Gdbserver can listen on local domain sockets.

classic Classic list List threaded Threaded
40 messages Options
12
Reply | Threaded
Open this post in threaded view
|

Gdbserver can listen on local domain sockets.

John Darrington-4
This is the complement to commit c1168a2f66553cd4730931cf59e3be8378a1a03f
It allows gdbserver to use a local (unix) domain socket instead of a TCP
socket.

It probably doesn't have much practical use, except that it makes automated
testing of gdb's remote target a little easier.
Reply | Threaded
Open this post in threaded view
|

[PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

John Darrington-4
When invoking gdbserver, if the COMM parameter does not include a colon (:) and
is not the name of an existing character device, then a local (unix) domain
socket will be created with that name and gdbserver will listen for connections
on that.

    gdb/doc/
    * gdb.texinfo (Server): Describe connection over a local domain socket.

    gdb/gdbserver/
    * NEWS: Mention new feature.
    * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
    * remote-utils.c (remote_prepare): Create a local socket if requested.
    * remote-utils.c (remote_open):  Don't attempt to open a file if it's a socket.
    * remote-utils.c (handle_accept_event): Display the name of the socket on connection.
---
 gdb/NEWS                     |   4 ++
 gdb/doc/gdb.texinfo          |  26 +++++--
 gdb/gdbserver/configure.ac   |   2 +-
 gdb/gdbserver/remote-utils.c | 164 ++++++++++++++++++++++++++++++-------------
 4 files changed, 141 insertions(+), 55 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 78d20713a8..95c5083d9b 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -15,6 +15,10 @@
   can be passed using the '[ADDRESS]:PORT' notation, or the regular
   'ADDRESS:PORT' method.
 
+* GDB and GDBserver now support local domain socket connections.  The
+  name of a local domain socket may be provided instead of the
+  [ADDRESS]:PORT notation.
+
 * DWARF index cache: GDB can now automatically save indices of DWARF
   symbols on disk to speed up further loading of the same binaries.
 
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index efd6dffb1e..44b319ebc7 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -21075,9 +21075,13 @@ syntax is:
 target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
 @end smallexample
 
-@var{comm} is either a device name (to use a serial line), or a TCP
+@var{comm} is either an existing device name (to use a serial line), or a TCP
 hostname and portnumber, or @code{-} or @code{stdio} to use
 stdin/stdout of @code{gdbserver}.
+If @var{comm} is none of the above, then a local domain socket
+will be created with that name.
+@cindex local socket
+@cindex Unix domain socket
 For example, to debug Emacs with the argument
 @samp{foo.txt} and communicate with @value{GDBN} over the serial port
 @file{/dev/com1}:
@@ -21107,6 +21111,20 @@ conflicts with another service, @code{gdbserver} prints an error message
 and exits.}  You must use the same port number with the host @value{GDBN}
 @code{target remote} command.
 
+If the target and local machine are one and the same, then you can
+use local domain socket instead of a TCP connection:
+
+@smallexample
+target> gdbserver /tmp/local-socket emacs foo.txt
+@end smallexample
+
+A local domain socket called @file{/tmp/local-socket} will be created
+in the filesystem.
+If there is already a local domain socket with this name it will be removed.
+@smallexample
+(gdb) target remote /tmp/local-socket
+@end smallexample
+
 The @code{stdio} connection is useful when starting @code{gdbserver}
 with ssh:
 
@@ -21155,10 +21173,10 @@ In case more than one copy of @var{program} is running, or @var{program}
 has multiple threads, most versions of @code{pidof} support the
 @code{-s} option to only return the first process ID.
 
-@subsubsection TCP port allocation lifecycle of @code{gdbserver}
+@subsubsection Socket lifecycle of @code{gdbserver}
 
 This section applies only when @code{gdbserver} is run to listen on a TCP
-port.
+port or a unix domain socket.
 
 @code{gdbserver} normally terminates after all of its debugged processes have
 terminated in @kbd{target remote} mode.  On the other hand, for @kbd{target
@@ -21174,7 +21192,7 @@ Such reconnecting is useful for features like @ref{disconnected tracing}.  For
 completeness, at most one @value{GDBN} can be connected at a time.
 
 @cindex @option{--once}, @code{gdbserver} option
-By default, @code{gdbserver} keeps the listening TCP port open, so that
+By default, @code{gdbserver} keeps the listening socket open, so that
 subsequent connections are possible.  However, if you start @code{gdbserver}
 with the @option{--once} option, it will stop listening for any further
 connection attempts after connecting to the first @value{GDBN} session.  This
diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
index fa3ca53efd..de7e7d4103 100644
--- a/gdb/gdbserver/configure.ac
+++ b/gdb/gdbserver/configure.ac
@@ -98,7 +98,7 @@ ACX_CONFIGURE_DIR(["../../libiberty"], ["build-libiberty-gdbserver"])
 AC_CHECK_HEADERS(termios.h sys/reg.h string.h dnl
  proc_service.h sys/procfs.h linux/elf.h dnl
  fcntl.h signal.h sys/file.h dnl
- sys/ioctl.h netinet/in.h sys/socket.h netdb.h dnl
+ sys/ioctl.h netinet/in.h sys/socket.h sys/un.h netdb.h dnl
  netinet/tcp.h arpa/inet.h)
 AC_FUNC_FORK
 AC_CHECK_FUNCS(getauxval pread pwrite pread64 setns)
diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
index 9199a9c7ad..00e3340156 100644
--- a/gdb/gdbserver/remote-utils.c
+++ b/gdb/gdbserver/remote-utils.c
@@ -38,6 +38,9 @@
 #if HAVE_NETINET_IN_H
 #include <netinet/in.h>
 #endif
+#if HAVE_SYS_UN_H
+#include <sys/un.h>
+#endif
 #if HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
@@ -193,20 +196,35 @@ handle_accept_event (int err, gdb_client_data client_data)
      descriptor open for add_file_handler to wait for a new connection.  */
   delete_file_handler (listen_desc);
 
-  /* Convert IP address to string.  */
-  char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
-
-  int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
-       orig_host, sizeof (orig_host),
-       orig_port, sizeof (orig_port),
-       NI_NUMERICHOST | NI_NUMERICSERV);
+  if (sockaddr.ss_family == AF_UNIX)
+    {
+      struct sockaddr_un su;
+      socklen_t len;
+      if (0 != getsockname (listen_desc, (struct sockaddr *) &su, &len))
+ {
+  perror (_("Could not obtain remote address"));
+ }
 
-  if (r != 0)
-    fprintf (stderr, _("Could not obtain remote address: %s\n"),
-     gai_strerror (r));
+      fprintf (stderr, _("Remote debugging on local socket bound to %s\n"),
+       su.sun_path);
+    }
   else
-    fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
-     orig_host, orig_port);
+    {
+      /* Convert IP address to string.  */
+      char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
+
+      int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
+   orig_host, sizeof (orig_host),
+   orig_port, sizeof (orig_port),
+   NI_NUMERICHOST | NI_NUMERICSERV);
+
+      if (r != 0)
+ fprintf (stderr, _("Could not obtain remote address: %s\n"),
+ gai_strerror (r));
+      else
+ fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
+ orig_host, orig_port);
+    }
 
   enable_async_notification (remote_desc);
 
@@ -250,6 +268,9 @@ remote_prepare (const char *name)
   struct addrinfo hint;
   struct addrinfo *ainfo;
 
+  struct sockaddr *addr;
+  socklen_t addrlen;
+
   memset (&hint, 0, sizeof (hint));
   /* Assume no prefix will be passed, therefore we should use
      AF_UNSPEC.  */
@@ -260,10 +281,17 @@ remote_prepare (const char *name)
   parsed_connection_spec parsed
     = parse_connection_spec_without_prefix (name, &hint);
 
+  struct stat statbuf;
+  int stat_result = stat (name, &statbuf);
+
   if (parsed.port_str.empty ())
     {
-      cs.transport_is_reliable = 0;
-      return;
+      if (stat_result == 0
+  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
+ {
+  cs.transport_is_reliable = 0;
+  return;
+ }
     }
 
 #ifdef USE_WIN32API
@@ -276,47 +304,82 @@ remote_prepare (const char *name)
     }
 #endif
 
-  int r = getaddrinfo (parsed.host_str.c_str (), parsed.port_str.c_str (),
-       &hint, &ainfo);
+  struct sockaddr_un unix_addr;
 
-  if (r != 0)
-    error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
+#endif
 
-  scoped_free_addrinfo freeaddrinfo (ainfo);
+  if (parsed.port_str.empty ())
+    {
+      if (strlen (name) > UNIX_PATH_MAX - 1)
+ {
+  error
+    (_("%s is too long.  Socket names may be no longer than %s bytes."),
+     name, pulongest (UNIX_PATH_MAX - 1));
+  return;
+ }
+      listen_desc = socket (AF_UNIX,  SOCK_STREAM,  0);
+      if (listen_desc < 0)
+ perror_with_name ("Can't open socket");
+
+      memset (&unix_addr, 0, sizeof (unix_addr));
+      unix_addr.sun_family = AF_UNIX;
+      strncpy (unix_addr.sun_path, parsed.host_str.c_str(), UNIX_PATH_MAX - 1);
+      if (stat_result == 0
+  && (S_IFSOCK & statbuf.st_mode))
+ unlink (name);
+
+      addr = (struct sockaddr *) &unix_addr;
+      addrlen = sizeof (unix_addr);
+    }
+  else
+    {
+      struct addrinfo *iter;
 
-  struct addrinfo *iter;
+      int r = getaddrinfo (parsed.host_str.c_str (),
+   parsed.port_str.c_str (),
+   &hint, &ainfo);
 
-  for (iter = ainfo; iter != NULL; iter = iter->ai_next)
-    {
-      listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
- iter->ai_protocol);
+      if (r != 0)
+ error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
 
-      if (listen_desc >= 0)
- break;
-    }
+      scoped_free_addrinfo freeaddrinfo (ainfo);
 
-  if (iter == NULL)
-    perror_with_name ("Can't open socket");
+      for (iter = ainfo; iter != NULL; iter = iter->ai_next)
+ {
+  listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
+    iter->ai_protocol);
 
-  /* Allow rapid reuse of this port. */
-  tmp = 1;
-  setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
-      sizeof (tmp));
+  if (listen_desc >= 0)
+    break;
+ }
 
-  switch (iter->ai_family)
-    {
-    case AF_INET:
-      ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
-      break;
-    case AF_INET6:
-      ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
-      break;
-    default:
-      internal_error (__FILE__, __LINE__,
-      _("Invalid 'ai_family' %d\n"), iter->ai_family);
+      if (iter == NULL)
+ perror_with_name ("Can't open socket");
+
+      /* Allow rapid reuse of this port. */
+      tmp = 1;
+      setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
+  sizeof (tmp));
+
+      switch (iter->ai_family)
+ {
+ case AF_INET:
+  ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
+  break;
+ case AF_INET6:
+  ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
+  break;
+ default:
+  internal_error (__FILE__, __LINE__,
+  _("Invalid 'ai_family' %d\n"), iter->ai_family);
+ }
+      addr = iter->ai_addr;
+      addrlen = iter->ai_addrlen;
     }
 
-  if (bind (listen_desc, iter->ai_addr, iter->ai_addrlen) != 0)
+  if (bind (listen_desc, addr, addrlen) != 0)
     perror_with_name ("Can't bind address");
 
   if (listen (listen_desc, 1) != 0)
@@ -334,6 +397,9 @@ remote_open (const char *name)
   const char *port_str;
 
   port_str = strchr (name, ':');
+  struct stat statbuf;
+  int stat_result = stat (name, &statbuf);
+
 #ifdef USE_WIN32API
   if (port_str == NULL)
     error ("Only HOST:PORT is supported on this platform.");
@@ -353,12 +419,10 @@ remote_open (const char *name)
       add_file_handler (remote_desc, handle_serial_event, NULL);
     }
 #ifndef USE_WIN32API
-  else if (port_str == NULL)
+  else if (port_str == NULL && stat_result == 0
+   && 0 == (S_IFSOCK & statbuf.st_mode))
     {
-      struct stat statbuf;
-
-      if (stat (name, &statbuf) == 0
-  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
+      if (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode))
  remote_desc = open (name, O_RDWR);
       else
  {
--
2.11.0

Reply | Threaded
Open this post in threaded view
|

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

Eli Zaretskii
> From: John Darrington <[hidden email]>
> Cc: John Darrington <[hidden email]>
> Date: Tue,  9 Oct 2018 19:32:57 +0200
>
> When invoking gdbserver, if the COMM parameter does not include a colon (:) and
> is not the name of an existing character device, then a local (unix) domain
> socket will be created with that name and gdbserver will listen for connections
> on that.
>
>     gdb/doc/
>     * gdb.texinfo (Server): Describe connection over a local domain socket.
>
>     gdb/gdbserver/
>     * NEWS: Mention new feature.
>     * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
>     * remote-utils.c (remote_prepare): Create a local socket if requested.
>     * remote-utils.c (remote_open):  Don't attempt to open a file if it's a socket.
>     * remote-utils.c (handle_accept_event): Display the name of the socket on connection.

Thanks.  The documentation parts are approved, but I think we should
say somewhere that this feature is only available on systems that
support Unix domain sockets.
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

Pedro Alves-7
In reply to this post by John Darrington-4
On 10/09/2018 06:32 PM, John Darrington wrote:
> When invoking gdbserver, if the COMM parameter does not include a colon (:) and
> is not the name of an existing character device, then a local (unix) domain
> socket will be created with that name and gdbserver will listen for connections
> on that.

Is that "colon/no-colon" magic something that tools frequently do?
Off hand it doesn't seem like a good idea to me, because if you typo a
character device name or unix tcp host name, you end up creating a
unix socket.  I'd think an explicit option would be better.  E.g.,
reuse gdb's connection specs, i.e., a prefix, like:

 gdbserver unix:/tmp/some/path

which can be extended just like gdb's:

 gdbserver tcp:host:port
 gdbserver tcp6:host:port

etc.

That would suggest extending parse_connection_spec to support "unix" specs.

>
>     gdb/doc/
>     * gdb.texinfo (Server): Describe connection over a local domain socket.
>
>     gdb/gdbserver/
>     * NEWS: Mention new feature.

NEWS is under gdb/, not gdb/gdbserver/.

>     * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
>     * remote-utils.c (remote_prepare): Create a local socket if requested.
>     * remote-utils.c (remote_open):  Don't attempt to open a file if it's a socket.
>     * remote-utils.c (handle_accept_event): Display the name of the socket on connection.

Don't repeat "* remote-utils.c" for the second and third functions.

Add "* configure: Regenerate.".


> ---
>  gdb/NEWS                     |   4 ++
>  gdb/doc/gdb.texinfo          |  26 +++++--
>  gdb/gdbserver/configure.ac   |   2 +-
>  gdb/gdbserver/remote-utils.c | 164 ++++++++++++++++++++++++++++++-------------
>  4 files changed, 141 insertions(+), 55 deletions(-)
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 78d20713a8..95c5083d9b 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -15,6 +15,10 @@
>    can be passed using the '[ADDRESS]:PORT' notation, or the regular
>    'ADDRESS:PORT' method.
>  
> +* GDB and GDBserver now support local domain socket connections.  The
> +  name of a local domain socket may be provided instead of the
> +  [ADDRESS]:PORT notation.
> +
>  * DWARF index cache: GDB can now automatically save indices of DWARF
>    symbols on disk to speed up further loading of the same binaries.
>  
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index efd6dffb1e..44b319ebc7 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -21075,9 +21075,13 @@ syntax is:
>  target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
>  @end smallexample
>  
> -@var{comm} is either a device name (to use a serial line), or a TCP
> +@var{comm} is either an existing device name (to use a serial line), or a TCP
>  hostname and portnumber, or @code{-} or @code{stdio} to use
>  stdin/stdout of @code{gdbserver}.
> +If @var{comm} is none of the above, then a local domain socket
> +will be created with that name.
> +@cindex local socket
> +@cindex Unix domain socket
>  For example, to debug Emacs with the argument
>  @samp{foo.txt} and communicate with @value{GDBN} over the serial port
>  @file{/dev/com1}:
> @@ -21107,6 +21111,20 @@ conflicts with another service, @code{gdbserver} prints an error message
>  and exits.}  You must use the same port number with the host @value{GDBN}
>  @code{target remote} command.
>  
> +If the target and local machine are one and the same, then you can
> +use local domain socket instead of a TCP connection:
> +
> +@smallexample
> +target> gdbserver /tmp/local-socket emacs foo.txt
> +@end smallexample
> +
> +A local domain socket called @file{/tmp/local-socket} will be created
> +in the filesystem.
> +If there is already a local domain socket with this name it will be removed.
> +@smallexample
> +(gdb) target remote /tmp/local-socket
> +@end smallexample
> +
>  The @code{stdio} connection is useful when starting @code{gdbserver}
>  with ssh:
>  
> @@ -21155,10 +21173,10 @@ In case more than one copy of @var{program} is running, or @var{program}
>  has multiple threads, most versions of @code{pidof} support the
>  @code{-s} option to only return the first process ID.
>  
> -@subsubsection TCP port allocation lifecycle of @code{gdbserver}
> +@subsubsection Socket lifecycle of @code{gdbserver}
>  
>  This section applies only when @code{gdbserver} is run to listen on a TCP
> -port.
> +port or a unix domain socket.
>  
>  @code{gdbserver} normally terminates after all of its debugged processes have
>  terminated in @kbd{target remote} mode.  On the other hand, for @kbd{target
> @@ -21174,7 +21192,7 @@ Such reconnecting is useful for features like @ref{disconnected tracing}.  For
>  completeness, at most one @value{GDBN} can be connected at a time.
>  
>  @cindex @option{--once}, @code{gdbserver} option
> -By default, @code{gdbserver} keeps the listening TCP port open, so that
> +By default, @code{gdbserver} keeps the listening socket open, so that
>  subsequent connections are possible.  However, if you start @code{gdbserver}
>  with the @option{--once} option, it will stop listening for any further
>  connection attempts after connecting to the first @value{GDBN} session.  This
> diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
> index fa3ca53efd..de7e7d4103 100644
> --- a/gdb/gdbserver/configure.ac
> +++ b/gdb/gdbserver/configure.ac
> @@ -98,7 +98,7 @@ ACX_CONFIGURE_DIR(["../../libiberty"], ["build-libiberty-gdbserver"])
>  AC_CHECK_HEADERS(termios.h sys/reg.h string.h dnl
>   proc_service.h sys/procfs.h linux/elf.h dnl
>   fcntl.h signal.h sys/file.h dnl
> - sys/ioctl.h netinet/in.h sys/socket.h netdb.h dnl
> + sys/ioctl.h netinet/in.h sys/socket.h sys/un.h netdb.h dnl
>   netinet/tcp.h arpa/inet.h)
>  AC_FUNC_FORK
>  AC_CHECK_FUNCS(getauxval pread pwrite pread64 setns)
> diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
> index 9199a9c7ad..00e3340156 100644
> --- a/gdb/gdbserver/remote-utils.c
> +++ b/gdb/gdbserver/remote-utils.c
> @@ -38,6 +38,9 @@
>  #if HAVE_NETINET_IN_H
>  #include <netinet/in.h>
>  #endif
> +#if HAVE_SYS_UN_H
> +#include <sys/un.h>
> +#endif
>  #if HAVE_SYS_SOCKET_H
>  #include <sys/socket.h>
>  #endif
> @@ -193,20 +196,35 @@ handle_accept_event (int err, gdb_client_data client_data)
>       descriptor open for add_file_handler to wait for a new connection.  */
>    delete_file_handler (listen_desc);
>  
> -  /* Convert IP address to string.  */
> -  char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
> -
> -  int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
> -       orig_host, sizeof (orig_host),
> -       orig_port, sizeof (orig_port),
> -       NI_NUMERICHOST | NI_NUMERICSERV);
> +  if (sockaddr.ss_family == AF_UNIX)
> +    {
> +      struct sockaddr_un su;
> +      socklen_t len;
> +      if (0 != getsockname (listen_desc, (struct sockaddr *) &su, &len))

We don't use that "constant on lhs style".  Put the 0 != on the rhs.

> + {
> +  perror (_("Could not obtain remote address"));
> + }

Remove unnecessary curly braces.

>  
> -  if (r != 0)
> -    fprintf (stderr, _("Could not obtain remote address: %s\n"),
> -     gai_strerror (r));
> +      fprintf (stderr, _("Remote debugging on local socket bound to %s\n"),
> +       su.sun_path);
> +    }
>    else
> -    fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
> -     orig_host, orig_port);
> +    {
> +      /* Convert IP address to string.  */
> +      char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
> +
> +      int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
> +   orig_host, sizeof (orig_host),
> +   orig_port, sizeof (orig_port),
> +   NI_NUMERICHOST | NI_NUMERICSERV);
> +
> +      if (r != 0)
> + fprintf (stderr, _("Could not obtain remote address: %s\n"),
> + gai_strerror (r));
> +      else
> + fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
> + orig_host, orig_port);
> +    }
>  
>    enable_async_notification (remote_desc);
>  
> @@ -250,6 +268,9 @@ remote_prepare (const char *name)
>    struct addrinfo hint;
>    struct addrinfo *ainfo;
>  
> +  struct sockaddr *addr;
> +  socklen_t addrlen;
> +
>    memset (&hint, 0, sizeof (hint));
>    /* Assume no prefix will be passed, therefore we should use
>       AF_UNSPEC.  */
> @@ -260,10 +281,17 @@ remote_prepare (const char *name)
>    parsed_connection_spec parsed
>      = parse_connection_spec_without_prefix (name, &hint);
>  
> +  struct stat statbuf;
> +  int stat_result = stat (name, &statbuf);
> +
>    if (parsed.port_str.empty ())
>      {
> -      cs.transport_is_reliable = 0;
> -      return;
> +      if (stat_result == 0
> +  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
> + {
> +  cs.transport_is_reliable = 0;
> +  return;
> + }
>      }
>  
>  #ifdef USE_WIN32API
> @@ -276,47 +304,82 @@ remote_prepare (const char *name)
>      }
>  #endif
>  
> -  int r = getaddrinfo (parsed.host_str.c_str (), parsed.port_str.c_str (),
> -       &hint, &ainfo);
> +  struct sockaddr_un unix_addr;
>  
> -  if (r != 0)
> -    error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
> +#ifndef UNIX_PATH_MAX
> +#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
> +#endif
>  
> -  scoped_free_addrinfo freeaddrinfo (ainfo);
> +  if (parsed.port_str.empty ())
> +    {
> +      if (strlen (name) > UNIX_PATH_MAX - 1)
> + {
> +  error
> +    (_("%s is too long.  Socket names may be no longer than %s bytes."),
> +     name, pulongest (UNIX_PATH_MAX - 1));
> +  return;
> + }
> +      listen_desc = socket (AF_UNIX,  SOCK_STREAM,  0);
> +      if (listen_desc < 0)
> + perror_with_name ("Can't open socket");
> +
> +      memset (&unix_addr, 0, sizeof (unix_addr));
> +      unix_addr.sun_family = AF_UNIX;
> +      strncpy (unix_addr.sun_path, parsed.host_str.c_str(), UNIX_PATH_MAX - 1);
> +      if (stat_result == 0
> +  && (S_IFSOCK & statbuf.st_mode))
> + unlink (name);
> +
> +      addr = (struct sockaddr *) &unix_addr;
> +      addrlen = sizeof (unix_addr);
> +    }
> +  else
> +    {
> +      struct addrinfo *iter;
>  
> -  struct addrinfo *iter;
> +      int r = getaddrinfo (parsed.host_str.c_str (),
> +   parsed.port_str.c_str (),
> +   &hint, &ainfo);
>  
> -  for (iter = ainfo; iter != NULL; iter = iter->ai_next)
> -    {
> -      listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
> - iter->ai_protocol);
> +      if (r != 0)
> + error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
>  
> -      if (listen_desc >= 0)
> - break;
> -    }
> +      scoped_free_addrinfo freeaddrinfo (ainfo);
>  
> -  if (iter == NULL)
> -    perror_with_name ("Can't open socket");
> +      for (iter = ainfo; iter != NULL; iter = iter->ai_next)
> + {
> +  listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
> +    iter->ai_protocol);
>  
> -  /* Allow rapid reuse of this port. */
> -  tmp = 1;
> -  setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
> -      sizeof (tmp));
> +  if (listen_desc >= 0)
> +    break;
> + }
>  
> -  switch (iter->ai_family)
> -    {
> -    case AF_INET:
> -      ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
> -      break;
> -    case AF_INET6:
> -      ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
> -      break;
> -    default:
> -      internal_error (__FILE__, __LINE__,
> -      _("Invalid 'ai_family' %d\n"), iter->ai_family);
> +      if (iter == NULL)
> + perror_with_name ("Can't open socket");
> +
> +      /* Allow rapid reuse of this port. */
> +      tmp = 1;
> +      setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
> +  sizeof (tmp));
> +
> +      switch (iter->ai_family)
> + {
> + case AF_INET:
> +  ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
> +  break;
> + case AF_INET6:
> +  ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
> +  break;
> + default:
> +  internal_error (__FILE__, __LINE__,
> +  _("Invalid 'ai_family' %d\n"), iter->ai_family);
> + }
> +      addr = iter->ai_addr;
> +      addrlen = iter->ai_addrlen;
>      }
>  
> -  if (bind (listen_desc, iter->ai_addr, iter->ai_addrlen) != 0)
> +  if (bind (listen_desc, addr, addrlen) != 0)
>      perror_with_name ("Can't bind address");
>  
>    if (listen (listen_desc, 1) != 0)
> @@ -334,6 +397,9 @@ remote_open (const char *name)
>    const char *port_str;
>  
>    port_str = strchr (name, ':');
> +  struct stat statbuf;
> +  int stat_result = stat (name, &statbuf);
> +
>  #ifdef USE_WIN32API
>    if (port_str == NULL)
>      error ("Only HOST:PORT is supported on this platform.");
> @@ -353,12 +419,10 @@ remote_open (const char *name)
>        add_file_handler (remote_desc, handle_serial_event, NULL);
>      }
>  #ifndef USE_WIN32API
> -  else if (port_str == NULL)
> +  else if (port_str == NULL && stat_result == 0
> +   && 0 == (S_IFSOCK & statbuf.st_mode))

Constant on rhs.

>      {
> -      struct stat statbuf;
> -
> -      if (stat (name, &statbuf) == 0
> -  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
> +      if (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode))
>   remote_desc = open (name, O_RDWR);
>        else
>   {
>

Thanks,
Pedro Alves
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

John Darrington-4
On Tue, Oct 09, 2018 at 07:02:14PM +0100, Pedro Alves wrote:
     On 10/09/2018 06:32 PM, John Darrington wrote:
     > When invoking gdbserver, if the COMM parameter does not include a colon (:) and
     > is not the name of an existing character device, then a local (unix) domain
     > socket will be created with that name and gdbserver will listen for connections
     > on that.
     
     Is that "colon/no-colon" magic something that tools frequently do?

Not exactly.  Tools with which I'm familiar with work as follows:

:1234           Creates a unix domain socket on the local host called 1234
localhost:1234  Listens on TCP port 1234

which is the way I think gdb ought to work, but this would be
inconsistent with it's current behaviour and cause confusion if somebody
used an old version of gdb with a new version of gdbserver or
vici-versa.

J'
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

Pedro Alves-7
On 10/09/2018 07:41 PM, John Darrington wrote:

> On Tue, Oct 09, 2018 at 07:02:14PM +0100, Pedro Alves wrote:
>      On 10/09/2018 06:32 PM, John Darrington wrote:
>      > When invoking gdbserver, if the COMM parameter does not include a colon (:) and
>      > is not the name of an existing character device, then a local (unix) domain
>      > socket will be created with that name and gdbserver will listen for connections
>      > on that.
>      
>      Is that "colon/no-colon" magic something that tools frequently do?
>
> Not exactly.  Tools with which I'm familiar with work as follows:
>
> :1234           Creates a unix domain socket on the local host called 1234
> localhost:1234  Listens on TCP port 1234
>
> which is the way I think gdb ought to work, but this would be
> inconsistent with it's current behaviour and cause confusion if somebody
> used an old version of gdb with a new version of gdbserver or
> vici-versa.

In that example you didn't even pass a path to a unix domain socket.
You let the tool create it, I suppose.  It doesn't feel like
apples to apples.

In those tools you know, how would you pass the path to the local
socket then?

Thanks,
Pedro Alves
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

John Darrington-4
On Tue, Oct 09, 2018 at 07:53:55PM +0100, Pedro Alves wrote:
     On 10/09/2018 07:41 PM, John Darrington wrote:
     > On Tue, Oct 09, 2018 at 07:02:14PM +0100, Pedro Alves wrote:
     >      On 10/09/2018 06:32 PM, John Darrington wrote:
     >      > When invoking gdbserver, if the COMM parameter does not include a colon (:) and
     >      > is not the name of an existing character device, then a local (unix) domain
     >      > socket will be created with that name and gdbserver will listen for connections
     >      > on that.
     >      
     >      Is that "colon/no-colon" magic something that tools frequently do?
     >
     > Not exactly.  Tools with which I'm familiar with work as follows:
     >
     > :1234           Creates a unix domain socket on the local host called 1234
     > localhost:1234  Listens on TCP port 1234
     >
     > which is the way I think gdb ought to work, but this would be
     > inconsistent with it's current behaviour and cause confusion if somebody
     > used an old version of gdb with a new version of gdbserver or
     > vici-versa.
     
     In that example you didn't even pass a path to a unix domain socket.
     You let the tool create it, I suppose.  It doesn't feel like
     apples to apples.
     
     In those tools you know, how would you pass the path to the local
     socket then?
     

If you give no path, it'll refer to a socket in the current working
directory.  An example with a path would be  :/tmp/this/socket
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

Pedro Alves-7

--
Thanks,
Pedro Alves
On 10/09/2018 08:00 PM, John Darrington wrote:

> On Tue, Oct 09, 2018 at 07:53:55PM +0100, Pedro Alves wrote:
>      On 10/09/2018 07:41 PM, John Darrington wrote:
>      > On Tue, Oct 09, 2018 at 07:02:14PM +0100, Pedro Alves wrote:
>      >      On 10/09/2018 06:32 PM, John Darrington wrote:
>      >      > When invoking gdbserver, if the COMM parameter does not include a colon (:) and
>      >      > is not the name of an existing character device, then a local (unix) domain
>      >      > socket will be created with that name and gdbserver will listen for connections
>      >      > on that.
>      >      
>      >      Is that "colon/no-colon" magic something that tools frequently do?
>      >
>      > Not exactly.  Tools with which I'm familiar with work as follows:
>      >
>      > :1234           Creates a unix domain socket on the local host called 1234
>      > localhost:1234  Listens on TCP port 1234
>      >
>      > which is the way I think gdb ought to work, but this would be
>      > inconsistent with it's current behaviour and cause confusion if somebody
>      > used an old version of gdb with a new version of gdbserver or
>      > vici-versa.
>      
>      In that example you didn't even pass a path to a unix domain socket.
>      You let the tool create it, I suppose.  It doesn't feel like
>      apples to apples.
>      
>      In those tools you know, how would you pass the path to the local
>      socket then?
>      
>
> If you give no path, it'll refer to a socket in the current working
> directory.  An example with a path would be  :/tmp/this/socket

Ah, I see now.

Still, yeah, I don't think we can change GDB like that.

Thanks,
Pedro Alves
Reply | Threaded
Open this post in threaded view
|

[PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

John Darrington-4
In reply to this post by Pedro Alves-7
When invoking gdbserver, if the COMM parameter takes the form "unix::/path/name"
then a local (unix) domain socket will be created with that name and gdbserver
will listen for connections on that.

    gdb/
    * NEWS: Mention new feature.

    gdb/gdbserver/
    * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
    * configure: Regenerate.
    * remote-utils.c (remote_prepare): Create a local socket if requested.
     (remote_open):  Don't attempt to open a file if it's a socket.
     (handle_accept_event): Display the name of the socket on connection.

   gdb/common/
   * netstuff.c (parse_connection_spec)[prefixes]: New member for local domain sockets.
---
 gdb/NEWS                     |   4 ++
 gdb/common/netstuff.c        |   9 +++
 gdb/gdbserver/configure.ac   |   2 +-
 gdb/gdbserver/remote-utils.c | 148 ++++++++++++++++++++++++++++++-------------
 4 files changed, 117 insertions(+), 46 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 126e61e282..23de349324 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -15,6 +15,10 @@
   can be passed using the '[ADDRESS]:PORT' notation, or the regular
   'ADDRESS:PORT' method.
 
+* GDB and GDBserver now support local domain socket connections.  The
+  name of a local domain socket may be provided instead of the
+  [ADDRESS]:PORT notation.
+
 * DWARF index cache: GDB can now automatically save indices of DWARF
   symbols on disk to speed up further loading of the same binaries.
 
diff --git a/gdb/common/netstuff.c b/gdb/common/netstuff.c
index c1c401ccb2..8da6aba24e 100644
--- a/gdb/common/netstuff.c
+++ b/gdb/common/netstuff.c
@@ -57,6 +57,8 @@ parse_connection_spec_without_prefix (std::string spec, struct addrinfo *hint)
   || std::count (spec.begin (),
  spec.end (), ':') > 1)));
 
+  bool is_unix = hint->ai_family == AF_UNIX;
+
   if (is_ipv6)
     {
       if (spec[0] == '[')
@@ -109,6 +111,12 @@ parse_connection_spec_without_prefix (std::string spec, struct addrinfo *hint)
   if (ret.host_str.empty ())
     ret.host_str = "localhost";
 
+  if (is_unix && ret.host_str != "localhost")
+    error (_("The host name must be empty or 'localhost' for a unix domain socket."));
+
+  if (is_unix && ret.port_str.empty ())
+    error (_("A path name must be specified for a unix domain socket."));
+
   return ret;
 }
 
@@ -138,6 +146,7 @@ parse_connection_spec (const char *spec, struct addrinfo *hint)
       { "tcp4:", AF_INET,   SOCK_STREAM },
       { "udp6:", AF_INET6,  SOCK_DGRAM },
       { "tcp6:", AF_INET6,  SOCK_STREAM },
+      { "unix:", AF_LOCAL,  SOCK_STREAM },
     };
 
   for (const host_prefix prefix : prefixes)
diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
index fa3ca53efd..de7e7d4103 100644
--- a/gdb/gdbserver/configure.ac
+++ b/gdb/gdbserver/configure.ac
@@ -98,7 +98,7 @@ ACX_CONFIGURE_DIR(["../../libiberty"], ["build-libiberty-gdbserver"])
 AC_CHECK_HEADERS(termios.h sys/reg.h string.h dnl
  proc_service.h sys/procfs.h linux/elf.h dnl
  fcntl.h signal.h sys/file.h dnl
- sys/ioctl.h netinet/in.h sys/socket.h netdb.h dnl
+ sys/ioctl.h netinet/in.h sys/socket.h sys/un.h netdb.h dnl
  netinet/tcp.h arpa/inet.h)
 AC_FUNC_FORK
 AC_CHECK_FUNCS(getauxval pread pwrite pread64 setns)
diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
index 9199a9c7ad..0eb53c2116 100644
--- a/gdb/gdbserver/remote-utils.c
+++ b/gdb/gdbserver/remote-utils.c
@@ -38,6 +38,9 @@
 #if HAVE_NETINET_IN_H
 #include <netinet/in.h>
 #endif
+#if HAVE_SYS_UN_H
+#include <sys/un.h>
+#endif
 #if HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
@@ -193,20 +196,33 @@ handle_accept_event (int err, gdb_client_data client_data)
      descriptor open for add_file_handler to wait for a new connection.  */
   delete_file_handler (listen_desc);
 
-  /* Convert IP address to string.  */
-  char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
-
-  int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
-       orig_host, sizeof (orig_host),
-       orig_port, sizeof (orig_port),
-       NI_NUMERICHOST | NI_NUMERICSERV);
+  if (sockaddr.ss_family == AF_UNIX)
+    {
+      struct sockaddr_un su;
+      socklen_t len;
+      if (getsockname (listen_desc, (struct sockaddr *) &su, &len) != 0)
+ perror (_("Could not obtain remote address"));
 
-  if (r != 0)
-    fprintf (stderr, _("Could not obtain remote address: %s\n"),
-     gai_strerror (r));
+      fprintf (stderr, _("Remote debugging on local socket bound to %s\n"),
+       su.sun_path);
+    }
   else
-    fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
-     orig_host, orig_port);
+    {
+      /* Convert IP address to string.  */
+      char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
+
+      int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
+   orig_host, sizeof (orig_host),
+   orig_port, sizeof (orig_port),
+   NI_NUMERICHOST | NI_NUMERICSERV);
+
+      if (r != 0)
+ fprintf (stderr, _("Could not obtain remote address: %s\n"),
+ gai_strerror (r));
+      else
+ fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
+ orig_host, orig_port);
+    }
 
   enable_async_notification (remote_desc);
 
@@ -250,6 +266,9 @@ remote_prepare (const char *name)
   struct addrinfo hint;
   struct addrinfo *ainfo;
 
+  struct sockaddr *addr;
+  socklen_t addrlen;
+
   memset (&hint, 0, sizeof (hint));
   /* Assume no prefix will be passed, therefore we should use
      AF_UNSPEC.  */
@@ -258,7 +277,7 @@ remote_prepare (const char *name)
   hint.ai_protocol = IPPROTO_TCP;
 
   parsed_connection_spec parsed
-    = parse_connection_spec_without_prefix (name, &hint);
+    = parse_connection_spec (name, &hint);
 
   if (parsed.port_str.empty ())
     {
@@ -276,47 +295,86 @@ remote_prepare (const char *name)
     }
 #endif
 
-  int r = getaddrinfo (parsed.host_str.c_str (), parsed.port_str.c_str (),
-       &hint, &ainfo);
+  struct sockaddr_un unix_addr;
 
-  if (r != 0)
-    error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
+#endif
 
-  scoped_free_addrinfo freeaddrinfo (ainfo);
+  if (hint.ai_family == AF_LOCAL)
+    {
+      const char *sock_name = parsed.port_str.c_str ();
+      if (parsed.port_str.length() > UNIX_PATH_MAX - 1)
+ {
+  error
+    (_("%s is too long.  Socket names may be no longer than %s bytes."),
+     sock_name, pulongest (UNIX_PATH_MAX - 1));
+  return;
+ }
+      listen_desc = socket (AF_UNIX,  SOCK_STREAM,  0);
+      if (listen_desc < 0)
+ perror_with_name ("Can't open socket");
 
-  struct addrinfo *iter;
+      memset (&unix_addr, 0, sizeof (unix_addr));
+      unix_addr.sun_family = AF_UNIX;
+      strncpy (unix_addr.sun_path, sock_name, UNIX_PATH_MAX - 1);
 
-  for (iter = ainfo; iter != NULL; iter = iter->ai_next)
-    {
-      listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
- iter->ai_protocol);
+      struct stat statbuf;
+      int stat_result = stat (sock_name, &statbuf);
+      if (stat_result == 0
+  && (S_IFSOCK & statbuf.st_mode))
+ unlink (sock_name);
 
-      if (listen_desc >= 0)
- break;
+      addr = (struct sockaddr *) &unix_addr;
+      addrlen = sizeof (unix_addr);
     }
+  else
+    {
+      struct addrinfo *iter;
 
-  if (iter == NULL)
-    perror_with_name ("Can't open socket");
+      int r = getaddrinfo (parsed.host_str.c_str (),
+   parsed.port_str.c_str (),
+   &hint, &ainfo);
 
-  /* Allow rapid reuse of this port. */
-  tmp = 1;
-  setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
-      sizeof (tmp));
+      if (r != 0)
+ error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
 
-  switch (iter->ai_family)
-    {
-    case AF_INET:
-      ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
-      break;
-    case AF_INET6:
-      ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
-      break;
-    default:
-      internal_error (__FILE__, __LINE__,
-      _("Invalid 'ai_family' %d\n"), iter->ai_family);
+      scoped_free_addrinfo freeaddrinfo (ainfo);
+
+      for (iter = ainfo; iter != NULL; iter = iter->ai_next)
+ {
+  listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
+    iter->ai_protocol);
+
+  if (listen_desc >= 0)
+    break;
+ }
+
+      if (iter == NULL)
+ perror_with_name ("Can't open socket");
+
+      /* Allow rapid reuse of this port. */
+      tmp = 1;
+      setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
+  sizeof (tmp));
+
+      switch (iter->ai_family)
+ {
+ case AF_INET:
+  ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
+  break;
+ case AF_INET6:
+  ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
+  break;
+ default:
+  internal_error (__FILE__, __LINE__,
+  _("Invalid 'ai_family' %d\n"), iter->ai_family);
+ }
+      addr = iter->ai_addr;
+      addrlen = iter->ai_addrlen;
     }
 
-  if (bind (listen_desc, iter->ai_addr, iter->ai_addrlen) != 0)
+  if (bind (listen_desc, addr, addrlen) != 0)
     perror_with_name ("Can't bind address");
 
   if (listen (listen_desc, 1) != 0)
@@ -354,11 +412,11 @@ remote_open (const char *name)
     }
 #ifndef USE_WIN32API
   else if (port_str == NULL)
-    {
+     {
       struct stat statbuf;
 
       if (stat (name, &statbuf) == 0
-  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
+         && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
  remote_desc = open (name, O_RDWR);
       else
  {
--
2.11.0

Reply | Threaded
Open this post in threaded view
|

[PATCH 2/4] GDB: Document the unix::/path/to/socket of remote connection.

John Darrington-4
gdb/doc:
* gdb.texinfo (Connecting)[Remote Connection Commands]:  Provide alternative
  unix::/tmp/xxx example.  Include @code{unix::@var{local-socket} in
  the list of remote and extended-remote syntaxes.
---
 gdb/doc/gdb.texinfo | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index b0dc3bf67c..1e97d692b6 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -20829,6 +20829,15 @@ Note that this command has the same form as the command to connect
 to a serial line.  @value{GDBN} will automatically determine which
 kind of file you have specified and will make the appropriate kind
 of connection.
+The above command is identical to the command:
+
+@smallexample
+target remote unix::/tmp/gdb-socket1
+@end smallexample
+@noindent
+
+See below for the explanation of this syntax.
+
 This feature is not available if the host system does not support
 Unix domain sockets.
 
@@ -20839,6 +20848,7 @@ Unix domain sockets.
 @itemx target remote @code{tcp4:@var{host}:@var{port}}
 @itemx target remote @code{tcp6:@var{host}:@var{port}}
 @itemx target remote @code{tcp6:@var{[host]}:@var{port}}
+@itemx target remote @code{unix::@var{local-socket}}
 @itemx target extended-remote @code{@var{host}:@var{port}}
 @itemx target extended-remote @code{@var{[host]}:@var{port}}
 @itemx target extended-remote @code{tcp:@var{host}:@var{port}}
@@ -20846,8 +20856,10 @@ Unix domain sockets.
 @itemx target extended-remote @code{tcp4:@var{host}:@var{port}}
 @itemx target extended-remote @code{tcp6:@var{host}:@var{port}}
 @itemx target extended-remote @code{tcp6:@var{[host]}:@var{port}}
+@itemx target extended-remote @code{unix::@var{local-socket}}
 @cindex @acronym{TCP} port, @code{target remote}
-Debug using a @acronym{TCP} connection to @var{port} on @var{host}.
+Debug using a @acronym{TCP} connection to @var{port} on @var{host}
+or using the Unix domain socket @var{local-socket} on the local machine.
 The @var{host} may be either a host name, a numeric @acronym{IPv4}
 address, or a numeric @acronym{IPv6} address (with or without the
 square brackets to separate the address from the port); @var{port}
@@ -20895,6 +20907,16 @@ target remote :1234
 @noindent
 
 Note that the colon is still required here.
+Alternatively you can use a Unix domain socket:
+
+@smallexample
+target remote unix::/tmp/gdb-socket1
+@end smallexample
+@noindent
+
+This has the advantage that it'll not fail if the port number is already
+in use.
+
 
 @item target remote @code{udp:@var{host}:@var{port}}
 @itemx target remote @code{udp:@var{[host]}:@var{port}}
--
2.11.0

Reply | Threaded
Open this post in threaded view
|

[PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

John Darrington-4
In reply to this post by John Darrington-4
The documentation did not mention the possibility of invoking gdbserver
with the new connection forms such as tcp6:host:port.  This change fixes
that.

gdb/doc/

  * gdb.texinfo (Server): Tabulate the various permitted forms of the @var{comm}
   metasyntactical variable.  Include the unix:@var{host}:@var{socket} form as
   one of them.
---
 gdb/doc/gdb.texinfo | 60 +++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 44 insertions(+), 16 deletions(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 1e97d692b6..e3b62221cf 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -21097,9 +21097,19 @@ syntax is:
 target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
 @end smallexample
 
-@var{comm} is either a device name (to use a serial line), or a TCP
-hostname and portnumber, or @code{-} or @code{stdio} to use
-stdin/stdout of @code{gdbserver}.
+@code{gdbserver} waits passively for the host @value{GDBN} to communicate
+with it.
+
+@var{comm} may take several forms:
+
+@table @code
+@item @code{@var{device}}
+A serial line device.
+
+@item @code{-}
+@itemx @code{stdio}
+To use the stdin/stdout of @code{gdbserver}.
+
 For example, to debug Emacs with the argument
 @samp{foo.txt} and communicate with @value{GDBN} over the serial port
 @file{/dev/com1}:
@@ -21108,8 +21118,27 @@ For example, to debug Emacs with the argument
 target> gdbserver /dev/com1 emacs foo.txt
 @end smallexample
 
-@code{gdbserver} waits passively for the host @value{GDBN} to communicate
-with it.
+The @code{stdio} connection is useful when starting @code{gdbserver}
+with ssh:
+
+@smallexample
+(gdb) target remote | ssh -T hostname gdbserver - hello
+@end smallexample
+
+The @samp{-T} option to ssh is provided because we don't need a remote pty,
+and we don't want escape-character handling.  Ssh does this by default when
+a command is provided, the flag is provided to make it explicit.
+You could elide it if you want to.
+
+Programs started with stdio-connected gdbserver have @file{/dev/null} for
+@code{stdin}, and @code{stdout},@code{stderr} are sent back to gdb for
+display through a pipe connected to gdbserver.
+Both @code{stdout} and @code{stderr} use the same pipe.
+
+@item @code{@var{host}:@var{port}}
+@itemx @code{tcp:@var{host}:@var{port}}
+@itemx @code{tcp4:@var{host}:@var{port}}
+To use a @acronym{TCP} @acronym{IPv4} socket connection on port number @var{port}.
 
 To use a TCP connection instead of a serial line:
 
@@ -21129,22 +21158,21 @@ conflicts with another service, @code{gdbserver} prints an error message
 and exits.}  You must use the same port number with the host @value{GDBN}
 @code{target remote} command.
 
-The @code{stdio} connection is useful when starting @code{gdbserver}
-with ssh:
+
+@item @code{tcp6:@var{host}:@var{port}}
+To use a @acronym{TCP} @acronym{IPv6} socket connection on port number @var{port}.
+
+@item @code{unix:@var{host}:@var{local-socket}}
+To use a Unix domain socket.  This will create a socket with the file
+system entry @var{local-socket} and listen on that.  For example:
 
 @smallexample
-(gdb) target remote | ssh -T hostname gdbserver - hello
+target> gdbserver unix:localhost:/tmp/gdb-socket0 emacs foo.txt
 @end smallexample
 
-The @samp{-T} option to ssh is provided because we don't need a remote pty,
-and we don't want escape-character handling.  Ssh does this by default when
-a command is provided, the flag is provided to make it explicit.
-You could elide it if you want to.
+@var{host} must either be the null string or the literal string @code{localhost}.
+@end table
 
-Programs started with stdio-connected gdbserver have @file{/dev/null} for
-@code{stdin}, and @code{stdout},@code{stderr} are sent back to gdb for
-display through a pipe connected to gdbserver.
-Both @code{stdout} and @code{stderr} use the same pipe.
 
 @anchor{Attaching to a program}
 @subsubsection Attaching to a Running Program
--
2.11.0

Reply | Threaded
Open this post in threaded view
|

[PATCH 4/4] GDB: Remote target can now accept the form unix::/path/to/socket.

John Darrington-4
In reply to this post by John Darrington-4
Allow target remote to use the unix::/path/to/socket syntax as well as just
plain /path/to/socket

gdb/

  * ser-uds.c (uds_open): Use parse_connection_spec to deal with the
    comm form unix::/path/to/socket.

  * serial.c (serial_open): Consider the "unix:" prefix when deciding which
    interface to use.
---
 gdb/ser-uds.c | 18 ++++++++++++++++--
 gdb/serial.c  |  5 +++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/gdb/ser-uds.c b/gdb/ser-uds.c
index a98469f67b..acace258be 100644
--- a/gdb/ser-uds.c
+++ b/gdb/ser-uds.c
@@ -23,6 +23,8 @@
 
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <netdb.h>
+#include "netstuff.h"
 
 #ifndef UNIX_PATH_MAX
 #define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
@@ -33,9 +35,21 @@
 static int
 uds_open (struct serial *scb, const char *name)
 {
+  struct addrinfo hint;
+
+  memset (&hint, 0, sizeof (hint));
+  /* Assume no prefix will be passed, therefore we should use
+     AF_UNSPEC.  */
+  hint.ai_family = AF_UNSPEC;
+  hint.ai_socktype = SOCK_STREAM;
+
+  parsed_connection_spec parsed = parse_connection_spec (name, &hint);
+
+  const char *socket_name = parsed.port_str.empty() ? name : parsed.port_str.c_str ();
+
   struct sockaddr_un addr;
 
-  if (strlen (name) > UNIX_PATH_MAX - 1)
+  if (strlen (socket_name) > UNIX_PATH_MAX - 1)
     {
       warning
         (_("The socket name is too long.  It may be no longer than %s bytes."),
@@ -45,7 +59,7 @@ uds_open (struct serial *scb, const char *name)
 
   memset (&addr, 0, sizeof addr);
   addr.sun_family = AF_UNIX;
-  strncpy (addr.sun_path, name, UNIX_PATH_MAX - 1);
+  strncpy (addr.sun_path, socket_name, UNIX_PATH_MAX - 1);
 
   int sock = socket (AF_UNIX, SOCK_STREAM, 0);
 
diff --git a/gdb/serial.c b/gdb/serial.c
index 7f9362a3bf..f7c3e6e5ee 100644
--- a/gdb/serial.c
+++ b/gdb/serial.c
@@ -210,7 +210,7 @@ serial_open (const char *name)
   /* Check for a colon, suggesting an IP address/port pair.
      Do this *after* checking for all the interesting prefixes.  We
      don't want to constrain the syntax of what can follow them.  */
-  else if (strchr (name, ':'))
+  else if (!startswith (name, "unix:") && (strchr (name, ':')))
     ops = serial_interface_lookup ("tcp");
   else
     {
@@ -218,7 +218,8 @@ serial_open (const char *name)
       /* Check to see if name is a socket.  If it is, then treat it
          as such.  Otherwise assume that it's a character device.  */
       struct stat sb;
-      if (stat (name, &sb) == 0 && (sb.st_mode & S_IFMT) == S_IFSOCK)
+      if (startswith (name, "unix:") ||
+  (stat (name, &sb) == 0 && (sb.st_mode & S_IFMT) == S_IFSOCK))
  ops = serial_interface_lookup ("local");
       else
 #endif
--
2.11.0

Reply | Threaded
Open this post in threaded view
|

Re: [PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

Eli Zaretskii
In reply to this post by John Darrington-4
> From: John Darrington <[hidden email]>
> Cc: John Darrington <[hidden email]>
> Date: Sat, 13 Oct 2018 19:58:00 +0200
>
> The documentation did not mention the possibility of invoking gdbserver
> with the new connection forms such as tcp6:host:port.  This change fixes
> that.

Thanks.  Please see a few comments below.

> +@table @code
> +@item @code{@var{device}}
> +A serial line device.

Since your @table uses @code by default, there's no need to use @code
in each @item of the table.

> +@var{host} must either be the null string or the literal string @code{localhost}.

What is a "null string"?  Do you mean an empty string?

Thanks.
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH 2/4] GDB: Document the unix::/path/to/socket of remote connection.

Eli Zaretskii
In reply to this post by John Darrington-4
> From: John Darrington <[hidden email]>
> Cc: John Darrington <[hidden email]>
> Date: Sat, 13 Oct 2018 19:57:59 +0200
>
> gdb/doc:
> * gdb.texinfo (Connecting)[Remote Connection Commands]:  Provide alternative
>   unix::/tmp/xxx example.  Include @code{unix::@var{local-socket} in
>   the list of remote and extended-remote syntaxes.

OK.
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

Eli Zaretskii
In reply to this post by John Darrington-4
> From: John Darrington <[hidden email]>
> Cc: John Darrington <[hidden email]>
> Date: Sat, 13 Oct 2018 19:57:58 +0200
>
> When invoking gdbserver, if the COMM parameter takes the form "unix::/path/name"
> then a local (unix) domain socket will be created with that name and gdbserver
> will listen for connections on that.
>
>     gdb/
>     * NEWS: Mention new feature.
>
>     gdb/gdbserver/
>     * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
>     * configure: Regenerate.
>     * remote-utils.c (remote_prepare): Create a local socket if requested.
>      (remote_open):  Don't attempt to open a file if it's a socket.
>      (handle_accept_event): Display the name of the socket on connection.
>
>    gdb/common/
>    * netstuff.c (parse_connection_spec)[prefixes]: New member for local domain sockets.

OK for the NEWS part.

Thanks.
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH 2/4] GDB: Document the unix::/path/to/socket of remote connection.

Simon Tatham
In reply to this post by John Darrington-4
On 13/10/18 18:57, John Darrington wrote:

> +Alternatively you can use a Unix domain socket:
> +
> +@smallexample
> +target remote unix::/tmp/gdb-socket1
> +@end smallexample
> +@noindent
> +
> +This has the advantage that it'll not fail if the port number is already
> +in use.
> +

Hi,

I was pointed at this thread by a colleague, because last week I was
also considering submitting a patch to allow gdb and gdbserver to talk
to each other over Unix-domain sockets, and he pointed out that it was
already in progress :-)

I'd like to suggest that this documentation change under-stresses what I
see as the most important reason why this is a useful feature: security.

The gdbserver protocol is cleartext and unauthenticated. Running it on a
TCP port means that anyone who can connect to that port – and depending
on the network environment, that might be a lot of people – can request
gdbserver to execute arbitrary code in the context of the process being
debugged, without having to give a vestige of proof as to their right to
ask for it. This is not really the kind of feature we like about network
protocols in the modern world!

But Unix-domain sockets are access-controlled via the file permissions
on the path leading to the socket file. If you use this new feature to
make a Unix-domain socket inside a directory that only your user id has
access to, then any process physically capable of connecting to the
socket has already proved its right to run code under your user id. So
this solves the whole issue, while keeping all the other conveniences of
the socket-based gdbserver transport.

Also, current versions of OpenSSH support general forwarding of
Unix-domain sockets over SSH connections. Using that, it should even be
possible to use this system for genuinely _remote_ debugging (i.e.
between different machines), without reintroducing the same security
hazard, because the Unix socket at each end is access-controlled, and
the network connection in between them is cryptographically protected.

Cheers,
Simon
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH 2/4] GDB: Document the unix::/path/to/socket of remote connection.

John Darrington-4
On Mon, Oct 15, 2018 at 10:31:01AM +0100, Simon Tatham wrote:
     Hi,
     
     I was pointed at this thread by a colleague, because last week I was also
     considering submitting a patch to allow gdb and gdbserver to talk to each
     other over Unix-domain sockets, and he pointed out that it was already in
     progress :-)
     
     I'd like to suggest that this documentation change under-stresses what I
     see as the most important reason why this is a useful feature: security.
     
     The gdbserver protocol is cleartext and unauthenticated. Running it on a
     TCP port means that anyone who can connect to that port ??? and depending
     on the network environment, that might be a lot of people ??? can request
     gdbserver to execute arbitrary code in the context of the process being
     debugged, without having to give a vestige of proof as to their right to
     ask for it. This is not really the kind of feature we like about network
     protocols in the modern world!
     
     But Unix-domain sockets are access-controlled via the file permissions on
     the path leading to the socket file. If you use this new feature to make
     a Unix-domain socket inside a directory that only your user id has access
     to, then any process physically capable of connecting to the socket has
     already proved its right to run code under your user id. So this solves
     the whole issue, while keeping all the other conveniences of the
     socket-based gdbserver transport.
     
     
     Cheers,
     Simon

This is a good point.  But really it belongs under the heading of the
risks associated with TCP/IP sockets - not the risk which is absent when
using Unix sockets.

The documentation already has this warning:

     _Warning:_ 'gdbserver' does not have any built-in security.  Do not
     run 'gdbserver' connected to any public network; a GDB connection
     to 'gdbserver' provides access to the target system with the same
     privileges as the user running 'gdbserver'.

... perhaps that could be expanded to discuss the relative merits of
UDS vs. TCP/IP

J'

--
Avoid eavesdropping.  Send strong encrypted email.
PGP Public key ID: 1024D/2DE827B3
fingerprint = 8797 A26D 0854 2EAB 0285  A290 8A67 719C 2DE8 27B3
See http://sks-keyservers.net or any PGP keyserver for public key.

Reply | Threaded
Open this post in threaded view
|

Re: [PATCH 1/4] GDBSERVER: Listen on a unix domain (instead of TCP) socket if requested.

Sergio Durigan Junior
In reply to this post by John Darrington-4
On Saturday, October 13 2018, John Darrington wrote:

> When invoking gdbserver, if the COMM parameter takes the form "unix::/path/name"
> then a local (unix) domain socket will be created with that name and gdbserver
> will listen for connections on that.

Thanks for the patch.

>     gdb/
>     * NEWS: Mention new feature.
>
>     gdb/gdbserver/
>     * configure.ac (AC_CHECK_HEADERS): Add sys/un.h.
>     * configure: Regenerate.
>     * remote-utils.c (remote_prepare): Create a local socket if requested.
>      (remote_open):  Don't attempt to open a file if it's a socket.
>      (handle_accept_event): Display the name of the socket on connection.
>
>    gdb/common/
>    * netstuff.c (parse_connection_spec)[prefixes]: New member for local domain sockets.
> ---
>  gdb/NEWS                     |   4 ++
>  gdb/common/netstuff.c        |   9 +++
>  gdb/gdbserver/configure.ac   |   2 +-
>  gdb/gdbserver/remote-utils.c | 148 ++++++++++++++++++++++++++++++-------------
>  4 files changed, 117 insertions(+), 46 deletions(-)
>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 126e61e282..23de349324 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -15,6 +15,10 @@
>    can be passed using the '[ADDRESS]:PORT' notation, or the regular
>    'ADDRESS:PORT' method.
>  
> +* GDB and GDBserver now support local domain socket connections.  The
> +  name of a local domain socket may be provided instead of the
> +  [ADDRESS]:PORT notation.

Is it worth explicitly mentioning "UNIX domain socket"?

> +
>  * DWARF index cache: GDB can now automatically save indices of DWARF
>    symbols on disk to speed up further loading of the same binaries.
>  
> diff --git a/gdb/common/netstuff.c b/gdb/common/netstuff.c
> index c1c401ccb2..8da6aba24e 100644
> --- a/gdb/common/netstuff.c
> +++ b/gdb/common/netstuff.c
> @@ -57,6 +57,8 @@ parse_connection_spec_without_prefix (std::string spec, struct addrinfo *hint)
>    || std::count (spec.begin (),
>   spec.end (), ':') > 1)));
>  
> +  bool is_unix = hint->ai_family == AF_UNIX;

No need for a newline between the declarations of is_ipv6 and is_unix.

Here, and everywhere else, AF_UNIX may be undefined if building GDB on a
non-UNIX environment.  I'm afraid you may have to guard this code with
"HAVE_SYS_UN_H".

> +
>    if (is_ipv6)
>      {
>        if (spec[0] == '[')
> @@ -109,6 +111,12 @@ parse_connection_spec_without_prefix (std::string spec, struct addrinfo *hint)
>    if (ret.host_str.empty ())
>      ret.host_str = "localhost";
>  
> +  if (is_unix && ret.host_str != "localhost")
> +    error (_("The host name must be empty or 'localhost' for a unix domain socket."));

This line has more than 80 chars, so you will need to break it.

Also, IIRC the official name for the system is "UNIX" (all caps).

> +
> +  if (is_unix && ret.port_str.empty ())
> +    error (_("A path name must be specified for a unix domain socket."));

So "port_str" is actually a path name if we're dealing with a UNIX
socket?  What do you think about changing the name of the field to
"resource_str" or some such?

> +
>    return ret;
>  }
>  
> @@ -138,6 +146,7 @@ parse_connection_spec (const char *spec, struct addrinfo *hint)
>        { "tcp4:", AF_INET,   SOCK_STREAM },
>        { "udp6:", AF_INET6,  SOCK_DGRAM },
>        { "tcp6:", AF_INET6,  SOCK_STREAM },
> +      { "unix:", AF_LOCAL,  SOCK_STREAM },

The comment I made about AF_UNIX above also applies to AF_LOCAL.

>      };
>  
>    for (const host_prefix prefix : prefixes)
> diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
> index fa3ca53efd..de7e7d4103 100644
> --- a/gdb/gdbserver/configure.ac
> +++ b/gdb/gdbserver/configure.ac
> @@ -98,7 +98,7 @@ ACX_CONFIGURE_DIR(["../../libiberty"], ["build-libiberty-gdbserver"])
>  AC_CHECK_HEADERS(termios.h sys/reg.h string.h dnl
>   proc_service.h sys/procfs.h linux/elf.h dnl
>   fcntl.h signal.h sys/file.h dnl
> - sys/ioctl.h netinet/in.h sys/socket.h netdb.h dnl
> + sys/ioctl.h netinet/in.h sys/socket.h sys/un.h netdb.h dnl
>   netinet/tcp.h arpa/inet.h)
>  AC_FUNC_FORK
>  AC_CHECK_FUNCS(getauxval pread pwrite pread64 setns)

The change for "gdb/gdbserver/configure" hasn't been included in the
patch.  Perhaps you forgot to regenerate it?

> diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
> index 9199a9c7ad..0eb53c2116 100644
> --- a/gdb/gdbserver/remote-utils.c
> +++ b/gdb/gdbserver/remote-utils.c
> @@ -38,6 +38,9 @@
>  #if HAVE_NETINET_IN_H
>  #include <netinet/in.h>
>  #endif
> +#if HAVE_SYS_UN_H
> +#include <sys/un.h>
> +#endif
>  #if HAVE_SYS_SOCKET_H
>  #include <sys/socket.h>
>  #endif
> @@ -193,20 +196,33 @@ handle_accept_event (int err, gdb_client_data client_data)
>       descriptor open for add_file_handler to wait for a new connection.  */
>    delete_file_handler (listen_desc);
>  
> -  /* Convert IP address to string.  */
> -  char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
> -
> -  int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
> -       orig_host, sizeof (orig_host),
> -       orig_port, sizeof (orig_port),
> -       NI_NUMERICHOST | NI_NUMERICSERV);
> +  if (sockaddr.ss_family == AF_UNIX)
> +    {
> +      struct sockaddr_un su;
> +      socklen_t len;

Missing newline here.

According to getsockname(2), 'len' should contain the initial size of
the 'struct sockaddr' you're passing in the second argument.  Therefore,
you should declare 'len' as 'sizeof (su)'.

Also, there's another 'len' declare in the scope above.  In order to
avoid -Wshadow warnings, I'd recommend you to choose another variable
name here.

Last, but not least, this code also needs to be guarded with #ifdef's.

> +      if (getsockname (listen_desc, (struct sockaddr *) &su, &len) != 0)
> + perror (_("Could not obtain remote address"));
>  
> -  if (r != 0)
> -    fprintf (stderr, _("Could not obtain remote address: %s\n"),
> -     gai_strerror (r));
> +      fprintf (stderr, _("Remote debugging on local socket bound to %s\n"),
> +       su.sun_path);
> +    }
>    else
> -    fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
> -     orig_host, orig_port);
> +    {
> +      /* Convert IP address to string.  */
> +      char orig_host[GDB_NI_MAX_ADDR], orig_port[GDB_NI_MAX_PORT];
> +
> +      int r = getnameinfo ((struct sockaddr *) &sockaddr, len,
> +   orig_host, sizeof (orig_host),
> +   orig_port, sizeof (orig_port),
> +   NI_NUMERICHOST | NI_NUMERICSERV);
> +
> +      if (r != 0)
> + fprintf (stderr, _("Could not obtain remote address: %s\n"),
> + gai_strerror (r));
> +      else
> + fprintf (stderr, _("Remote debugging from host %s, port %s\n"),
> + orig_host, orig_port);
> +    }
>  
>    enable_async_notification (remote_desc);
>  
> @@ -250,6 +266,9 @@ remote_prepare (const char *name)
>    struct addrinfo hint;
>    struct addrinfo *ainfo;
>  
> +  struct sockaddr *addr;
> +  socklen_t addrlen;
> +
>    memset (&hint, 0, sizeof (hint));
>    /* Assume no prefix will be passed, therefore we should use
>       AF_UNSPEC.  */
> @@ -258,7 +277,7 @@ remote_prepare (const char *name)
>    hint.ai_protocol = IPPROTO_TCP;
>  
>    parsed_connection_spec parsed
> -    = parse_connection_spec_without_prefix (name, &hint);
> +    = parse_connection_spec (name, &hint);

There's a problem here: gdbserver doesn't work with UDP connections.
Actually, this is the only reason why there's a "_without_prefix"
variant of "parse_connection_spec": because, in this particular case, we
*don't* want to consider prefixes.  Because (so far) gdbserver deals
only with TCP sockets, and because IPv4 and IPv6 addresses are easily
distinguishable, we don't use any kind of prefix.

However, with your patch, we will probably need a prefix indeed (to
differentiate between serial tty devices and UNIX sockets, at least).
My suggestion is that you make a "parse_connection_spec_maybe_unix" or
some such, which takes into account *just* the UNIX prefix (and no
other).  After you extract the "unix:" prefix, you can pass the rest of
the string to "parse_connection_spec_without_prefix" (which would be
made "static" since it won't be used externally anymore).

>  
>    if (parsed.port_str.empty ())
>      {
> @@ -276,47 +295,86 @@ remote_prepare (const char *name)
>      }
>  #endif
>  
> -  int r = getaddrinfo (parsed.host_str.c_str (), parsed.port_str.c_str (),
> -       &hint, &ainfo);
> +  struct sockaddr_un unix_addr;
>  
> -  if (r != 0)
> -    error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
> +#ifndef UNIX_PATH_MAX
> +#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
                               ^

Missing whitespace between function and parens.

> +#endif

Even though I don't quite like using "PATH_MAX"-like because of
reproducibility issues, I don't really know what else could be done here
to prevent that.

>  
> -  scoped_free_addrinfo freeaddrinfo (ainfo);
> +  if (hint.ai_family == AF_LOCAL)
> +    {
> +      const char *sock_name = parsed.port_str.c_str ();
> +      if (parsed.port_str.length() > UNIX_PATH_MAX - 1)
                                   ^
Missing whitespace between function and parens.

> + {
> +  error
> +    (_("%s is too long.  Socket names may be no longer than %s bytes."),

s/bytes/characters/ (increases readability, IMHO)?

> +     sock_name, pulongest (UNIX_PATH_MAX - 1));
> +  return;
> + }
> +      listen_desc = socket (AF_UNIX,  SOCK_STREAM,  0);
> +      if (listen_desc < 0)
> + perror_with_name ("Can't open socket");
>  
> -  struct addrinfo *iter;
> +      memset (&unix_addr, 0, sizeof (unix_addr));
> +      unix_addr.sun_family = AF_UNIX;
> +      strncpy (unix_addr.sun_path, sock_name, UNIX_PATH_MAX - 1);
>  
> -  for (iter = ainfo; iter != NULL; iter = iter->ai_next)
> -    {
> -      listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
> - iter->ai_protocol);
> +      struct stat statbuf;
> +      int stat_result = stat (sock_name, &statbuf);

Missing newline here.  No need for the "stat_result" variable; you can
just check its return value in the "if" below.

> +      if (stat_result == 0
> +  && (S_IFSOCK & statbuf.st_mode))

Don't think you need to break the line.

You should use S_ISSOCK (statbuf.st_mode).

> + unlink (sock_name);
>  
> -      if (listen_desc >= 0)
> - break;
> +      addr = (struct sockaddr *) &unix_addr;
> +      addrlen = sizeof (unix_addr);
>      }
> +  else
> +    {
> +      struct addrinfo *iter;
>  
> -  if (iter == NULL)
> -    perror_with_name ("Can't open socket");
> +      int r = getaddrinfo (parsed.host_str.c_str (),
> +   parsed.port_str.c_str (),
> +   &hint, &ainfo);
>  
> -  /* Allow rapid reuse of this port. */
> -  tmp = 1;
> -  setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
> -      sizeof (tmp));
> +      if (r != 0)
> + error (_("%s: cannot resolve name: %s"), name, gai_strerror (r));
>  
> -  switch (iter->ai_family)
> -    {
> -    case AF_INET:
> -      ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
> -      break;
> -    case AF_INET6:
> -      ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
> -      break;
> -    default:
> -      internal_error (__FILE__, __LINE__,
> -      _("Invalid 'ai_family' %d\n"), iter->ai_family);
> +      scoped_free_addrinfo freeaddrinfo (ainfo);
> +
> +      for (iter = ainfo; iter != NULL; iter = iter->ai_next)
> + {
> +  listen_desc = gdb_socket_cloexec (iter->ai_family, iter->ai_socktype,
> +    iter->ai_protocol);
> +
> +  if (listen_desc >= 0)
> +    break;
> + }
> +
> +      if (iter == NULL)
> + perror_with_name ("Can't open socket");
> +
> +      /* Allow rapid reuse of this port. */
> +      tmp = 1;
> +      setsockopt (listen_desc, SOL_SOCKET, SO_REUSEADDR, (char *) &tmp,
> +  sizeof (tmp));
> +
> +      switch (iter->ai_family)
> + {
> + case AF_INET:
> +  ((struct sockaddr_in *) iter->ai_addr)->sin_addr.s_addr = INADDR_ANY;
> +  break;
> + case AF_INET6:
> +  ((struct sockaddr_in6 *) iter->ai_addr)->sin6_addr = in6addr_any;
> +  break;
> + default:
> +  internal_error (__FILE__, __LINE__,
> +  _("Invalid 'ai_family' %d\n"), iter->ai_family);
> + }
> +      addr = iter->ai_addr;
> +      addrlen = iter->ai_addrlen;
>      }
>  
> -  if (bind (listen_desc, iter->ai_addr, iter->ai_addrlen) != 0)
> +  if (bind (listen_desc, addr, addrlen) != 0)
>      perror_with_name ("Can't bind address");
>  
>    if (listen (listen_desc, 1) != 0)
> @@ -354,11 +412,11 @@ remote_open (const char *name)
>      }
>  #ifndef USE_WIN32API
>    else if (port_str == NULL)
> -    {
> +     {
>        struct stat statbuf;
>  
>        if (stat (name, &statbuf) == 0
> -  && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))
> +         && (S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)))

These two changes are unrelated and should go in a separate patch (they
can be pushed as obvious, BTW).

>   remote_desc = open (name, O_RDWR);
>        else
>   {
> --
> 2.11.0

Thanks,

--
Sergio
GPG key ID: 237A 54B1 0287 28BF 00EF  31F4 D0EB 7628 65FC 5E36
Please send encrypted e-mail if possible
http://sergiodj.net/
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH 2/4] GDB: Document the unix::/path/to/socket of remote connection.

Sergio Durigan Junior
In reply to this post by John Darrington-4
On Saturday, October 13 2018, John Darrington wrote:

> gdb/doc:
> * gdb.texinfo (Connecting)[Remote Connection Commands]:  Provide alternative
>   unix::/tmp/xxx example.  Include @code{unix::@var{local-socket} in
                                                                   ^

Missing close-curly bracket.

>   the list of remote and extended-remote syntaxes.
> ---
>  gdb/doc/gdb.texinfo | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index b0dc3bf67c..1e97d692b6 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -20829,6 +20829,15 @@ Note that this command has the same form as the command to connect
>  to a serial line.  @value{GDBN} will automatically determine which
>  kind of file you have specified and will make the appropriate kind
>  of connection.
> +The above command is identical to the command:
> +
> +@smallexample
> +target remote unix::/tmp/gdb-socket1
> +@end smallexample
> +@noindent
> +
> +See below for the explanation of this syntax.
> +
>  This feature is not available if the host system does not support
>  Unix domain sockets.
>  
> @@ -20839,6 +20848,7 @@ Unix domain sockets.
>  @itemx target remote @code{tcp4:@var{host}:@var{port}}
>  @itemx target remote @code{tcp6:@var{host}:@var{port}}
>  @itemx target remote @code{tcp6:@var{[host]}:@var{port}}
> +@itemx target remote @code{unix::@var{local-socket}}
>  @itemx target extended-remote @code{@var{host}:@var{port}}
>  @itemx target extended-remote @code{@var{[host]}:@var{port}}
>  @itemx target extended-remote @code{tcp:@var{host}:@var{port}}
> @@ -20846,8 +20856,10 @@ Unix domain sockets.
>  @itemx target extended-remote @code{tcp4:@var{host}:@var{port}}
>  @itemx target extended-remote @code{tcp6:@var{host}:@var{port}}
>  @itemx target extended-remote @code{tcp6:@var{[host]}:@var{port}}
> +@itemx target extended-remote @code{unix::@var{local-socket}}
>  @cindex @acronym{TCP} port, @code{target remote}
> -Debug using a @acronym{TCP} connection to @var{port} on @var{host}.
> +Debug using a @acronym{TCP} connection to @var{port} on @var{host}
> +or using the Unix domain socket @var{local-socket} on the local machine.
>  The @var{host} may be either a host name, a numeric @acronym{IPv4}
>  address, or a numeric @acronym{IPv6} address (with or without the
>  square brackets to separate the address from the port); @var{port}
> @@ -20895,6 +20907,16 @@ target remote :1234
>  @noindent
>  
>  Note that the colon is still required here.
> +Alternatively you can use a Unix domain socket:
> +
> +@smallexample
> +target remote unix::/tmp/gdb-socket1
> +@end smallexample
> +@noindent
> +
> +This has the advantage that it'll not fail if the port number is already
> +in use.
> +
>  
>  @item target remote @code{udp:@var{host}:@var{port}}
>  @itemx target remote @code{udp:@var{[host]}:@var{port}}
> --
> 2.11.0

--
Sergio
GPG key ID: 237A 54B1 0287 28BF 00EF  31F4 D0EB 7628 65FC 5E36
Please send encrypted e-mail if possible
http://sergiodj.net/
Reply | Threaded
Open this post in threaded view
|

Re: [PATCH 3/4] GDB: Fix documentation for invoking GDBSERVER

Sergio Durigan Junior
In reply to this post by John Darrington-4
On Saturday, October 13 2018, John Darrington wrote:

> The documentation did not mention the possibility of invoking gdbserver
> with the new connection forms such as tcp6:host:port.  This change fixes
> that.

Thanks for the patch.

As I mentioned while reviewing patch #1, there is a reason why gdbserver
doesn't accept prefixes (which means that there isn't a mistake in the
docs).  If you go with my suggestion and implement just the support for
the "unix:" prefix, then this patch will need to be changed because it
still won't be correct to mention the "tcp" prefixes.

> gdb/doc/
>
>   * gdb.texinfo (Server): Tabulate the various permitted forms of the @var{comm}
>    metasyntactical variable.  Include the unix:@var{host}:@var{socket} form as
>    one of them.
> ---
>  gdb/doc/gdb.texinfo | 60 +++++++++++++++++++++++++++++++++++++++--------------
>  1 file changed, 44 insertions(+), 16 deletions(-)
>
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 1e97d692b6..e3b62221cf 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -21097,9 +21097,19 @@ syntax is:
>  target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
>  @end smallexample
>  
> -@var{comm} is either a device name (to use a serial line), or a TCP
> -hostname and portnumber, or @code{-} or @code{stdio} to use
> -stdin/stdout of @code{gdbserver}.
> +@code{gdbserver} waits passively for the host @value{GDBN} to communicate
> +with it.
> +
> +@var{comm} may take several forms:
> +
> +@table @code
> +@item @code{@var{device}}
> +A serial line device.
> +
> +@item @code{-}
> +@itemx @code{stdio}
> +To use the stdin/stdout of @code{gdbserver}.
> +
>  For example, to debug Emacs with the argument
>  @samp{foo.txt} and communicate with @value{GDBN} over the serial port
>  @file{/dev/com1}:
> @@ -21108,8 +21118,27 @@ For example, to debug Emacs with the argument
>  target> gdbserver /dev/com1 emacs foo.txt
>  @end smallexample
>  
> -@code{gdbserver} waits passively for the host @value{GDBN} to communicate
> -with it.
> +The @code{stdio} connection is useful when starting @code{gdbserver}
> +with ssh:
> +
> +@smallexample
> +(gdb) target remote | ssh -T hostname gdbserver - hello
> +@end smallexample
> +
> +The @samp{-T} option to ssh is provided because we don't need a remote pty,
> +and we don't want escape-character handling.  Ssh does this by default when
> +a command is provided, the flag is provided to make it explicit.
> +You could elide it if you want to.
> +
> +Programs started with stdio-connected gdbserver have @file{/dev/null} for
> +@code{stdin}, and @code{stdout},@code{stderr} are sent back to gdb for
> +display through a pipe connected to gdbserver.
> +Both @code{stdout} and @code{stderr} use the same pipe.
> +
> +@item @code{@var{host}:@var{port}}
> +@itemx @code{tcp:@var{host}:@var{port}}
> +@itemx @code{tcp4:@var{host}:@var{port}}
> +To use a @acronym{TCP} @acronym{IPv4} socket connection on port number @var{port}.
>  
>  To use a TCP connection instead of a serial line:
>  
> @@ -21129,22 +21158,21 @@ conflicts with another service, @code{gdbserver} prints an error message
>  and exits.}  You must use the same port number with the host @value{GDBN}
>  @code{target remote} command.
>  
> -The @code{stdio} connection is useful when starting @code{gdbserver}
> -with ssh:
> +
> +@item @code{tcp6:@var{host}:@var{port}}
> +To use a @acronym{TCP} @acronym{IPv6} socket connection on port number @var{port}.
> +
> +@item @code{unix:@var{host}:@var{local-socket}}
> +To use a Unix domain socket.  This will create a socket with the file
> +system entry @var{local-socket} and listen on that.  For example:
>  
>  @smallexample
> -(gdb) target remote | ssh -T hostname gdbserver - hello
> +target> gdbserver unix:localhost:/tmp/gdb-socket0 emacs foo.txt
>  @end smallexample
>  
> -The @samp{-T} option to ssh is provided because we don't need a remote pty,
> -and we don't want escape-character handling.  Ssh does this by default when
> -a command is provided, the flag is provided to make it explicit.
> -You could elide it if you want to.
> +@var{host} must either be the null string or the literal string @code{localhost}.
> +@end table
>  
> -Programs started with stdio-connected gdbserver have @file{/dev/null} for
> -@code{stdin}, and @code{stdout},@code{stderr} are sent back to gdb for
> -display through a pipe connected to gdbserver.
> -Both @code{stdout} and @code{stderr} use the same pipe.
>  
>  @anchor{Attaching to a program}
>  @subsubsection Attaching to a Running Program
> --
> 2.11.0

--
Sergio
GPG key ID: 237A 54B1 0287 28BF 00EF  31F4 D0EB 7628 65FC 5E36
Please send encrypted e-mail if possible
http://sergiodj.net/
12