LURP Details

1
LURP Details
2
LURP Lab
3
Details

• 1.Given a GET http// call a proxy CGI script in
  the same way you would for a normal CGI request
• 2.This UDP perl script
• If it is in the cache, return it.
• If it is not in the cache, send a UDP request to
  the broadcast address port 5656
• IP Address, random port, URL sent to broadcast
  address
• Listen on that port for a response
• If no response get it yourself from the source
• Send the result back to the browser
• 3. UDP Listen process
• Recv on port 5656
• If it is in the cache, send it to the address and
  port in the request.

4
Proxy Cache

• The file can contain a simple comma delimited
  list of (URL, Filename, timestamp).
• Keep a fixed number of entries in the cache (20)
• When the cache is full, replace the least
  recently used entry

5
Protocol

• Broadcast message
• IP AddressPortURLCRLF
• 192.168.2.2112345http//cnn.com/foo.html
• Response
• Normal Response including HTTP/1.0 200 OK
• Dont generate this from your web server

6
Proxy Session Request

• GET http//star.cs.byu.edu/test.html HTTP/1.1
• Host star.cs.byu.edu
• User-Agent Mozilla/5.0 (Macintosh U Intel Mac
  OS X en-US rv1.8.0.8) Gecko/20061025
  Firefox/1.5.0.8
• Accept text/xml,application/xml,application/xhtml
  xml,text/htmlq0.9,text/plainq0.8,image/png,/
  q0.5
• Accept-Language en-us,enq0.5
• Accept-Encoding gzip,deflate
• Accept-Charset ISO-8859-1,utf-8q0.7,q0.7
• Keep-Alive 300
• Proxy-Connection keep-alive

7
Proxy Response

• HTTP/1.0 200 OK
• Date Mon, 27 Nov 2006 140214 GMT
• Server Apache/2.0.52 (Fedora)
• Last-Modified Fri, 15 Sep 2006 194141 GMT
• ETag "8839e-14-369ca740"
• Accept-Ranges bytes
• Content-Length 20
• Content-Type text/html charsetISO-8859-1
• X-Cache MISS from weau-proxy
• Proxy-Connection keep-alive
• lthtmlgt
• TEST
• lt/htmlgt

8
Normal Response

• HTTP/1.1 200 OK
• Date Mon, 27 Nov 2006 141707 GMT
• Server Apache/2.0.52 (Fedora)
• Last-Modified Mon, 27 Nov 2006 141703 GMT
• ETag "8839e-14-300c55c0"
• Accept-Ranges bytes
• Content-Length 20
• Connection close
• Content-Type text/html charsetISO-8859-1
• lthtmlgt
• TEST
• lt/htmlgt

9
Details

• You will need to read the Content-Length from the
  first response you receive so you can know where
  it ends
• You may get multiple responses to the same
  request
• You should put in a different random port each
  time so you dont get responses from the last
  request.

10
Compatibility

• An existing proxy server will be listening on
  port 5656 and will respond to requests for
  http//star.cs.byu.edu/test.html
• You can use this to test for compatibility