path: root/utils/rpctrace.c

/* Trace RPCs sent to selected ports

   Copyright (C) 1998, 1999 Free Software Foundation, Inc.

   Written by Jose M. Moya <josem@gnu.org>

   This file is part of the GNU Hurd.

   The GNU Hurd is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   The GNU Hurd is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307, USA. */
#include <hurd.h>
#include <hurd/ports.h>
#include <hurd/ihash.h>
#include <mach/message.h>
#include <assert.h>
#include <fcntl.h>
#include <unistd.h>
#include <argp.h>
#include <error.h>
#include <string.h>
#include <version.h>
#include <sys/wait.h>

const char *argp_program_version = STANDARD_HURD_VERSION (rpctrace);

static const struct argp_option options[] = {
  {"output", 'o', "FILE", 0, "Send trace output to FILE instead of stderr."},
  {0}
};

static const char *args_doc = "COMMAND [ARG...]";
static const char *doc =
"Trace Mach Remote Procedure Calls."
"\v.";

pid_t traced_spawn (char **argv, char **envp);


struct traced_info
{
  struct port_info pi;
  union
  {
    struct traced_info *nextfree; /* Link when on free list.  */

    /* For a send right wrapper, the position in the traced_names hash table.
       For a send-once right wrapper, this is null.  */
    void **locp;
#define INFO_SEND_ONCE(info) ((info)->u.locp == 0)
  } u;
  mach_port_t forward;
};

static struct traced_info *freelist;

task_t traced_task;
ihash_t traced_names;
struct port_class *traced_class;
struct port_bucket *traced_bucket;
FILE *ostream;


/* Create a new wrapper port and do `ports_get_right' on it.  */
static mach_port_t
new_send_wrapper (mach_port_t right)
{
  error_t err;
  struct traced_info *info;
  mach_port_t wrapper;


  /* Use a free send-once wrapper port if we have one.  */
  if (freelist)
    {
      info = freelist;
      freelist = info->u.nextfree;
    }
  else
    {
      /* Create a new wrapper port that forwards to *RIGHT.  */
      err = ports_create_port (traced_class, traced_bucket,
			       sizeof *info, &info);
      assert_perror (err);
    }

  info->forward = right;

  /* Store it in the reverse-lookup hash table, so we can
     look up this same right again to find the wrapper port.
     The entry in the hash table holds a weak ref on INFO.  */
  err = ihash_add (traced_names, info->forward, info, &info->u.locp);
  assert_perror (err);
  ports_port_ref_weak (info);
  assert (info->u.locp != 0);

  wrapper = ports_get_right (info);
  ports_port_deref (info);

  return wrapper;
}

/* Create a new wrapper port and do `ports_get_right' on it.  */
static mach_port_t
new_send_once_wrapper (mach_port_t right)
{
  error_t err;
  struct traced_info *info;
  mach_port_t wrapper;

  /* Use a free send-once wrapper port if we have one.  */
  if (freelist)
    {
      info = freelist;
      freelist = info->u.nextfree;
    }
  else
    {
      /* Create a new wrapper port that forwards to *RIGHT.  */
      err = ports_create_port (traced_class, traced_bucket,
			       sizeof *info, &info);
      assert_perror (err);
    }

  info->forward = right;

  /* Send-once never compare equal to any other right (even another
     send-once right), so there is no point in putting them in the
     reverse-lookup table.

     Since we never make send rights to this port, we don't want to
     use the normal libports mechanisms (ports_get_right) that are
     designed for send rights and no-senders notifications.
     Instead, we hold on to the initial hard ref to INFO until we
     receive a message on it.  The kernel automatically sends a
     MACH_NOTIFY_SEND_ONCE message if the send-once right dies.  */

  info->u.locp = 0;		/* Used to mark this as send-once.  */
  wrapper = info->pi.port_right;

  return wrapper;
}


/* This gets called when a wrapper port has no hard refs (send rights),
   only weak refs.  The only weak ref is the one held in the reverse-lookup
   hash table.  */
static void
traced_dropweak (void *pi)
{
  struct traced_info *const info = pi;

  assert (info->u.locp);

  /* Remove INFO from the hash table.  */
  ihash_locp_remove (traced_names, info->u.locp);
  ports_port_deref_weak (info);

  /* Deallocate the forward port, so the real port also sees no-senders.  */
  mach_port_deallocate (mach_task_self (), info->forward);

  /* There are no rights to this port, so we can reuse it.
     Add a hard ref and put INFO on the free list.  */
  ports_port_ref (info);
  info->u.nextfree = freelist;
  freelist = info;
}



/* Rewrite a port right in a message with an appropriate wrapper port.  */
static error_t
rewrite_right (mach_port_t *right, mach_msg_type_name_t *type)
{
  error_t err;
  struct traced_info *info;

  /* We can never do anything special with a null or dead port right.  */
  if (!MACH_PORT_VALID (*right))
    return 0;

  switch (*type)
    {
    case MACH_MSG_TYPE_PORT_SEND:
      /* See if we are already tracing this port.  */
      info = ihash_find (traced_names, *right);
      if (info)
	{
	  /* We are already tracing this port.  We will pass on a right
	     to our existing wrapper port.  */
	  *right = ports_get_right (info);
	  *type = MACH_MSG_TYPE_MAKE_SEND;
	  return 0;
	}

      /* See if this is already one of our own wrapper ports.  */
      info = ports_lookup_port (traced_bucket, *right, 0);
      if (info)
	{
	  /* This is a send right to an existing wrapper port,
	     so just send it on through.  */
	  ports_port_deref (info);
	  return 0;
	}

      /* We have never seen this port before.  Create a new wrapper port
	 and replace the right in the message with a right to it.  */
      *right = new_send_wrapper (*right);
      *type = MACH_MSG_TYPE_MAKE_SEND;
      return 0;

    case MACH_MSG_TYPE_PORT_SEND_ONCE:
      /* There is no way to know if this send-once right is to the same
	 receive right as any other send-once or send right we have seen.
	 Fortunately, it doesn't matter, since the recipient of the
	 send-once right we pass along can't tell either.  We always just
	 make a new send-once wrapper object, that will trace the one
	 message it receives, and then die.  */
      *type = MACH_MSG_TYPE_MAKE_SEND_ONCE;
      *right = new_send_once_wrapper (*right);
      return 0;

    case MACH_MSG_TYPE_PORT_RECEIVE:
      /* We have got a receive right, call it A.  We will pass along a
	 different receive right of our own, call it B.  We ourselves will
	 receive messages on A, trace them, and forward them on to B.

	 If A is the receive right to a send right that we have wrapped,
	 then B must be that wrapper receive right, moved from us to the
	 intended receiver of A--that way it matches previous send rights
	 to A that were sent through and replaced with our wrapper (B).
	 If not, we create a new receive right.  */
      {
	mach_port_t rr;		/* B */

	info = ihash_find (traced_names, *right);
	if (info)
	  {
	    /* This is a receive right that we have been tracing sends to.  */
	    rr = ports_claim_right (info);
	    /* That released the refs on INFO, so it's been freed now.  */
	  }
	else
	  /* This is a port we know nothing about.  */
	  rr = mach_reply_port ();

	/* Create a new wrapper object that receives on this port.  */
	err = ports_import_port (traced_class, traced_bucket,
				 *right, sizeof *info, &info);
	assert_perror (err);

	/* Get us a send right that we will forward on.  */
	err = mach_port_insert_right (mach_task_self (), rr, rr,
				      MACH_MSG_TYPE_MAKE_SEND);
	assert_perror (err);
	info->forward = rr;

	err = ihash_add (traced_names, info->forward, info, &info->u.locp);
	assert_perror (err);
	ports_port_ref_weak (info);

	/* If there are no extant send rights to this port, then INFO will
	   die right here and release its send right to RR.
	   XXX what to do?
	*/
	ports_port_deref (info);

	*right = rr;
	return 0;
      }

    default:
      assert (!"??? bogus port type from kernel!");
      return EGRATUITOUS;
    }
}


static void
print_header (mach_msg_header_t *msg)
{
  fprintf (ostream,
	   "msgid %d, %d bytes in msg\n"
	   "\treply port %d (type %d)\n",
	   msg->msgh_id,
	   msg->msgh_size,
	   msg->msgh_remote_port, MACH_MSGH_BITS_REMOTE(msg->msgh_bits));
}

static void
print_data (mach_msg_type_name_t type,
	    const void *data,
	    mach_msg_type_number_t nelt,
	    mach_msg_type_number_t eltsize)
{
  switch (type)
    {
    case MACH_MSG_TYPE_STRING:
      fprintf (ostream, "\t\"%.*s\"\n",
	       (int) (nelt * eltsize), (const char *) data);
      break;

    case MACH_MSG_TYPE_BIT:
    case MACH_MSG_TYPE_INTEGER_8:
    case MACH_MSG_TYPE_INTEGER_16:
    case MACH_MSG_TYPE_INTEGER_32:
    case MACH_MSG_TYPE_INTEGER_64:
    case MACH_MSG_TYPE_CHAR:
    case MACH_MSG_TYPE_REAL:
    default:
      /* XXX */
      fprintf (ostream, "\t%#x (type %d, %d*%d)\n", *(const int *)data, type,
	       nelt, eltsize);
      break;
    }
}


int
trace_and_forward (mach_msg_header_t *inp, mach_msg_header_t *outp)
{
  error_t err;
  struct traced_info *info;
  void *msg_buf_ptr = inp + 1;
  mach_msg_bits_t complex;

  /* Look up our record for the receiving port.  There is no need to check
     the class, because our port bucket only ever contains one class of
     ports (traced_class).  */
  info = ports_lookup_port (traced_bucket, inp->msgh_local_port, 0);
  assert (info);

  if (MACH_MSGH_BITS_LOCAL (inp->msgh_bits) == MACH_MSG_TYPE_MOVE_SEND_ONCE)
    {
      if (inp->msgh_id == MACH_NOTIFY_DEAD_NAME)
	{
	  /* If INFO is a send-once wrapper, this could be a forged
	     notification; oh well.  XXX */

	  const mach_dead_name_notification_t *const n = (void *) inp;

	  assert (n->not_port == info->forward);
	  /* Deallocate extra ref allocated by the notification.  */
	  mach_port_deallocate (mach_task_self (), n->not_port);
	  ports_destroy_right (info);
	  ports_port_deref (info);
	  ((mig_reply_header_t *) outp)->RetCode = MIG_NO_REPLY;
	  return 1;
	}
      else if (inp->msgh_id == MACH_NOTIFY_NO_SENDERS
	       && !INFO_SEND_ONCE (info))
	{
	  /* No more senders for a send right we are tracing.  Now INFO
	     will die, and we will release the tracee send right so it too
	     can see a no-senders notification.  */
	  mach_no_senders_notification_t *n = (void *) inp;
	  ports_no_senders (info, n->not_count);
	  ports_port_deref (info);
	  ((mig_reply_header_t *) outp)->RetCode = MIG_NO_REPLY;
	  return 1;
	}
    }

  complex = inp->msgh_bits & MACH_MSGH_BITS_COMPLEX;

  /* Print something about the message header.  */
  fprintf (ostream, "port %d(=>%d) receives (type %d) ",
	   inp->msgh_local_port, info->forward,
	   MACH_MSGH_BITS_LOCAL (inp->msgh_bits));
  print_header (inp);

  /* Swap the header data like a crossover cable. */
  {
    mach_msg_type_name_t this_type = MACH_MSGH_BITS_LOCAL (inp->msgh_bits);
    mach_msg_type_name_t reply_type = MACH_MSGH_BITS_REMOTE (inp->msgh_bits);

    inp->msgh_local_port = inp->msgh_remote_port;
    if (reply_type)
      {
	err = rewrite_right (&inp->msgh_local_port, &reply_type);
	assert_perror (err);
      }

    inp->msgh_remote_port = info->forward;
    if (this_type == MACH_MSG_TYPE_MOVE_SEND_ONCE)
      {
	/* We have a message to forward for a send-once wrapper object.
	   Since each wrapper object only lives for a single message, this
	   one can be reclaimed now.  We continue to hold a hard ref to the
	   ports object, but we know that nothing else refers to it now, and
	   we are consuming its `forward' right in the message we send.  */
	info->u.nextfree = freelist;
	freelist = info;
      }
    else
      this_type = MACH_MSG_TYPE_COPY_SEND;

    inp->msgh_bits = complex | MACH_MSGH_BITS (this_type, reply_type);
  }

  /* Process the message data, wrapping ports and printing data.  */
  while (msg_buf_ptr < (void *) inp + inp->msgh_size)
    {
      mach_msg_type_t *const type = msg_buf_ptr;
      mach_msg_type_long_t *const lt = (void *) type;
      void *data;
      mach_msg_type_number_t nelt; /* Number of data items.  */
      mach_msg_type_size_t eltsize; /* Bytes per item.  */
      mach_msg_type_name_t name; /* MACH_MSG_TYPE_* code */

      if (!type->msgt_longform)
	{
	  name = type->msgt_name;
	  nelt = type->msgt_number;
	  eltsize = type->msgt_size / 8;
	  data = msg_buf_ptr = type + 1;
	}
      else
	{
	  name = lt->msgtl_name;
	  nelt = lt->msgtl_number;
	  eltsize = lt->msgtl_size / 8;
	  data = msg_buf_ptr = lt + 1;
	}

      if (!type->msgt_inline)
	{
	  /* This datum is out-of-line, meaning the message actually
	     contains a pointer to a vm_allocate'd region of data.  */
	  data = *(void **) data;
	  msg_buf_ptr += sizeof (void *);
	}
      else
	msg_buf_ptr += ((nelt * eltsize + sizeof(natural_t) - 1)
			& ~(sizeof(natural_t) - 1));

      /* Note that MACH_MSG_TYPE_PORT_NAME does not indicate a port right.
	 It indicates a port name, i.e. just an integer--and we don't know
	 what task that port name is meaningful in.  If it's meaningful in
	 a traced task, then it refers to our intercepting port rather than
	 the original port anyway.  */
      if (MACH_MSG_TYPE_PORT_ANY_RIGHT (name))
	{
	  /* These are port rights.  Translate them into wrappers.  */
	  mach_port_t *const portnames = data;
	  mach_msg_type_number_t i;
	  mach_msg_type_name_t newtypes[nelt];
	  int poly;

	  assert (complex);
	  assert (eltsize == sizeof (mach_port_t));

	  fprintf (ostream, "\t%d ports, type %d\n", nelt, name);

	  poly = 0;
	  for (i = 0; i < nelt; ++i)
	    {
	      mach_port_t o=portnames[i];
	      newtypes[i] = name;

	      if (inp->msgh_id == 3215) /* mach_port_insert_right */
		{
		  /* XXX
		   */
		  fprintf (ostream,
			   "\t\t[%d] = pass through port %d, type %d\n",
			   i, portnames[i], name);
		  continue;
		}
	      else if (inp->msgh_id == 2089) /* vm_map */
		{
		  /* XXX
		   */
		  struct traced_info *p = ports_lookup_port (traced_bucket,
							     portnames[i], 0);
		  if (p == 0)
		    fprintf (ostream,
			     "\t\t[%d] = pass through port %d, type %d\n",
			     i, portnames[i], name);
		  else
		    {
		      fprintf (ostream,
			       "\t\t[%d] = traced port %d, type %d -> original port %d\n",
			       i, portnames[i], name, p->forward);
		      mach_port_deallocate (mach_task_self (), portnames[i]);
		      portnames[i] = p->forward;
		      newtypes[i] = MACH_MSG_TYPE_COPY_SEND;
		      ports_port_deref (p);
		      continue;
		    }
		}

	      err = rewrite_right (&portnames[i], &newtypes[i]);
	      assert_perror (err);

	      if (portnames[i] == MACH_PORT_NULL)
		fprintf (ostream, "\t\t[%d] = null\n", i);
	      else if (portnames[i] == MACH_PORT_DEAD)
		fprintf (ostream, "\t\t[%d] = dead name\n", i);
	      else
		fprintf (ostream,
			 "\t\t[%d] = port %d, type %d => port %d, type %d\n",
			 i, o, name, portnames[i], newtypes[i]);

	      if (i > 0 && newtypes[i] != newtypes[0])
		poly = 1;
	    }

	  if (poly)
	    {
	      if (name == MACH_MSG_TYPE_MOVE_SEND_ONCE)
		{
		  /* Some of the new rights are MAKE_SEND_ONCE.
		     Turn them all into MOVE_SEND_ONCE.  */
		  for (i = 0; i < nelt; ++i)
		    if (newtypes[i] == MACH_MSG_TYPE_MAKE_SEND_ONCE)
		      {
			err = mach_port_insert_right (mach_task_self (),
						      portnames[i],
						      portnames[i],
						      newtypes[i]);
			assert_perror (err);
		      }
		    else
		      assert (newtypes[i] == MACH_MSG_TYPE_MOVE_SEND_ONCE);
		}
	      else
		{
		  for (i = 0; i < nelt; ++i)
		    switch (newtypes[i])
		      {
		      case MACH_MSG_TYPE_COPY_SEND:
			err = mach_port_mod_refs (mach_task_self (),
						  portnames[i],
						  MACH_PORT_TYPE_SEND, +1);
			assert_perror (err);
			break;
		      case MACH_MSG_TYPE_MAKE_SEND:
			err = mach_port_insert_right (mach_task_self (),
						      portnames[i],
						      portnames[i],
						      newtypes[i]);
			assert_perror (err);
			break;
		      default:
			assert (newtypes[i] == MACH_MSG_TYPE_MOVE_SEND);
			break;
		      }

		  name = MACH_MSG_TYPE_MOVE_SEND;
		}
	      (type->msgt_longform ? lt->msgtl_name : type->msgt_name) = name;
	    }
	  else if (newtypes[0] != name)
	    (type->msgt_longform ? lt->msgtl_name : type->msgt_name)
	      = newtypes[0];
	}
      else
	print_data (name, data, nelt, eltsize);
    }

  /* Resend the message to the tracee.  */
  err = mach_msg (inp, MACH_SEND_MSG, inp->msgh_size, 0,
		  MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
  if (err == MACH_SEND_INVALID_DEST)
    {
      /* The tracee port died.  No doubt we are about to receive the dead-name
	 notification.  */
      /* XXX MAKE_SEND, MAKE_SEND_ONCE rights in msg not handled */
      mach_msg_destroy (inp);
    }
  else
    assert_perror (err);

  ports_port_deref (info);

  /* We already sent the message, so the server loop shouldn't do it again.  */
  ((mig_reply_header_t *) outp)->RetCode = MIG_NO_REPLY;

  return 1;
}


/* This function runs in the tracing thread and drives all the tracing.  */
static any_t
trace_thread_function (void *arg)
{
  struct port_bucket *const bucket = arg;
  ports_manage_port_operations_one_thread (bucket, trace_and_forward, 0);
  return 0;
}


int
main (int argc, char **argv, char **envp)
{
  const char *outfile = 0;
  char **cmd_argv = 0;
  error_t err;

  /* Parse our options...  */
  error_t parse_opt (int key, char *arg, struct argp_state *state)
    {
      switch (key)
	{
	case 'o':
	  outfile = arg;
	  break;

	case ARGP_KEY_NO_ARGS:
	  argp_usage (state);
	  return EINVAL;

	case ARGP_KEY_ARG:
	  cmd_argv = &state->argv[state->next - 1];
	  state->next = state->argc;
	  break;

	default:
	  return ARGP_ERR_UNKNOWN;
	}
      return 0;
    }
  const struct argp argp = { options, parse_opt, args_doc, doc };

  /* Parse our arguments.  */
  argp_parse (&argp, argc, argv, ARGP_IN_ORDER, 0, 0);

  if (outfile)
    {
      ostream = fopen (outfile, "w");
      if (!ostream)
	error (1, errno, "%s", outfile);
    }
  else
    ostream = stderr;

  traced_bucket = ports_create_bucket ();
  traced_class = ports_create_class (0, &traced_dropweak);

  err = ihash_create (&traced_names);
  assert_perror (err);

  /* Spawn a single thread that will receive intercepted messages, print
     them, and interpose on the ports they carry.  The access to the
     `traced_info' and ihash data structures is all single-threaded,
     happening only in this new thread.  */
  cthread_detach (cthread_fork (trace_thread_function, traced_bucket));

  /* Run the program on the command line and wait for it to die.
     The other thread does all the tracing and interposing.  */
  {
    pid_t child, pid;
    int status;
    child = traced_spawn (cmd_argv, envp);
    pid = waitpid (child, &status, 0);
    sleep (1);			/* XXX gives other thread time to print */
    if (pid != child)
      error (1, errno, "waitpid");
    if (WIFEXITED (status))
      fprintf (ostream, "Child %d exited with %d\n",
	       pid, WEXITSTATUS (status));
    else
      fprintf (ostream, "Child %d %s\n", pid, strsignal (WTERMSIG (status)));
  }

  return 0;
}


/* Run a child and have it do more or else `execvpe (argv, envp);'.  */
pid_t
traced_spawn (char **argv, char **envp)
{
  error_t err;
  pid_t pid;
  mach_port_t task_wrapper;
  file_t file = file_name_path_lookup (argv[0], getenv ("PATH"),
				       O_EXEC, 0, 0);

  if (file == MACH_PORT_NULL)
    error (1, errno, "command not found: %s", argv[0]);

  err = task_create (mach_task_self (), 0, &traced_task);
  assert_perror (err);

  /* Create a trace wrapper for the task port.  */
  task_wrapper = new_send_wrapper (traced_task);/* consumes ref */

  /* Replace the task's kernel port with the wrapper.  When this task calls
     `mach_task_self ()', it will get our wrapper send right instead of its
     own real task port.  */
  err = mach_port_insert_right (mach_task_self (), task_wrapper,
				task_wrapper, MACH_MSG_TYPE_MAKE_SEND);
  assert_perror (err);
  err = task_set_special_port (traced_task, TASK_KERNEL_PORT, task_wrapper);
  assert_perror (err);

  /* Declare the new task to be our child.  This is what a fork does.  */
  err = proc_child (getproc (), traced_task);
  if (err)
    error (2, err, "proc_child");
  pid = task2pid (traced_task);
  if (pid < 0)
    error (2, errno, "task2pid");

  /* Now actually run the command they told us to trace.  We do the exec on
     the actual task, so the RPCs to map in the program itself do not get
     traced.  Could have an option to use TASK_WRAPPER here instead.  */
  err = _hurd_exec (traced_task, file, argv, envp);
  if (err)
    error (2, err, "cannot exec `%s'", argv[0]);

  /* We were keeping this send right alive so that the wrapper object
     cannot die and hence our TRACED_TASK ref cannot have been released.  */
  mach_port_deallocate (mach_task_self (), task_wrapper);

  return pid;
}