[zeromq-dev] ZMQ appends weird characters to message

Dávid Kaya mail at davidkaya.sk
Mon Sep 15 19:17:49 CEST 2014 

If it would be because of memory, the std::string.replace() would not 
fix, would it? Everything is done in one function, I don't think this is 
the problem.


On 15.09.2014 19:11, gonzalo diethelm wrote:
> That usually happens... Try to focus on the differences between your
> short example and your real code.
>
> One point to focus on could be memory management: are you sure the
> messages you are sending are actually surviving until they get sent? 
> A
> simple wrong way to manage this would be putting your messages in an
> automatic variable that gets overwritten when you leave the function
> that sends the message. Another wrong way would be using a static
> buffer for your messages, that gets overwritten with each message.
>
> HTH.
>
> --
> Gonzalo Diethelm
> DCV Chile
>
>> -----Original Message-----
>> From: zeromq-dev-bounces at lists.zeromq.org [mailto:zeromq-dev-
>> bounces at lists.zeromq.org] On Behalf Of Dávid Kaya
>> Sent: Monday, September 15, 2014 2:02 PM
>> To: ZeroMQ development list
>> Subject: Re: [zeromq-dev] ZMQ appends weird characters to message
>>
>> Well I tried to recreate the problem but it works as intended in my 
>> short
>> example. I really don't know where could be the problem since I am 
>> doing it
>> exactly the same way in my example as in my application. Maybe the
>> problem is in the std::string, because when I use
>> std::string.replace() to replace some characters in the URL then it 
>> works fine.
>> But when I dont use it and append the URL to "success:"
>> message right away, then it does not work. So maybe
>> std::string.replace() somehow fixes the string when it rearranges 
>> it.
>> The first problem with "login" was because I wasn't using size() in 
>> string
>> constructor.
>>
>> David
>>
>> On 15.09.2014 17:56, gonzalo diethelm wrote:
>> > Please create a short (as short as possible) example that shows 
>> this
>> > symptom, and post it to the list.
>> >
>> > --
>> > Gonzalo Diethelm
>> > DCV Chile
>> >
>> >> -----Original Message-----
>> >> From: zeromq-dev-bounces at lists.zeromq.org [mailto:zeromq-dev-
>> >> bounces at lists.zeromq.org] On Behalf Of Dávid Kaya
>> >> Sent: Monday, September 15, 2014 12:39 PM
>> >> To: ZeroMQ development list
>> >> Subject: Re: [zeromq-dev] ZMQ appends weird characters to message
>> >>
>> >> Yes, I've printed that message. There can't be any NULL byte 
>> there.
>> >> It is string
>> >> "success:" appended with url. It is normal url like
>> >> "http://example.org/path/to/jsp?lang=en_US?session="session id 
>> here".
>> >> That session ID contains numbers, characters and dashes.
>> >>
>> >>
>> >> On 15.09.2014 17:30, gonzalo diethelm wrote:
>> >> > No, this is not a (known) limitation. Did you print exactly 
>> what
>> >> you
>> >> > are sending and what you are receiving? My guess is you are
>> >> putting a
>> >> > null byte in the middle of what you are sending.
>> >> >
>> >> > --
>> >> > Gonzalo Diethelm
>> >> > DCV Chile
>> >> >
>> >> >> -----Original Message-----
>> >> >> From: zeromq-dev-bounces at lists.zeromq.org [mailto:zeromq-dev-
>> >> >> bounces at lists.zeromq.org] On Behalf Of Dávid Kaya
>> >> >> Sent: Monday, September 15, 2014 12:21 PM
>> >> >> To: zeromq-dev at lists.zeromq.org
>> >> >> Subject: Re: [zeromq-dev] ZMQ appends weird characters to 
>> message
>> >> >>
>> >> >> Well, I've printed out size and it is correct. I've also
>> >> shortened
>> >> >> the message by 5 characters and it stopped cutting off the 
>> last
>> >> >> characters (atleast I think it stopped, tried 15 times and it
>> >> came
>> >> >> correct every time). So I think the problem was in the length 
>> of
>> >> the
>> >> >> message. I don't know if it is a bug in ZMQ or system 
>> limitation
>> >> of
>> >> >> socket files?
>> >> >>
>> >> >> David
>> >> >>
>> >> >>
>> >> >> On 15.09.2014 16:47, gonzalo diethelm wrote:
>> >> >> > Good point. Forgot about the specific details for that C++
>> >> >> > constructor. The null byte should not be required.
>> >> >> >
>> >> >> > As Tom points out, you should print out what you are sending
>> >> and
>> >> >> > receiving (contents and length) and make sure it makes 
>> sense.
>> >> >> >
>> >> >> > HTH.
>> >> >> >
>> >> >> > --
>> >> >> > Gonzalo Diethelm
>> >> >> > DCV Chile
>> >> >> >
>> >> >> >> -----Original Message-----
>> >> >> >> From: zeromq-dev-bounces at lists.zeromq.org 
>> [mailto:zeromq-dev-
>> >> >> >> bounces at lists.zeromq.org] On Behalf Of Tom Quarendon
>> >> >> >> Sent: Monday, September 15, 2014 11:42 AM
>> >> >> >> To: ZeroMQ development list
>> >> >> >> Subject: Re: [zeromq-dev] ZMQ appends weird characters to
>> >> message
>> >> >> >>
>> >> >> >> > You have two choices:
>> >> >> >> > 1. Send the '\0' as part of the message (and set length 
>> to
>> >> one
>> >> >> >> more byte).
>> >> >> >> > 2. Append a '\0' after receiving the message.
>> >> >> >>
>> >> >> >> Uh, why?
>> >> >> >> string(static_cast<char*>(reply.data()),reply.size());
>> >> >> >> doesn't assume the string is null terminated. It constructs
>> >> >> string
>> >> >> >> from pointer and length. Isn't adding a in a null just 
>> going
>> >> mask
>> >> >> the
>> >> >> >> real issue and make it look like the std::string only
>> >> contained
>> >> >> >> "login" when really it still contained the extra stuff as
>> >> well.
>> >> >> >> David, Do you know what reply.size() actually contains? 
>> Have
>> >> you
>> >> >> >> tried printing that out and comparing it to what you 
>> expect?
>> >> >> >>
>> >> >> >> _______________________________________________
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>> >> > -----------------------------------------
>> >> > Declaración de confidencialidad: Este Mensaje esta destinado 
>> para
>> >> el
>> >> > uso de la o las personas o entidades a quien ha sido dirigido y
>> >> puede
>> >> > contener información reservada y confidencial que no puede ser
>> >> > divulgada, difundida, ni aprovechada en forma alguna. El uso no
>> >> > autorizado de la información contenida en este correo podrá ser
>> >> > sancionado de conformidad con la ley chilena.
>> >> > Si usted ha recibido este correo electrónico por error, le 
>> pedimos
>> >> > eliminarlo junto con los archivos adjuntos y avisar 
>> inmediatamente
>> >> al
>> >> > remitente, respondiendo este mensaje.
>> >> >
>> >> > "Before printing this e-mail think if is really necesary".
>> >> > Disclosure: This Message is to be used by the individual,
>> >> individuals
>> >> > or entities that it is addressed to and may include private and
>> >> > confidential information that may not be disclosed, made public
>> >> nor
>> >> > used in any way at all. Unauthorized use of the information in
>> >> this
>> >> > electronic mail message may be subject to the penalties set 
>> forth
>> >> by
>> >> > Chilean law.
>> >> > If you have received this electronic mail message in error, we 
>> ask
>> >> you
>> >> > to destroy the message and its attached file(s) and to 
>> immediately
>> >> > notify the sender by answering this message.
>> >> > _______________________________________________
>> >> > zeromq-dev mailing list
>> >> > zeromq-dev at lists.zeromq.org
>> >> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>> >>
>> >> _______________________________________________
>> >> zeromq-dev mailing list
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>> >> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>> > _______________________________________________
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>> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>>
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>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>
> -----------------------------------------
> Declaración de confidencialidad: Este Mensaje esta destinado para
> el uso de la o las personas o entidades a quien ha sido dirigido y
> puede contener información reservada y confidencial que no puede
> ser divulgada, difundida, ni aprovechada en forma alguna. El uso no
> autorizado de la información contenida en este correo podrá ser
> sancionado de conformidad con la ley chilena.
> Si usted ha recibido este correo electrónico por error, le pedimos
> eliminarlo junto con los archivos adjuntos y avisar inmediatamente
> al remitente, respondiendo este mensaje.
>
> "Before printing this e-mail think if is really necesary".
> Disclosure: This Message is to be used by the individual,
> individuals or entities that it is addressed to and may include
> private and confidential information that may not be disclosed,
> made public nor used in any way at all. Unauthorized use of the
> information in this electronic mail message may be subject to the
> penalties set forth by Chilean law.
> If you have received this electronic mail message in error, we ask
> you to destroy the message and its attached file(s) and to
> immediately notify the sender by answering this message.
> _______________________________________________
> zeromq-dev mailing list
> zeromq-dev at lists.zeromq.org
> http://lists.zeromq.org/mailman/listinfo/zeromq-dev

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