From a64913eafbee3501a677b1232470838a4ad0fc65 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Fri, 5 Jun 2009 22:16:47 -0700
Subject: Unicorn::App::Inetd: reinventing Unix, poorly :)

This includes an example of tunneling the git protocol inside a
TE:chunked HTTP request.  The example is unfortunately contrived
in that it relies on the custom examples/cat-chunk-proxy.rb
script in the client.  My initial wish was to have a generic
tool like curl(1) operate like this:

  cat > ~/bin/cat-chunk-proxy.sh <<EOF
  #!/bin/sh
  exec curl -sfNT- http://$1:$2/
  EOF
  chmod +x ~/bin/cat-chunk-proxy.sh
  GIT_PROXY_COMMAND=cat-chunk-proxy.sh git clone git://0:8080/foo

Unfortunately, curl will attempt a blocking read on stdin before
reading the TCP socket; causing the git-clone consumer to
starve.  This does not appear to be a problem with the new
server code for handling chunked requests.
---
 Manifest                    |   3 ++
 examples/cat-chunk-proxy.rb |  60 +++++++++++++++++++++++++
 examples/git.ru             |   9 ++++
 lib/unicorn/app/inetd.rb    | 106 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 178 insertions(+)
 create mode 100755 examples/cat-chunk-proxy.rb
 create mode 100644 examples/git.ru
 create mode 100644 lib/unicorn/app/inetd.rb

diff --git a/Manifest b/Manifest
index 229572c..f8396c4 100644
--- a/Manifest
+++ b/Manifest
@@ -14,7 +14,9 @@ TODO
 TUNING
 bin/unicorn
 bin/unicorn_rails
+examples/cat-chunk-proxy.rb
 examples/echo.ru
+examples/git.ru
 examples/init.sh
 ext/unicorn/http11/ext_help.h
 ext/unicorn/http11/extconf.rb
@@ -24,6 +26,7 @@ ext/unicorn/http11/http11_parser.rl
 ext/unicorn/http11/http11_parser_common.rl
 lib/unicorn.rb
 lib/unicorn/app/exec_cgi.rb
+lib/unicorn/app/inetd.rb
 lib/unicorn/app/old_rails.rb
 lib/unicorn/app/old_rails/static.rb
 lib/unicorn/cgi_wrapper.rb
diff --git a/examples/cat-chunk-proxy.rb b/examples/cat-chunk-proxy.rb
new file mode 100755
index 0000000..3a5921f
--- /dev/null
+++ b/examples/cat-chunk-proxy.rb
@@ -0,0 +1,60 @@
+#!/home/ew/bin/ruby
+# I wish I could just use curl -sfNT- http://host:port/, but
+# unfortunately curl will attempt to read stdin in blocking mode,
+# preventing it from getting responses from the server until
+# stdin has been written to.
+#
+# Usage: GIT_PROXY_COMMAND=/path/to/here git clone git://host:port/project
+#
+# Where host:port is what the Unicorn server is bound to
+
+require 'socket'
+require 'unicorn'
+require 'unicorn/chunked_reader'
+
+$stdin.sync = $stdout.sync = $stderr.sync = true
+$stdin.binmode
+$stdout.binmode
+
+usage = "#$0 HOST PORT"
+host = ARGV.shift or abort usage
+port = ARGV.shift or abort usage
+s = TCPSocket.new(host, port.to_i)
+s.sync = true
+s.write("PUT / HTTP/1.1\r\n" \
+        "Host: #{host}\r\n" \
+        "Transfer-Encoding: chunked\r\n\r\n")
+buf = s.readpartial(16384)
+while /\r\n\r\n/ !~ buf
+  buf << s.readpartial(16384)
+end
+
+head, body = buf.split(/\r\n\r\n/, 2)
+
+input = fork {
+  $0 = "input #$0"
+  begin
+    loop {
+      $stdin.readpartial(16384, buf)
+      s.write("#{'%x' % buf.size}\r\n#{buf}\r\n")
+    }
+  rescue EOFError,Errno::EPIPE,Errno::EBADF,Errno::EINVAL => e
+  end
+  s.write("0\r\n\r\n")
+}
+
+output = fork {
+  $0 = "output #$0"
+
+  c = Unicorn::ChunkedReader.new
+  c.reopen(s, body)
+  begin
+    loop { $stdout.write(c.readpartial(16384, buf)) }
+  rescue EOFError,Errno::EPIPE,Errno::EBADF,Errno::EINVAL => e
+  end
+}
+
+2.times {
+  pid, status = Process.waitpid2
+  $stderr.write("reaped: #{status.inspect}\n") unless status.success?
+}
diff --git a/examples/git.ru b/examples/git.ru
new file mode 100644
index 0000000..3762d3d
--- /dev/null
+++ b/examples/git.ru
@@ -0,0 +1,9 @@
+#\-E none
+require 'unicorn/app/inetd'
+
+use Rack::Lint
+use Rack::Chunked
+# run Unicorn::App::Inetd.new('tee', '/tmp/tee.out')
+run Unicorn::App::Inetd.new(
+ *%w(git daemon --verbose --inetd --export-all --base-path=/home/ew/unicorn)
+)
diff --git a/lib/unicorn/app/inetd.rb b/lib/unicorn/app/inetd.rb
new file mode 100644
index 0000000..97dc5d3
--- /dev/null
+++ b/lib/unicorn/app/inetd.rb
@@ -0,0 +1,106 @@
+# this class *must* be used with Rack::Chunked
+
+module Unicorn::App
+  class Inetd
+
+    Z = ''
+    Z.force_encoding(Encoding::BINARY) if Z.respond_to?(:force_encoding)
+
+    class CatBody
+      def initialize(env, cmd)
+        @cmd = cmd
+        @input, @errors = env['rack.input'], env['rack.errors']
+        in_rd, in_wr = IO.pipe
+        @err_rd, err_wr = IO.pipe
+        @out_rd, out_wr = IO.pipe
+
+        @cmd_pid = fork {
+          inp, out, err = (0..2).map { |i| IO.new(i) }
+          inp.reopen(in_rd)
+          out.reopen(out_wr)
+          err.reopen(err_wr)
+          [ in_rd, in_wr, @err_rd, err_wr, @out_rd, out_wr ].each { |io|
+            io.close
+          }
+          exec(*cmd)
+        }
+        [ in_rd, err_wr, out_wr ].each { |io| io.close }
+        [ in_wr, @err_rd, @out_rd ].each { |io| io.binmode }
+        in_wr.sync = true
+
+        # Unfortunately, input here must be processed inside a seperate
+        # thread/process using blocking I/O since env['rack.input'] is not
+        # IO.select-able and attempting to make it so would trip Rack::Lint
+        @inp_pid = fork {
+          [ @err_rd, @out_rd ].each { |io| io.close }
+          buf = Z.dup
+
+          # this is dependent on @input.read having readpartial semantics:
+          while @input.read(16384, buf)
+            in_wr.write(buf)
+          end
+          in_wr.close
+        }
+        in_wr.close
+      end
+
+      def each(&block)
+        buf = Z.dup
+        begin
+          rd, = IO.select([@err_rd, @out_rd])
+          rd && rd.first or next
+
+          if rd.include?(@err_rd)
+            begin
+              @errors.write(@err_rd.read_nonblock(16384, buf))
+            rescue Errno::EINTR
+            rescue Errno::EAGAIN
+              break
+            end while true
+          end
+
+          rd.include?(@out_rd) or next
+
+          begin
+            yield @out_rd.read_nonblock(16384, buf)
+          rescue Errno::EINTR
+          rescue Errno::EAGAIN
+            break
+          end while true
+        rescue EOFError,Errno::EPIPE,Errno::EBADF,Errno::EINVAL
+          break
+        end while true
+
+        self
+      end
+
+      def close
+        @input = nil
+        [ [ @cmd.inspect, @cmd_pid ], [ 'input streamer', @inp_pid ]
+        ].each { |str, pid|
+          begin
+            pid, status = Process.waitpid2(pid)
+            status.success? or
+              @errors.write("#{str}: #{status.inspect} (PID:#{pid})\n")
+          rescue Errno::ECHILD
+            @errors.write("Failed to reap #{str} (PID:#{pid})\n")
+          end
+        }
+      end
+
+    end
+
+    def initialize(*cmd)
+      # enable streaming input mode in Unicorn
+      Unicorn::HttpRequest::DEFAULTS["unicorn.stream_input"] = true
+      @cmd = cmd
+    end
+
+    def call(env)
+      [ 200, { 'Content-Type' => 'application/octet-stream' },
+       CatBody.new(env, @cmd) ]
+    end
+
+  end
+
+end
-- 
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