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bacon-message-connection.c

/*
 * Copyright (C) 2003 Bastien Nocera <hadess@hadess.net>
 *
 * This program 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 of the License, or
 * (at your option) any later version.
 *
 * This program 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 <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <errno.h>

#include "bacon-message-connection.h"

#ifndef UNIX_PATH_MAX
#define UNIX_PATH_MAX 108
#endif

struct BaconMessageConnection {
      /* A server accepts connections */
      gboolean is_server;

      /* The socket path itself */
      char *path;

      /* File descriptor of the socket */
      int fd;
      /* Channel to watch */
      GIOChannel *chan;
      /* Event id returned by g_io_add_watch() */
      int conn_id;

      /* Connections accepted by this connection */
      GSList *accepted_connections;

      /* callback */
      void (*func) (const char *message, gpointer user_data);
      gpointer data;
};

static gboolean
test_is_socket (const char *path)
{
      struct stat s;

      if (stat (path, &s) == -1)
            return FALSE;

      if (S_ISSOCK (s.st_mode))
            return TRUE;

      return FALSE;
}

static gboolean
is_owned_by_user_and_socket (const char *path)
{
      struct stat s;

      if (stat (path, &s) == -1)
            return FALSE;

      if (s.st_uid != geteuid ())
            return FALSE;

      if ((s.st_mode & S_IFSOCK) != S_IFSOCK)
            return FALSE;
      
      return TRUE;
}

static gboolean server_cb (GIOChannel *source,
                     GIOCondition condition, gpointer data);

static gboolean
setup_connection (BaconMessageConnection *conn)
{
      g_return_val_if_fail (conn->chan == NULL, FALSE);

      conn->chan = g_io_channel_unix_new (conn->fd);
      if (!conn->chan) {
            return FALSE;
      }
      g_io_channel_set_line_term (conn->chan, "\n", 1);
      conn->conn_id = g_io_add_watch (conn->chan, G_IO_IN, server_cb, conn);

      return TRUE;
}

static void
accept_new_connection (BaconMessageConnection *server_conn)
{
      BaconMessageConnection *conn;
      int alen;

      g_return_if_fail (server_conn->is_server);

      conn = g_new0 (BaconMessageConnection, 1);
      conn->is_server = FALSE;
      conn->func = server_conn->func;
      conn->data = server_conn->data;

      conn->fd = accept (server_conn->fd, NULL, (guint *)&alen);

      server_conn->accepted_connections =
            g_slist_prepend (server_conn->accepted_connections, conn);

      setup_connection (conn);
}

static gboolean
server_cb (GIOChannel *source, GIOCondition condition, gpointer data)
{
      BaconMessageConnection *conn = (BaconMessageConnection *)data;
      char *message, *subs, buf;
      int cd, rc, offset;
      gboolean finished;

      offset = 0;
      if (conn->is_server && conn->fd == g_io_channel_unix_get_fd (source)) {
            accept_new_connection (conn);
            return TRUE;
      }
      message = g_malloc (1);
      cd = conn->fd;
      rc = read (cd, &buf, 1);
      while (rc > 0 && buf != '\n')
      {
            message = g_realloc (message, rc + offset + 1);
            message[offset] = buf;
            offset = offset + rc;
            rc = read (cd, &buf, 1);
      }
      if (rc <= 0) {
            g_io_channel_shutdown (conn->chan, FALSE, NULL);
            g_io_channel_unref (conn->chan);
            conn->chan = NULL;
            close (conn->fd);
            conn->fd = -1;
            g_free (message);
            conn->conn_id = 0;

            return FALSE;
      }
      message[offset] = '\0';

      subs = message;
      finished = FALSE;

      while (finished == FALSE && *subs != '\0')
      {
            if (conn->func != NULL)
                  (*conn->func) (subs, conn->data);

            subs += strlen (subs) + 1;
            if (subs - message >= offset)
                  finished = TRUE;
      }

      g_free (message);

      return TRUE;
}

static char *
find_file_with_pattern (const char *dir, const char *pattern)
{
      GDir *filedir;
      char *found_filename;
      const char *filename;
      GPatternSpec *pat;

      filedir = g_dir_open (dir, 0, NULL);
      if (filedir == NULL)
            return NULL;

      pat = g_pattern_spec_new (pattern);
      if (pat == NULL)
      {
            g_dir_close (filedir);
            return NULL;
      }

      found_filename = NULL;

      while ((filename = g_dir_read_name (filedir)))
      {
            if (g_pattern_match_string (pat, filename))
            {
                  char *tmp = g_build_filename (dir, filename, NULL);
                  if (is_owned_by_user_and_socket (tmp))
                        found_filename = g_strdup (filename);
                  g_free (tmp);
            }

            if (found_filename != NULL)
                  break;
      }

      g_pattern_spec_free (pat);
      g_dir_close (filedir);

      return found_filename;
}

static char *
socket_filename (const char *prefix)
{
      char *pattern, *newfile, *path, *filename;
      const char *tmpdir;

      pattern = g_strdup_printf ("%s.%s.*", prefix, g_get_user_name ());
      tmpdir = g_get_tmp_dir ();
      filename = find_file_with_pattern (tmpdir, pattern);
      if (filename == NULL)
      {
            newfile = g_strdup_printf ("%s.%s.%u", prefix,
                        g_get_user_name (), g_random_int ());
            path = g_build_filename (tmpdir, newfile, NULL);
            g_free (newfile);
      } else {
            path = g_build_filename (tmpdir, filename, NULL);
            g_free (filename);
      }

      g_free (pattern);
      return path;
}

static gboolean
try_server (BaconMessageConnection *conn)
{
      struct sockaddr_un uaddr;

      uaddr.sun_family = AF_UNIX;
      strncpy (uaddr.sun_path, conn->path,
                  MIN (strlen(conn->path)+1, UNIX_PATH_MAX));
      conn->fd = socket (PF_UNIX, SOCK_STREAM, 0);
      if (bind (conn->fd, (struct sockaddr *) &uaddr, sizeof (uaddr)) == -1)
      {
            conn->fd = -1;
            return FALSE;
      }
      listen (conn->fd, 5);

      if (!setup_connection (conn))
            return FALSE;
      return TRUE;
}

static gboolean
try_client (BaconMessageConnection *conn)
{
      struct sockaddr_un uaddr;

      uaddr.sun_family = AF_UNIX;
      strncpy (uaddr.sun_path, conn->path,
                  MIN(strlen(conn->path)+1, UNIX_PATH_MAX));
      conn->fd = socket (PF_UNIX, SOCK_STREAM, 0);
      if (connect (conn->fd, (struct sockaddr *) &uaddr,
                        sizeof (uaddr)) == -1)
      {
            conn->fd = -1;
            return FALSE;
      }

      return setup_connection (conn);
}

BaconMessageConnection *
bacon_message_connection_new (const char *prefix)
{
      BaconMessageConnection *conn;

      g_return_val_if_fail (prefix != NULL, NULL);

      conn = g_new0 (BaconMessageConnection, 1);
      conn->path = socket_filename (prefix);

      if (test_is_socket (conn->path) == FALSE)
      {
            if (!try_server (conn))
            {
                  bacon_message_connection_free (conn);
                  return NULL;
            }

            conn->is_server = TRUE;
            return conn;
      }

      if (try_client (conn) == FALSE)
      {
            unlink (conn->path);
            try_server (conn);
            if (conn->fd == -1)
            {
                  bacon_message_connection_free (conn);
                  return NULL;
            }

            conn->is_server = TRUE;
            return conn;
      }

      conn->is_server = FALSE;
      return conn;
}

void
bacon_message_connection_free (BaconMessageConnection *conn)
{
      GSList *child_conn;

      g_return_if_fail (conn != NULL);
      /* Only servers can accept other connections */
      g_return_if_fail (conn->is_server != FALSE ||
                    conn->accepted_connections == NULL);

      child_conn = conn->accepted_connections;
      while (child_conn != NULL) {
            bacon_message_connection_free (child_conn->data);
            child_conn = g_slist_next (child_conn);
      }
      g_slist_free (conn->accepted_connections);

      if (conn->conn_id) {
            g_source_remove (conn->conn_id);
            conn->conn_id = 0;
      }
      if (conn->chan) {
            g_io_channel_shutdown (conn->chan, FALSE, NULL);
            g_io_channel_unref (conn->chan);
      }

      if (conn->is_server != FALSE) {
            unlink (conn->path);
      }
      if (conn->fd != -1) {
            close (conn->fd);
      }

      g_free (conn->path);
      g_free (conn);
}

void
bacon_message_connection_set_callback (BaconMessageConnection *conn,
                               BaconMessageReceivedFunc func,
                               gpointer user_data)
{
      g_return_if_fail (conn != NULL);

      conn->func = func;
      conn->data = user_data;
}

void
bacon_message_connection_send (BaconMessageConnection *conn,
                         const char *message)
{
      g_return_if_fail (conn != NULL);
      g_return_if_fail (message != NULL);

      g_io_channel_write_chars (conn->chan, message, strlen (message),
                          NULL, NULL);
      g_io_channel_write_chars (conn->chan, "\n", 1, NULL, NULL);
      g_io_channel_flush (conn->chan, NULL);
}

gboolean
bacon_message_connection_get_is_server (BaconMessageConnection *conn)
{
      g_return_val_if_fail (conn != NULL, FALSE);

      return conn->is_server;
}


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