/*
   * Copyright (c) 2012 Jakub Zawadzki
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   * notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote
   * products derived from this software without specific prior written
   * permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #ifdef HAVE_CONFIG_H
  #include <config.h>
  #endif
  
  #include <string.h>
  
  #include <time.h>
  #include <sys/time.h>
  
  #include <dbus/dbus.h>
  
  #include "pcap-int.h"
  #include "pcap-dbus.h"
  
  /*
   * Private data for capturing on D-Bus.
   */
  struct pcap_dbus {
  	DBusConnection *conn;
  	u_int	packets_read;	/* count of packets read */
  };
  
  static int
  dbus_read(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user)
  {
  	struct pcap_dbus *handlep = handle->priv;
  
  	struct pcap_pkthdr pkth;
  	DBusMessage *message;
  
  	char *raw_msg;
  	int raw_msg_len;
  
  	int count = 0;
  
  	message = dbus_connection_pop_message(handlep->conn);
  
  	while (!message) {
  		/* XXX handle->opt.timeout = timeout_ms; */
  		if (!dbus_connection_read_write(handlep->conn, 100)) {
  			pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Connection closed");
  			return -1;
  		}
  
  		if (handle->break_loop) {
  			handle->break_loop = 0;
  			return -2;
  		}
  
  		message = dbus_connection_pop_message(handlep->conn);
  	}
  
  	if (dbus_message_is_signal(message, DBUS_INTERFACE_LOCAL, "Disconnected")) {
  		pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Disconnected");
  		return -1;
  	}
  
  	if (dbus_message_marshal(message, &raw_msg, &raw_msg_len)) {
  		pkth.caplen = pkth.len = raw_msg_len;
  		/* pkth.caplen = min (payload_len, handle->snapshot); */
  
  		gettimeofday(&pkth.ts, NULL);
  		if (handle->fcode.bf_insns == NULL ||
  		    bpf_filter(handle->fcode.bf_insns, (u_char *)raw_msg, pkth.len, pkth.caplen)) {
  			handlep->packets_read++;
  			callback(user, &pkth, (u_char *)raw_msg);
  			count++;
  		}
  
  		dbus_free(raw_msg);
  	}
  	return count;
  }
  
  static int
  dbus_write(pcap_t *handle, const void *buf, size_t size)
  {
  	/* XXX, not tested */
  	struct pcap_dbus *handlep = handle->priv;
  
  	DBusError error = DBUS_ERROR_INIT;
  	DBusMessage *msg;
  
  	if (!(msg = dbus_message_demarshal(buf, size, &error))) {
  		pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dbus_message_demarshal() failed: %s", error.message);
  		dbus_error_free(&error);
  		return -1;
  	}
  
  	dbus_connection_send(handlep->conn, msg, NULL);
  	dbus_connection_flush(handlep->conn);
  
  	dbus_message_unref(msg);
  	return 0;
  }
  
  static int
  dbus_stats(pcap_t *handle, struct pcap_stat *stats)
  {
  	struct pcap_dbus *handlep = handle->priv;
  
  	stats->ps_recv = handlep->packets_read;
  	stats->ps_drop = 0;
  	stats->ps_ifdrop = 0;
  	return 0;
  }
  
  static void
  dbus_cleanup(pcap_t *handle)
  {
  	struct pcap_dbus *handlep = handle->priv;
  
  	dbus_connection_unref(handlep->conn);
  
  	pcap_cleanup_live_common(handle);
  }
  
  /*
   * We don't support non-blocking mode.  I'm not sure what we'd
   * do to support it and, given that we don't support select()/
   * poll()/epoll_wait()/kevent() etc., it probably doesn't
   * matter.
   */
  static int
  dbus_getnonblock(pcap_t *p)
  {
  	pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
  	    "Non-blocking mode isn't supported for capturing on D-Bus");
  	return (-1);
  }
  
  static int
  dbus_setnonblock(pcap_t *p, int nonblock _U_)
  {
  	pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
  	    "Non-blocking mode isn't supported for capturing on D-Bus");
  	return (-1);
  }
  
  static int
  dbus_activate(pcap_t *handle)
  {
  #define EAVESDROPPING_RULE "eavesdrop=true,"
  
  	static const char *rules[] = {
  		EAVESDROPPING_RULE "type='signal'",
  		EAVESDROPPING_RULE "type='method_call'",
  		EAVESDROPPING_RULE "type='method_return'",
  		EAVESDROPPING_RULE "type='error'",
  	};
  
  	#define N_RULES sizeof(rules)/sizeof(rules[0])
  
  	struct pcap_dbus *handlep = handle->priv;
  	const char *dev = handle->opt.device;
  
  	DBusError error = DBUS_ERROR_INIT;
  	u_int i;
  
  	if (strcmp(dev, "dbus-system") == 0) {
  		if (!(handlep->conn = dbus_bus_get(DBUS_BUS_SYSTEM, &error))) {
  			pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to get system bus: %s", error.message);
  			dbus_error_free(&error);
  			return PCAP_ERROR;
  		}
  
  	} else if (strcmp(dev, "dbus-session") == 0) {
  		if (!(handlep->conn = dbus_bus_get(DBUS_BUS_SESSION, &error))) {
  			pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to get session bus: %s", error.message);
  			dbus_error_free(&error);
  			return PCAP_ERROR;
  		}
  
  	} else if (strncmp(dev, "dbus://", 7) == 0) {
  		const char *addr = dev + 7;
  
  		if (!(handlep->conn = dbus_connection_open(addr, &error))) {
  			pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to open connection to: %s: %s", addr, error.message);
  			dbus_error_free(&error);
  			return PCAP_ERROR;
  		}
  
  		if (!dbus_bus_register(handlep->conn, &error)) {
  			pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to register bus %s: %s\n", addr, error.message);
  			dbus_error_free(&error);
  			return PCAP_ERROR;
  		}
  
  	} else {
  		pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't get bus address from %s", handle->opt.device);
  		return PCAP_ERROR;
  	}
  
  	/* Initialize some components of the pcap structure. */
  	handle->bufsize = 0;
  	handle->offset = 0;
  	handle->linktype = DLT_DBUS;
  	handle->read_op = dbus_read;
  	handle->inject_op = dbus_write;
  	handle->setfilter_op = install_bpf_program; /* XXX, later add support for dbus_bus_add_match() */
  	handle->setdirection_op = NULL;
  	handle->set_datalink_op = NULL;      /* can't change data link type */
  	handle->getnonblock_op = dbus_getnonblock;
  	handle->setnonblock_op = dbus_setnonblock;
  	handle->stats_op = dbus_stats;
  	handle->cleanup_op = dbus_cleanup;
  
  #ifndef _WIN32
  	/*
  	 * Unfortunately, trying to do a select()/poll()/epoll_wait()/
  	 * kevent()/etc. on a D-Bus connection isn't a simple
  	 * case of "give me an FD on which to wait".
  	 *
  	 * Apparently, you have to register "add watch", "remove watch",
  	 * and "toggle watch" functions with
  	 * dbus_connection_set_watch_functions(),
  	 * keep a *set* of FDs, add to that set in the "add watch"
  	 * function, subtract from it in the "remove watch" function,
  	 * and either add to or subtract from that set in the "toggle
  	 * watch" function, and do the wait on *all* of the FDs in the
  	 * set.  (Yes, you need the "toggle watch" function, so that
  	 * the main loop doesn't itself need to check for whether
  	 * a given watch is enabled or disabled - most libpcap programs
  	 * know nothing about D-Bus and shouldn't *have* to know anything
  	 * about D-Bus other than how to decode D-Bus messages.)
  	 *
  	 * Implementing that would require considerable changes in
  	 * the way libpcap exports "selectable FDs" to its client.
  	 * Until that's done, we just say "you can't do that".
  	 */
  	handle->selectable_fd = handle->fd = -1;
  #endif
  
  	if (handle->opt.rfmon) {
  		/*
  		 * Monitor mode doesn't apply to dbus connections.
  		 */
  		dbus_cleanup(handle);
  		return PCAP_ERROR_RFMON_NOTSUP;
  	}
  
  	/*
  	 * Turn a negative snapshot value (invalid), a snapshot value of
  	 * 0 (unspecified), or a value bigger than the normal maximum
  	 * value, into the maximum message length for D-Bus (128MB).
  	 */
  	if (handle->snapshot <= 0 || handle->snapshot > 134217728)
  		handle->snapshot = 134217728;
  
  	/* dbus_connection_set_max_message_size(handlep->conn, handle->snapshot); */
  	if (handle->opt.buffer_size != 0)
  		dbus_connection_set_max_received_size(handlep->conn, handle->opt.buffer_size);
  
  	for (i = 0; i < N_RULES; i++) {
  		dbus_bus_add_match(handlep->conn, rules[i], &error);
  		if (dbus_error_is_set(&error)) {
  			dbus_error_free(&error);
  
  			/* try without eavesdrop */
  			dbus_bus_add_match(handlep->conn, rules[i] + strlen(EAVESDROPPING_RULE), &error);
  			if (dbus_error_is_set(&error)) {
  				pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to add bus match: %s\n", error.message);
  				dbus_error_free(&error);
  				dbus_cleanup(handle);
  				return PCAP_ERROR;
  			}
  		}
  	}
  
  	return 0;
  }
  
  pcap_t *
  dbus_create(const char *device, char *ebuf, int *is_ours)
  {
  	pcap_t *p;
  
  	if (strcmp(device, "dbus-system") &&
  		strcmp(device, "dbus-session") &&
  		strncmp(device, "dbus://", 7))
  	{
  		*is_ours = 0;
  		return NULL;
  	}
  
  	*is_ours = 1;
  	p = pcap_create_common(ebuf, sizeof (struct pcap_dbus));
  	if (p == NULL)
  		return (NULL);
  
  	p->activate_op = dbus_activate;
  	/*
  	 * Set these up front, so that, even if our client tries
  	 * to set non-blocking mode before we're activated, or
  	 * query the state of non-blocking mode, they get an error,
  	 * rather than having the non-blocking mode option set
  	 * for use later.
  	 */
  	p->getnonblock_op = dbus_getnonblock;
  	p->setnonblock_op = dbus_setnonblock;
  	return (p);
  }
  
  int
  dbus_findalldevs(pcap_if_list_t *devlistp, char *err_str)
  {
  	/*
  	 * The notion of "connected" vs. "disconnected" doesn't apply.
  	 * XXX - what about the notions of "up" and "running"?
  	 */
  	if (add_dev(devlistp, "dbus-system",
  	    PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "D-Bus system bus",
  	    err_str) == NULL)
  		return -1;
  	if (add_dev(devlistp, "dbus-session",
  	    PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "D-Bus session bus",
  	    err_str) == NULL)
  		return -1;
  	return 0;
  }