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?

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

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]

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

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

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

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)

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.

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 :)

On 06/26/2015 07:39 AM, freeman wrote:

> Is this worthy of a bug report?

If it's a bug, yes. :)

Ali