Bug #21786: Net::HTTP::Response#read_body crashes on nil body when response_body_encoding is a String

• Status: Open
• Assignee: -
• Target version: -
• ruby -v: ruby 3.2.0p0 (2022-12-25 revision a528908271) [x86_64-linux]
• Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[[e-mail] (Karina Mendez)]

When response_body_encoding is set to a String value (e.g., 'UTF-8'), and the HTTP response body is nil due to network failures, read_body attempts to call force_encoding on nil at line 360, raising NoMethodError. The issue occurs because String values fall through to the else branch which calls detect_encoding(@body) without checking if @body is nil. Line 360 should verify @body is not nil before calling force_encoding.

Category: lib

Target version:current

Reproducible script:

require 'net/http'

# Monkey patch to simulate nil body scenario
class Net::HTTP::Response
  alias_method :original_reading_body, :reading_body
  
  def reading_body(sock, reqmethodallowbody)
    @socket = sock
    @body_exist = false  # Force nil body
    begin
      yield
      self.body  # Triggers the bug
    ensure
      @socket = nil
    end
  end
end

# Trigger the bug
http = Net::HTTP.new('example.com', 443)
http.use_ssl = true
http.response_body_encoding = 'UTF-8'  # String triggers else branch

begin
  http.request(Net::HTTP::Get.new('/'))
rescue NoMethodError => e
  puts "BUG: #{e.message}"
  puts "Location: #{e.backtrace.first}"
end

# Expected: Graceful handling
# Actual: NoMethodError: undefined method `force_encoding' for nil:NilClass
#         from lib/net/http/response.rb:360:in `read_body'

Suggested fix:
In lib/net/http/response.rb line 360, change:

@body.force_encoding(enc) if enc

to:

@body.force_encoding(enc) if enc && @body

[Eregon (Benoit Daloze)]

• Description updated (diff)