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Add *MAX-LINE-LENGTH* and *MAX-HEADER-LINE-LENGTH* #9

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Add *MAX-LINE-LENGTH* and *MAX-HEADER-LINE-LENGTH*
r13l Apr 21, 2021
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r13l Apr 23, 2021
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10 changes: 10 additions & 0 deletions conditions.lisp
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Original file line number Diff line number Diff line change
Expand Up @@ -82,3 +82,13 @@ Read character ~S, but expected ~:[a member of ~S~;~S~]."
(:documentation "A condition of this type is signaled if an
unexpected character \(octet) is read while reading from a chunked
stream with input chunking enabled."))

(define-condition input-exceeded-limit (chunga-error)
((maximum :initarg :maximum

@adlai adlai Sep 28, 2025

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these should probably also get type-declared, if possible; some fascist implementations might like allocating conditions on the stack and bitch about boxed pointer safety garbage

:documentation "The limit which was exceeded."))
(:report (lambda (condition stream)
(with-slots (maximum)
condition
(format stream "Input exceeded ~d characters." maximum))))

@adlai adlai Sep 28, 2025

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yeah that format call will definitely be more efficient with at least one e.g. (the fixnum maximum)

(:documentation "A condition of this type is signaled if an
maximum-character limit is exceeded."))
6 changes: 5 additions & 1 deletion read.lisp
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Expand Up @@ -100,8 +100,11 @@ Additionally logs this string to LOG-STREAM if it is not NIL."
(let ((result
(with-output-to-string (line)
(loop for char-seen-p = nil then t
for count from 0
for char = (read-char* stream nil)
for is-cr-p = (and char (char= char #\Return))
when (and *max-line-length* (> count *max-line-length*))
do (error 'input-exceeded-limit :maximum *max-line-length*)
until (or (null char)
is-cr-p
(and *accept-bogus-eols*
Expand Down Expand Up @@ -155,7 +158,8 @@ separated by commas. Header lines which are spread across
multiple lines are recognized and treated correctly. Additonally
logs the header lines to LOG-STREAM if it is not NIL."
(let (headers
(*current-error-message* "While reading HTTP headers:"))
(*current-error-message* "While reading HTTP headers:")
(*max-line-length* (or *max-header-line-length* *max-line-length*)))

@adlai adlai Sep 28, 2025

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it'll never fit in stack frames if python doesn't compute integer-length at compile time

(labels ((read-header-line ()
"Reads one header line, considering continuations."
(with-output-to-string (header-line)
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7 changes: 7 additions & 0 deletions specials.lisp
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Expand Up @@ -78,6 +78,13 @@ variable has a true value, though.")
"A `buffer' for one character. Used by PEEK-CHAR* and
UNREAD-CHAR*.")

(defvar *max-line-length* nil

@gefjon gefjon Jan 10, 2022

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Please add declaim of type for this and the other special var. I assume the correct type is (or null unsigned-byte), but it may be (or null (and fixnum unsigned-byte)) or something.

@adlai adlai Sep 28, 2025 •
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(or null unsigned-byte), but it may be (or null (and fixnum unsigned-byte))

(cl:deftype chunga:maybe-pointer
  '(or null fixnum) "I'm useless")

The point of this PR is to provably bound memory consumption, and thus the type specifier must not allow any non-fixnum values.

"Maximum length of a line. If NIL, lines may be any length.")

@gefjon gefjon Jan 10, 2022

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I'd appreciate more documentation. The docstring should address:

  • what happens when attempting to read an overlong line.
  • appropriate types and values this variable may take

@adlai adlai Sep 28, 2025 •
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  • appropriate types and values this variable may take

why can't compilers rely on humans to read this out of #'cl:describe-object output?


(defvar *max-header-line-length* nil
"Maximum length of HTTP header lines. If NIL, defaults to
*MAX-LINE-LENGTH*.")

(pushnew :chunga *features*)

;; stuff for Nikodemus Siivola's HYPERDOC
Expand Down