sdp_neg.c

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/* $Id: sdp_neg.c 1071 2007-03-15 21:56:33Z bennylp $ */
/* 
 * Copyright (C) 2003-2007 Benny Prijono <[e-mail]>
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 */
#include <pjmedia/sdp_neg.h>
#include <pjmedia/sdp.h>
#include <pjmedia/errno.h>
#include <pj/assert.h>
#include <pj/pool.h>
#include <pj/string.h>
#include <pj/ctype.h>
#include <pj/array.h>

/**
 * This structure describes SDP media negotiator.
 */
struct pjmedia_sdp_neg
{
    pjmedia_sdp_neg_state state;	    /**< Negotiator state.	     */
    pj_bool_t		  prefer_remote_codec_order;
    pj_bool_t		  has_remote_answer;
    pj_bool_t		  answer_was_remote;

    pjmedia_sdp_session	*initial_sdp,	    /**< Initial local SDP	     */
			*active_local_sdp,  /**< Currently active local SDP. */
			*active_remote_sdp, /**< Currently active remote's.  */
			*neg_local_sdp,	    /**< Temporary local SDP.	     */
			*neg_remote_sdp;    /**< Temporary remote SDP.	     */
};

static const char *state_str[] = 
{
    "STATE_NULL",
    "STATE_LOCAL_OFFER",
    "STATE_REMOTE_OFFER",
    "STATE_WAIT_NEGO",
    "STATE_DONE",
};

/*
 * Get string representation of negotiator state.
 */
PJ_DEF(const char*) pjmedia_sdp_neg_state_str(pjmedia_sdp_neg_state state)
{
    if (state >=0 && state < PJ_ARRAY_SIZE(state_str))
	return state_str[state];

    return "<?UNKNOWN?>";
}


/*
 * Create with local offer.
 */
PJ_DEF(pj_status_t) 
pjmedia_sdp_neg_create_w_local_offer( pj_pool_t *pool,
				      const pjmedia_sdp_session *local,
				      pjmedia_sdp_neg **p_neg)
{
    pjmedia_sdp_neg *neg;
    pj_status_t status;

    /* Check arguments are valid. */
    PJ_ASSERT_RETURN(pool && local && p_neg, PJ_EINVAL);

    *p_neg = NULL;

    /* Validate local offer. */
    PJ_ASSERT_RETURN((status=pjmedia_sdp_validate(local))==PJ_SUCCESS, status);

    /* Create and initialize negotiator. */
    neg = pj_pool_zalloc(pool, sizeof(pjmedia_sdp_neg));
    PJ_ASSERT_RETURN(neg != NULL, PJ_ENOMEM);

    neg->state = PJMEDIA_SDP_NEG_STATE_LOCAL_OFFER;
    neg->prefer_remote_codec_order = PJMEDIA_SDP_NEG_PREFER_REMOTE_CODEC_ORDER;
    neg->initial_sdp = pjmedia_sdp_session_clone(pool, local);
    neg->neg_local_sdp = pjmedia_sdp_session_clone(pool, local);

    *p_neg = neg;
    return PJ_SUCCESS;
}

/*
 * Create with remote offer and initial local offer/answer.
 */
PJ_DEF(pj_status_t) 
pjmedia_sdp_neg_create_w_remote_offer(pj_pool_t *pool,
				      const pjmedia_sdp_session *initial,
				      const pjmedia_sdp_session *remote,
				      pjmedia_sdp_neg **p_neg)
{
    pjmedia_sdp_neg *neg;
    pj_status_t status;

    /* Check arguments are valid. */
    PJ_ASSERT_RETURN(pool && remote && p_neg, PJ_EINVAL);

    *p_neg = NULL;

    /* Validate remote offer and initial answer */
    status = pjmedia_sdp_validate(remote);
    if (status != PJ_SUCCESS)
	return status;

    /* Create and initialize negotiator. */
    neg = pj_pool_zalloc(pool, sizeof(pjmedia_sdp_neg));
    PJ_ASSERT_RETURN(neg != NULL, PJ_ENOMEM);

    neg->prefer_remote_codec_order = PJMEDIA_SDP_NEG_PREFER_REMOTE_CODEC_ORDER;
    neg->neg_remote_sdp = pjmedia_sdp_session_clone(pool, remote);

    if (initial) {
	PJ_ASSERT_RETURN((status=pjmedia_sdp_validate(initial))==PJ_SUCCESS, 
			 status);

	neg->initial_sdp = pjmedia_sdp_session_clone(pool, initial);
	neg->neg_local_sdp = pjmedia_sdp_session_clone(pool, initial);

	neg->state = PJMEDIA_SDP_NEG_STATE_WAIT_NEGO;

    } else {
	
	neg->state = PJMEDIA_SDP_NEG_STATE_REMOTE_OFFER;

    }

    *p_neg = neg;
    return PJ_SUCCESS;
}


/*
 * Set codec order preference.
 */
PJ_DEF(pj_status_t)
pjmedia_sdp_neg_set_prefer_remote_codec_order(pjmedia_sdp_neg *neg,
					      pj_bool_t prefer_remote)
{
    PJ_ASSERT_RETURN(neg, PJ_EINVAL);
    neg->prefer_remote_codec_order = prefer_remote;
    return PJ_SUCCESS;
}


/*
 * Get SDP negotiator state.
 */
PJ_DEF(pjmedia_sdp_neg_state)
pjmedia_sdp_neg_get_state( pjmedia_sdp_neg *neg )
{
    /* Check arguments are valid. */
    PJ_ASSERT_RETURN(neg != NULL, PJMEDIA_SDP_NEG_STATE_NULL);
    return neg->state;
}


PJ_DEF(pj_status_t) 
pjmedia_sdp_neg_get_active_local( pjmedia_sdp_neg *neg,
				  const pjmedia_sdp_session **local)
{
    PJ_ASSERT_RETURN(neg && local, PJ_EINVAL);
    PJ_ASSERT_RETURN(neg->active_local_sdp, PJMEDIA_SDPNEG_ENOACTIVE);

    *local = neg->active_local_sdp;
    return PJ_SUCCESS;
}


PJ_DEF(pj_status_t) 
pjmedia_sdp_neg_get_active_remote( pjmedia_sdp_neg *neg,
				   const pjmedia_sdp_session **remote)
{
    PJ_ASSERT_RETURN(neg && remote, PJ_EINVAL);
    PJ_ASSERT_RETURN(neg->active_remote_sdp, PJMEDIA_SDPNEG_ENOACTIVE);

    *remote = neg->active_remote_sdp;
    return PJ_SUCCESS;
}


PJ_DEF(pj_bool_t)
pjmedia_sdp_neg_was_answer_remote(pjmedia_sdp_neg *neg)
{
    PJ_ASSERT_RETURN(neg, PJ_FALSE);

    return neg->answer_was_remote;
}


PJ_DEF(pj_status_t)
pjmedia_sdp_neg_get_neg_remote( pjmedia_sdp_neg *neg,
				const pjmedia_sdp_session **remote)
{
    PJ_ASSERT_RETURN(neg && remote, PJ_EINVAL);
    PJ_ASSERT_RETURN(neg->neg_remote_sdp, PJMEDIA_SDPNEG_ENONEG);

    *remote = neg->neg_remote_sdp;
    return PJ_SUCCESS;
}

PJ_DEF(pj_status_t) 
pjmedia_sdp_neg_get_neg_local( pjmedia_sdp_neg *neg,
			       const pjmedia_sdp_session **local)
{
    PJ_ASSERT_RETURN(neg && local, PJ_EINVAL);
    PJ_ASSERT_RETURN(neg->neg_local_sdp, PJMEDIA_SDPNEG_ENONEG);

    *local = neg->neg_local_sdp;
    return PJ_SUCCESS;
}


/*
 * Modify local SDP and wait for remote answer.
 */
PJ_DEF(pj_status_t) 
pjmedia_sdp_neg_modify_local_offer( pj_pool_t *pool,
				    pjmedia_sdp_neg *neg,
				    const pjmedia_sdp_session *local)
{
    /* Check arguments are valid. */
    PJ_ASSERT_RETURN(pool && neg && local, PJ_EINVAL);

    /* Can only do this in STATE_DONE. */
    PJ_ASSERT_RETURN(neg->state == PJMEDIA_SDP_NEG_STATE_DONE, 
		     PJMEDIA_SDPNEG_EINSTATE);

    /* Change state to STATE_LOCAL_OFFER */
    neg->state = PJMEDIA_SDP_NEG_STATE_LOCAL_OFFER;
    neg->initial_sdp = pjmedia_sdp_session_clone(pool, local);
    neg->neg_local_sdp = pjmedia_sdp_session_clone(pool, local);

    return PJ_SUCCESS;
}


PJ_DEF(pj_status_t) 
pjmedia_sdp_neg_send_local_offer( pj_pool_t *pool,
				  pjmedia_sdp_neg *neg,
				  const pjmedia_sdp_session **offer)
{
    /* Check arguments are valid. */
    PJ_ASSERT_RETURN(neg && offer, PJ_EINVAL);

    *offer = NULL;

    /* Can only do this in STATE_DONE or STATE_LOCAL_OFFER. */
    PJ_ASSERT_RETURN(neg->state == PJMEDIA_SDP_NEG_STATE_DONE ||
		     neg->state == PJMEDIA_SDP_NEG_STATE_LOCAL_OFFER, 
		     PJMEDIA_SDPNEG_EINSTATE);

    if (neg->state == PJMEDIA_SDP_NEG_STATE_DONE) {
	/* If in STATE_DONE, set the active SDP as the offer. */
	PJ_ASSERT_RETURN(neg->active_local_sdp, PJMEDIA_SDPNEG_ENOACTIVE);

	neg->state = PJMEDIA_SDP_NEG_STATE_LOCAL_OFFER;
	neg->neg_local_sdp = pjmedia_sdp_session_clone(pool, 
						       neg->active_local_sdp);
	*offer = neg->active_local_sdp;

    } else {
	/* We assume that we're in STATE_LOCAL_OFFER.
	 * In this case set the neg_local_sdp as the offer.
	 */
	*offer = neg->neg_local_sdp;
    }

    
    return PJ_SUCCESS;
}


PJ_DEF(pj_status_t) 
pjmedia_sdp_neg_set_remote_answer( pj_pool_t *pool,
				   pjmedia_sdp_neg *neg,
				   const pjmedia_sdp_session *remote)
{
    /* Check arguments are valid. */
    PJ_ASSERT_RETURN(pool && neg && remote, PJ_EINVAL);

    /* Can only do this in STATE_LOCAL_OFFER.
     * If we haven't provided local offer, then rx_remote_offer() should
     * be called instead of this function.
     */
    PJ_ASSERT_RETURN(neg->state == PJMEDIA_SDP_NEG_STATE_LOCAL_OFFER, 
		     PJMEDIA_SDPNEG_EINSTATE);

    /* We're ready to negotiate. */
    neg->state = PJMEDIA_SDP_NEG_STATE_WAIT_NEGO;
    neg->has_remote_answer = PJ_TRUE;
    neg->neg_remote_sdp = pjmedia_sdp_session_clone(pool, remote);
 
    return PJ_SUCCESS;
}

PJ_DEF(pj_status_t) 
pjmedia_sdp_neg_set_remote_offer( pj_pool_t *pool,
				  pjmedia_sdp_neg *neg,
				  const pjmedia_sdp_session *remote)
{
    /* Check arguments are valid. */
    PJ_ASSERT_RETURN(pool && neg && remote, PJ_EINVAL);

    /* Can only do this in STATE_DONE.
     * If we already provide local offer, then rx_remote_answer() should
     * be called instead of this function.
     */
    PJ_ASSERT_RETURN(neg->state == PJMEDIA_SDP_NEG_STATE_DONE, 
		     PJMEDIA_SDPNEG_EINSTATE);

    /* State now is STATE_REMOTE_OFFER. */
    neg->state = PJMEDIA_SDP_NEG_STATE_REMOTE_OFFER;
    neg->neg_remote_sdp = pjmedia_sdp_session_clone(pool, remote);

    return PJ_SUCCESS;
}

PJ_DEF(pj_status_t) 
pjmedia_sdp_neg_set_local_answer( pj_pool_t *pool,
				  pjmedia_sdp_neg *neg,
				  const pjmedia_sdp_session *local)
{
    /* Check arguments are valid. */
    PJ_ASSERT_RETURN(pool && neg && local, PJ_EINVAL);

    /* Can only do this in STATE_REMOTE_OFFER.
     * If we already provide local offer, then rx_remote_answer() should
     * be called instead of this function.
     */
    PJ_ASSERT_RETURN(neg->state == PJMEDIA_SDP_NEG_STATE_REMOTE_OFFER, 
		     PJMEDIA_SDPNEG_EINSTATE);

    /* State now is STATE_WAIT_NEGO. */
    neg->state = PJMEDIA_SDP_NEG_STATE_WAIT_NEGO;
    if (local)
	neg->neg_local_sdp = pjmedia_sdp_session_clone(pool, local);
    else {
	PJ_ASSERT_RETURN(neg->initial_sdp, PJMEDIA_SDPNEG_ENOINITIAL);
	neg->neg_local_sdp = pjmedia_sdp_session_clone(pool, neg->initial_sdp);
    }

    return PJ_SUCCESS;
}

PJ_DEF(pj_bool_t) pjmedia_sdp_neg_has_local_answer(pjmedia_sdp_neg *neg)
{
    pj_assert(neg && neg->state==PJMEDIA_SDP_NEG_STATE_WAIT_NEGO);
    return !neg->has_remote_answer;
}


/* Swap string. */
static void str_swap(pj_str_t *str1, pj_str_t *str2)
{
    pj_str_t tmp = *str1;
    *str1 = *str2;
    *str2 = tmp;
}

static void remove_all_media_directions(pjmedia_sdp_media *m)
{
    pjmedia_sdp_media_remove_all_attr(m, "inactive");
    pjmedia_sdp_media_remove_all_attr(m, "sendrecv");
    pjmedia_sdp_media_remove_all_attr(m, "sendonly");
    pjmedia_sdp_media_remove_all_attr(m, "recvonly");
}

/* Update media direction based on peer's media direction */
static void update_media_direction(pj_pool_t *pool,
				   const pjmedia_sdp_media *remote,
				   pjmedia_sdp_media *local)
{
    pjmedia_dir old_dir = PJMEDIA_DIR_ENCODING_DECODING,
	        new_dir;

    /* Get the media direction of local SDP */
    if (pjmedia_sdp_media_find_attr2(local, "sendonly", NULL))
	old_dir = PJMEDIA_DIR_ENCODING;
    else if (pjmedia_sdp_media_find_attr2(local, "recvonly", NULL))
	old_dir = PJMEDIA_DIR_DECODING;
    else if (pjmedia_sdp_media_find_attr2(local, "inactive", NULL))
	old_dir = PJMEDIA_DIR_NONE;

    new_dir = old_dir;

    /* Adjust local media direction based on remote media direction */
    if (pjmedia_sdp_media_find_attr2(remote, "inactive", NULL) != NULL) {
	/* If remote has "a=inactive", then local is inactive too */

	new_dir = PJMEDIA_DIR_NONE;

    } else if(pjmedia_sdp_media_find_attr2(remote, "sendonly", NULL) != NULL) {
	/* If remote has "a=sendonly", then set local to "recvonly" if
	 * it is currently "sendrecv". Otherwise if local is NOT "recvonly",
	 * then set local direction to "inactive".
	 */
	switch (old_dir) {
	case PJMEDIA_DIR_ENCODING_DECODING:
	    new_dir = PJMEDIA_DIR_DECODING;
	    break;
	case PJMEDIA_DIR_DECODING:
	    /* No change */
	    break;
	default:
	    new_dir = PJMEDIA_DIR_NONE;
	    break;
	}

    } else if(pjmedia_sdp_media_find_attr2(remote, "recvonly", NULL) != NULL) {
	/* If remote has "a=recvonly", then set local to "sendonly" if
	 * it is currently "sendrecv". Otherwise if local is NOT "sendonly",
	 * then set local direction to "inactive"
	 */
    
	switch (old_dir) {
	case PJMEDIA_DIR_ENCODING_DECODING:
	    new_dir = PJMEDIA_DIR_ENCODING;
	    break;
	case PJMEDIA_DIR_ENCODING:
	    /* No change */
	    break;
	default:
	    new_dir = PJMEDIA_DIR_NONE;
	    break;
	}

    } else {
	/* Remote indicates "sendrecv" capability. No change to local 
	 * direction 
	 */
    }

    if (new_dir != old_dir) {
	pjmedia_sdp_attr *a = NULL;

	remove_all_media_directions(local);

	switch (new_dir) {
	case PJMEDIA_DIR_NONE:
	    a = pjmedia_sdp_attr_create(pool, "inactive", NULL);
	    break;
	case PJMEDIA_DIR_ENCODING:
	    a = pjmedia_sdp_attr_create(pool, "sendonly", NULL);
	    break;
	case PJMEDIA_DIR_DECODING:
	    a = pjmedia_sdp_attr_create(pool, "recvonly", NULL);
	    break;
	default:
	    /* sendrecv */
	    break;
	}
	
	if (a) {
	    pjmedia_sdp_media_add_attr(local, a);
	}
    }
}

/* Update single local media description to after receiving answer
 * from remote.
 */
static pj_status_t process_m_answer( pj_pool_t *pool,
				     pjmedia_sdp_media *offer,
				     pjmedia_sdp_media *answer,
				     pj_bool_t allow_asym)
{
    unsigned i;

    /* Check that the media type match our offer. */

    if (pj_strcmp(&answer->desc.media, &offer->desc.media)!=0) {
	/* The media type in the answer is different than the offer! */
	return PJMEDIA_SDPNEG_EINVANSMEDIA;
    }


    /* Chec that transport in the answer match our offer. */

    if (pj_strcmp(&answer->desc.transport, 
		  &offer->desc.transport)!=0) 
    {
	/* The transport in the answer is different than the offer! */
	return PJMEDIA_SDPNEG_EINVANSTP;
    }

    /* Check if remote has rejected our offer */
    
    if (answer->desc.port == 0) {
	
	/* Remote has rejected our offer. 
	 * Set our port to zero too in active SDP.
	 */
	offer->desc.port = 0;
    }


    /* Process direction attributes */
    update_media_direction(pool, answer, offer);
 
    /* If asymetric media is allowed, then just check that remote answer has 
     * codecs that are within the offer. 
     *
     * Otherwise if asymetric media is not allowed, then we will choose only
     * one codec in our initial offer to match the answer.
     */
    if (allow_asym) {
	for (i=0; i<answer->desc.fmt_count; ++i) {
	    unsigned j;
	    pj_str_t *rem_fmt = &answer->desc.fmt[i];

	    for (j=0; j<offer->desc.fmt_count; ++j) {