This commit introduces the replacement of the client address based on the value
of a specified HTTP header. This is intended for use when Unit is placed
behind a reverse proxy like nginx or a CDN.
You must specify the source addresses of the trusted proxies. This can be
accomplished with any valid IP pattern supported by Unit's match block:
["10.0.0.1", "10.4.0.0/16", "!192.168.1.1"]
The feature is configured per listener.
The client address replacement functionality only operates when there is a
source IP match and the specified header is present. Typically this would be
an 'X-Forwarded-For' header.
{
"listeners": {
"127.0.0.1:8080": {
"client_ip": {
"header": "X-Forwarded-For",
"source": [
"10.0.0.0/8"
]
},
"pass": "applications/my_app"
},
}
}
If a request occurs and Unit receives a header like below:
"X-Forwarded-For: 84.123.23.23"
By default, Unit trusts the last rightmost IP in the header, so REMOTE_ADDR
will be set to 84.123.23.23 if the connection originated from 10.0.0.0/8.
If Unit runs behind consecutive reverse proxies and receives a header similar
to the following:
"X-Forwarded-For: 84.123.23.23, 10.0.0.254"
You will need to enable "recursive" checking, which walks the header from
last address to first and chooses the first non-trusted address it finds.
{
"listeners": {
"127.0.0.1:8080": {
"client_ip": {
"header": "X-Forwarded-For",
"source": [
"10.0.0.0/8"
]
"recursive": true,
},
"pass": "applications/my_app"
},
}
}
If a connection from 10.0.0.0/8 occurs, the chain is walked. Here, 10.0.0.254
is also a trusted address so the client address will be replaced with
84.123.23.23.
If all IP addresses in the header are trusted, the client address is set to
the first address in the header:
If 10.0.0.0/8 is trusted and "X-Forwarded-For: 10.0.0.3, 10.0.0.2, 10.0.0.1",
the client address will be replaced with 10.0.0.3.
This is required due to lack of a graceful shutdown: there is a small gap
between the runtime's memory pool release and router process's exit. Thus, a
worker thread may start processing a request between these two operations,
which may result in an http fields hash access and subsequent crash.
To simplify issue reproduction, it makes sense to add a 2 sec sleep before
exit() in nxt_runtime_exit().
Previously, the nxt_router_prepare_msg() function expected server host among
other headers unmodified. It's not true anymore since normalization of the
Host header has been introduced in 77aad2c142a0.
The nxt_unit_split_host() function was removed. It didn't work correctly with
IPv6 literals. Anyway, after 77aad2c142a0 the port splitting is done in router
while Host header processing.
Timers that don't require maximum precision (most of them, actually) can be
triggered earlier or later within the bias interval.
To reduce wakeups by timers, the expire function now triggers not only all
timers that fall within the elapsed time, but also those whose bias falls
within this interval.
