Re: Can we redirect from the middle of the transformation in a plugin?

[Bryan Call]

Leif is correct.  They have already been sent to the origin or the 
client depending on the type of transformation plugin.  You can't take 
back the bytes you have already written out to the socket connection.

-Bryan
On 06/29/2011 09:16 PM, Leif Hedstrom wrote:
I'm not in my office, but I'm fairly certain that you can't change the HTTP 
headers (including status code) once the transform has started. Maybe someone 
else with docs / code can confirm.

-- Leif

On Jun 29, 2011, at 5:16 AM, aniket ray<aniket....@gmail.com>  wrote:

I'm trying to process the response data inside a transformation and
based on the processing send a 301 response header to the client with
a different redirect URL each time.
The code was unfortunately crashing (even on TS 3.0)

In an attempt to locate the crash i created a minimalistic code which
is an amalgamation of null transform and redirect-1 plugin codes
(attached).

This code compiles and crashes with the following callstack

#0  operator= (this=0x464ec250, p=0x464ec380) at ../../lib/ts/Ptr.h:414
#1  clone_reader (this=0x464ec250, p=0x464ec380) at
../../iocore/eventsystem/P_IOBuffer.h:859
#2  HttpTunnel::producer_run (this=0x464ec250, p=0x464ec380) at
HttpTunnel.cc:821
#3  0x081a4a21 in HttpTunnel::tunnel_run (this=0x464ec250, p_arg=0x0)
at HttpTunnel.cc:694
#4  0x0816cab0 in HttpSM::setup_internal_transfer (this=0x464eaa90,
handler_arg=(int (HttpSM::*)(HttpSM *, int, void *)) 0x81549b0
<HttpSM::tunnel_handler(int, void*)>)
    at HttpSM.cc:5477
#5  0x0816cfe7 in HttpSM::handle_api_return (this=0x464eaa90) at HttpSM.cc:1574
#6  0x081642c8 in HttpSM::state_api_callout (this=0x464eaa90,
event=60000, data=0x0) at HttpSM.cc:1448
#7  0x081693bf in HttpSM::state_api_callback (this=0x464eaa90,
event=60000, data=0x0) at HttpSM.cc:1267
#8  0x080e3ea9 in TSHttpTxnReenable (txnp=0x464eaa90,
event=TS_EVENT_HTTP_CONTINUE) at InkAPI.cc:5350
#9  0x4005a1ad in handle_response (contp=0x453a4360,
event=TS_EVENT_HTTP_SEND_RESPONSE_HDR, edata=0x464eaa90) at
redirect-1.c:133
#10 redirect_plugin (contp=0x453a4360,
event=TS_EVENT_HTTP_SEND_RESPONSE_HDR, edata=0x464eaa90) at
redirect-1.c:152
#11 0x08164534 in HttpSM::state_api_callout (this=0x464eaa90, event=0,
data=0x0) at HttpSM.cc:1374
#12 0x0816e5c7 in HttpSM::do_api_callout() ()
#13 0x0816ba6b in HttpSM::set_next_state (this=0x464eaa90) at HttpSM.cc:6684
#14 0x08154e1b in HttpSM::call_transact_and_set_next_state
(this=0x464eaa90, f=0x8189ed0
<HttpTransact::HandleApiErrorJump(HttpTransact::State*)>) at
HttpSM.cc:6325
#15 0x08164427 in HttpSM::state_api_callout (this=0x464eaa90,
event=60001, data=0x0) at HttpSM.cc:1460
#16 0x081693bf in HttpSM::state_api_callback (this=0x464eaa90,
event=60001, data=0x0) at HttpSM.cc:1267
#17 0x080e3ea9 in TSHttpTxnReenable (txnp=0x464eaa90,
event=TS_EVENT_HTTP_ERROR) at InkAPI.cc:5350
#18 0x4005a376 in handle_transform (contp=0x973fff0,
event=TS_EVENT_IMMEDIATE, edata=0x46395dd0) at redirect-1.c:271
#19 eventHandler (contp=0x973fff0, event=TS_EVENT_IMMEDIATE,
edata=0x46395dd0) at redirect-1.c:371
#20 0x082e8702 in handleEvent (this=0x40b4e008, e=0x46395dd0,
calling_code=1) at I_Continuation.h:146
#21 EThread::process_event (this=0x40b4e008, e=0x46395dd0,
calling_code=1) at UnixEThread.cc:140
#22 0x082e912c in EThread::execute (this=0x40b4e008) at UnixEThread.cc:189
#23 0x082e6604 in spawn_thread_internal (a=0x96f0fa8) at Thread.cc:88
#24 0x40063cc9 in start_thread (arg=0x40e50b70) at pthread_create.c:304
#25 0x4057069e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130


I think I am not using TSHttpTxnReenable the way it should be. I'd
like to know what the proper way to abort the transformation and place
the HTTP State Machine to the SEND_RESPONSE state would be.

Thanks,
Aniket Ray
<redirect-1.c>


--
-Bryan