/*
  Copyright (c) 2012, Matthias Schiffer <mschiffer@universe-factory.net>
  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.

  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 HOLDER 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.
*/


#include "ffd.h"
#include "neigh.h"
#include "packet.h"
#include "send.h"
#include "tlv.h"
#include "tlv_types.h"

#include <errno.h>
#include <stdio.h>
#include <string.h>

#include <netpacket/packet.h>

#include <sys/socket.h>
#include <sys/uio.h>



typedef struct _announce_info_t {
	ffd_node_id_t node;
	uint16_t type;
	uint16_t key;
} announce_info_t;

struct _ffd_update_t {
	ffd_iface_t *iface;
	ffd_neigh_t *neigh;

	ffd_packet_t *packet;
	size_t max_len;

	ffd_node_id_t node;

	unsigned n_updates;
	announce_info_t announces[];
};


static bool send_eth(const eth_addr_t *addr, unsigned ifindex, const void *buf, size_t len) {
	static const uint8_t zeros[46] = {0};

	struct sockaddr_ll sa;
	memset(&sa, 0, sizeof(sa));
	sa.sll_family = AF_PACKET;
	sa.sll_protocol = htons(FFD_PROTO);
	sa.sll_ifindex = ifindex;
	sa.sll_halen = ETH_ALEN;
	memcpy(sa.sll_addr, addr->d, ETH_ALEN);

	struct iovec vec[2] = {
		{ .iov_base = (void*)buf, .iov_len = len },
		{ .iov_base = (void*)zeros, .iov_len = sizeof(zeros) - len },
	};

	struct msghdr msg;
	memset(&msg, 0, sizeof(msg));
	msg.msg_name = &sa;
	msg.msg_namelen = sizeof(sa);
	msg.msg_iov = vec;
	msg.msg_iovlen = (len < 46) ? 2 : 1;


	while (sendmsg(sockfd, &msg, 0) < 0) {
		if (errno != EINTR)
			return false;
	}

	return true;
}

static inline bool send_neigh(const ffd_neigh_t *neigh, const ffd_packet_t *packet) {
	if (!neigh->iface)
		return false;

	if (!send_eth(&neigh->addr, neigh->iface->ifindex, packet, sizeof(ffd_packet_t)+ntohs(packet->len))) {
		fprintf(stderr, "send_eth: %m\n");
		return false;
	}

	return true;
}

static inline bool send_iface(const ffd_iface_t *iface, const ffd_packet_t *packet) {
	if (!send_eth(&ffd_addr, iface->ifindex, packet, sizeof(ffd_packet_t)+ntohs(packet->len))) {
		fprintf(stderr, "send_eth: %m\n");
		return false;
	}

	return true;
}

static inline void send_broadcast(const ffd_packet_t *packet) {
	ffd_iface_t *iface;
	for (iface = iface_list; iface; iface = iface->next)
		send_iface(iface, packet);
}

static inline void send_any(const ffd_iface_t *iface, const ffd_neigh_t *neigh, const ffd_packet_t *packet) {
	if (neigh)
		send_neigh(neigh, packet);
	else if(iface)
		send_iface(iface, packet);
	else
		send_broadcast(packet);
}

void ffd_send_ack(ffd_neigh_t *neigh, uint16_t nonce) {
	ffd_packet_t *packet = alloca(sizeof(ffd_packet_t)+FFD_PACKET_MAX);

	packet->version_magic = htons(FFD_VERSION_MAGIC);
	packet->len = 0;

	ffd_tlv_ack_t *ack = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_ACK, sizeof(ffd_tlv_ack_t));
	if (!ack)
		return;

	ack->nonce = htons(nonce);

	send_neigh(neigh, packet);
}

static void add_ihus(ffd_packet_t *packet, size_t max_len, const ffd_iface_t *iface) {
	const ffd_neigh_t *neigh;

	for (neigh = iface->neigh_list; neigh; neigh = neigh->next) {
		ffd_tlv_ihu_t *ihu = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_IHU, sizeof(ffd_tlv_ihu_t)+sizeof(eth_addr_t));
		if (!ihu)
			return;

		ihu->ae = ADDR_ENC_ETH;
		ihu->reserved = 0;
		ihu->rxcost = htons(ffd_neigh_get_rxcost(neigh));
		ihu->interval = htons(FFD_IHU_INTERVAL);
		memcpy(ihu->address, &neigh->addr, sizeof(eth_addr_t));
	}
}

void ffd_send_hellos(void) {
	ffd_packet_t *packet = alloca(sizeof(ffd_packet_t)+FFD_PACKET_MAX);

	packet->version_magic = htons(FFD_VERSION_MAGIC);
	packet->len = 0;

	ffd_tlv_hello_t *hello = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_HELLO, sizeof(ffd_tlv_hello_t));
	if (!hello)
		return;

	hello->reserved = 0;
	hello->interval = htons(FFD_HELLO_INTERVAL);

	uint16_t len = packet->len;

	ffd_iface_t *iface;
	for (iface = iface_list; iface; iface = iface->next) {
		hello->seqno = htons(iface->seqno++);

		packet->len = len;

		add_ihus(packet, FFD_PACKET_MAX, iface);

		send_iface(iface, packet);
	}
}

static bool add_ack_request(ffd_packet_t *packet, uint16_t nonce) {
	ffd_tlv_ack_req_t *tlv = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_ACK_REQ, sizeof(ffd_tlv_ack_req_t));
	if (!tlv)
		return false;

	tlv->reserved = 0;
	tlv->nonce = htons(nonce);
	tlv->interval = htons(FFD_ACK_INTERVAL);

	return true;
}

static bool add_node_id(ffd_packet_t *packet, size_t max_len, ffd_node_id_t node_id) {
	ffd_tlv_node_id_t *tlv = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_NODE_ID, sizeof(ffd_tlv_node_id_t));
	if (!tlv)
		return false;

	tlv->id = node_id;

	return true;
}

static bool add_update(ffd_packet_t *packet, size_t max_len, ffd_node_id_t *node_id, ffd_announce_t *announce, bool with_data, bool targetted) {
	if (announce->len && !announce->data) {
		/* incomplete announce, handle like non-existant announce */
		return true;
	}

	uint16_t len = packet->len;

	if (!node_id || !ffd_are_node_ids_equal(node_id, &announce->node)) {
		if (!add_node_id(packet, max_len, announce->node))
			return false;

		if (node_id)
			*node_id = announce->node;
	}

	ffd_tlv_update_t *update = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_UPDATE, sizeof(ffd_tlv_update_t)+announce->len);
	if (!update) {
		packet->len = len;
		return false;
	}

	update->flags = 0;
	update->reserved = 0;
	update->interval = htons(FFD_UPDATE_INTERVAL);
	update->seqno = htons(announce->metric.seqno);
	update->metric = htons(announce->metric.metric);
	update->type = htons(announce->type);
	update->key = htons(announce->key);

	if (announce->len && announce->metric.metric != 0xff) {
		update->flags |= FFD_UPDATE_WITH_DATA;

		if (with_data) {
			memcpy(update->data, announce->data, announce->len);
		}
	}

	if (ffd_is_metric_better(announce->metric, announce->feasibility_distance))
	    announce->feasibility_distance = announce->metric;

	if (!targetted)
		announce->last_metric = announce->metric.metric;

	return true;
}

static bool add_retract(ffd_packet_t *packet, size_t max_len, ffd_node_id_t *node_id, ffd_node_id_t node, uint16_t type, uint16_t key) {
	uint16_t len = packet->len;

	if (!node_id || !ffd_are_node_ids_equal(node_id, &node)) {
		if (!add_node_id(packet, max_len, node))
			return false;

		if (node_id)
			*node_id = node;
	}

	ffd_tlv_update_t *update = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_UPDATE, sizeof(ffd_tlv_update_t));
	if (!update) {
		packet->len = len;
		return false;
	}

	update->flags = 0;
	update->reserved = 0;
	update->interval = htons(FFD_UPDATE_INTERVAL);
	update->seqno = 0;
	update->metric = 0xffff; /* no need to htons */
	update->type = htons(type);
	update->key = htons(key);

	return true;
}

void ffd_send_update(ffd_iface_t *iface, ffd_neigh_t *neigh, ffd_announce_t *announce, bool with_data) {
	ffd_packet_t *packet = alloca(sizeof(ffd_packet_t)+FFD_PACKET_MAX);

	packet->version_magic = htons(FFD_VERSION_MAGIC);
	packet->len = 0;

	if (announce) {
		add_update(packet, FFD_PACKET_MAX, NULL, announce, with_data, iface || neigh);
	}
	else {
		ffd_node_id_t node_id = FFD_NODE_ID_UNSPEC;

		ffd_announce_t *a;
		for (a = announce_list; a; a = a->next) {
			if (!add_update(packet, FFD_PACKET_MAX, &node_id, a, with_data, iface || neigh)) {
				send_any(iface, neigh, packet);

				node_id = FFD_NODE_ID_UNSPEC;
				packet->len = 0;

				if (!add_update(packet, FFD_PACKET_MAX, &node_id, a, with_data, iface || neigh)) {
					fprintf(stderr, "error: add_update failed\n");
					return;
				}
			}
		}
	}

	if (packet->len)
		send_any(iface, neigh, packet);
}

void ffd_send_retract(ffd_neigh_t *neigh, ffd_node_id_t node, uint16_t type, uint16_t key) {
	ffd_packet_t *packet = alloca(sizeof(ffd_packet_t)+FFD_PACKET_MAX);

	packet->version_magic = htons(FFD_VERSION_MAGIC);
	packet->len = 0;

	if (!add_node_id(packet, FFD_PACKET_MAX, node))
		return;

	ffd_tlv_update_t *update = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_UPDATE, sizeof(ffd_tlv_update_t));
	if (!update)
		return;

	update->flags = 0;
	update->reserved = 0;
	update->interval = htons(FFD_UPDATE_INTERVAL);
	update->seqno = 0;
	update->metric = 0xffff; /* no need to htons */
	update->type = htons(type);
	update->key = htons(key);

	send_neigh(neigh, packet);
}

ffd_update_t* ffd_send_update_new(ffd_iface_t *iface, ffd_neigh_t *neigh, const uint16_t *nonce) {
	unsigned max_updates = (FFD_PACKET_MAX+sizeof(ffd_tlv_update_t)+1)/(sizeof(ffd_tlv_update_t)+2);
	ffd_update_t *update = calloc(1, sizeof(ffd_update_t) + max_updates*sizeof(announce_info_t));
	update->iface = iface;
	update->neigh = neigh;

	update->max_len = FFD_PACKET_MAX;
	update->packet = malloc(sizeof(ffd_packet_t)+FFD_PACKET_MAX);
	update->packet->version_magic = htons(FFD_VERSION_MAGIC);
	update->packet->len = 0;

	if (nonce)
		add_ack_request(update->packet, *nonce);

	return update;
}

static inline bool is_update_duplicate(ffd_update_t *update, ffd_node_id_t node, uint16_t type, uint16_t key) {
	unsigned i;
	for (i = 0; i < update->n_updates; i++) {
		if (ffd_are_node_ids_equal(&update->announces[i].node, &node)
		    && update->announces[i].type == type && update->announces[i].key == key)
			return true;
	}

	return false;
}

bool ffd_send_update_add(ffd_update_t *update, ffd_announce_t *announce) {
	if (is_update_duplicate(update, announce->node, announce->type, announce->key))
		return false;

	if (!add_update(update->packet, update->max_len, &update->node, announce, false, update->neigh))
		return false;

	update->announces[update->n_updates++] = (announce_info_t){announce->node, announce->type, announce->key};

	return true;
}

bool ffd_send_update_retract(ffd_update_t *update, ffd_node_id_t node, uint16_t type, uint16_t key) {
	if (is_update_duplicate(update, node, type, key))
		return false;

	if (!add_retract(update->packet, update->max_len, &update->node, node, type, key))
		return false;

	update->announces[update->n_updates++] = (announce_info_t){node, type, key};

	return true;
}

void ffd_send_update_finish(ffd_update_t *update) {
	fprintf(stderr, "debug: sending %u aggregated update(s).\n", update->n_updates);

	if (update->packet->len)
		send_any(update->iface, update->neigh, update->packet);

	free(update->packet);
	free(update);
}

void ffd_send_announce_request(ffd_iface_t *iface, ffd_neigh_t *neigh, ffd_node_id_t node, uint16_t type, uint16_t key, bool with_data) {
	ffd_packet_t *packet = alloca(sizeof(ffd_packet_t)+FFD_PACKET_MAX);

	packet->version_magic = htons(FFD_VERSION_MAGIC);
	packet->len = 0;

	ffd_tlv_announce_req_t *req = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_ANNOUNCE_REQ, sizeof(ffd_tlv_announce_req_t));
	if (!req)
		return;

	req->node = node;
	req->flags = 0;
	req->reserved = 0;
	req->type = htons(type);
	req->key = htons(key);

	if (with_data)
		req->flags |= FFD_UPDATE_WITH_DATA;

	send_any(iface, neigh, packet);
}

void ffd_send_seqno_request(ffd_neigh_t *neigh, ffd_announce_t *announce, uint16_t seqno) {
	ffd_packet_t *packet = alloca(sizeof(ffd_packet_t)+FFD_PACKET_MAX);

	packet->version_magic = htons(FFD_VERSION_MAGIC);
	packet->len = 0;

	ffd_tlv_seqno_req_t *req = ffd_tlv_add(packet, FFD_PACKET_MAX, TLV_SEQNO_REQ, sizeof(ffd_tlv_seqno_req_t));
	if (!req)
		return;

	req->seqno = htons(seqno);
	req->node = announce->node;
	req->type = htons(announce->type);
	req->key = htons(announce->key);

	send_any(NULL, neigh, packet);
}