Squashed commit of the following:

commit 1dca99ad4f8082d8daaa17c6600f3036c25f8e50
Author: Tom Prats <tprats108@gmail.com>
Date:   Thu Aug 5 18:07:00 2021 -0400

    Moved header

commit 62201870ff5c4124d90912989745819b05d94516
Merge: 5fa3ecae74 c91a8135c7
Author: Tom Prats <tprats108@gmail.com>
Date:   Thu Aug 5 14:41:22 2021 -0400

    Merge branch 'main' into active-storage-byte-range

commit 5fa3ecae745b4f7c67a6b6b1b7ec420877c96fb8
Author: Tom Prats <tprats108@gmail.com>
Date:   Thu Aug 5 14:39:53 2021 -0400

    Apply suggestions from code review

    Syntax updates

    Co-authored-by: Rafael França <rafael@franca.dev>

commit b9553e3698a7af5105171f9d63bd7b89cbb7e2c3
Author: Tom Prats <tprats108@gmail.com>
Date:   Wed Jun 23 17:36:26 2021 -0400

    Added Active Storage support for byte ranges

activestorage/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Add support for byte range requests
+
+    *Tom Prats*
+
 *   Attachments can be deleted after their association is no longer defined.
 
     Fixes #42514

activestorage/app/controllers/active_storage/blobs/proxy_controller.rb

@@ -10,8 +10,15 @@ class ActiveStorage::Blobs::ProxyController < ActiveStorage::BaseController
   include ActiveStorage::SetBlob
 
   def show
-    http_cache_forever public: true do
+    if request.headers["Range"].present?
-      send_blob_stream @blob
+      send_blob_byte_range_data @blob, request.headers["Range"]
+    else
+      http_cache_forever public: true do
+        response.headers["Accept-Ranges"] = "bytes"
+        response.headers["Content-Length"] = @blob.byte_size.to_s
+
+        send_blob_stream @blob
+      end
     end
   end
 end

activestorage/app/controllers/concerns/active_storage/streaming.rb

@@ -1,11 +1,55 @@
 # frozen_string_literal: true
 
+require "securerandom"
+
 module ActiveStorage::Streaming
   DEFAULT_BLOB_STREAMING_DISPOSITION = "inline"
 
+  include ActionController::DataStreaming
   include ActionController::Live
 
   private
+    # Stream the blob in byte ranges specified through the header
+    def send_blob_byte_range_data(blob, range_header, disposition: nil) #:doc:
+      ranges = Rack::Utils.get_byte_ranges(range_header, blob.byte_size)
+
+      return head(:range_not_satisfiable) if ranges.blank? || ranges.all?(&:blank?)
+
+      if ranges.length == 1
+        range = ranges.first
+        content_type = blob.content_type_for_serving
+        data = blob.download_chunk(range)
+
+        response.headers["Content-Range"] = "bytes #{range.begin}-#{range.end}/#{blob.byte_size}"
+      else
+        boundary = SecureRandom.hex
+        content_type = "multipart/byteranges; boundary=#{boundary}"
+        data = +""
+
+        ranges.compact.each do |range|
+          chunk = blob.download_chunk(range)
+
+          data << "\r\n--#{boundary}\r\n"
+          data << "Content-Type: #{blob.content_type_for_serving}\r\n"
+          data << "Content-Range: bytes #{range.begin}-#{range.end}/#{blob.byte_size}\r\n\r\n"
+          data << chunk
+        end
+
+        data << "\r\n--#{boundary}--\r\n"
+      end
+
+      response.headers["Accept-Ranges"] = "bytes"
+      response.headers["Content-Length"] = data.length.to_s
+
+      send_data(
+        data,
+        disposition: blob.forced_disposition_for_serving || disposition || DEFAULT_BLOB_STREAMING_DISPOSITION,
+        filename: blob.filename.sanitized,
+        status: :partial_content,
+        type: content_type
+      )
+    end
+
     # Stream the blob from storage directly to the response. The disposition can be controlled by setting +disposition+.
     # The content type and filename is set directly from the +blob+.
     def send_blob_stream(blob, disposition: nil) #:doc:

activestorage/app/models/active_storage/blob.rb

@@ -253,6 +253,11 @@ class ActiveStorage::Blob < ActiveStorage::Record
     service.download key, &block
   end
 
+  # Downloads a part of the file associated with this blob.
+  def download_chunk(range)
+    service.download_chunk key, range
+  end
+
   # Downloads the blob to a tempfile on disk. Yields the tempfile.
   #
   # The tempfile's name is prefixed with +ActiveStorage-+ and the blob's ID. Its extension matches that of the blob.

activestorage/test/controllers/blobs/proxy_controller_test.rb

@@ -2,6 +2,7 @@
 
 require "test_helper"
 require "database/setup"
+require "minitest/mock"
 
 class ActiveStorage::Blobs::ProxyControllerTest < ActionDispatch::IntegrationTest
   test "invalid signed ID" do
@@ -36,6 +37,48 @@ class ActiveStorage::Blobs::ProxyControllerTest < ActionDispatch::IntegrationTes
     get url
     assert_response :not_found
   end
+
+  test "single Byte Range" do
+    get rails_storage_proxy_url(create_file_blob(filename: "racecar.jpg")), headers: { "Range" => "bytes=5-9" }
+    assert_response :partial_content
+    assert_equal "5", response.headers["Content-Length"]
+    assert_equal "bytes 5-9/1124062", response.headers["Content-Range"]
+    assert_equal "image/jpeg", response.headers["Content-Type"]
+    assert_equal " Exif", response.body
+  end
+
+  test "invalid Byte Range" do
+    get rails_storage_proxy_url(create_file_blob(filename: "racecar.jpg")), headers: { "Range" => "bytes=*/1234" }
+    assert_response :range_not_satisfiable
+  end
+
+  test "multiple Byte Ranges" do
+    boundary = SecureRandom.hex
+    SecureRandom.stub :hex, boundary do
+      get rails_storage_proxy_url(create_file_blob(filename: "racecar.jpg")), headers: { "Range" => "bytes=5-9,13-17" }
+      assert_response :partial_content
+      assert_equal "252", response.headers["Content-Length"]
+      assert_equal "multipart/byteranges; boundary=#{boundary}", response.headers["Content-Type"]
+      assert_equal(
+        [
+          "",
+          "--#{boundary}",
+          "Content-Type: image/jpeg",
+          "Content-Range: bytes 5-9/1124062",
+          "",
+          " Exif",
+          "--#{boundary}",
+          "Content-Type: image/jpeg",
+          "Content-Range: bytes 13-17/1124062",
+          "",
+          "I*\u0000\b\u0000",
+          "--#{boundary}--",
+          ""
+        ].join("\r\n"),
+        response.body
+      )
+    end
+  end
 end
 
 class ActiveStorage::Blobs::ExpiringProxyControllerTest < ActionDispatch::IntegrationTest