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digitalmars.D.learn - Abstract sockets (linux)

reply "freeman" <jamilio123+dlang gmail.com> writes:
I am having trouble using abstract sockets on Linux.

Here is sample python code that works, which works:
     ptm_sockname = "\0/var/run/ptmd.socket"
     sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
     sock.connect(ptm_sockname)
     sock.setblocking(1)
     sock.sendall('get-status detail')

Similar code in D, which does not work:
     string socket_name = "\0/var/run/ptmd.socket";
     auto address = new UnixAddress(socket_name);
     auto sock = new Socket(AddressFamily.UNIX, SocketType.STREAM);
     scope(exit) sock.close();
     sock.blocking = true;
     sock.connect(address);
     sock.send("get-status detail");

This is the equivalent with socat, which works:
     $ echo "get-status detail" | socat - 
ABSTRACT-CLIENT:/var/run/ptmd.socket

My test D program exits on connect:
std.socket.SocketOSException runtime/phobos/std/socket.d(2674): 
Unable to connect socket: Connection refused

Any pointers?
Jun 25 2015
next sibling parent reply Steven Schveighoffer <schveiguy yahoo.com> writes:
On 6/25/15 11:56 AM, freeman wrote:

 I am having trouble using abstract sockets on Linux.

 Here is sample python code that works, which works:
      ptm_sockname = "\0/var/run/ptmd.socket"
      sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
      sock.connect(ptm_sockname)
      sock.setblocking(1)
      sock.sendall('get-status detail')

 Similar code in D, which does not work:
      string socket_name = "\0/var/run/ptmd.socket";
      auto address = new UnixAddress(socket_name);
      auto sock = new Socket(AddressFamily.UNIX, SocketType.STREAM);
      scope(exit) sock.close();
      sock.blocking = true;
      sock.connect(address);
      sock.send("get-status detail");

 This is the equivalent with socat, which works:
      $ echo "get-status detail" | socat -
 ABSTRACT-CLIENT:/var/run/ptmd.socket

 My test D program exits on connect:
 std.socket.SocketOSException runtime/phobos/std/socket.d(2674): Unable
 to connect socket: Connection refused

 Any pointers?


I believe there was a recently fixed bug regarding unix sockets. The 
upcoming 2.068 may help, have you tried the beta?

http://downloads.dlang.org/pre-releases/2.x/2.068.0/

-Steve
Jun 25 2015
parent "freeman" <jamilio123+dlang gmail.com> writes:
On Thursday, 25 June 2015 at 16:07:51 UTC, Steven Schveighoffer 
wrote:

 I believe there was a recently fixed bug regarding unix 
 sockets. The upcoming 2.068 may help, have you tried the beta?

 http://downloads.dlang.org/pre-releases/2.x/2.068.0/

 -Steve


Unfortunately the problem persists (I was using ldc2 before):

$ ./test
std.socket.SocketOSException std/socket.d(2808): Unable to 
connect socket: Connection refused
----------------
./test(_Dmain+0xce) [0x443b42]
./test(_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFZv+0x1f)
[0x44ad7b]
./test(void rt.dmain2._d_run_main(int, char**, extern (C) int 
function(char[][])*).tryExec(scope void delegate())+0x2a) 
[0x44acd6]
./test(void rt.dmain2._d_run_main(int, char**, extern (C) int 
function(char[][])*).runAll()+0x2b) [0x44ad37]
./test(void rt.dmain2._d_run_main(int, char**, extern (C) int 
function(char[][])*).tryExec(scope void delegate())+0x2a) 
[0x44acd6]
./test(_d_run_main+0x1d2) [0x44ac56]
./test(main+0x12) [0x447e96]
/lib64/libc.so.6(__libc_start_main+0xfd) [0x7f1bff50cd5d]
Jun 25 2015
prev sibling next sibling parent reply Daniel Kozak via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> writes:
On Thu, 25 Jun 2015 15:56:04 +0000
freeman via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> wrote:


 I am having trouble using abstract sockets on Linux.
 
 Here is sample python code that works, which works:
      ptm_sockname = "\0/var/run/ptmd.socket"
      sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
      sock.connect(ptm_sockname)
      sock.setblocking(1)
      sock.sendall('get-status detail')
 
 Similar code in D, which does not work:
      string socket_name = "\0/var/run/ptmd.socket";
      auto address = new UnixAddress(socket_name);
      auto sock = new Socket(AddressFamily.UNIX, SocketType.STREAM);
      scope(exit) sock.close();
      sock.blocking = true;
      sock.connect(address);
      sock.send("get-status detail");
 
 This is the equivalent with socat, which works:
      $ echo "get-status detail" | socat - 
 ABSTRACT-CLIENT:/var/run/ptmd.socket
 
 My test D program exits on connect:
 std.socket.SocketOSException runtime/phobos/std/socket.d(2674): 
 Unable to connect socket: Connection refused
 
 Any pointers?


instead of:
string socket_name = "\0/var/run/ptmd.socket";
try:
string socket_name = "/var/run/ptmd.socket";
works for me
Jun 25 2015
parent "freeman" <jamilio123+dlang gmail.com> writes:
On Thursday, 25 June 2015 at 18:50:29 UTC, Daniel Kozak wrote:

 Any pointers?


 instead of:
 string socket_name = "\0/var/run/ptmd.socket";
 try:
 string socket_name = "/var/run/ptmd.socket";
 works for me


It is the null character that makes it an abstract socket (see 
man unix).  There is no file /var/run/ptmd.socket, as what 
follows the null character is just a name:
     $ ls -al /var/run/ptmd.socket
     ls: cannot access /var/run/ptmd.socket: No such file or 
directory

Here is what happens when I remove the null:
     
std.socket.SocketOSException runtime/phobos/std/socket.d(2674): 
Unable to connect socket: No such file or directory
Jun 25 2015
prev sibling next sibling parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 06/25/2015 08:56 AM, freeman wrote:

 I am having trouble using abstract sockets on Linux.

 Here is sample python code that works, which works:
      ptm_sockname = "\0/var/run/ptmd.socket"
      sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
      sock.connect(ptm_sockname)
      sock.setblocking(1)
      sock.sendall('get-status detail')

 Similar code in D, which does not work:
      string socket_name = "\0/var/run/ptmd.socket";
      auto address = new UnixAddress(socket_name);
      auto sock = new Socket(AddressFamily.UNIX, SocketType.STREAM);
      scope(exit) sock.close();
      sock.blocking = true;
      sock.connect(address);
      sock.send("get-status detail");

 This is the equivalent with socat, which works:
      $ echo "get-status detail" | socat -
 ABSTRACT-CLIENT:/var/run/ptmd.socket

 My test D program exits on connect:
 std.socket.SocketOSException runtime/phobos/std/socket.d(2674): Unable
 to connect socket: Connection refused

 Any pointers?


I've found an old example of mine, which uses abstract sockets. 
Apparently, it was a concurrency experiment as well. Just translated 
from Turkish to English:

   http://ddili.org/ornek_kod/client_server.d

One difference I see is that mine doesn't set blocking. You can use it 
like this:

1) Start it as a server:

   ./deneme --role=server

2) Start as many clients as needed:

   ./deneme --role=client

Ali

P.S. And here is the original Turkish version:

   http://ddili.org/ornek_kod/istemci_sunucu.d
Jun 25 2015
parent reply "freeman" <jamilio123+dlang gmail.com> writes:
On Thursday, 25 June 2015 at 19:47:37 UTC, Ali Çehreli wrote:

 I've found an old example of mine, which uses abstract sockets. 
 Apparently, it was a concurrency experiment as well. Just 
 translated from Turkish to English:

   http://ddili.org/ornek_kod/client_server.d

 One difference I see is that mine doesn't set blocking. You can 
 use it like this:

 1) Start it as a server:

   ./deneme --role=server

 2) Start as many clients as needed:

   ./deneme --role=client

 Ali

 P.S. And here is the original Turkish version:

   http://ddili.org/ornek_kod/istemci_sunucu.d


Thank you for the example code!  I verified that client and 
server communicated, and that a standard file-based unix socket 
was not created.  Then I simply changed the socketName to the 
socket I was interested in, and tried the client against it.  
Still no luck unfortunately, same error as earlier.

I have noticed that successful connect calls appear to show the 
size as 23, whereas unsuccessful connect calls show 24.

This works (socat):
     connect(3, {sa_family=AF_FILE, path= "/var/run/ptmd.socket"}, 
23) = 0

This does not (from deneme, modified):
     connect(3, {sa_family=AF_FILE, path= "/var/run/ptmd.socket"}, 
24) = -1 ECONNREFUSED (Connection refused)
Jun 26 2015
parent "Kagamin" <spam here.lot> writes:
On Friday, 26 June 2015 at 13:36:49 UTC, freeman wrote:

 This works (socat):
     connect(3, {sa_family=AF_FILE, 
 path= "/var/run/ptmd.socket"}, 23) = 0

 This does not (from deneme, modified):
     connect(3, {sa_family=AF_FILE, 
 path= "/var/run/ptmd.socket"}, 24) = -1 ECONNREFUSED 
 (Connection refused)


Looks like contrary to other sockets, name of an abstract socket 
is treated as byte array instead of a string, hence every byte 
counts.
Jun 26 2015
prev sibling parent reply "freeman" <jamilio123+dlang gmail.com> writes:
On Thursday, 25 June 2015 at 15:56:06 UTC, freeman wrote:

 I am having trouble using abstract sockets on Linux.

 Here is sample python code that works, which works:
     ptm_sockname = "\0/var/run/ptmd.socket"
     sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
     sock.connect(ptm_sockname)
     sock.setblocking(1)
     sock.sendall('get-status detail')

 Similar code in D, which does not work:
     string socket_name = "\0/var/run/ptmd.socket";
     auto address = new UnixAddress(socket_name);
     auto sock = new Socket(AddressFamily.UNIX, 
 SocketType.STREAM);
     scope(exit) sock.close();
     sock.blocking = true;
     sock.connect(address);
     sock.send("get-status detail");

 This is the equivalent with socat, which works:
     $ echo "get-status detail" | socat - 
 ABSTRACT-CLIENT:/var/run/ptmd.socket

 My test D program exits on connect:
 std.socket.SocketOSException runtime/phobos/std/socket.d(2674): 
 Unable to connect socket: Connection refused

 Any pointers?


OK, I believe I've figured it out.  The strace output I posted 
was the clue I needed to see what was going on.  The length of 
abstract sockets are seemingly improperly calculated.

In socket.d, I modified the constructor for UnixAddress as such:
         this(in char[] path)
         {
             //len = 
cast(socklen_t)(sockaddr_un.init.sun_path.offsetof + path.length 
+ 1);
             len = 
cast(socklen_t)(sockaddr_un.init.sun_path.offsetof + path.length);
             writefln("inside UnixSocket, len is %s", len);
             sun = cast(sockaddr_un*) (new ubyte[len]).ptr;
             sun.sun_family = AF_UNIX;
             sun.sun_path.ptr[0..path.length] = (cast(byte[]) 
path)[];
             sun.sun_path.ptr[path.length] = 0;
         }

This also explains why Ali's client/server code works with 
itself, but it doesn't work with my test case.

This seems to be a bug in socket.d.  If the first character of 
the path is a null character, do not add 1 to the length.  I 
don't have much socket programming experience, but my test code 
does work now.

My full test.d code follows, which now works as expected.  I 
compiled it with » ldc2 test.d std2/socket.d std2/socketstream.d. 
  The only modifications to socketstream.d was the module name and 
std.socket import.

     import std.stdio;
     import std2.socket;
     import std.stream;
     import std2.socketstream;

     void main() {
         enum string socket_name = "\0/var/run/ptmd.socket";
         auto address = new UnixAddress(socket_name);
         writefln("path is --%s--", address.path);
         writefln("length of string is --%s--", 
socket_name.length);
         writefln("length of address is --%s--", address.nameLen);
         auto sock = new Socket(AddressFamily.UNIX, 
SocketType.STREAM);
         scope(exit) sock.close();
         sock.blocking = true;
         sock.connect(address);
         writeln("connected!");

         Stream streamer = new SocketStream(sock);
         scope(exit) streamer.close();
         streamer.writeLine("get-status detail");
         while(true) {
             auto line = streamer.readLine();
             if (line.length == 0 || line == "EOF") {
                 break;
             }
             writeln(line);
         }
     }

Is this worthy of a bug report?  Not a lot of people use abstract 
sockets, but this was certainly frustrating for my use case :)
Jun 26 2015
parent =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 06/26/2015 07:39 AM, freeman wrote:


 Is this worthy of a bug report?


If it's a bug, yes. :)

Ali
Jun 26 2015