Add set_secure_random_hex

[ckiickA]

Create a random hexadecimal string. Very useful for making trace-ids in X-B3-* headers for zipkin.

[agentzh]

@ckiickA Have you looked at the existing set_secure_random_* directives?

See https://github.com/openresty/set-misc-nginx-module#set_secure_random_alphanum for example.

[ckiickA]

I have. However, there's no way to restrict the string generated to just hex digits. The Zipkin spec says traceid's are random hexadecimal 64 bit numbers. I attempted to use get_random and hex_encode, but hex_encode just gives the ascii codes of the digits.

[agentzh]

@ckiickA Hmm, maybe you should use the ngx_lua module for such special requirements instead. Otherwise this simple ngx_set_misc module would keep growing forever, which is a bad thing IMHO :)

[ckiickA]

Not an option for our environment. I can use a custom patch for now. Just
thought you might find it useful.
Producing a random hex string doesn't seem that much of a special
requirement to me. I was surprised that none of the existing modules could
do it.
Anyway, do what you want with the PR. Just trying to give back.

On Mon, Nov 23, 2015 at 9:29 AM, Yichun Zhang [email protected]
wrote:

@ckiickA https://github.com/ckiickA Hmm, maybe you should use the
ngx_lua module for such special requirements instead. Otherwise this simple
ngx_set_misc module would keep growing forever, which is a bad thing IMHO :)

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Chris J. Kiick
Senior Performance Engineer, Atlassian
[email protected]