Class: HTML::Pipeline::CamoFilter
- Defined in:
- lib/html/pipeline_plus/camo_filter.rb
Overview
HTML Filter for replacing http image URLs with camo versions. See:
All images provided in user content should be run through this filter so that http image sources do not cause mixed-content warnings in browser clients.
Context options:
:asset_proxy (required) - Base URL for constructed asset proxy URLs.
:asset_proxy_secret_key (required) - The shared secret used to encode URLs.
:asset_proxy_whitelist - Array of host Strings or Regexps to skip
src rewriting.
This filter does not write additional information to the context.
Instance Attribute Summary
Attributes inherited from Filter
Instance Method Summary collapse
- #asset_host_whitelisted?(host) ⇒ Boolean
-
#asset_proxy_enabled? ⇒ Boolean
Private: Return true if asset proxy filter should be enabled.
-
#asset_proxy_host ⇒ Object
Private: the host to use for generated asset proxied URLs.
- #asset_proxy_secret_key ⇒ Object
-
#asset_proxy_url(url) ⇒ Object
The camouflaged URL for a given image URL.
- #asset_proxy_whitelist ⇒ Object
-
#asset_url_hash(url) ⇒ Object
Private: calculate the HMAC digest for a image source URL.
-
#call ⇒ Object
Hijacks images in the markup provided, replacing them with URLs that go through the github asset proxy.
-
#hexencode(str) ⇒ Object
Private: helper to hexencode a string.
-
#validate ⇒ Object
Implementation of validate hook.
Methods inherited from Filter
#base_url, call, #current_user, #doc, #has_ancestor?, #html, #initialize, #needs, #parse_html, #repository, to_document, to_html
Constructor Details
This class inherits a constructor from HTML::Pipeline::Filter
Instance Method Details
#asset_host_whitelisted?(host) ⇒ Boolean
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# File 'lib/html/pipeline_plus/camo_filter.rb', line 80 def asset_host_whitelisted?(host) asset_proxy_whitelist.any? do |test| test.is_a?(String) ? host == test : test.match(host) end end |
#asset_proxy_enabled? ⇒ Boolean
Private: Return true if asset proxy filter should be enabled
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# File 'lib/html/pipeline_plus/camo_filter.rb', line 63 def asset_proxy_enabled? !context[:disable_asset_proxy] end |
#asset_proxy_host ⇒ Object
Private: the host to use for generated asset proxied URLs.
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# File 'lib/html/pipeline_plus/camo_filter.rb', line 68 def asset_proxy_host context[:asset_proxy] end |
#asset_proxy_secret_key ⇒ Object
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# File 'lib/html/pipeline_plus/camo_filter.rb', line 72 def asset_proxy_secret_key context[:asset_proxy_secret_key] end |
#asset_proxy_url(url) ⇒ Object
The camouflaged URL for a given image URL.
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# File 'lib/html/pipeline_plus/camo_filter.rb', line 53 def asset_proxy_url(url) "#{asset_proxy_host}/#{asset_url_hash(url)}/#{hexencode(url)}" end |
#asset_proxy_whitelist ⇒ Object
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# File 'lib/html/pipeline_plus/camo_filter.rb', line 76 def asset_proxy_whitelist context[:asset_proxy_whitelist] || [] end |
#asset_url_hash(url) ⇒ Object
Private: calculate the HMAC digest for a image source URL.
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# File 'lib/html/pipeline_plus/camo_filter.rb', line 58 def asset_url_hash(url) OpenSSL::HMAC.hexdigest('sha1', asset_proxy_secret_key, url) end |
#call ⇒ Object
Hijacks images in the markup provided, replacing them with URLs that go through the github asset proxy.
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# File 'lib/html/pipeline_plus/camo_filter.rb', line 24 def call return doc unless asset_proxy_enabled? doc.search('img').each do |element| original_src = element['src'] next unless original_src begin uri = URI.parse(original_src) rescue Exception next end next if uri.host.nil? next if asset_host_whitelisted?(uri.host) element['src'] = asset_proxy_url(original_src) element['data-canonical-src'] = original_src end doc end |
#hexencode(str) ⇒ Object
Private: helper to hexencode a string. Each byte ends up encoded into two characters, zero padded value in the range [0-9a-f].
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# File 'lib/html/pipeline_plus/camo_filter.rb', line 88 def hexencode(str) str.to_enum(:each_byte).map { |byte| format('%02x', byte) }.join end |
#validate ⇒ Object
Implementation of validate hook. Errors should raise exceptions or use an existing validator.
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# File 'lib/html/pipeline_plus/camo_filter.rb', line 48 def validate needs :asset_proxy, :asset_proxy_secret_key end |