Thanks for your response Christopher. What I want is to overwrite each http response with another custom response. I'm not talking about manipulating headers only; I want to overwrite the whole response.
Thanks, Seyed > On Apr 12, 2018, at 8:44 AM, Christopher Faulet <cfau...@haproxy.com> wrote: > >> Le 11/04/2018 à 16:11, Hessam Mirsadeghi a écrit : >> Hi Christopher, >> You're right; that segfault happens with the build at the faulty commit and >> not later versions such as v1.8.5. >> However, version v1.8.5 does segfault with the attached modified Lua script. >> As far as I can tell, the problem arises after any call to "txn.res:set()". >> In the attached Lua script, if you remove the call to either of >> "txn.res:set(txn.res:get())" or "txn.res:forward(txn.res:get_in_len())", the >> segfault will disappear. >> Also, when I only have a call to "txn.res:set(txn.res:get())" in the script, >> haproxy becomes unresponsive to all but the first request on each persistent >> connection. That is, something like "curl -sig localhost:80 localhost:80" >> will only get the response for the first request; the second one times out >> on the existing connection and succeeds only on a a second connection >> established by curl. > > So, with this script, I have a segfault. But not only with HAProxy 1.8 and > higher. It also crashes on HAProxy 1.7. Actually, It will crash on all > versions. This is a Lua problem not a HTTP one. > > IMHO, "Channel.set" or "Channel.get" must never be used on HTTP messages. > These functions totally hijack the HTTP parser. There is an attempt to > restore the HTTP parser state. But this is only partially done (the headers' > analysis is done, but not all of the ensuing analysis). So the result is > undefined. It will seem to work for simpler cases but will fail most of time. > Same remarks are true for "Channel.getline" and "Channel.append". > > "Channel.forward" (and "Channel.send") must also never be used on HTTP > messages. When called, the messages analysis is in progress. The HTTP parser > expects to have all the headers at this stage. Mixing message analysis and > data forward is totally unexpected. > > I will let Thierry (the Lua maintainer) decide what to do. But, I guess he > will restrict usage of all these functions to TCP streams only. > > So now, maybe you can describe what you try to do. There is probably another > way to achieve it. I hope so, because it will never work this way. > > -- > Christopher Faulet
