/**
 * @file kernel_interface.c
 *
 * @brief Implementation of kernel_interface_t.
 *
 */

/*
 * Copyright (C) 2005 Jan Hutter, Martin Willi
 * Hochschule fuer Technik Rapperswil
 * Copyright (C) 2003 Herbert Xu.
 * 
 * Contains modified parts from pluto.
 *
 * 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * 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.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <pthread.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>

#include "kernel_interface.h"

#include <daemon.h>
#include <utils/allocator.h>
#include <utils/linked_list.h>


#define KERNEL_ESP 50
#define KERNEL_AH 51

#define SPD_PRIORITY 1024

#define XFRM_DATA_LENGTH 512


typedef struct xfrm_data_t xfrm_data_t;

/**
 * Lenght/Type/data struct for userdata in xfrm
 * We dont use the "I-don't-know-where-they-come-from"-structs
 * used in the kernel.
 */
struct xfrm_data_t {
	/**
	 * length of the data
	 */
	u_int16_t length;
	
	/**
	 * type of data 
	 */
	u_int16_t type;
	
	/**
	 * and the data itself, for different purposes
	 */
	union {
		/** algorithm */
		struct xfrm_algo algo;
		/** policy tmpl */
		struct xfrm_user_tmpl tmpl[2];
	};
};


typedef struct netlink_message_t netlink_message_t;

/**
 * Representation of ANY netlink message used
 */
struct netlink_message_t {
	
	/**
	 * header of the netlink message 
	 */
	struct nlmsghdr hdr;

	union {
		/** error message */
		struct nlmsgerr e;
		/** message for spi allocation */
		struct xfrm_userspi_info spi;
		/** message for SA manipulation */
		struct xfrm_usersa_id sa_id;
		/** message for SA installation */
		struct xfrm_usersa_info sa;
		/** message for policy manipulation */
		struct xfrm_userpolicy_id policy_id;
		/** message for policy installation */
		struct xfrm_userpolicy_info policy;
	};
	u_int8_t data[XFRM_DATA_LENGTH];
};


typedef struct private_kernel_interface_t private_kernel_interface_t;

 /**
 * @brief Private Variables and Functions of kernel_interface class.
 *
 */
struct private_kernel_interface_t {
	/**
	 * Public part of the kernel_interface_t object.
	 */
	kernel_interface_t public;
	
	/**
	 * Netlink communication socket.
	 */
	int socket;
	
	pid_t pid;
	/**
	 * Sequence number for messages.
	 */
	u_int32_t seq;
	
	/** 
	 * List of responded messages.
	 */
	linked_list_t *responses;
	
	/**
	 * Thread which receives messages.
	 */
	pthread_t thread;
	
	/**
	 * Mutex locks access to replies list.
	 */
	pthread_mutex_t mutex;
	
	/**
	 * Condvar allows signaling of threads waiting for a reply.
	 */
	pthread_cond_t condvar;
	
	/**
	 * Function for the thread, receives messages.
	 */
	void (*receive_messages) (private_kernel_interface_t *this);
	
	/**
	 * Sends a netlink_message_t down to the kernel and wait for reply.
	 */
	status_t (*send_message) (private_kernel_interface_t *this, netlink_message_t *request, netlink_message_t **response);
};

/**
 * In the kernel, algorithms are identified as strings, we use our
 * mapping functions...
 * Algorithms for encryption.
 * TODO: Add missing algorithm strings
 */
mapping_t kernel_encryption_algs_m[] = {
	{ENCR_DES_IV64, ""},
	{ENCR_DES, "des"},
	{ENCR_3DES, "des3_ede"},
	{ENCR_RC5, ""},
	{ENCR_IDEA, "idea"},
	{ENCR_CAST, "cast128"},
	{ENCR_BLOWFISH, "blowfish"},
	{ENCR_3IDEA, ""},
	{ENCR_DES_IV32, ""},
	{ENCR_NULL, ""},
	{ENCR_AES_CBC, "aes"},
	{ENCR_AES_CTR, ""},
	{MAPPING_END, NULL}
};
/**
 * In the kernel, algorithms are identified as strings, we use our
 * mapping functions...
 * Algorithms for integrity protection.
 * TODO: Add missing algorithm strings
 */
mapping_t kernel_integrity_algs_m[] = {
	{AUTH_HMAC_MD5_96, "md5"},
	{AUTH_HMAC_SHA1_96, "sha1"},
	{AUTH_DES_MAC, ""},
	{AUTH_KPDK_MD5, ""},
	{AUTH_AES_XCBC_96, ""},
	{MAPPING_END, NULL}
};

/**
 * Implementation of kernel_interface_t.get_spi.
 */
static status_t get_spi(private_kernel_interface_t *this, 
						host_t *src, host_t *dest, 
						protocol_id_t protocol, u_int32_t reqid,
						u_int32_t *spi)
{
	netlink_message_t request, *response;
	status_t status = SUCCESS;
	
	memset(&request, 0, sizeof(request));
	request.hdr.nlmsg_len = NLMSG_ALIGN(NLMSG_LENGTH(sizeof(request.spi)));
	request.hdr.nlmsg_flags = NLM_F_REQUEST;
	request.hdr.nlmsg_type = XFRM_MSG_ALLOCSPI;
	request.spi.info.saddr = src->get_xfrm_addr(src);
	request.spi.info.id.daddr = dest->get_xfrm_addr(dest);
	request.spi.info.mode = TRUE; /* tunnel mode */
	request.spi.info.reqid = reqid;
	request.spi.info.id.proto = (protocol == ESP) ? KERNEL_ESP : KERNEL_AH;
	request.spi.info.family = PF_INET;
	request.spi.min = 0xc0000000;
	request.spi.max = 0xcFFFFFFF;
	
	if (this->send_message(this, &request, &response) != SUCCESS)
	{
		status = FAILED;
	}
	else if (response->hdr.nlmsg_type == NLMSG_ERROR)
	{
		status = FAILED;
	}
	else if (response->hdr.nlmsg_type != XFRM_MSG_NEWSA)
	{
		status = FAILED;
	}
	else if (response->hdr.nlmsg_len < NLMSG_LENGTH(sizeof(response->sa)))
	{
		status = FAILED;
	}
	
	*spi = response->sa.id.spi;
	allocator_free(response);
	
	return status;
}

/**
 * Implementation of kernel_interface_t.add_sa.
 */
static status_t add_sa(	private_kernel_interface_t *this,
						host_t *me,
						host_t *other,
						u_int32_t spi,
						int protocol,
						u_int32_t reqid,
						encryption_algorithm_t enc_alg,
						chunk_t encryption_key,
						integrity_algorithm_t int_alg,
						chunk_t integrity_key,
						bool replace)
{
	netlink_message_t request, *response;
	memset(&request, 0, sizeof(request));
	status_t status;
	
	request.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	request.hdr.nlmsg_type = replace ? XFRM_MSG_UPDSA : XFRM_MSG_NEWSA;
	
	request.sa.saddr = me->get_xfrm_addr(me);
	request.sa.id.daddr = other->get_xfrm_addr(other);
	
	request.sa.id.spi = spi;
	request.sa.id.proto = (protocol == ESP) ? KERNEL_ESP : KERNEL_AH;
	request.sa.family = me->get_family(me);
	request.sa.mode = TRUE; /* tunnel mode */
	request.sa.replay_window = 0; //sa->replay_window; ???
	request.sa.reqid = reqid;
	request.sa.lft.soft_byte_limit = XFRM_INF;
	request.sa.lft.soft_packet_limit = XFRM_INF;
	request.sa.lft.hard_byte_limit = XFRM_INF;
	request.sa.lft.hard_packet_limit = XFRM_INF;
	
	request.hdr.nlmsg_len = NLMSG_ALIGN(NLMSG_LENGTH(sizeof(request.sa)));
	
	if (enc_alg != ENCR_UNDEFINED)
	{
		xfrm_data_t *data = (xfrm_data_t*)(((u_int8_t*)&request) + request.hdr.nlmsg_len);
		
		data->type = XFRMA_ALG_CRYPT;
		data->length = 4 + sizeof(data->algo) + encryption_key.len;
		data->algo.alg_key_len = encryption_key.len * 8;
		request.hdr.nlmsg_len += data->length;
		if (request.hdr.nlmsg_len > sizeof(request))
		{
			return FAILED;
		}
		strcpy(data->algo.alg_name, mapping_find(kernel_encryption_algs_m, enc_alg));
		memcpy(data->algo.alg_key, encryption_key.ptr, encryption_key.len);
	}
	
	if (int_alg != AUTH_UNDEFINED)
	{
		xfrm_data_t *data = (xfrm_data_t*)(((u_int8_t*)&request) + request.hdr.nlmsg_len);
		
		data->type = XFRMA_ALG_AUTH;
		data->length = 4 + sizeof(data->algo) + integrity_key.len;
		data->algo.alg_key_len = integrity_key.len * 8;
		request.hdr.nlmsg_len += data->length;
		if (request.hdr.nlmsg_len > sizeof(request))
		{
			return FAILED;
		}
		strcpy(data->algo.alg_name, mapping_find(kernel_integrity_algs_m, int_alg));
		memcpy(data->algo.alg_key, integrity_key.ptr, integrity_key.len);
	}
	
	/* TODO: add IPComp here*/
	
	if (this->send_message(this, &request, &response) != SUCCESS)
	{
		status = FAILED;
	}
	else if (response->hdr.nlmsg_type != NLMSG_ERROR)
	{
		status = FAILED;
	}
	else if (response->e.error)
	{
		status = FAILED;
	}
	
	allocator_free(response);
	return SUCCESS;
}

static status_t del_sa(	private_kernel_interface_t *this,
						host_t *dst,
						u_int32_t spi,
						protocol_id_t protocol)
{
	netlink_message_t request, *response;
	memset(&request, 0, sizeof(request));
	status_t status;
	
	request.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	request.hdr.nlmsg_type = XFRM_MSG_DELSA;
	
	request.sa_id.daddr = dst->get_xfrm_addr(dst);
	
	request.sa_id.spi = spi;
	request.sa_id.proto = (protocol == ESP) ? KERNEL_ESP : KERNEL_AH;
	request.sa_id.family = dst->get_family(dst);
	
	request.hdr.nlmsg_len = NLMSG_ALIGN(NLMSG_LENGTH(sizeof(request.sa_id)));
	
	if (this->send_message(this, &request, &response) != SUCCESS)
	{
		status = FAILED;
	}
	else if (response->hdr.nlmsg_type != NLMSG_ERROR)
	{
		status = FAILED;
	}
	else if (response->e.error)
	{
		status = FAILED;
	}
	
	allocator_free(response);
	return SUCCESS;
}

/**
 * Implementation of kernel_interface_t.add_policy.
 */
static status_t add_policy(private_kernel_interface_t *this, 
						  host_t *me, host_t *other, 
						  host_t *src, host_t *dst,
						  u_int8_t src_hostbits, u_int8_t dst_hostbits,
						  int direction, int upper_proto, 
						  bool ah, bool esp,
						  u_int32_t reqid)
{
	netlink_message_t request, *response;
	status_t status = SUCCESS;
	
	memset(&request, 0, sizeof(request));
	request.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;

	request.policy.sel.sport = htons(src->get_port(src));
	request.policy.sel.dport = htons(dst->get_port(dst));
	request.policy.sel.sport_mask = (request.policy.sel.sport) ? ~0 : 0;
	request.policy.sel.dport_mask = (request.policy.sel.dport) ? ~0 : 0;
	request.policy.sel.saddr = src->get_xfrm_addr(src);
	request.policy.sel.daddr = dst->get_xfrm_addr(dst);
	request.policy.sel.prefixlen_s = src_hostbits;
	request.policy.sel.prefixlen_d = dst_hostbits;
	request.policy.sel.proto = upper_proto;
	request.policy.sel.family = src->get_family(src);

	request.hdr.nlmsg_type = XFRM_MSG_NEWPOLICY;
	request.hdr.nlmsg_len = NLMSG_ALIGN(NLMSG_LENGTH(sizeof(request.policy)));

	request.policy.dir = direction;
	request.policy.priority = SPD_PRIORITY;
	request.policy.action = XFRM_POLICY_ALLOW;
	request.policy.share = XFRM_SHARE_ANY;
	
	request.policy.lft.soft_byte_limit = XFRM_INF;
	request.policy.lft.soft_packet_limit = XFRM_INF;
	request.policy.lft.hard_byte_limit = XFRM_INF;
	request.policy.lft.hard_packet_limit = XFRM_INF;
	
	if (esp || ah)
	{
		xfrm_data_t *data;
		int tmpl_pos = 0;
		data = (xfrm_data_t*)(((u_int8_t*)&request) + request.hdr.nlmsg_len);
		data->type = XFRMA_TMPL;
		if (esp)
		{
			data->tmpl[tmpl_pos].reqid = reqid;
			data->tmpl[tmpl_pos].id.proto = KERNEL_ESP;
			data->tmpl[tmpl_pos].aalgos = data->tmpl[tmpl_pos].ealgos = data->tmpl[tmpl_pos].calgos = ~0;
			data->tmpl[tmpl_pos].mode = TRUE;
			
			data->tmpl[tmpl_pos].saddr = me->get_xfrm_addr(me);
			data->tmpl[tmpl_pos].id.daddr = me->get_xfrm_addr(other);
			
			tmpl_pos++;
		}	
		if (ah)
		{
			data->tmpl[tmpl_pos].reqid = reqid;
			data->tmpl[tmpl_pos].id.proto = KERNEL_AH;
			data->tmpl[tmpl_pos].aalgos = data->tmpl[tmpl_pos].ealgos = data->tmpl[tmpl_pos].calgos = ~0;
			data->tmpl[tmpl_pos].mode = TRUE;
			
			data->tmpl[tmpl_pos].saddr = me->get_xfrm_addr(me);
			data->tmpl[tmpl_pos].id.daddr = other->get_xfrm_addr(other);
			
			tmpl_pos++;
		}
		data->length = 4 + sizeof(struct xfrm_user_tmpl) * tmpl_pos;
		request.hdr.nlmsg_len += data->length;
	}
	
	if (this->send_message(this, &request, &response) != SUCCESS)
	{
		status = FAILED;
	}
	else if (response->hdr.nlmsg_type != NLMSG_ERROR)
	{
		status = FAILED;
	}
	else if (response->e.error)
	{
		status = FAILED;
	}
	
	allocator_free(response);
	return status;
}

/**
 * Implementation of kernel_interface_t.del_policy.
 */
static status_t del_policy(private_kernel_interface_t *this, 
						   host_t *me, host_t *other, 
						   host_t *src, host_t *dst,
						   u_int8_t src_hostbits, u_int8_t dst_hostbits,
						   int direction, int upper_proto)
{
	netlink_message_t request, *response;
	status_t status = SUCCESS;
	
	memset(&request, 0, sizeof(request));
	request.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;

	request.policy_id.sel.sport = htons(src->get_port(src));
	request.policy_id.sel.dport = htons(dst->get_port(dst));
	request.policy_id.sel.sport_mask = (request.policy.sel.sport) ? ~0 : 0;
	request.policy_id.sel.dport_mask = (request.policy.sel.dport) ? ~0 : 0;
	request.policy_id.sel.saddr = src->get_xfrm_addr(src);
	request.policy_id.sel.daddr = dst->get_xfrm_addr(dst);
	request.policy_id.sel.prefixlen_s = src_hostbits;
	request.policy_id.sel.prefixlen_d = dst_hostbits;
	request.policy_id.sel.proto = upper_proto;
	request.policy_id.sel.family = src->get_family(src);
	
	request.policy_id.dir = direction;

	request.hdr.nlmsg_type = XFRM_MSG_DELPOLICY;
	request.hdr.nlmsg_len = NLMSG_ALIGN(NLMSG_LENGTH(sizeof(request.policy_id)));
	
	if (this->send_message(this, &request, &response) != SUCCESS)
	{
		status = FAILED;
	}
	else if (response->hdr.nlmsg_type != NLMSG_ERROR)
	{
		status = FAILED;
	}
	else if (response->e.error)
	{
		status = FAILED;
	}
	
	allocator_free(response);
	return status;
}

/**
 * Implementation of private_kernel_interface_t.send_message.
 */
static status_t send_message(private_kernel_interface_t *this, netlink_message_t *request, netlink_message_t **response)
{
	size_t length;
	struct sockaddr_nl addr;
	
	request->hdr.nlmsg_seq = ++this->seq;
	request->hdr.nlmsg_pid = this->pid;
	
	memset(&addr, 0, sizeof(struct sockaddr_nl));
	addr.nl_family = AF_NETLINK;
	addr.nl_pid = 0;
	addr.nl_groups = 0;
	
	length = sendto(this->socket,(void *)request, request->hdr.nlmsg_len, 0, (struct sockaddr *)&addr, sizeof(addr));
	
	if (length < 0)
	{
		return FAILED;
	}
	else if (length != request->hdr.nlmsg_len)
	{
		return FAILED;
	}
	
	pthread_mutex_lock(&(this->mutex));
	
	while (TRUE)
	{
		iterator_t *iterator; 
		bool found = FALSE;
		/* search list, break if found */
		iterator = this->responses->create_iterator(this->responses, TRUE);
		while (iterator->has_next(iterator))
		{
			netlink_message_t *listed_response;
			iterator->current(iterator, (void**)&listed_response);
			if (listed_response->hdr.nlmsg_seq == request->hdr.nlmsg_seq)
			{
				/* matches our request, this is the reply */
				*response = listed_response;
				found = TRUE;
				break;
			}
		}
		iterator->destroy(iterator);
		
		if (found)
		{
			break;
		}
		/* TODO: we should time out, if something goes wrong!??? */
		pthread_cond_wait(&(this->condvar), &(this->mutex));
	}
	
	pthread_mutex_unlock(&(this->mutex));
	
	return SUCCESS;
}

/**
 * Implementation of private_kernel_interface_t.receive_messages.
 */
static void receive_messages(private_kernel_interface_t *this)
{
	while(TRUE) 
	{
		netlink_message_t response, *listed_response;
		while (TRUE)
		{
			struct sockaddr_nl addr;
			socklen_t addr_length;
			size_t length;
			
			addr_length = sizeof(addr);
			
			response.hdr.nlmsg_type = XFRM_MSG_NEWSA;
			length = recvfrom(this->socket, &response, sizeof(response), 0, (struct sockaddr*)&addr, &addr_length);
			if (length < 0)
			{
				if (errno == EINTR)
				{
					/* interrupted, try again */
					continue;
				}
				charon->kill(charon, "receiving from netlink socket failed");
			}
			if (!NLMSG_OK(&response.hdr, length))
			{
				/* bad netlink message */
				continue;
			}
			if (addr.nl_pid != 0)
			{
				/* not from kernel. not interested, try another one */
				continue;
			}
			break;
		}
		
		/* got a valid message.
		 * requests are handled on our own, 
		 * responses are listed for the requesters
		 */
		if (response.hdr.nlmsg_flags & NLM_F_REQUEST)
		{
			/* handle request */	
		}
		else
		{
			/* add response to queue */			
			listed_response = allocator_alloc(sizeof(response));
			memcpy(listed_response, &response, sizeof(response));

			pthread_mutex_lock(&(this->mutex));
			this->responses->insert_last(this->responses, (void*)listed_response);
			pthread_mutex_unlock(&(this->mutex));
			/* signal ALL waiting threads */
			pthread_cond_broadcast(&(this->condvar));
		}
		/* get the next one */
	}
}

/**
 * Implementation of kernel_interface_t.destroy.
 */
static void destroy(private_kernel_interface_t *this)
{	
	pthread_cancel(this->thread);
	pthread_join(this->thread, NULL);
	close(this->socket);
	this->responses->destroy(this->responses);
	allocator_free(this);
}

/*
 * Described in header.
 */
kernel_interface_t *kernel_interface_create()
{
	private_kernel_interface_t *this = allocator_alloc_thing(private_kernel_interface_t);
	
	/* public functions */
	this->public.get_spi = (status_t(*)(kernel_interface_t*,host_t*,host_t*,protocol_id_t,u_int32_t,u_int32_t*))get_spi;
	this->public.add_sa  = (status_t(*)(kernel_interface_t *,host_t*,host_t*,u_int32_t,protocol_id_t,u_int32_t,encryption_algorithm_t,chunk_t,integrity_algorithm_t,chunk_t,bool))add_sa;
	this->public.add_policy = (status_t(*)(kernel_interface_t*,host_t*, host_t*,host_t*,host_t*,u_int8_t,u_int8_t,int,int,bool,bool,u_int32_t))add_policy;
	this->public.del_sa = (status_t(*)(kernel_interface_t*,host_t*,u_int32_t,protocol_id_t))del_sa;
	this->public.del_policy = (status_t(*)(kernel_interface_t*,host_t*,host_t*,host_t*,host_t*,u_int8_t,u_int8_t,int,int))del_policy;
	
	this->public.destroy = (void(*)(kernel_interface_t*)) destroy;

	/* private members */
	this->receive_messages = receive_messages;
	this->send_message = send_message;
	this->pid = getpid();
	this->responses = linked_list_create();
	pthread_mutex_init(&(this->mutex),NULL);
	pthread_cond_init(&(this->condvar),NULL);
	this->seq = 0;
	this->socket = socket(PF_NETLINK, SOCK_RAW, NETLINK_XFRM);
	if (this->socket <= 0)
	{
		allocator_free(this);
		charon->kill(charon, "Unable to create netlink socket");	
	}
	
	if (pthread_create(&(this->thread), NULL, (void*(*)(void*))this->receive_messages, this) != 0)
	{
		close(this->socket);
		allocator_free(this);
		charon->kill(charon, "Unable to create netlink thread");
	}
	
	charon->logger_manager->enable_logger_level(charon->logger_manager, TESTER, FULL);
	return (&this->public);
}