path: root/tinyNET/src/tnet_nat.c

/*
* Copyright (C) 2010-2011 Mamadou Diop.
*
* This file is part of Open Source Doubango Framework.
*
* DOUBANGO 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 3 of the License, or
* (at your option) any later version.
*	
* DOUBANGO 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 DOUBANGO.
*
*/

/**@file tnet_nat.c
 * @brief NAT Traversal helper functions using STUN, TURN and ICE.
 *
 */
#include "tnet_nat.h"
#include "stun/tnet_stun_types.h"
#include "stun/tnet_stun_utils.h"
#include "stun/tnet_stun_pkt.h"
#include "stun/tnet_stun_attr.h"
#include "stun/tnet_stun_binding.h"

#include "tnet_endianness.h"
#include "tnet_socket.h"

#include "tsk_string.h"
#include "tsk_memory.h"

#include "tsk_debug.h"

/**@defgroup tnet_nat_group NAT Traversal API (STUN, TURN and ICE).
*/

typedef struct tnet_nat_ctx_s
{
	TSK_DECLARE_OBJECT;

	tnet_socket_type_t socket_type;

	char* username; /**< The username to use to authenticate against the TURN/STUN server. */
	char* password;	/**< The password to use to authenticate against the TURN/STUN server. */

	char* server_address; /**< TURN/STUN server address (could be FQDN or IP) */
	tnet_port_t server_port; /**< TURN/STUN server port. */

	uint16_t RTO; /**< Estimate of the round-trip time (RTT) in millisecond. */
	uint16_t Rc; /**< Number of retransmissions for UDP in millisecond. */

	unsigned use_dnsquery:1; /**< Indicates whether to use DNS SRV query to find the stun/turn ip address. */
	
	tnet_stun_bindings_L_t *stun_bindings; /**< List of all STUN2 bindings associated to this context. */
}
tnet_nat_ctx_t;


/**@ingroup tnet_nat_group
* Creates new NAT context.
*/
struct tnet_nat_ctx_s* tnet_nat_context_create(tnet_socket_type_t socket_type, const char* pc_username, const char* pc_password)
{
	extern const tsk_object_def_t *tnet_nat_context_def_t;
	struct tnet_nat_ctx_s* p_ctx;

	if (!(p_ctx = tsk_object_new(tnet_nat_context_def_t)) || !(p_ctx->stun_bindings = tsk_list_create())) {
		TSK_OBJECT_SAFE_FREE(p_ctx);
		TSK_DEBUG_ERROR("Failed to create NAT context");
		return tsk_null;
	}

	p_ctx->socket_type = socket_type;
	p_ctx->username = tsk_strdup(pc_username);
	p_ctx->password = tsk_strdup(pc_password);
	p_ctx->server_port = kStunPortDefaultTcpUdp;
	/*	7.2.1.  Sending over UDP
		In fixed-line access links, a value of 500 ms is RECOMMENDED.
	*/
	p_ctx->RTO = kStunRTO;
	/*	7.2.1.  Sending over UDP
		Rc SHOULD be configurable and SHOULD have a default of 7.
	*/
	p_ctx->Rc = kStunRC;

	return p_ctx;
}

/** Predicate function to find stun binding by id. 
 *
 * @param [in,out]	item	The current list item. 
 * @param [in,out]	id		A pointer to the binding identifier. 
 *
 * @return	Zero if current list item hold a binding with the same id and -1 otherwise.  
**/
int __pred_find_stun_binding(const tsk_list_item_t* item, const void* id)
{
	if(item) {
		tnet_stun_binding_t *p_bind = item->data;
		if (p_bind) {
			tnet_stun_binding_id_t binding_id = *((tnet_stun_binding_id_t*)id);
			return (p_bind->id == binding_id) ? 0 : -1;
		}
	}
	return -1;
}

/**@ingroup tnet_nat_group
 *
 * Sets the address of the STUN/TURN server.
 *
 * @param [in,out]	p_self			The NAT context. 
 * @param [in,out]	pc_server_address	The address of server. 
 *
 * @return	Zero if succeed and non zero error code otherwise. 
**/
int tnet_nat_set_server_address(struct tnet_nat_ctx_s* p_self, const char* pc_server_address)
{
	if (!p_self) {
		TSK_DEBUG_ERROR("Invalid parameter");
		return -1;
	}
	tsk_strupdate(&(p_self->server_address), pc_server_address);
	return 0;
}

/**@ingroup tnet_nat_group
 *
 * Sets the address and port of the STUN/TURN server.
 *
 * @param [in,out]	p_self			The NAT context. 
 * @param [in,out]	pc_server_address	The address of server. 
 * @param	u_server_port				The server port. 
 *
 * @return	Zero if succeed and non zero error code otherwise.  
**/
int tnet_nat_set_server(struct tnet_nat_ctx_s* p_self, const char* pc_server_address,  tnet_port_t u_server_port)
{
	if (!p_self) {
		TSK_DEBUG_ERROR("Invalid parameter");
		return -1;
	}
	tsk_strupdate(&(p_self->server_address), pc_server_address);
	p_self->server_port = u_server_port;
	return 0;	
}

/**@ingroup tnet_nat_group
 *
 * Creates and sends a STUN2 binding request to the STUN/TURN server in order to get the server reflexive
 *			address associated to this file descriptor (or socket). The caller should call @ref tnet_nat_stun_unbind to destroy the binding.
 *
 * @param [in,out]	p_self	The NAT context.  
 * @param	localFD			The local file descriptor (or socket) for which to get the reflexive server address.
 *
 * @return	A valid binding id if succeed and @ref kStunBindingInvalidId otherwise. If the returned id is valid then
 *			the newly created binding will contain the server-reflexive address associated to the local file descriptor.
 *
 * @sa @ref tnet_nat_stun_unbind.
**/
tnet_stun_binding_id_t tnet_nat_stun_bind(const struct tnet_nat_ctx_s* p_self, const tnet_fd_t localFD)
{
	tnet_stun_binding_id_t id = kStunBindingInvalidId;
	tnet_stun_binding_t *p_binding = tsk_null;
	int ret;
	if (!p_self || localFD == TNET_INVALID_FD) {
		TSK_DEBUG_ERROR("Invalid parameter");
		goto bail;
	}
    if ((ret = tnet_stun_binding_create(localFD, p_self->socket_type, p_self->server_address, p_self->server_port, p_self->username, p_self->password, &p_binding))) {
        goto bail;
    }
    if ((ret = tnet_nat_stun_send_bind(p_self, p_binding))) {
        goto bail;
    }
    id = p_binding->id;
    tsk_list_push_back_data(p_self->stun_bindings, (void**)&p_binding);

bail:
	TSK_OBJECT_SAFE_FREE(p_binding);
    return id;
}


/**@ingroup tnet_nat_group
 * 	Internal function to send a STUN2 binding request over the network.
 *
 * @param [in,out]	p_self	The NAT context holding the user preferences.
 * @param [in,out]	p_binding	The STUN binding object used to create the message to send.
 *
 * @return	Zero if succeed and non-zero error code otherwise.
**/
int tnet_nat_stun_send_bind(const struct tnet_nat_ctx_s* pc_self, struct tnet_stun_binding_s *p_binding)
{
	int ret = -1;
    tnet_stun_pkt_resp_t *p_pkt_resp = tsk_null;
    tnet_stun_pkt_req_t *p_pkt_req = tsk_null;

	if (!pc_self || !p_binding) {
		TSK_DEBUG_ERROR("Invalid parameter");
		return -1;
	}

	if (!TNET_SOCKET_TYPE_IS_DGRAM(p_binding->socket_type)) {
		TSK_DEBUG_ERROR("Only DGRAM could be used for STUN transport");
		return -2;
	}

    if ((ret = tnet_stun_binding_create_req(p_binding, &p_pkt_req))) {
        goto bail;
    }

    /*	RFC 5389 - 10.2.1.1.  First Request
    	If the client has not completed a successful request/response
    	transaction with the server (as identified by hostname, if the DNS
    	procedures of Section 9 are used, else IP address if not), it SHOULD
    	omit the USERNAME, MESSAGE-INTEGRITY, REALM, and NONCE attributes.
    	In other words, the very first request is sent as if there were no
    	authentication or message integrity applied.
    */
stun_phase0: {
		if ((ret = tnet_stun_utils_send_unreliably(p_binding->localFD, pc_self->RTO, pc_self->Rc, p_pkt_req, (struct sockaddr*)&p_binding->addr_server, &p_pkt_resp))) {
			goto bail;
		}

        if (p_pkt_resp) {
            if (TNET_STUN_PKT_RESP_IS_ERROR(p_pkt_resp)) {
				uint16_t u_code;
				if ((ret = tnet_stun_pkt_get_errorcode(p_pkt_resp, &u_code))) {
					goto bail;
				}
				if (u_code == kStunErrCodeUnauthorized || u_code == kStunErrCodeStaleNonce) {
					if (u_code == kStunErrCodeUnauthorized) {
						// Make sure this is not an authentication failure (#2 401)
						// Do not send another req to avoid endless messages
						if ((tnet_stun_pkt_attr_exists(p_pkt_req, tnet_stun_attr_type_message_integrity))) { // already has a MESSAGE-INTEGRITY?
							TSK_DEBUG_ERROR("STUN authentication failed");
							goto bail;
						}
					}
					if ((ret = tnet_stun_pkt_auth_prepare_2(p_pkt_req, p_binding->p_username, p_binding->p_password, p_pkt_resp))) {
						goto bail;
					}
					// Try to send again now that authinfo is up2date
					goto stun_phase0;
				}
				else if (u_code == kStunErrCodeUnknownAttributes) {
					if((ret = tnet_stun_pkt_process_err420(p_pkt_req, p_pkt_resp))) {
						goto bail;
					}
					// Try to send again now that authinfo is up2date
					goto stun_phase0;
				}
				ret = -3;
            }
            else {
				const tnet_stun_attr_address_t* pc_addr;
				if ((ret = tnet_stun_pkt_attr_find_first(p_pkt_resp, tnet_stun_attr_type_xor_mapped_address, (const tnet_stun_attr_t**)&pc_addr)) == 0 && pc_addr) {
					TSK_OBJECT_SAFE_FREE(p_binding->p_xmaddr);
					p_binding->p_xmaddr = tsk_object_ref(TSK_OBJECT(pc_addr));
				}
				if ((ret = tnet_stun_pkt_attr_find_first(p_pkt_resp, tnet_stun_attr_type_mapped_address, (const tnet_stun_attr_t**)&pc_addr)) == 0 && pc_addr) {
					TSK_OBJECT_SAFE_FREE(p_binding->p_maddr);
					p_binding->p_maddr = tsk_object_ref(TSK_OBJECT(pc_addr));
				}
			}
        }
    }
    /* END OF stun_phase0 */

bail:
    TSK_OBJECT_SAFE_FREE(p_pkt_resp);
    TSK_OBJECT_SAFE_FREE(p_pkt_req);

    return ret;
}

/**@ingroup tnet_nat_group
 * Gets the server reflexive address associated to this STUN2 binding.
 *
 *
 * @param [in,out]	p_self		The NAT context. 
 * @param	id					The id of the STUN2 binding conetxt (obtained using @ref tnet_nat_stun_bind) holding the server-reflexive address. 
 * @param [in,out]	pp_ip	The reflexive IP address. It is up the the caller to free the returned string 
 * @param [in,out]	pu_port		The reflexive port. 
 *
 * @return	Zero if succeed and non zero error code otherwise. 
**/
int tnet_nat_stun_get_reflexive_address(const struct tnet_nat_ctx_s* p_self, tnet_stun_binding_id_t id, char** pp_ip, tnet_port_t *pu_port)
{
	const tsk_list_item_t* item;
	if (!p_self) {
		TSK_DEBUG_ERROR("Invalid parameter");
		return -1;
	}
	if (!pp_ip && !pu_port) {
		return 0;
	}
	
	if ((item = tsk_list_find_item_by_pred(p_self->stun_bindings, __pred_find_stun_binding, &id)) && item->data) {
		const tnet_stun_binding_t *pc_bind = (const tnet_stun_binding_t *)item->data;
		const struct tnet_stun_attr_address_s *pc_addr = pc_bind->p_xmaddr ? pc_bind->p_xmaddr : pc_bind->p_maddr;
		if (pc_addr) {
			tnet_ip_t ip;
			int ret;
			if ((ret = tnet_stun_utils_inet_ntop((pc_addr->e_family == tnet_stun_address_family_ipv6), &pc_addr->address, &ip))) {
				return ret;
			}
			if (pp_ip) {
				tsk_strupdate(pp_ip, ip);
			}
			if (pu_port) {
				*pu_port = pc_addr->u_port;
			}
			return 0;
		}
	}
	return -2;
}

/**@ingroup tnet_nat_group
 *
 * Removes a STUN2 binding from the NAT context.
 *
 * @param [in,out]	p_self	The NAT context from which to remove the STUN2 binding. 
 * @param	id				The id of the STUN2 binding to remove. 
 *
 * @return	Zero if succeed and non zero error code otherwise.
 *
 *
 * @sa @ref tnet_nat_stun_bind.
**/
int tnet_nat_stun_unbind(const struct tnet_nat_ctx_s* p_self, tnet_stun_binding_id_t id)
{
	if (!p_self) {
		TSK_DEBUG_ERROR("Invalid parameter");
		return -1;
	}
	tsk_list_remove_item_by_pred(p_self->stun_bindings, __pred_find_stun_binding, &id);
	return 0;	
}


//=================================================================================================
//	NAT CONTEXT object definition
//
static tsk_object_t* tnet_nat_context_ctor(tsk_object_t * self, va_list * app)
{
	tnet_nat_ctx_t *p_ctx = (tnet_nat_ctx_t*)self;
	if (p_ctx) {
	}
	return self;
}
static tsk_object_t* tnet_nat_context_dtor(tsk_object_t * self)
{ 
	tnet_nat_ctx_t *p_ctx = (tnet_nat_ctx_t*)self;
	if (p_ctx) {
		TSK_FREE(p_ctx->username);
		TSK_FREE(p_ctx->password);
		TSK_FREE(p_ctx->server_address);

		TSK_OBJECT_SAFE_FREE(p_ctx->stun_bindings);
		TSK_DEBUG_INFO("*** NAT context destroyed ***");
	}

	return self;
}
static const tsk_object_def_t tnet_nat_context_def_s = 
{
	sizeof(tnet_nat_ctx_t),
	tnet_nat_context_ctor, 
	tnet_nat_context_dtor,
	tsk_null, 
};
const tsk_object_def_t *tnet_nat_context_def_t = &tnet_nat_context_def_s;