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Parse extension headers with HTTP whitespace and full boundaries #9

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Parse extension headers with HTTP whitespace and full boundaries #9

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5377e57
Parse extension headers with HTTP whitespace and full boundaries
OskarEichler Aug 28, 2026
8874ee8
Skip separator bytes without allocating strings
OskarEichler Aug 28, 2026
e6db210
Combine leading whitespace with the first extension scan
OskarEichler Aug 28, 2026
4440d94
Add parser regression coverage
OskarEichler Aug 28, 2026
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13 changes: 7 additions & 6 deletions lib/websocket/extensions/parser.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -7,10 +7,11 @@ class Parser
TOKEN = /([!#\$%&'\*\+\-\.\^_`\|~0-9A-Za-z]+)/
NOTOKEN = /([^!#\$%&'\*\+\-\.\^_`\|~0-9A-Za-z])/
QUOTED = /"((?:\\[\x00-\x7f]|[^\x00-\x08\x0a-\x1f\x7f"\\])*)"/
PARAM = %r{#{ TOKEN.source }(?:=(?:#{ TOKEN.source }|#{ QUOTED.source }))?}
EXT = %r{#{ TOKEN.source }(?: *; *#{ PARAM.source })*}
EXT_LIST = %r{^#{ EXT.source }(?: *, *#{ EXT.source })*$}
NUMBER = /^-?(0|[1-9][0-9]*)(\.[0-9]+)?$/
PARAM = %r{#{ TOKEN.source }(?:[ \t]*=[ \t]*(?:#{ TOKEN.source }|#{ QUOTED.source }))?}
EXT = %r{#{ TOKEN.source }(?:[ \t]*;[ \t]*#{ PARAM.source })*}
EXT_START = %r{[ \t]*#{ EXT.source }}
EXT_LIST = %r{\A[ \t]*#{ EXT.source }(?:[ \t]*,[ \t]*#{ EXT.source })*[ \t]*\z}
NUMBER = /\A-?(0|[1-9][0-9]*)(\.[0-9]+)?\z/

ParseError = Class.new(ArgumentError)

Expand All @@ -23,7 +24,7 @@ def self.parse_header(header)
end

scanner = StringScanner.new(header)
value = scanner.scan(EXT)
value = scanner.scan(EXT_START)

until value.nil?
params = value.scan(PARAM)
Expand Down Expand Up @@ -51,7 +52,7 @@ def self.parse_header(header)

offers.push(name, offer)

scanner.scan(/ *, */)
scanner.skip(/[ \t]*,[ \t]*/)
value = scanner.scan(EXT)
end
offers
Expand Down
12 changes: 12 additions & 0 deletions spec/websocket/extensions/parser_spec.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,18 @@ def parse(string)
]
end

it "parses HTTP whitespace around delimiters" do
expect(parse " \ta \t; mode \t= compress \t, other \t").to eq [
{ :name => "a", :params => { "mode" => "compress" } },
{ :name => "other", :params => {} }
]
end

it "rejects input outside the complete header value" do
expect { parse "\na" }.to raise_error(WebSocket::Extensions::Parser::ParseError)
expect { parse "a\n" }.to raise_error(WebSocket::Extensions::Parser::ParseError)
end

it "parses two offers with no params" do
expect(parse 'a, b').to eq [
{ :name => "a", :params => {} }, { :name => "b", :params => {} }
Expand Down