/*
  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.
*/


#define _GNU_SOURCE

#include <libgen.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_arp.h>

#include <sys/types.h>
#include <sys/stat.h>


#define ANNOUNCE_INTERVAL 20
#define ANNOUNCE_TIMEOUT 60

#define SYSFS_PATH_MAX 256
#define SYSFS_CLASS_NET "/sys/class/net"

#define FFD_MAGIC 0xffd
#define FFVISD_VERSION 0


//static char *mesh = "bat0";


typedef struct _ffvisd_eth_address_t {
	uint8_t address[ETH_ALEN];
} ffvisd_eth_address_t;

typedef struct _ffvisd_ipv6_host_address_t {
	uint8_t address[8];
} ffvisd_ipv6_host_address_t;

typedef struct _ffvisd_server_announce_t {
	ffvisd_eth_address_t eth_address;
	uint16_t reserved;
	ffvisd_ipv6_host_address_t address;
	uint32_t age;
} ffvisd_server_announce_t;

typedef struct _ffvisd_announce_t {
	uint16_t magic;
	uint16_t version;
	uint32_t n_servers;
	uint32_t reserved;
	ffvisd_server_announce_t servers[];
} ffvisd_announce_t;

typedef enum _ffvisd_iftype_t {
	IF_UNKNOWN = 0,
	IF_WIRED,
	IF_WIRELESS,
	IF_VIRTUAL,
	IF_BRIDGE,
	IF_MESH,
	IF_MAX
} ffvisd_iftype_t;

typedef struct _ffvisd_iface_t {
	unsigned ifindex;
	ffvisd_iftype_t iftype;
	char *ifname;
	char *bridge_iface;
	char *mesh_iface;
} ffvisd_iface_t;

static const char *ffvisd_iftype_names[IF_MAX] = {
	[IF_UNKNOWN] = "unknown",
	[IF_WIRED] = "wired",
	[IF_WIRELESS] = "wireless",
	[IF_VIRTUAL] = "virtual",
	[IF_BRIDGE] = "bridge",
	[IF_MESH] = "mesh",
};

typedef void (*iface_cb)(const ffvisd_iface_t *iface, void *arg);


void ffvisd_iface_free(ffvisd_iface_t *iface);


bool file_readv(const char *file, const char *format, va_list ap) {
	FILE *f = fopen(file, "r");
	if (!f)
		return false;

	int ret = vfscanf(f, format, ap);

	fclose(f);

	return (ret > 0);
}

bool iface_file_read(const char *ifname, const char *file, const char *format, ...) {
	char filename[SYSFS_PATH_MAX];

	snprintf(filename, SYSFS_PATH_MAX, SYSFS_CLASS_NET"/%s/%s", ifname, file);

	va_list ap;
	va_start(ap, format);
	bool ret = file_readv(filename, format, ap);
	va_end(ap);

	return ret;
}

bool iface_file_exists(const char *ifname, const char *file) {
	char filename[SYSFS_PATH_MAX];

	snprintf(filename, SYSFS_PATH_MAX, SYSFS_CLASS_NET"/%s/%s", ifname, file);

	struct stat st;
	return (stat(filename, &st) == 0);
}

char* get_bridge(const char *ifname) {
	char filename[SYSFS_PATH_MAX], filename2[SYSFS_PATH_MAX] = {0};

	snprintf(filename, SYSFS_PATH_MAX, SYSFS_CLASS_NET"/%s/brport/bridge", ifname);
	if (readlink(filename, filename2, sizeof(filename2)) < 0)
		return NULL;

	return strdup(basename(filename2));
}

ffvisd_iface_t* ffvisd_iface_new(const char *ifname, unsigned ifindex) {
	ffvisd_iface_t *iface = calloc(1, sizeof(ffvisd_iface_t));

	iface->ifname = strdup(ifname);
	iface->ifindex = ifindex;

	if (!iface_file_read(ifname, "batman_adv/mesh_iface", "%as", &iface->mesh_iface) || !strcmp(iface->mesh_iface, "none")) {
		free(iface->mesh_iface);
		iface->mesh_iface = NULL;
	}

	iface->bridge_iface = get_bridge(ifname);

	int type;
	if (iface_file_read(ifname, "type", "%i", &type) && type == ARPHRD_ETHER) {
		if(iface_file_exists(ifname, "mesh"))
			iface->iftype = IF_MESH;
		else if(iface_file_exists(ifname, "bridge"))
			iface->iftype = IF_BRIDGE;
		else if(iface_file_exists(ifname, "tun_flags"))
			iface->iftype = IF_VIRTUAL;
		else if(iface_file_exists(ifname, "wireless"))
			iface->iftype = IF_WIRELESS;
		else
			iface->iftype = IF_WIRED;
	}

	return iface;
}

void ffvisd_iface_free(ffvisd_iface_t *iface) {
	if (iface) {
		free(iface->ifname);
		free(iface->bridge_iface);
		free(iface->mesh_iface);
		free(iface);
	}
}

void ffvisd_iface_foreach(iface_cb cb, void *arg) {
	struct if_nameindex *ifaces = if_nameindex();

	if (!ifaces) {
		fprintf(stderr, "error: if_nameindex: %m");
		return;
	}

	int i;
	for (i = 0; ifaces[i].if_name; i++) {
		ffvisd_iface_t *iface = ffvisd_iface_new(ifaces[i].if_name, ifaces[i].if_index);

		if (iface)
			cb(iface, arg);

		ffvisd_iface_free(iface);
	}

	if_freenameindex(ifaces);
}


void pr_iface_info(const ffvisd_iface_t *iface, void *arg) {
	printf("Interface %s: ifindex=%i bridge_iface=%s mesh_iface=%s iftype=%s\n", iface->ifname, iface->ifindex, iface->bridge_iface, iface->mesh_iface, ffvisd_iftype_names[iface->iftype]);
}


int main() {
	ffvisd_iface_foreach(pr_iface_info, NULL);

	return 0;
}