Classify header parse errors as bad requests.

Assisted-By: devx/71d171da-b98c-42c2-922b-36328d89d0d6

Author: samuel-williams-shopify

lib/protocol/http/error.rb

@@ -22,15 +22,17 @@ class RemoteError < Error
 		# @deprecated Use {RefusedError} instead.
 		RequestRefusedError = RefusedError
 
-		# Represents a bad request error (as opposed to a server error).
-		# This is used to indicate that the request was malformed or invalid.
+		# Marks errors which may indicate a malformed or invalid request when raised while processing an incoming request.
 		module BadRequest
 		end
 
-		# Raised when a singleton (e.g. `content-length`) header is duplicated in a request or response.
-		class DuplicateHeaderError < Error
+		# Raised when an HTTP header is malformed or invalid. When raised while processing an incoming request, it may be treated as a bad request.
+		class InvalidHeaderError < Error
 			include BadRequest
-			
+		end
+		
+		# Raised when a singleton (e.g. `content-length`) header is duplicated in a request or response.
+		class DuplicateHeaderError < InvalidHeaderError
 			# @parameter key [String] The header key that was duplicated.
 			def initialize(key, existing_value, new_value)
 				super("Duplicate singleton header key: #{key.inspect}")
@@ -62,9 +64,7 @@ def detailed_message(highlight: false)
 		end
 
 		# Raised when an invalid trailer header is encountered in headers.
-		class InvalidTrailerError < Error
-			include BadRequest
-			
+		class InvalidTrailerError < InvalidHeaderError
 			# @parameter key [String] The trailer key that is invalid.
 			def initialize(key)
 				super("Invalid trailer key: #{key.inspect}")

lib/protocol/http/header/accept.rb

@@ -23,7 +23,7 @@ class Accept < Split
 					(?=,|\z)                  # Match until a comma or end of string
 				/x
 
-				ParseError = Class.new(Error)
+				ParseError = Class.new(InvalidHeaderError)
 
 				MEDIA_RANGE = /\A(?<type>#{TOKEN})\/(?<subtype>#{TOKEN})(?<parameters>.*)\z/
 

lib/protocol/http/header/accept_charset.rb

@@ -12,7 +12,7 @@ module HTTP
 		module Header
 			# The `accept-charset` header represents a list of character sets that the client can accept.
 			class AcceptCharset < Split
-				ParseError = Class.new(Error)
+				ParseError = Class.new(InvalidHeaderError)
 
 				# https://tools.ietf.org/html/rfc7231#section-5.3.3
 				CHARSET = /\A(?<name>#{TOKEN})(;q=(?<q>#{QVALUE}))?\z/

lib/protocol/http/header/accept_encoding.rb

@@ -12,7 +12,7 @@ module HTTP
 		module Header
 			# The `accept-encoding` header represents a list of encodings that the client can accept.
 			class AcceptEncoding < Split
-				ParseError = Class.new(Error)
+				ParseError = Class.new(InvalidHeaderError)
 
 				# https://tools.ietf.org/html/rfc7231#section-5.3.1
 				QVALUE = /0(\.[0-9]{0,3})?|1(\.[0]{0,3})?/

lib/protocol/http/header/accept_language.rb

@@ -12,7 +12,7 @@ module HTTP
 		module Header
 			# The `accept-language` header represents a list of languages that the client can accept.
 			class AcceptLanguage < Split
-				ParseError = Class.new(Error)
+				ParseError = Class.new(InvalidHeaderError)
 
 				# https://tools.ietf.org/html/rfc3066#section-2.1
 				NAME = /\*|[A-Z]{1,8}(-[A-Z0-9]{1,8})*/i

lib/protocol/http/header/digest.rb

@@ -23,7 +23,7 @@ module Header
 			# # => "sha-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=, md5=9bb58f26192e4ba00f01e2e7b136bbd8"
 			# ```
 			class Digest < Split
-				ParseError = Class.new(Error)
+				ParseError = Class.new(InvalidHeaderError)
 
 				# https://tools.ietf.org/html/rfc3230#section-4.3.2
 				ENTRY = /\A(?<algorithm>[a-zA-Z0-9][a-zA-Z0-9\-]*)\s*=\s*(?<value>.*)\z/

lib/protocol/http/header/range.rb

@@ -10,7 +10,7 @@ module HTTP
 		module Header
 			# Represents a `range` request header.
 			class Range
-				ParseError = Class.new(Error)
+				ParseError = Class.new(InvalidHeaderError)
 
 				TOKEN = /[!#$%&'*+\-.0-9A-Z^_`a-z|~]+/
 				HEADER = /\A(?<unit>#{TOKEN})=(?<ranges>.*)\z/

lib/protocol/http/header/server_timing.rb

@@ -23,7 +23,7 @@ module Header
 			# # => "db;dur=53.2, cache;dur=12.1;desc=\"Redis lookup\""
 			# ```
 			class ServerTiming < Split
-				ParseError = Class.new(Error)
+				ParseError = Class.new(InvalidHeaderError)
 
 				# https://www.w3.org/TR/server-timing/
 				METRIC = /\A(?<name>[a-zA-Z0-9][a-zA-Z0-9_\-]*)(;(?<parameters>.*))?\z/

lib/protocol/http/header/te.rb

@@ -14,7 +14,7 @@ module Header
 			#
 			# The `te` header allows a client to indicate which transfer encodings it can handle, and in what order of preference using quality factors.
 			class TE < Split
-				ParseError = Class.new(Error)
+				ParseError = Class.new(InvalidHeaderError)
 
 				# Transfer encoding token pattern
 				TOKEN = /[!#$%&'*+\-.0-9A-Z^_`a-z|~]+/

readme.md

@@ -30,6 +30,10 @@ Please see the [project documentation](https://socketry.github.io/protocol-http/
 
 Please see the [project releases](https://socketry.github.io/protocol-http/releases/index) for all releases.
 
+### Unreleased
+
+  - Introduce `Protocol::HTTP::InvalidHeaderError` for malformed or invalid headers, which can be treated as bad requests.
+
 ### v0.71.0
 
   - Parse all cookie pairs from `Cookie` header fields, including multiple semicolon-separated pairs within each field.