Re: [lldb-dev] Remote connection expansion?

2020-11-11 Thread Greg Clayton via lldb-dev


> On Nov 11, 2020, at 11:11 AM, Mike Mestnik 
>  wrote:
> 
> On Mon, Nov 9, 2020 at 5:37 PM Greg Clayton  wrote:
>> 
>> 
>> 
>>> On Nov 4, 2020, at 1:28 PM, Mike Mestnik via lldb-dev 
>>>  wrote:
>>> 
>>> I'm looking for support running lldb over ssh.  I can forward the
>>> originating connection, but the run command is attempting to use
>>> random ports on localhost to attain another connection.  This fails as
>>> the localhost's are not the same.
>> 
>> When you say you want to run lldb over ssh, do you mean run "lldb-server"
> Is there really an issue with saying these are both lldb?  Seems like
> my statements were unambiguous without noting a distinction.
> 
>> remotely and then have a local LLDB connect to that lldb-server?
> That's the usual way lldb is used remotely, so I don't really get that
> lldb does not, in some cases, mean lldb-server.

I am trying to figure out what exactly you would like to see happen here. There 
are many people that run ssh to open a terminal to another computer and run 
lldb on the command line on that remote machine, hence why I was trying to 
clarify what you are are asking for with regards to ssh. 
> 
>> You are looking to avoid "lldb-server" from having to bind to port 0 and 
>> then tell you which port it was actually bound to?
> This is indeed a *feature* of lldb-server and not lldb, so I don't
> really get your confusion when I claim lldb has a feature that's
> entirely implemented with regard to lldb-server.

Again, trying to understand exactly what you are asking for any not sure why 
the snippy answer.


> 
> 
>>> 
>>> Is there a platform, preferably real time, for lldb support?
>>> 
> This is a really important question of mine!  If we can only go back
> and forth on email I'd like ppl to make a best effort to lessen the
> effects this has.  One tip I have, even for when ppl are chatting, is
> to phrase questions in the form of an answer...  Don't ask yes/no
> questions or even questions with say less than 7 answers.  Instead
> provide bullet points of all the possible answers, one at a time.
> There are many good reasons for everyone doing this, but here the most
> relevant is to avoid round-trips that are expansive.


LLDB does have an IRC channel on the LLVM IRC chatbot named "lldb". Many LLDB 
developers do hang out on this chat and can provide some realtime answers for 
LLDB and lldb-server.

> 
> Can you answer your question twice?  Once If I claim that "Yes" I do
> plan on having lldb choose a port to listen on and have ssh forward
> that port and again for if I answer "No".

> 
> I hope you can appreciate that having ssh forward a handful of ports
> for a single service is not optimal.  I'd actually do better by
> writing another set of client-server applications that tunnel the IPC
> over ssh...  Something I'd only do if the program was closed source.
> As lldb is not, the obvious path forward is to re-implement the lldb
> IPC so it's more friendly to ssh.

We are happy to help make remote debugging better and more friendly to ssh. We 
don't have a lot of ssh expertise in the LLDB core group of developers as far 
as I know, so if you have expertise here and can add ways for us to be better 
in that respect, we would love to see any patches. See more detailed solution 
suggestion below on where I think this would fit the best in LLDB.

> 
>>> One might ask why ssh, the basic answer is I don't want to open
>>> *another port on my remote host...  Even if I did I'd still have the
>>> same problem, a random port would fail to connect(this time because of
>>> a firewall).  The main answer is, without ssh, lldb is limited to
>>> running on local or VPN networks.  I'd rather use ssh than configure a
>>> VPN for this one use case.
>>> 
>>> * lldb doesn't sound like something one would want to host, even if
>>> connections were blocked from everywhere "else."
>>> 
>>> Now I'm attempting forward error correction by guessing where this
>>> topic could lead.  I would be willing to expand the network code to
>>> include domain sockets, to replace the whole idea of using, IMHO
>>> barbaric, port numbers.  This work could potentially include direct
>>> support for ssh.  

lldb-server is not limited to port connections. LLDB has a plug-in mechanism 
for communications that is URL based. For example, if you are going to launch 
lldb-server on a remote system and specify a port number of 1234, you would 
connect to it with:

(lldb) process connect connect://remote.foo.com:1234 


"process connect" uses a communication plug-in that is specified by the URL for 
the first argument: "connect://". Each communication plug-in built into lldb 
and lldb-server registers a URL with the LLDB codebase so it can be easily 
found and used. "connect://" will get you a direct TCP connection using IPV4 of 
IPV6 depending on the rest of the URL. There isn't a valid URL for direct TCP 
connections so we made one up ("connect://"). 

The reason I mention this is this is where I would 

Re: [lldb-dev] Remote connection expansion?

2020-11-11 Thread Mike Mestnik via lldb-dev
On Mon, Nov 9, 2020 at 5:37 PM Greg Clayton  wrote:
>
>
>
> > On Nov 4, 2020, at 1:28 PM, Mike Mestnik via lldb-dev 
> >  wrote:
> >
> > I'm looking for support running lldb over ssh.  I can forward the
> > originating connection, but the run command is attempting to use
> > random ports on localhost to attain another connection.  This fails as
> > the localhost's are not the same.
>
> When you say you want to run lldb over ssh, do you mean run "lldb-server"
Is there really an issue with saying these are both lldb?  Seems like
my statements were unambiguous without noting a distinction.

> remotely and then have a local LLDB connect to that lldb-server?
That's the usual way lldb is used remotely, so I don't really get that
lldb does not, in some cases, mean lldb-server.

> You are looking to avoid "lldb-server" from having to bind to port 0 and then 
> tell you which port it was actually bound to?
This is indeed a *feature* of lldb-server and not lldb, so I don't
really get your confusion when I claim lldb has a feature that's
entirely implemented with regard to lldb-server.

> >
> > Is there a platform, preferably real time, for lldb support?
> >
This is a really important question of mine!  If we can only go back
and forth on email I'd like ppl to make a best effort to lessen the
effects this has.  One tip I have, even for when ppl are chatting, is
to phrase questions in the form of an answer...  Don't ask yes/no
questions or even questions with say less than 7 answers.  Instead
provide bullet points of all the possible answers, one at a time.
There are many good reasons for everyone doing this, but here the most
relevant is to avoid round-trips that are expansive.

Can you answer your question twice?  Once If I claim that "Yes" I do
plan on having lldb choose a port to listen on and have ssh forward
that port and again for if I answer "No".

I hope you can appreciate that having ssh forward a handful of ports
for a single service is not optimal.  I'd actually do better by
writing another set of client-server applications that tunnel the IPC
over ssh...  Something I'd only do if the program was closed source.
As lldb is not, the obvious path forward is to re-implement the lldb
IPC so it's more friendly to ssh.

> > One might ask why ssh, the basic answer is I don't want to open
> > *another port on my remote host...  Even if I did I'd still have the
> > same problem, a random port would fail to connect(this time because of
> > a firewall).  The main answer is, without ssh, lldb is limited to
> > running on local or VPN networks.  I'd rather use ssh than configure a
> > VPN for this one use case.
> >
> > * lldb doesn't sound like something one would want to host, even if
> > connections were blocked from everywhere "else."
> >
> > Now I'm attempting forward error correction by guessing where this
> > topic could lead.  I would be willing to expand the network code to
> > include domain sockets, to replace the whole idea of using, IMHO
> > barbaric, port numbers.  This work could potentially include direct
> > support for ssh.  I understand that this would likely be a breaking
> > change, is there version negotiation?
> > ___
> > lldb-dev mailing list
> > lldb-dev@lists.llvm.org
> > https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>
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