Parsing referer URL

luis.gasca · 2014-10-03T20:30:21+00:00

Hello! On Tue, Oct 14, 2014 at 12:19 AM, Michal Cichra wrote: > So you are saying, that callback driven C libraries like expat and yajl are > not comp...

Parsing referer URL

luis.gasca

Hi,

In a log_by_lua handler I need to access a given query string parameter in the referer field. Is there any easy way to parse the referer field value and decode its query string ? I am looking for something like ngx.req.get_uri_args() but for some arbitrary URL.

thanks,

Luis

aapo.talvensaari

On Friday, October 3, 2014 3:30:21 PM UTC+3, luis....@interactive3g.com wrote:

Hi,

In a log_by_lua handler I need to access a given query string parameter in the referer field. Is there any easy way to parse the referer field value and decode its query string ? I am looking for something like ngx.req.get_uri_args() but for some arbitrary URL.

You mean header called Referer?

Try this:

ngx.var.http_referer

luis.gasca

Yes, Referer header. Using ngx.var.http_referer I can access its value, but now I need to parse it and extract the value of a given query param. For example:

Referer: http://www.example.com?a=1&b=2

I need to log the value of the "b" param. Is there any openresty call to parse a given URL ?

Thanks,

Luis

El viernes, 3 de octubre de 2014 15:20:18 UTC+2, Aapo Talvensaari escribió:

On Friday, October 3, 2014 3:30:21 PM UTC+3, luis....@interactive3g.com wrote:
Hi,

In a log_by_lua handler I need to access a given query string parameter in the referer field. Is there any easy way to parse the referer field value and decode its query string ? I am looking for something like ngx.req.get_uri_args() but for some arbitrary URL.

You mean header called Referer?

Try this:

ngx.var.http_referer

aapo.talvensaari

On Friday, October 3, 2014 4:20:18 PM UTC+3, Aapo Talvensaari wrote:

On Friday, October 3, 2014 3:30:21 PM UTC+3, luis....@interactive3g.com wrote:
Hi,

In a log_by_lua handler I need to access a given query string parameter in the referer field. Is there any easy way to parse the referer field value and decode its query string ? I am looking for something like ngx.req.get_uri_args() but for some arbitrary URL.

You mean header called Referer?

Try this:

ngx.var.http_referer

And you can use ngx.decode_args to parse then:

local args = ngx.decode_args(ngx.var.http_referer, 0)

In my testing, this didn't return the first parameter, so there might be a bug in there.

aapo.talvensaari

On Friday, October 3, 2014 4:28:12 PM UTC+3, Aapo Talvensaari wrote:

In my testing, this didn't return the first parameter, so there might be a bug in there.

I opened an issue about this here:

https://github.com/openresty/lua-nginx-module/issues/427

hamish.forbes

Thats because ngx.decode_args() decodes *just* the argument string, not a full URI.

You need to split the URI on '?' and only pass 'a=1&b=2' into the function.

On Friday, 3 October 2014 14:33:10 UTC+1, Aapo Talvensaari wrote:

On Friday, October 3, 2014 4:28:12 PM UTC+3, Aapo Talvensaari wrote:
In my testing, this didn't return the first parameter, so there might be a bug in there.

I opened an issue about this here:
https://github.com/openresty/lua-nginx-module/issues/427

aapo.talvensaari

On Friday, October 3, 2014 4:48:51 PM UTC+3, Hamish Forbes wrote:

Thats because ngx.decode_args() decodes *just* the argument string, not a full URI.
You need to split the URI on '?' and only pass 'a=1&b=2' into the function.

It seems to decode everything just fine from the first `&`, why no to decode correctly from the first `?`. Maybe this is how it is designed, so this could be a feature request / invalid as well. It's fair enough that there is a workaround for it.

luis.gasca

I ended up using ngx.re.match to workaround this.

About the issue, I see it as a feature request; not a bug as it is documented to work only with the query string

Maybe another function like ngx.get_query_string() would fit here.

Thanks,

Luis

El viernes, 3 de octubre de 2014 16:08:23 UTC+2, Aapo Talvensaari escribió:

On Friday, October 3, 2014 4:48:51 PM UTC+3, Hamish Forbes wrote:
Thats because ngx.decode_args() decodes *just* the argument string, not a full URI.
You need to split the URI on '?' and only pass 'a=1&b=2' into the function.

It seems to decode everything just fine from the first `&`, why no to decode correctly from the first `?`. Maybe this is how it is designed, so this could be a feature request / invalid as well. It's fair enough that there is a workaround for it.

aapo.talvensaari

On Friday, October 3, 2014 7:01:17 PM UTC+3, luis....@interactive3g.com wrote:

I ended up using ngx.re.match to workaround this.

About the issue, I see it as a feature request; not a bug as it is documented to work only with the query string
Maybe another function like ngx.get_query_string() would fit here.

I agree. This should probably reside somewhere like in lua-resty-string or something. Easily work-around with Lua.

agentzh

Hello!

On Fri, Oct 3, 2014 at 12:20 PM, Aapo Talvensaari wrote:
> I agree. This should probably reside somewhere like in lua-resty-string or
> something. Easily work-around with Lua.
>

lua-resty-string is becoming a messy mixture :) Better be in a
separate library like lua-resty-uri :)

Regards,
-agentzh

golgote

If you need an url parser in Lua, you can try mine :

https://github.com/golgote/neturl

Feel free to fork and improve.

On Fri, Oct 3, 2014 at 9:37 PM, Yichun Zhang (agentzh) <age...@gmail.com> wrote:

Hello!

On Fri, Oct 3, 2014 at 12:20 PM, Aapo Talvensaari wrote:
> I agree. This should probably reside somewhere like in lua-resty-string or
> something. Easily work-around with Lua.
>

lua-resty-string is becoming a messy mixture :) Better be in a
separate library like lua-resty-uri :)

Regards,
-agentzh

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