sdp.c

来自「基于sip协议的网络电话源码」· C语言 代码 · 共 1,286 行 · 第 1/3 页

    ctx->last_error = PJMEDIA_SDP_EINSDP;

    /* check equal sign */
    if (*(scanner->curptr+1) != '=') {
	on_scanner_error(scanner);
	return;
    }

    /* x= */
    pj_scan_advance_n(scanner, 2, SKIP_WS);

    /* get anything until newline (including whitespaces). */
    pj_scan_get_until_ch(scanner, '\r', str);

    /* newline. */
    pj_scan_get_newline(scanner);
}

static void parse_connection_info(pj_scanner *scanner, pjmedia_sdp_conn *conn,
				  parse_context *ctx)
{
    ctx->last_error = PJMEDIA_SDP_EINCONN;

    /* c= */
    pj_scan_advance_n(scanner, 2, SKIP_WS);

    /* network-type */
    pj_scan_get_until_ch(scanner, ' ', &conn->net_type);
    pj_scan_get_char(scanner);

    /* addr-type */
    pj_scan_get_until_ch(scanner, ' ', &conn->addr_type);
    pj_scan_get_char(scanner);

    /* address. */
    pj_scan_get_until_chr(scanner, " \t\r", &conn->addr);

    /* We've got what we're looking for, skip anything until newline */
    pj_scan_skip_line(scanner);
}

static void parse_media(pj_scanner *scanner, pjmedia_sdp_media *med,
			parse_context *ctx)
{
    pj_str_t str;

    ctx->last_error = PJMEDIA_SDP_EINMEDIA;

    /* check the equal sign */
    if (*(scanner->curptr+1) != '=') {
	on_scanner_error(scanner);
	return;
    }

    /* m= */
    pj_scan_advance_n(scanner, 2, SKIP_WS);

    /* type */
    pj_scan_get_until_ch(scanner, ' ', &med->desc.media);
    pj_scan_get_char(scanner);

    /* port */
    pj_scan_get(scanner, &cs_token, &str);
    med->desc.port = (unsigned short)pj_strtoul(&str);
    if (*scanner->curptr == '/') {
	/* port count */
	pj_scan_get_char(scanner);
	pj_scan_get(scanner, &cs_token, &str);
	med->desc.port_count = pj_strtoul(&str);

    } else {
	med->desc.port_count = 0;
    }

    if (pj_scan_get_char(scanner) != ' ') {
	PJ_THROW(SYNTAX_ERROR);
    }

    /* transport */
    pj_scan_get_until_ch(scanner, ' ', &med->desc.transport);

    /* format list */
    med->desc.fmt_count = 0;
    while (*scanner->curptr == ' ') {
	pj_scan_get_char(scanner);

	/* Check again for the end of the line */
	if ((*scanner->curptr == '\r') || (*scanner->curptr == '\n'))
		break;

	pj_scan_get(scanner, &cs_token, &med->desc.fmt[med->desc.fmt_count++]);
    }

    /* We've got what we're looking for, skip anything until newline */
    pj_scan_skip_line(scanner);
}

static void on_scanner_error(pj_scanner *scanner)
{
    PJ_UNUSED_ARG(scanner);

    PJ_THROW(SYNTAX_ERROR);
}

static pjmedia_sdp_attr *parse_attr( pj_pool_t *pool, pj_scanner *scanner,
				    parse_context *ctx)
{
    pjmedia_sdp_attr *attr;

    ctx->last_error = PJMEDIA_SDP_EINATTR;

    attr = pj_pool_alloc(pool, sizeof(pjmedia_sdp_attr));

    /* check equal sign */
    if (*(scanner->curptr+1) != '=') {
	on_scanner_error(scanner);
	return NULL;
    }

    /* skip a= */
    pj_scan_advance_n(scanner, 2, SKIP_WS);
    
    /* get attr name. */
    pj_scan_get(scanner, &cs_token, &attr->name);

    if (*scanner->curptr != '\r' && *scanner->curptr != '\n') {
	/* skip ':' if present. */
	if (*scanner->curptr == ':')
	    pj_scan_get_char(scanner);

	/* get value */
	if (*scanner->curptr != '\r') {
	    pj_scan_get_until_ch(scanner, '\r', &attr->value);
	} else {
	    attr->value.ptr = NULL;
	    attr->value.slen = 0;
	}

    } else {
	attr->value.ptr = NULL;
	attr->value.slen = 0;
    }

    /* We've got what we're looking for, skip anything until newline */
    pj_scan_skip_line(scanner);

    return attr;
}

/*
 * Parse SDP message.
 */
PJ_DEF(pj_status_t) pjmedia_sdp_parse( pj_pool_t *pool,
				       char *buf, pj_size_t len, 
				       pjmedia_sdp_session **p_sdp)
{
    pj_scanner scanner;
    pjmedia_sdp_session *session;
    pjmedia_sdp_media *media = NULL;
    void *attr;
    pjmedia_sdp_conn *conn;
    pj_str_t dummy;
    int cur_name = 254;
    parse_context ctx;
    PJ_USE_EXCEPTION;

    ctx.last_error = PJ_SUCCESS;

    init_sdp_parser();

    pj_scan_init(&scanner, buf, len, 0, &on_scanner_error);
    session = pj_pool_calloc(pool, 1, sizeof(pjmedia_sdp_session));
    PJ_ASSERT_RETURN(session != NULL, PJ_ENOMEM);

    PJ_TRY {
	while (!pj_scan_is_eof(&scanner)) {
		cur_name = *scanner.curptr;
		switch (cur_name) {
		case 'a':
		    attr = parse_attr(pool, &scanner, &ctx);
		    if (attr) {
			if (media) {
			    media->attr[media->attr_count++] = attr;
			} else {
			    session->attr[session->attr_count++] = attr;
			}
		    }
		    break;
		case 'o':
		    parse_origin(&scanner, session, &ctx);
		    break;
		case 's':
		    parse_generic_line(&scanner, &session->name, &ctx);
		    break;
		case 'c':
		    conn = pj_pool_calloc(pool, 1, sizeof(*conn));
		    parse_connection_info(&scanner, conn, &ctx);
		    if (media) {
			media->conn = conn;
		    } else {
			session->conn = conn;
		    }
		    break;
		case 't':
		    parse_time(&scanner, session, &ctx);
		    break;
		case 'm':
		    media = pj_pool_calloc(pool, 1, sizeof(*media));
		    parse_media(&scanner, media, &ctx);
		    session->media[ session->media_count++ ] = media;
		    break;
		case 'v':
		    parse_version(&scanner, &ctx);
		    break;
		case 13:
		    /* Allow empty newline at the end of the message */
		    pj_scan_get_char(&scanner);
		    /* Continue below */
		case 10:
		    pj_scan_get_char(&scanner);
		    if (!pj_scan_is_eof(&scanner)) {
			on_scanner_error(&scanner);
		    }
		    break;
		default:
		    if (cur_name >= 'a' && cur_name <= 'z')
			parse_generic_line(&scanner, &dummy, &ctx);
		    else  {
			ctx.last_error = PJMEDIA_SDP_EINSDP;
			on_scanner_error(&scanner);
		    }
		    break;
		}
	}

	ctx.last_error = PJ_SUCCESS;

    }
    PJ_CATCH(SYNTAX_ERROR) {
	
	char errmsg[PJ_ERR_MSG_SIZE];
	pj_strerror(ctx.last_error, errmsg, sizeof(errmsg));

	PJ_LOG(4, (THIS_FILE, "Error parsing SDP in line %d col %d: %s",
		   scanner.line, pj_scan_get_col(&scanner),
		   errmsg));

	session = NULL;

	pj_assert(ctx.last_error != PJ_SUCCESS);
    }
    PJ_END;

    pj_scan_fini(&scanner);

    *p_sdp = session;
    return ctx.last_error;
}

/*
 * Print SDP description.
 */
PJ_DEF(int) pjmedia_sdp_print( const pjmedia_sdp_session *desc, 
			       char *buf, pj_size_t size)
{
    return print_session(desc, buf, size);
}


/*
 * Clone session
 */
PJ_DEF(pjmedia_sdp_session*) 
pjmedia_sdp_session_clone( pj_pool_t *pool,
			   const pjmedia_sdp_session *rhs)
{
    pjmedia_sdp_session *sess;
    unsigned i;

    PJ_ASSERT_RETURN(pool && rhs, NULL);

    sess = pj_pool_zalloc(pool, sizeof(pjmedia_sdp_session));
    PJ_ASSERT_RETURN(sess != NULL, NULL);

    /* Clone origin line. */
    pj_strdup(pool, &sess->origin.user, &rhs->origin.user);
    sess->origin.id = rhs->origin.id;
    sess->origin.version = rhs->origin.version;
    pj_strdup(pool, &sess->origin.net_type, &rhs->origin.net_type);
    pj_strdup(pool, &sess->origin.addr_type, &rhs->origin.addr_type);
    pj_strdup(pool, &sess->origin.addr, &rhs->origin.addr);

    /* Clone subject line. */
    pj_strdup(pool, &sess->name, &rhs->name);

    /* Clone connection line */
    if (rhs->conn) {
	sess->conn = pjmedia_sdp_conn_clone(pool, rhs->conn);
	PJ_ASSERT_RETURN(sess->conn != NULL, NULL);
    }

    /* Clone time line. */
    sess->time.start = rhs->time.start;
    sess->time.stop = rhs->time.stop;

    /* Duplicate session attributes. */
    sess->attr_count = rhs->attr_count;
    for (i=0; i<rhs->attr_count; ++i) {
	sess->attr[i] = pjmedia_sdp_attr_clone(pool, rhs->attr[i]);
    }

    /* Duplicate media descriptors. */
    sess->media_count = rhs->media_count;
    for (i=0; i<rhs->media_count; ++i) {
	sess->media[i] = pjmedia_sdp_media_clone(pool, rhs->media[i]);
    }

    return sess;
}


#define CHECK(exp,ret)	do {			\
			    /*pj_assert(exp);*/	\
			    if (!(exp))		\
				return ret;	\
			} while (0)

/* Validate SDP connetion info. */
static pj_status_t validate_sdp_conn(const pjmedia_sdp_conn *c)
{
    CHECK( c, PJ_EINVAL);
    CHECK( pj_strcmp2(&c->net_type, "IN")==0, PJMEDIA_SDP_EINCONN);
    CHECK( pj_strcmp2(&c->addr_type, "IP4")==0 ||
	   pj_strcmp2(&c->addr_type, "IP6")==0, 
	   PJMEDIA_SDP_EINCONN);
    CHECK( c->addr.slen != 0, PJMEDIA_SDP_EINCONN);

    return PJ_SUCCESS;
}


/* Validate SDP session descriptor. */
PJ_DEF(pj_status_t) pjmedia_sdp_validate(const pjmedia_sdp_session *sdp)
{
    unsigned i;
    const pj_str_t STR_RTPMAP = { "rtpmap", 6 };

    CHECK( sdp != NULL, PJ_EINVAL);

    /* Validate origin line. */
    CHECK( sdp->origin.user.slen != 0, PJMEDIA_SDP_EINORIGIN);
    CHECK( pj_strcmp2(&sdp->origin.net_type, "IN")==0, 
	   PJMEDIA_SDP_EINORIGIN);
    CHECK( pj_strcmp2(&sdp->origin.addr_type, "IP4")==0 ||
	   pj_strcmp2(&sdp->origin.addr_type, "IP6")==0, 
	   PJMEDIA_SDP_EINORIGIN);
    CHECK( sdp->origin.addr.slen != 0, PJMEDIA_SDP_EINORIGIN);

    /* Validate subject line. */
    CHECK( sdp->name.slen != 0, PJMEDIA_SDP_EINNAME);

    /* Ignore start and stop time. */

    /* If session level connection info is present, validate it. */
    if (sdp->conn) {
	pj_status_t status = validate_sdp_conn(sdp->conn);
	if (status != PJ_SUCCESS)
	    return status;
    }

    /* Validate each media. */
    for (i=0; i<sdp->media_count; ++i) {
	const pjmedia_sdp_media *m = sdp->media[i];
	unsigned j;

	/* Validate the m= line. */
	CHECK( m->desc.media.slen != 0, PJMEDIA_SDP_EINMEDIA);
	CHECK( m->desc.transport.slen != 0, PJMEDIA_SDP_EINMEDIA);
	CHECK( m->desc.fmt_count != 0 || m->desc.port==0, PJMEDIA_SDP_ENOFMT);

	/* If media level connection info is present, validate it. */
	if (m->conn) {
	    pj_status_t status = validate_sdp_conn(m->conn);
	    if (status != PJ_SUCCESS)
		return status;
	}

	/* If media doesn't have connection info, then connection info
	 * must be present in the session.
	 */
	if (m->conn == NULL) {
	    if (sdp->conn == NULL)
		return PJMEDIA_SDP_EMISSINGCONN;
	}

	/* Verify payload type. */
	for (j=0; j<m->desc.fmt_count; ++j) {

	    /* Arrgh noo!! Payload type can be non-numeric!!
	     * RTC based programs sends "null" for instant messaging!
	     */
	    if (pj_isdigit(*m->desc.fmt[j].ptr)) {
		unsigned pt = pj_strtoul(&m->desc.fmt[j]);

		/* Payload type is between 0 and 127. 
		 */
		CHECK( pt <= 127, PJMEDIA_SDP_EINPT);

		/* If port is not zero, then for each dynamic payload type, an
		 * rtpmap attribute must be specified.
		 */
		if (m->desc.port != 0 && pt >= 96) {
		    const pjmedia_sdp_attr *a;

		    a = pjmedia_sdp_media_find_attr(m, &STR_RTPMAP, 
						    &m->desc.fmt[j]);
		    CHECK( a != NULL, PJMEDIA_SDP_EMISSINGRTPMAP);
		}
	    }
	}
    }

    /* Looks good. */
    return PJ_SUCCESS;
}