From d97479f9c966bd2c9d52c8be28aca9431760c610 Mon Sep 17 00:00:00 2001
From: Andrew Kane <andrew@ankane.org>
Date: Fri, 13 Jan 2023 20:27:05 -0800
Subject: [PATCH] [ruby/open-uri] Add :max_redirects option

https://github.com/ruby/open-uri/commit/7fd5ea09a7
---
 lib/open-uri.rb                |  3 +++
 test/open-uri/test_open-uri.rb | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/lib/open-uri.rb b/lib/open-uri.rb
index 00e4c2d9b8..56dac75b29 100644
--- a/lib/open-uri.rb
+++ b/lib/open-uri.rb
@@ -108,6 +108,7 @@ module OpenURI
     :ftp_active_mode => false,
     :redirect => true,
     :encoding => nil,
+    :max_redirects => nil,
   }
 
   def OpenURI.check_options(options) # :nodoc:
@@ -211,6 +212,7 @@ module OpenURI
     end
 
     uri_set = {}
+    max_redirects = options[:max_redirects]
     buf = nil
     while true
       redirect = catch(:open_uri_redirect) {
@@ -238,6 +240,7 @@ module OpenURI
         uri = redirect
         raise "HTTP redirection loop: #{uri}" if uri_set.include? uri.to_s
         uri_set[uri.to_s] = true
+        raise "Too many redirects" if max_redirects && uri_set.size > max_redirects
       else
         break
       end
diff --git a/test/open-uri/test_open-uri.rb b/test/open-uri/test_open-uri.rb
index 86aefc52c8..6bad7f4bdf 100644
--- a/test/open-uri/test_open-uri.rb
+++ b/test/open-uri/test_open-uri.rb
@@ -558,6 +558,25 @@ class TestOpenURI < Test::Unit::TestCase
     }
   end
 
+  def test_max_redirects_success
+    with_http {|srv, dr, url|
+      srv.mount_proc("/r1/") {|req, res| res.status = 301; res["location"] = "#{url}/r2"; res.body = "r1" }
+      srv.mount_proc("/r2/") {|req, res| res.status = 301; res["location"] = "#{url}/r3"; res.body = "r2" }
+      srv.mount_proc("/r3/") {|req, res| res.body = "r3" }
+      URI.open("#{url}/r1/", max_redirects: 2) { |f| assert_equal("r3", f.read) }
+    }
+  end
+
+  def test_max_redirects_too_many
+    with_http {|srv, dr, url|
+      srv.mount_proc("/r1/") {|req, res| res.status = 301; res["location"] = "#{url}/r2"; res.body = "r1" }
+      srv.mount_proc("/r2/") {|req, res| res.status = 301; res["location"] = "#{url}/r3"; res.body = "r2" }
+      srv.mount_proc("/r3/") {|req, res| res.body = "r3" }
+      exc = assert_raise(RuntimeError) { URI.open("#{url}/r1/", max_redirects: 1) {} }
+      assert_equal("Too many redirects", exc.message)
+    }
+  end
+
   def test_userinfo
     assert_raise(ArgumentError) { URI.open("http://user:pass@127.0.0.1/") {} }
   end