Added files via upload

examples/networking/http_filter/README.md

@@ -1,40 +1,47 @@
-#HTTP Filter
+# HTTP Filter
 
 eBPF application that parses HTTP packets and extracts (and prints on screen) the URL contained in the GET/POST request.
 
-[eBPF HTTP Filter - Short Presentation](https://github.com/iovisor/bpf-docs/blob/master/ebpf_http_filter.pdf)
+[eBPF HTTP Filter - Short Presentation](ebpf_http_filter-short.pdf)
 
-#Usage Example
+## Usage Example
 
-```Shell
-$ sudo python http-parse-complete.py 
-GET /pipermail/iovisor-dev/ HTTP/1.1
-HTTP/1.1 200 OK
-GET /favicon.ico HTTP/1.1
-HTTP/1.1 404 Not Found
-GET /pipermail/iovisor-dev/2016-January/thread.html HTTP/1.1
-HTTP/1.1 200 OK
-GET /pipermail/iovisor-dev/2016-January/000046.html HTTP/1.1
-HTTP/1.1 200 OK
-```
 
-#Implementation using BCC
+ $ sudo python http-parse-complete.py 
+ GET /pipermail/iovisor-dev/ HTTP/1.1
+ HTTP/1.1 200 OK
+ GET /favicon.ico HTTP/1.1
+ HTTP/1.1 404 Not Found
+ GET /pipermail/iovisor-dev/2016-January/thread.html HTTP/1.1
+ HTTP/1.1 200 OK
+ GET /pipermail/iovisor-dev/2016-January/000046.html HTTP/1.1
+ HTTP/1.1 200 OK
 
-eBPF socket filter.<br />
-Filters IP and TCP packets, containing "HTTP", "GET", "POST" in payload and all subsequent packets belonging to the same session, having the same (ip_src,ip_dst,port_src,port_dst).<br />
-Program is loaded as PROG_TYPE_SOCKET_FILTER and attached to a socket, bind to eth0. <br />
-Matching packets are forwarded to user space, others dropped by the filter.<br />
-<br />
-Python script reads filtered raw packets from the socket, if necessary reassembles packets belonging to the same session, and prints on stdout the first line of the HTTP GET/POST request. <br />
 
-#simple vs complete
+## Implementation overview
 
-simple version: if the url is too long (splitted in more than one packet) is truncated. <br />
-complete version: if necessary reassembles packets belonging to the same session and prints the complete url.
+The implementation is split in two portions: the former that exploits eBPF code, the latter that performs some additional processing in user space (the python wrapper).
 
-#To run:
+### First part: eBPF filter
+This component filters IP and TCP packets containing the "HTTP", "GET", "POST" strings in their payload and all subsequent packets belonging to the same session, having the same (ip.src,ip.dst,port.src,port.dst) tuple.
 
-```Shell
-$ sudo python http-parse-simple.py
-$ sudo python http-parse-complete.py
-```
+The program is loaded as PROG_TYPE_SOCKET_FILTER and attached to a socket, bind to eth0.
+
+Matching packets are forwarded to user space, the others are dropped by the filter.
+
+### Second part: python code in user space
+The Python script reads filtered raw packets from the socket, if necessary reassembles packets belonging to the same session, and prints on stdout the first line of the HTTP GET/POST request.
+
+## Simple vs. complete
+
+Two versions of this code are available in this repository:
+
+* simple version: it does not handle URLs that span across multiple packets. For instance, if the URL is too long it shows only the portion contained in the first packet.
+* complete version: it is able to cope with URLs spanning across multiple packets; if such a situation is detected, the code reassembles packets belonging to the same session and prints the complete URL.
+
+## How to execute this sample
+
+This sample can be executed by typing either one the two commands below:
+
+ $ sudo python http-parse-simple.py
+ $ sudo python http-parse-complete.py