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Marcello Costagliola
414ff3376e
The deadline in Opengraph::Fetch started after the lookup of the pasted host, and an unfurl looks up more hosts outside any fetch: the canonical URL's, and the image's, once to check its content type and again to validate it. Each of those waits as long as the resolver takes to give up. Move the deadline up to UnfurlLinksController, around everything the link leads to; Opengraph::Fetch keeps its per-operation timeouts and makes no retries. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Bj8KnxpTf9sj2Ysa8aLAVa
88 lines
2.9 KiB
Ruby
88 lines
2.9 KiB
Ruby
require "net/http"
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require "restricted_http/private_network_guard"
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class Opengraph::Fetch
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ALLOWED_DOCUMENT_CONTENT_TYPE = "text/html"
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MAX_BODY_SIZE = 5.megabytes
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MAX_REDIRECTS = 10
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TIMEOUT = 7.seconds # to connect (TLS included), and for each read and write, as Webhook does
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class TooManyRedirectsError < StandardError; end
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class RedirectDeniedError < StandardError; end
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def fetch_document(url, ip: RestrictedHTTP::PrivateNetworkGuard.resolve(url.host))
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request(url, Net::HTTP::Get, ip: ip) do |response|
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return body_if_acceptable(response)
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end
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end
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def fetch_content_type(url, ip: RestrictedHTTP::PrivateNetworkGuard.resolve(url.host))
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request(url, Net::HTTP::Head, ip: ip) do |response|
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return response["Content-Type"]
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end
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end
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private
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# The timeouts bound each operation. A host can still send its headers or body a byte at a time,
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# in as many reads as it likes: UnfurlLinksController puts the whole unfurl under one deadline.
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def request(url, request_class, ip:)
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MAX_REDIRECTS.times do
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Net::HTTP.start(url.host, url.port, ipaddr: ip, use_ssl: url.scheme == "https", **timeouts) do |http|
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http.request request_class.new(url) do |response|
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if response.is_a?(Net::HTTPRedirection)
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url, ip = resolve_redirect(response["location"])
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else
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yield response
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end
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end
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end
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end
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raise TooManyRedirectsError
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end
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# Without max_retries: 0, Net::HTTP sends a GET or HEAD that timed out a second time.
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def timeouts
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{ open_timeout: TIMEOUT, read_timeout: TIMEOUT, write_timeout: TIMEOUT, max_retries: 0 }
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end
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def resolve_redirect(location)
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url = URI.parse(location)
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raise RedirectDeniedError unless url.is_a?(URI::HTTP)
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[ url, RestrictedHTTP::PrivateNetworkGuard.resolve(url.host) ]
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end
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def body_if_acceptable(response)
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size_restricted_body(response) if response_valid?(response)
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end
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def size_restricted_body(response)
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# We've already checked the Content-Length header, to try to avoid reading
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# the body of any large responses. But that header could be wrong or
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# missing. To be on the safe side, we'll read the body in chunks, and bail
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# if it runs over our size limit.
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StringIO.new.tap do |body|
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response.read_body do |chunk|
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return nil if body.string.bytesize + chunk.bytesize > MAX_BODY_SIZE
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body << chunk
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end
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end.string
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end
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def response_valid?(response)
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status_valid?(response) && content_type_valid?(response) && content_length_valid?(response)
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end
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def status_valid?(response)
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response.is_a?(Net::HTTPOK)
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end
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def content_type_valid?(response)
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response.content_type == ALLOWED_DOCUMENT_CONTENT_TYPE
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end
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def content_length_valid?(response)
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response.content_length.to_i <= MAX_BODY_SIZE
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end
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end
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