Segmentation fault on request transformation

[PasqualePuzio]

I'm trying to write a simple encryption/decryption plugin for Apache Traffic Server. The plugin should transform requests/responses in order to encrypt/decrypt them.

function encrypt(data, eos)
if (data == '') then
    return data, eos
end

if (eos == 1) then
    ts.debug('End of Stream')
end

return data, eos
end

function do_remap()
ts.debug('do_remap')
if (ts.client_request.get_method() == 'POST') then
    ts.hook(TS_LUA_REQUEST_TRANSFORM, encrypt)
end

ts.http.resp_cache_transformed(0)
ts.http.resp_cache_untransformed(0)
return 0
end

Everything works fine for GET and DELETE requests, but when I send a POST chunked-encoded request, ATS crashes almost every time.

Here is the stack trace:

[May 20 13:16:28.105] Server {0x7f045a1c1700} DEBUG: (http_redirect) [HttpSM::do_redirect] [May 20 13:16:28.105] Server {0x7f045a1c1700} DEBUG: (http_redirect) [HttpTunnel::deallocate_postdata_copy_buffers] NOTE: Traffic Server received Sig 11: Segmentation fault bin/traffic_server - STACK TRACE: /lib/x86_64-linux-gnu/libpthread.so.0(+0xfcb0)[0x7f045cd29cb0] bin/traffic_server(_ZN6HttpSM17handle_api_returnEv+0x171)[0x5c274f] bin/traffic_server(_ZN6HttpSM17state_api_calloutEiPv+0x883)[0x5c24cf] bin/traffic_server(_ZN6HttpSM23do_api_callout_internalEv+0x1b7)[0x5ceaef] bin/traffic_server(_ZN6HttpSM14do_api_calloutEv+0x26)[0x5dc18e] bin/traffic_server(_ZN6HttpSM14set_next_stateEv+0x12f9)[0x5d6a19] bin/traffic_server(_ZN6HttpSM32call_transact_and_set_next_stateEPFvPN12HttpTransact5StateEE+0x1ba)[0x5d5718] bin/traffic_server(ZN6HttpSM36state_common_wait_for_transform_readEP17HttpTransformInfoMS_FiiPvEiS2+0x39b)[0x5c1a11] bin/traffic_server(_ZN6HttpSM37state_request_wait_for_transform_readEiPv+0x1e1)[0x5c1483] bin/traffic_server(_ZN6HttpSM12main_handlerEiPv+0x333)[0x5c5eeb] bin/traffic_server(_ZN12Continuation11handleEventEiPv+0x68)[0x4f06b2] bin/traffic_server(_ZN17TransformTerminus12handle_eventEiPv+0x2f6)[0x538d2a] bin/traffic_server(_ZN12Continuation11handleEventEiPv+0x68)[0x4f06b2] bin/traffic_server(_ZN7EThread13process_eventEP5Eventi+0x11e)[0x7537e2] bin/traffic_server(_ZN7EThread7executeEv+0xc9)[0x753a27] bin/traffic_server[0x752ca7] /lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a)[0x7f045cd21e9a] /lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f045c0383fd] Segmentation fault (core dumped) I've already tried to use one of the example plugins for request transformation and I still have the same problem. The only way to make the problem disappear is to avoid request transformation.

Is there something wrong in the way I'm transforming requests? What does this segmentation fault depend on?

Thanks

[portl4t]

The way as I see, apache traffic server doesn't support post chunked request, and there may be bug exist if the request body should be transformed. We can get information in HttpSM::state_request_wait_for_transform_read(..)

1111 // No content length from the post. This is a no go 1112 // since http spec requires content length when 1113 // sending a request message body. Change the event 1114 // to an error and fall through

[PasqualePuzio]

That's really bad!! By the way, if I don't activate the request transformation hook, the chunked request is forwarded perfectly. Also, ATS doesn't crash on every POST request, let's it crashes the 50% of the times (most of the time, if one request is forwarded succesfully, the one after crashes).

[portl4t]

We can say that apache traffic server can not work well with post chunked request if the body should be transformed.

Function HttpSM:: state_request_wait_for_transform_read() may not be used if there is no transform exists.

I think we have to improve ats to support this feature.

[portl4t]

I think this can make some help.

https://groups.google.com/forum/#!topic/ts-lua/8cIMN78bDB0

On Wed, May 21, 2014 at 5:39 PM, PasqualePuzio [email protected] wrote:

That's really bad!! By the way, if I don't activate the request transformation hook, the chunked request is forwarded perfectly. Also, ATS doesn't crash on every POST request, let's it crashes the 50% of the times (most of the time, if one request is forwarded succesfully, the one after crashes).

— Reply to this email directly or view it on GitHub https://github.com/portl4t/ts-lua/issues/7#issuecomment-43734188.