[Libevent-users] Patch: evhttp_connection_set_local_port

[Richard Jones]

Hi,
In order to open more than 2^16 connections (HTTP connections in my
case) *from* one machine, you need to use multiple local IPs, because
the maximum local port number is 65536.
evhttp_connection_set_local_address already exists and is suitable for
this.

The ephemeral port allocator, which is used when you don't specify a
local port numbebr, doesn't distinguish between local addresses though,
so you need to specify the local port manually. 

I added "evhttp_connection_set_local_port", which in conjunction with
evhttp_connection_set_local_address and some tcp/kernel tuning allowed
me to open 1 million http connections from one machine. I brought up 16
IPs and opened 62,500 from each.

Please find my patch attached - if there's svn/git/something repo I
should patch against instead of the release tarball I would be happy to
do so.

Thanks,
RJ

diff libevent-1.4.8-stable/evhttp.h libevent-1.4.8-stable-rj-clean/evhttp.h
269a270,273
> /** sets the local port from which http connections are made */
> void evhttp_connection_set_local_port(struct evhttp_connection *evcon,
>     u_short port);
>
diff libevent-1.4.8-stable/http.c libevent-1.4.8-stable-rj-clean/http.c
1040a1041,1048
> void
> evhttp_connection_set_local_port(struct evhttp_connection *evcon,
>     u_short port)
> {
>       assert(evcon->state == EVCON_DISCONNECTED);
>     evcon->bind_port = port;
> }
>
1654a1663
>     evcon->bind_port = 0; /* by default, use ephemeral local port */
1734c1743
<       evcon->fd = bind_socket(evcon->bind_address, 0 /*port*/, 0 /*reuse*/);
---
>       evcon->fd = bind_socket(evcon->bind_address, evcon->bind_port, 0 
> /*reuse*/);
diff libevent-1.4.8-stable/http-internal.h 
libevent-1.4.8-stable-rj-clean/http-internal.h
63a64
>       u_short bind_port;      /* port to use for binding the src */


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