広場投稿追加画面の刷新 (#399) (#413)

Reviewed-on: #413
Co-authored-by: miteruzo <miteruzo@naver.com>
Co-committed-by: miteruzo <miteruzo@naver.com>

backend/spec/services/preview/thumbnail_fetcher_spec.rb

@@ -2,7 +2,7 @@ require 'rails_helper'
 
 RSpec.describe Preview::ThumbnailFetcher do
   describe '.fetch' do
-    it 'rejects svg thumbnails' do
+    it 'accepts svg thumbnails for the common safe rasterisation path' do
       page = Preview::HttpFetcher::Response.new(
           '<meta property="og:image" content="https://example.com/thumb.svg">',
           'text/html',
@@ -12,8 +12,9 @@ RSpec.describe Preview::ThumbnailFetcher do
           'image/svg+xml',
           'https://example.com/thumb.svg')
 
-      allow(Preview::UrlSafety).to receive(:validate)
-          .and_return([URI.parse('https://example.com/page'), ['203.0.113.10']])
+      allow(Preview::UrlSafety).to receive(:validate) do |url|
+        [URI.parse(url), ['203.0.113.10']]
+      end
       allow(Preview::HttpFetcher).to receive(:fetch)
           .with('https://example.com/page', max_bytes: described_class::HTML_MAX_BYTES)
           .and_return(page)
@@ -21,9 +22,7 @@ RSpec.describe Preview::ThumbnailFetcher do
           .with('https://example.com/thumb.svg')
           .and_return(svg)
 
-      expect {
-        described_class.fetch('https://example.com/page')
-      }.to raise_error(Preview::ThumbnailFetcher::GenerationFailed)
+      expect(described_class.fetch('https://example.com/page')).to eq('<svg></svg>')
     end
 
     it 'accepts allowed image content type with parameters' do
@@ -32,12 +31,13 @@ RSpec.describe Preview::ThumbnailFetcher do
           'text/html',
           'https://example.com/page')
       image = Preview::HttpFetcher::Response.new(
-          'jpeg-bytes',
+          "\xFF\xD8\xFFjpeg-bytes".b,
           'image/jpeg; charset=binary',
           'https://example.com/thumb.jpg')
 
-      allow(Preview::UrlSafety).to receive(:validate)
-          .and_return([URI.parse('https://example.com/page'), ['203.0.113.10']])
+      allow(Preview::UrlSafety).to receive(:validate) do |url|
+        [URI.parse(url), ['203.0.113.10']]
+      end
       allow(Preview::HttpFetcher).to receive(:fetch)
           .with('https://example.com/page', max_bytes: described_class::HTML_MAX_BYTES)
           .and_return(page)
@@ -45,7 +45,60 @@ RSpec.describe Preview::ThumbnailFetcher do
           .with('https://example.com/thumb.jpg')
           .and_return(image)
 
-      expect(described_class.fetch('https://example.com/page')).to eq('jpeg-bytes')
+      expect(described_class.fetch('https://example.com/page'))
+          .to eq("\xFF\xD8\xFFjpeg-bytes".b)
+    end
+  end
+
+  describe '.fetch_image_response' do
+    it 'rejects an unsafe input URL before HTTP fetch' do
+      allow(Preview::UrlSafety).to receive(:validate)
+          .and_raise(Preview::UrlSafety::UnsafeUrl, '安全でない接続先は使用できません．')
+      expect(Preview::HttpFetcher).not_to receive(:fetch)
+
+      expect {
+        described_class.fetch_image_response('https://unsafe.example.com/thumb.jpg')
+      }.to raise_error(Preview::UrlSafety::UnsafeUrl, '安全でない接続先は使用できません．')
+    end
+
+    it 'rejects an unsafe redirect target' do
+      allow(Preview::UrlSafety).to receive(:validate)
+          .and_return([URI.parse('https://example.com/thumb.jpg'), ['8.8.8.8']])
+      allow(Preview::HttpFetcher).to receive(:fetch)
+          .with('https://example.com/thumb.jpg')
+          .and_raise(Preview::UrlSafety::UnsafeUrl, '安全でない接続先は使用できません．')
+
+      expect {
+        described_class.fetch_image_response('https://example.com/thumb.jpg')
+      }.to raise_error(Preview::UrlSafety::UnsafeUrl, '安全でない接続先は使用できません．')
+    end
+
+    it 'rejects an oversized image response' do
+      allow(Preview::UrlSafety).to receive(:validate)
+          .and_return([URI.parse('https://example.com/thumb.jpg'), ['8.8.8.8']])
+      allow(Preview::HttpFetcher).to receive(:fetch)
+          .with('https://example.com/thumb.jpg')
+          .and_raise(Preview::HttpFetcher::ResponseTooLarge, 'too large')
+
+      expect {
+        described_class.fetch_image_response('https://example.com/thumb.jpg')
+      }.to raise_error(Preview::HttpFetcher::ResponseTooLarge)
+    end
+
+    it 'rejects a non-image content type' do
+      allow(Preview::UrlSafety).to receive(:validate)
+          .and_return([URI.parse('https://example.com/thumb.jpg'), ['8.8.8.8']])
+      allow(Preview::HttpFetcher).to receive(:fetch)
+          .with('https://example.com/thumb.jpg')
+          .and_return(
+              Preview::HttpFetcher::Response.new(
+                  '<html></html>',
+                  'text/html',
+                  'https://example.com/thumb.jpg'))
+
+      expect {
+        described_class.fetch_image_response('https://example.com/thumb.jpg')
+      }.to raise_error(Preview::ThumbnailFetcher::GenerationFailed)
     end
   end
 end