/*
    net_setup.c -- Setup.
    Copyright (C) 1998-2005 Ivo Timmermans,
                  2000-2012 Guus Sliepen <guus@tinc-vpn.org>
                  2006      Scott Lamb <slamb@slamb.org>
                  2010      Brandon Black <blblack@gmail.com>

    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.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "system.h"

#include <openssl/pem.h>
#include <openssl/rsa.h>
#include <openssl/rand.h>
#include <openssl/err.h>
#include <openssl/evp.h>

#include "avl_tree.h"
#include "conf.h"
#include "connection.h"
#include "device.h"
#include "event.h"
#include "graph.h"
#include "logger.h"
#include "net.h"
#include "netutl.h"
#include "process.h"
#include "protocol.h"
#include "route.h"
#include "subnet.h"
#include "utils.h"
#include "xalloc.h"

char *myport;
devops_t devops;

bool read_rsa_public_key(connection_t *c) {
	FILE *fp;
	char *fname;
	char *key;

	if(!c->rsa_key) {
		c->rsa_key = RSA_new();
//		RSA_blinding_on(c->rsa_key, NULL);
	}

	/* First, check for simple PublicKey statement */

	if(get_config_string(lookup_config(c->config_tree, "PublicKey"), &key)) {
		BN_hex2bn(&c->rsa_key->n, key);
		BN_hex2bn(&c->rsa_key->e, "FFFF");
		free(key);
		return true;
	}

	/* Else, check for PublicKeyFile statement and read it */

	if(get_config_string(lookup_config(c->config_tree, "PublicKeyFile"), &fname)) {
		fp = fopen(fname, "r");

		if(!fp) {
			logger(LOG_ERR, "Error reading RSA public key file `%s': %s",
				   fname, strerror(errno));
			free(fname);
			return false;
		}

		free(fname);
		c->rsa_key = PEM_read_RSAPublicKey(fp, &c->rsa_key, NULL, NULL);
		fclose(fp);

		if(c->rsa_key)
			return true;		/* Woohoo. */

		/* If it fails, try PEM_read_RSA_PUBKEY. */
		fp = fopen(fname, "r");

		if(!fp) {
			logger(LOG_ERR, "Error reading RSA public key file `%s': %s",
				   fname, strerror(errno));
			free(fname);
			return false;
		}

		free(fname);
		c->rsa_key = PEM_read_RSA_PUBKEY(fp, &c->rsa_key, NULL, NULL);
		fclose(fp);

		if(c->rsa_key) {
//				RSA_blinding_on(c->rsa_key, NULL);
			return true;
		}

		logger(LOG_ERR, "Reading RSA public key file `%s' failed: %s",
			   fname, strerror(errno));
		return false;
	}

	/* Else, check if a harnessed public key is in the config file */

	xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
	fp = fopen(fname, "r");

	if(!fp) {
		logger(LOG_ERR, "Error reading RSA public key file `%s': %s", fname, strerror(errno));
		free(fname);
		return false;
	}

	c->rsa_key = PEM_read_RSAPublicKey(fp, &c->rsa_key, NULL, NULL);
	fclose(fp);
	free(fname);

	if(c->rsa_key)
		return true;

	/* Try again with PEM_read_RSA_PUBKEY. */

	xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
	fp = fopen(fname, "r");

	if(!fp) {
		logger(LOG_ERR, "Error reading RSA public key file `%s': %s", fname, strerror(errno));
		free(fname);
		return false;
	}

	c->rsa_key = PEM_read_RSA_PUBKEY(fp, &c->rsa_key, NULL, NULL);
//	RSA_blinding_on(c->rsa_key, NULL);
	fclose(fp);
	free(fname);

	if(c->rsa_key)
		return true;

	logger(LOG_ERR, "No public key for %s specified!", c->name);

	return false;
}

static bool read_rsa_private_key(void) {
	FILE *fp;
	char *fname, *key, *pubkey;
	struct stat s;

	if(get_config_string(lookup_config(config_tree, "PrivateKey"), &key)) {
		if(!get_config_string(lookup_config(config_tree, "PublicKey"), &pubkey)) {
			logger(LOG_ERR, "PrivateKey used but no PublicKey found!");
			return false;
		}
		myself->connection->rsa_key = RSA_new();
//		RSA_blinding_on(myself->connection->rsa_key, NULL);
		BN_hex2bn(&myself->connection->rsa_key->d, key);
		BN_hex2bn(&myself->connection->rsa_key->n, pubkey);
		BN_hex2bn(&myself->connection->rsa_key->e, "FFFF");
		free(key);
		free(pubkey);
		return true;
	}

	if(!get_config_string(lookup_config(config_tree, "PrivateKeyFile"), &fname))
		xasprintf(&fname, "%s/rsa_key.priv", confbase);

	fp = fopen(fname, "r");

	if(!fp) {
		logger(LOG_ERR, "Error reading RSA private key file `%s': %s",
			   fname, strerror(errno));
		free(fname);
		return false;
	}

#if !defined(HAVE_MINGW) && !defined(HAVE_CYGWIN)
	if(fstat(fileno(fp), &s)) {
		logger(LOG_ERR, "Could not stat RSA private key file `%s': %s'",
				fname, strerror(errno));
		free(fname);
		return false;
	}

	if(s.st_mode & ~0100700)
		logger(LOG_WARNING, "Warning: insecure file permissions for RSA private key file `%s'!", fname);
#endif

	myself->connection->rsa_key = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
	fclose(fp);

	if(!myself->connection->rsa_key) {
		logger(LOG_ERR, "Reading RSA private key file `%s' failed: %s",
			   fname, strerror(errno));
		free(fname);
		return false;
	}

	free(fname);
	return true;
}

/*
  Read Subnets from all host config files
*/
void load_all_subnets(void) {
	DIR *dir;
	struct dirent *ent;
	char *dname;
	char *fname;
	avl_tree_t *config_tree;
	config_t *cfg;
	subnet_t *s, *s2;
	node_t *n;

	xasprintf(&dname, "%s/hosts", confbase);
	dir = opendir(dname);
	if(!dir) {
		logger(LOG_ERR, "Could not open %s: %s", dname, strerror(errno));
		free(dname);
		return;
	}

	while((ent = readdir(dir))) {
		if(!check_id(ent->d_name))
			continue;

		n = lookup_node(ent->d_name);
		#ifdef _DIRENT_HAVE_D_TYPE
		//if(ent->d_type != DT_REG)
		//	continue;
		#endif

		xasprintf(&fname, "%s/hosts/%s", confbase, ent->d_name);
		init_configuration(&config_tree);
		read_config_options(config_tree, ent->d_name);
		read_config_file(config_tree, fname);
		free(fname);

		if(!n) {
			n = new_node();
			n->name = xstrdup(ent->d_name);
			node_add(n);
		}

		for(cfg = lookup_config(config_tree, "Subnet"); cfg; cfg = lookup_config_next(config_tree, cfg)) {
			if(!get_config_subnet(cfg, &s))
				continue;

			if((s2 = lookup_subnet(n, s))) {
				s2->expires = -1;
			} else {
				subnet_add(n, s);
			}
		}

		exit_configuration(&config_tree);
	}

	closedir(dir);
}

/*
  Configure node_t myself and set up the local sockets (listen only)
*/
static bool setup_myself(void) {
	config_t *cfg;
	subnet_t *subnet;
	char *name, *hostname, *mode, *afname, *cipher, *digest, *type;
	char *fname = NULL;
	char *address = NULL;
	char *envp[5];
	struct addrinfo *ai, *aip, hint = {0};
	bool choice;
	int i, err;
	int replaywin_int;

	myself = new_node();
	myself->connection = new_connection();

	myself->hostname = xstrdup("MYSELF");
	myself->connection->hostname = xstrdup("MYSELF");

	myself->connection->options = 0;
	myself->connection->protocol_version = PROT_CURRENT;

	if(!get_config_string(lookup_config(config_tree, "Name"), &name)) {	/* Not acceptable */
		logger(LOG_ERR, "Name for tinc daemon required!");
		return false;
	}

	if(!check_id(name)) {
		logger(LOG_ERR, "Invalid name for myself!");
		free(name);
		return false;
	}

	myself->name = name;
	myself->connection->name = xstrdup(name);
	xasprintf(&fname, "%s/hosts/%s", confbase, name);
	read_config_options(config_tree, name);
	read_config_file(config_tree, fname);
	free(fname);

	if(!read_rsa_private_key())
		return false;

	if(!get_config_string(lookup_config(config_tree, "Port"), &myport))
		myport = xstrdup("655");

	if(!atoi(myport)) {
		struct addrinfo *ai = str2addrinfo("localhost", myport, SOCK_DGRAM);
		sockaddr_t sa;
		if(!ai || !ai->ai_addr)
			return false;
		free(myport);
		memcpy(&sa, ai->ai_addr, ai->ai_addrlen);
		sockaddr2str(&sa, NULL, &myport);
	}

	/* Read in all the subnets specified in the host configuration file */

	cfg = lookup_config(config_tree, "Subnet");

	while(cfg) {
		if(!get_config_subnet(cfg, &subnet))
			return false;

		subnet_add(myself, subnet);

		cfg = lookup_config_next(config_tree, cfg);
	}

	/* Check some options */

	if(get_config_bool(lookup_config(config_tree, "IndirectData"), &choice) && choice)
		myself->options |= OPTION_INDIRECT;

	if(get_config_bool(lookup_config(config_tree, "TCPOnly"), &choice) && choice)
		myself->options |= OPTION_TCPONLY;

	if(myself->options & OPTION_TCPONLY)
		myself->options |= OPTION_INDIRECT;

	get_config_bool(lookup_config(config_tree, "DirectOnly"), &directonly);
	get_config_bool(lookup_config(config_tree, "StrictSubnets"), &strictsubnets);
	get_config_bool(lookup_config(config_tree, "TunnelServer"), &tunnelserver);
	get_config_bool(lookup_config(config_tree, "LocalDiscovery"), &localdiscovery);
	strictsubnets |= tunnelserver;

	if(get_config_string(lookup_config(config_tree, "Mode"), &mode)) {
		if(!strcasecmp(mode, "router"))
			routing_mode = RMODE_ROUTER;
		else if(!strcasecmp(mode, "switch"))
			routing_mode = RMODE_SWITCH;
		else if(!strcasecmp(mode, "hub"))
			routing_mode = RMODE_HUB;
		else {
			logger(LOG_ERR, "Invalid routing mode!");
			return false;
		}
		free(mode);
	}

	if(get_config_string(lookup_config(config_tree, "Forwarding"), &mode)) {
		if(!strcasecmp(mode, "off"))
			forwarding_mode = FMODE_OFF;
		else if(!strcasecmp(mode, "internal"))
			forwarding_mode = FMODE_INTERNAL;
		else if(!strcasecmp(mode, "kernel"))
			forwarding_mode = FMODE_KERNEL;
		else {
			logger(LOG_ERR, "Invalid forwarding mode!");
			return false;
		}
		free(mode);
	}

	choice = true;
	get_config_bool(lookup_config(config_tree, "PMTUDiscovery"), &choice);
	if(choice)
		myself->options |= OPTION_PMTU_DISCOVERY;

	choice = true;
	get_config_bool(lookup_config(config_tree, "ClampMSS"), &choice);
	if(choice)
		myself->options |= OPTION_CLAMP_MSS;

	get_config_bool(lookup_config(config_tree, "PriorityInheritance"), &priorityinheritance);
	get_config_bool(lookup_config(config_tree, "DecrementTTL"), &decrement_ttl);
	get_config_bool(lookup_config(config_tree, "Broadcast"), &broadcast);

#if !defined(SOL_IP) || !defined(IP_TOS)
	if(priorityinheritance)
		logger(LOG_WARNING, "%s not supported on this platform", "PriorityInheritance");
#endif

	if(!get_config_int(lookup_config(config_tree, "MACExpire"), &macexpire))
		macexpire = 600;

	if(get_config_int(lookup_config(config_tree, "MaxTimeout"), &maxtimeout)) {
		if(maxtimeout <= 0) {
			logger(LOG_ERR, "Bogus maximum timeout!");
			return false;
		}
	} else
		maxtimeout = 900;

	if(get_config_int(lookup_config(config_tree, "UDPRcvBuf"), &udp_rcvbuf)) {
		if(udp_rcvbuf <= 0) {
			logger(LOG_ERR, "UDPRcvBuf cannot be negative!");
			return false;
		}
	}

	if(get_config_int(lookup_config(config_tree, "UDPSndBuf"), &udp_sndbuf)) {
		if(udp_sndbuf <= 0) {
			logger(LOG_ERR, "UDPSndBuf cannot be negative!");
			return false;
		}
	}

	if(get_config_int(lookup_config(config_tree, "ReplayWindow"), &replaywin_int)) {
		if(replaywin_int < 0) {
			logger(LOG_ERR, "ReplayWindow cannot be negative!");
			return false;
		}
		replaywin = (unsigned)replaywin_int;
	}

	if(get_config_string(lookup_config(config_tree, "AddressFamily"), &afname)) {
		if(!strcasecmp(afname, "IPv4"))
			addressfamily = AF_INET;
		else if(!strcasecmp(afname, "IPv6"))
			addressfamily = AF_INET6;
		else if(!strcasecmp(afname, "any"))
			addressfamily = AF_UNSPEC;
		else {
			logger(LOG_ERR, "Invalid address family!");
			return false;
		}
		free(afname);
	}

	get_config_bool(lookup_config(config_tree, "Hostnames"), &hostnames);

	/* Generate packet encryption key */

	if(get_config_string
	   (lookup_config(config_tree, "Cipher"), &cipher)) {
		if(!strcasecmp(cipher, "none")) {
			myself->incipher = NULL;
		} else {
			myself->incipher = EVP_get_cipherbyname(cipher);

			if(!myself->incipher) {
				logger(LOG_ERR, "Unrecognized cipher type!");
				return false;
			}
		}
	} else
		myself->incipher = EVP_bf_cbc();

	if(myself->incipher)
		myself->inkeylength = myself->incipher->key_len + myself->incipher->iv_len;
	else
		myself->inkeylength = 1;

	myself->connection->outcipher = EVP_bf_ofb();

	if(!get_config_int(lookup_config(config_tree, "KeyExpire"), &keylifetime))
		keylifetime = 3600;

	keyexpires = now + keylifetime;
	
	/* Check if we want to use message authentication codes... */

	if(get_config_string(lookup_config(config_tree, "Digest"), &digest)) {
		if(!strcasecmp(digest, "none")) {
			myself->indigest = NULL;
		} else {
			myself->indigest = EVP_get_digestbyname(digest);

			if(!myself->indigest) {
				logger(LOG_ERR, "Unrecognized digest type!");
				return false;
			}
		}
	} else
		myself->indigest = EVP_sha1();

	myself->connection->outdigest = EVP_sha1();

	if(get_config_int(lookup_config(config_tree, "MACLength"), &myself->inmaclength)) {
		if(myself->indigest) {
			if(myself->inmaclength > myself->indigest->md_size) {
				logger(LOG_ERR, "MAC length exceeds size of digest!");
				return false;
			} else if(myself->inmaclength < 0) {
				logger(LOG_ERR, "Bogus MAC length!");
				return false;
			}
		}
	} else
		myself->inmaclength = 4;

	myself->connection->outmaclength = 0;

	/* Compression */

	if(get_config_int(lookup_config(config_tree, "Compression"), &myself->incompression)) {
		if(myself->incompression < 0 || myself->incompression > 11) {
			logger(LOG_ERR, "Bogus compression level!");
			return false;
		}
	} else
		myself->incompression = 0;

	myself->connection->outcompression = 0;

	/* Done */

	myself->nexthop = myself;
	myself->via = myself;
	myself->status.reachable = true;
	node_add(myself);

	graph();

	if(strictsubnets)
		load_all_subnets();

	/* Open device */

	devops = os_devops;

	if(get_config_string(lookup_config(config_tree, "DeviceType"), &type)) {
		if(!strcasecmp(type, "dummy"))
			devops = dummy_devops;
		else if(!strcasecmp(type, "raw_socket"))
			devops = raw_socket_devops;
		else if(!strcasecmp(type, "multicast"))
			devops = multicast_devops;
#ifdef ENABLE_UML
		else if(!strcasecmp(type, "uml"))
			devops = uml_devops;
#endif
#ifdef ENABLE_VDE
		else if(!strcasecmp(type, "vde"))
			devops = vde_devops;
#endif
	}

	if(!devops.setup())
		return false;

	/* Run tinc-up script to further initialize the tap interface */
	xasprintf(&envp[0], "NETNAME=%s", netname ? : "");
	xasprintf(&envp[1], "DEVICE=%s", device ? : "");
	xasprintf(&envp[2], "INTERFACE=%s", iface ? : "");
	xasprintf(&envp[3], "NAME=%s", myself->name);
	envp[4] = NULL;

	execute_script("tinc-up", envp);

	for(i = 0; i < 5; i++)
		free(envp[i]);

	/* Run subnet-up scripts for our own subnets */

	subnet_update(myself, NULL, true);

	/* Open sockets */

	if(!do_detach && getenv("LISTEN_FDS")) {
		sockaddr_t sa;
		socklen_t salen;

		listen_sockets = atoi(getenv("LISTEN_FDS"));
#ifdef HAVE_UNSETENV
		unsetenv("LISTEN_FDS");
#endif

		if(listen_sockets > MAXSOCKETS) {
			logger(LOG_ERR, "Too many listening sockets");
			return false;
		}

		for(i = 0; i < listen_sockets; i++) {
			salen = sizeof sa;
			if(getsockname(i + 3, &sa.sa, &salen) < 0) {
				logger(LOG_ERR, "Could not get address of listen fd %d: %s", i + 3, sockstrerror(errno));
				return false;
			}

			listen_socket[i].tcp = i + 3;

#ifdef FD_CLOEXEC
		        fcntl(i + 3, F_SETFD, FD_CLOEXEC);
#endif

			listen_socket[i].udp = setup_vpn_in_socket(&sa);
			if(listen_socket[i].udp < 0)
				return false;

			ifdebug(CONNECTIONS) {
				hostname = sockaddr2hostname(&sa);
				logger(LOG_NOTICE, "Listening on %s", hostname);
				free(hostname);
			}

			memcpy(&listen_socket[i].sa, &sa, salen);
		}
	} else {
		listen_sockets = 0;
		cfg = lookup_config(config_tree, "BindToAddress");

		do {
			get_config_string(cfg, &address);
			if(cfg)
				cfg = lookup_config_next(config_tree, cfg);

			char *port = myport;

			if(address) {
				char *space = strchr(address, ' ');
				if(space) {
					*space++ = 0;
					port = space;
				}

				if(!strcmp(address, "*"))
					*address = 0;
			}

			hint.ai_family = addressfamily;
			hint.ai_socktype = SOCK_STREAM;
			hint.ai_protocol = IPPROTO_TCP;
			hint.ai_flags = AI_PASSIVE;

			err = getaddrinfo(address && *address ? address : NULL, port, &hint, &ai);
			free(address);

			if(err || !ai) {
				logger(LOG_ERR, "System call `%s' failed: %s", "getaddrinfo",
					   gai_strerror(err));
				return false;
			}

			for(aip = ai; aip; aip = aip->ai_next) {
				if(listen_sockets >= MAXSOCKETS) {
					logger(LOG_ERR, "Too many listening sockets");
					return false;
				}

				listen_socket[listen_sockets].tcp =
					setup_listen_socket((sockaddr_t *) aip->ai_addr);

				if(listen_socket[listen_sockets].tcp < 0)
					continue;

				listen_socket[listen_sockets].udp =
					setup_vpn_in_socket((sockaddr_t *) aip->ai_addr);

				if(listen_socket[listen_sockets].udp < 0)
					continue;

				ifdebug(CONNECTIONS) {
					hostname = sockaddr2hostname((sockaddr_t *) aip->ai_addr);
					logger(LOG_NOTICE, "Listening on %s", hostname);
					free(hostname);
				}

				memcpy(&listen_socket[listen_sockets].sa, aip->ai_addr, aip->ai_addrlen);
				listen_sockets++;
			}

			freeaddrinfo(ai);
		} while(cfg);
	}

	if(listen_sockets)
		logger(LOG_NOTICE, "Ready");
	else {
		logger(LOG_ERR, "Unable to create any listening socket!");
		return false;
	}

	return true;
}

/*
  initialize network
*/
bool setup_network(void) {
	now = time(NULL);

	init_events();
	init_connections();
	init_subnets();
	init_nodes();
	init_edges();
	init_requests();

	if(get_config_int(lookup_config(config_tree, "PingInterval"), &pinginterval)) {
		if(pinginterval < 1) {
			pinginterval = 86400;
		}
	} else
		pinginterval = 60;

	if(!get_config_int(lookup_config(config_tree, "PingTimeout"), &pingtimeout))
		pingtimeout = 5;
	if(pingtimeout < 1 || pingtimeout > pinginterval)
		pingtimeout = pinginterval;

	if(!get_config_int(lookup_config(config_tree, "MaxOutputBufferSize"), &maxoutbufsize))
		maxoutbufsize = 10 * MTU;

	if(!setup_myself())
		return false;

	return true;
}

/*
  close all open network connections
*/
void close_network_connections(void) {
	avl_node_t *node, *next;
	connection_t *c;
	char *envp[5];
	int i;

	for(node = connection_tree->head; node; node = next) {
		next = node->next;
		c = node->data;
		c->outgoing = NULL;
		terminate_connection(c, false);
	}

	for(list_node_t *node = outgoing_list->head; node; node = node->next) {
		outgoing_t *outgoing = node->data;

		if(outgoing->event)
			event_del(outgoing->event);
	}

	list_delete_list(outgoing_list);

	if(myself && myself->connection) {
		subnet_update(myself, NULL, false);
		terminate_connection(myself->connection, false);
		free_connection(myself->connection);
	}

	for(i = 0; i < listen_sockets; i++) {
		close(listen_socket[i].tcp);
		close(listen_socket[i].udp);
	}

	xasprintf(&envp[0], "NETNAME=%s", netname ? : "");
	xasprintf(&envp[1], "DEVICE=%s", device ? : "");
	xasprintf(&envp[2], "INTERFACE=%s", iface ? : "");
	xasprintf(&envp[3], "NAME=%s", myself->name);
	envp[4] = NULL;

	exit_requests();
	exit_edges();
	exit_subnets();
	exit_nodes();
	exit_connections();
	exit_events();

	execute_script("tinc-down", envp);

	if(myport) free(myport);

	for(i = 0; i < 4; i++)
		free(envp[i]);

	devops.close();

	return;
}