't put the environment variable detect part which I think isn't necessary when we have --cflags options.

Your checklist for this pull request

• I have reviewed the guidelines for contributing to this repository.
• I have added an entry to History.md if this PR fixes a bug or adds a feature. If it doesn't need an entry to HISTORY.md, I have added [changelog skip] or [ci skip] to the pull request title.
• I have added appropriate tests if this PR fixes a bug or adds a feature.
• My pull request is 100 lines added/removed or less so that it can be easily reviewed.
• If this PR doesn't need tests (docs change), I added [ci skip] to the title of the PR.
• If this closes any issues, I have added "Closes #issue" to the PR description or my commit messages.
• I have updated the documentation accordingly.
• All new and existing tests passed, including Rubocop.

[maleksiuk]

One problem with this, which my commit had too, is that the error message in the exception that gets raised has changed from

HTTP element QUERY_STRING is longer than the 1024*10 allowed length (was 900000)

to

HTTP element QUERY_STRING is longer than the PUMA_QUERY_STRING_MAX_LENGTH allowed length (was 900000)

That might be reasonable when the user has specified PUMA_QUERY_STRING_MAX_LENGTH but is confusing and unhelpful when they haven't.

[elct9620]

How about this

/** Defines common length and error messages for input length validation. */
#define QUOTE(s) #s
#define EXPLAND_MAX_LENGHT_VALUE(s) QUOTE(s)
#define DEF_MAX_LENGTH(N,length) const size_t MAX_##N##_LENGTH = length; const char *MAX_##N##_LENGTH_ERR = "HTTP element " # N  " is longer than the " EXPLAND_MAX_LENGHT_VALUE(length) " allowed length (was %d)"

Validated with gcc -E ext/puma_http11/puma_http11.c will generated

# 59 "ext/puma_http11/puma_http11.c"
const size_t MAX_FIELD_NAME_LENGTH = 256; const char *MAX_FIELD_NAME_LENGTH_ERR = "HTTP element " "FIELD_NAME" " is longer than the " "256" " allowed length (was %d)";
const size_t MAX_FIELD_VALUE_LENGTH = 80 * 1024; const char *MAX_FIELD_VALUE_LENGTH_ERR = "HTTP element " "FIELD_VALUE" " is longer than the " "80 * 1024" " allowed length (was %d)";
const size_t MAX_REQUEST_URI_LENGTH = 1024 * 12; const char *MAX_REQUEST_URI_LENGTH_ERR = "HTTP element " "REQUEST_URI" " is longer than the " "1024 * 12" " allowed length (was %d)";
const size_t MAX_FRAGMENT_LENGTH = 1024; const char *MAX_FRAGMENT_LENGTH_ERR = "HTTP element " "FRAGMENT" " is longer than the " "1024" " allowed length (was %d)";
const size_t MAX_REQUEST_PATH_LENGTH = 8192; const char *MAX_REQUEST_PATH_LENGTH_ERR = "HTTP element " "REQUEST_PATH" " is longer than the " "8192" " allowed length (was %d)";
const size_t MAX_QUERY_STRING_LENGTH = (1024 * 10); const char *MAX_QUERY_STRING_LENGTH_ERR = "HTTP element " "QUERY_STRING" " is longer than the " "(1024 * 10)" " allowed length (was %d)";
const size_t MAX_HEADER_LENGTH = (1024 * (80 + 32)); const char *MAX_HEADER_LENGTH_ERR = "HTTP element " "HEADER" " is longer than the " "(1024 * (80 + 32))" " allowed length (was %d)";

But I think the QUOTE and EXPLAN_MAX_LENGTH_VALUE isn't a good naming in this case.

[nateberkopec]

@elct9620 That's OK with me

[elct9620]

@nateberkopec I have updated the code to expand the common length variable in the error message. If there is no other issue to fix, I will update the document for it.

[nateberkopec]

@elct9620 Looks good to me. Please update docs and changelog and we'll merge 👍

[nateberkopec]

🎉