12.39

 +------+      +------+       +------+
 |      |----->|      |------>|      |
 |client|      |proxy |       |server|
 |      |<-----|      |<------|      |
 +------+      +------+       +------+
       as server      as client

proxy play with client as a server, with server as a client, interesting.

the key point is when normal situation

 +------+      +------+
 |      |----->|      |
 |client|      |server|
 |      |<-----|      |
 +------+      +------+

HTTP request from client is something like

GET / HTTP/1.1
Host: address:port

but with proxy, it’ll be

GET http://address:port/ HTTP/1.1
Host: address:port

so proxy have to separate host from uri

A.

!INCLUDE "./code/12.39/proxy.c"

B.

move process into thread function

!INCLUDE "./code/12.39/proxy-thread.c"

how to benchmark:

run proxy

(cd chapter12/code/12.39; make && ./proxy)
# or
(cd chapter12/code/12.39; make && ./proxy-thread)

open another terminal, start a local http server

(python3 -m http.server 8000)

open one another terminal, benchmark

# -X means proxy, -n means how many requests, -c means concurrent
(ab -X localhost:5000 -n 100 -c 10 http://localhost:8000/)