sdp_parse.c

Sofia SIP is an open-source SIP User-Agent library, compliant with the IETF RFC3261 specification.

/*
 * This file is part of the Sofia-SIP package
 *
 * Copyright (C) 2005 Nokia Corporation.
 *
 * Contact: Pekka Pessi <[e-mail]>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 */

/**@ingroup sdp_parser
 * @CFILE sdp_parse.c 
 * @brief Simple SDP parser interface.
 *
 * @author Pekka Pessi <[e-mail]>
 * @author Kai Vehmanen <[e-mail]>
 *
 * @date  Created: Fri Feb 18 10:25:08 2000 ppessi
 */

#include "config.h"

#include <sofia-sip/su_alloc.h>

#include "sofia-sip/sdp.h"

#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <stdio.h>
#include <limits.h>
#include <assert.h>

/** @typedef struct sdp_parser_s sdp_parser_t; 
 *
 * SDP parser handle.
 *
 * The SDP parser handle is returned by sdp_parse(). It contains either
 * successfully parse SDP session #sdp_session_t or an error message.
 * If sdp_session() returns non-NULL, parsing was successful.
 *
 * @sa #sdp_session_t, sdp_parse(), sdp_session(), sdp_parsing_error(),
 * sdp_sanity_check(), sdp_parser_home(), sdp_parser_free().
 */

struct sdp_parser_s {
  su_home_t       pr_home[1];
  union {
    char          pru_error[128];
    sdp_session_t pru_session[1];
  } pr_output;
  char      *pr_message;

  sdp_mode_t pr_session_mode;

  unsigned   pr_ok : 1;

  unsigned   pr_strict : 1;
  unsigned   pr_anynet : 1;
  unsigned   pr_mode_0000 : 1;
  unsigned   pr_mode_manual : 1;
  unsigned   pr_insane : 1;
  unsigned   pr_c_missing : 1;
  unsigned   pr_config : 1;
};

#define is_posdigit(c) ((c) >= '1' && (c) <= '9')
#define is_digit(c) ((c) >= '0' && (c) <= '9')
#define is_space(c) ((c) == ' ')
#define is_tab(c) ((c) == '\t')

#define pr_error   pr_output.pru_error
#define pr_session pr_output.pru_session

#define STRICT(pr) (pr->pr_strict)

/* Static parser object used when running out of memory */
static const struct sdp_parser_s no_mem_error =
{
  { SU_HOME_INIT(no_mem_error) },
  { "sdp: not enough memory" }
};

/* Internal prototypes */
static void parse_message(sdp_parser_t *p);
static int parsing_error(sdp_parser_t *p, char const *fmt, ...);

/** Parse an SDP message.
 *
 * The function sdp_parse() parses an SDP message @a msg of size @a
 * msgsize. Parsing is done according to the given @a flags. The SDP message
 * may not contain a NUL.
 * 
 * The parsing result is stored to an #sdp_session_t structure.
 *
 * @param home    memory home
 * @param msg     pointer to message
 * @param msgsize size of the message (excluding final NUL, if any)
 * @param flags   flags affecting the parsing.
 *
 * The following flags are used by parser:
 *
 * @li #sdp_f_strict Parser should accept only messages conforming strictly 
 *                   to the specification.
 * @li #sdp_f_anynet Parser accepts unknown network or address types.
 * @li #sdp_f_insane Do not run sanity check.
 * @li #sdp_f_c_missing  Sanity check does not require c= for each m= line
 * @li #sdp_f_mode_0000 Parser regards "c=IN IP4 0.0.0.0" as "a=inactive"
 *                      (likewise with c=IN IP6 ::)
 * @li #sdp_f_mode_manual Do not generate or parse SDP mode
 * @li #sdp_f_config   Parse config files (any line can be missing)
 *
 * @return
 * Always a valid parser handle.
 *
 * @todo Parser accepts some non-conforming SDP even with #sdp_f_strict.
 */
sdp_parser_t *
sdp_parse(su_home_t *home, char const msg[], issize_t msgsize, int flags)
{
  sdp_parser_t *p;
  char *b;
  size_t len;

  if (msgsize == -1 || msg == NULL) {
    p = su_home_clone(home, sizeof(*p));
    if (p) 
      parsing_error(p, "invalid input message");
    else
      p = (sdp_parser_t*)&no_mem_error;
    return p;
  }

  if (msgsize == -1 && msg)
    len = strlen(msg);
  else
    len = msgsize;

  if (len > ISSIZE_MAX)
    len = ISSIZE_MAX;

  p = su_home_clone(home, sizeof(*p) + len + 1);

  if (p) {
    b = strncpy((void *)(p + 1), msg, len);
    b[len] = 0;

    p->pr_message = b;
    p->pr_strict = (flags & sdp_f_strict) != 0;
    p->pr_anynet = (flags & sdp_f_anynet) != 0;
    p->pr_mode_0000 = (flags & sdp_f_mode_0000) != 0;
    p->pr_insane = (flags & sdp_f_insane) != 0;
    p->pr_c_missing = (flags & sdp_f_c_missing) != 0;
    if (flags & sdp_f_config)
      p->pr_c_missing = 1, p->pr_config = 1;
    p->pr_mode_manual = (flags & sdp_f_mode_manual) != 0;
    p->pr_session_mode = sdp_sendrecv;

    parse_message(p);
    
    return p;
  }

  if (p)
    sdp_parser_free(p);

  return (sdp_parser_t*)&no_mem_error;
}


/** Obtain memory home used by parser */
su_home_t *sdp_parser_home(sdp_parser_t *parser)
{
  if (parser != &no_mem_error)
    return parser->pr_home;
  else
    return NULL;
}

/** Retrieve an SDP session structure.
 *
 * The function sdp_session() returns a pointer to the SDP session
 * structure associated with the SDP parser @a p. The pointer and all the
 * data in the structure are valid until sdp_parser_free() is called.
 *
 * @param p SDP parser
 *
 * @return
 *   The function sdp_session() returns a pointer to an parsed SDP message
 *   or NULL, if an error has occurred.  */
sdp_session_t *
sdp_session(sdp_parser_t *p)
{
  return p && p->pr_ok ? p->pr_session : NULL;
}

/** Get a parsing error message.
 *
 * The function sdp_parsing_error() returns the error message associated
 * with an SDP parser @a p.
 *
 * @param p SDP parser
 *
 * @return 
 * The function sdp_parsing_error() returns a C string describing parsing
 * error, or NULL if no error occurred.
 */
char const *sdp_parsing_error(sdp_parser_t *p)
{
  return !p->pr_ok ? p->pr_error : NULL;
}

/** Free an SDP parser.
 *
 * The function sdp_parser_free() frees an SDP parser object along with
 * the memory blocks associated with it.
 *
 * @param p pointer to the SDP parser to be freed 
 */
void sdp_parser_free(sdp_parser_t *p)
{
  if (p && p != &no_mem_error)
    su_home_unref(p->pr_home);
}

/* ========================================================================= */

/* =========================================================================
 * Private part
 */

/* Parsing tokens */
#define SPACE " "
#define TAB   "\011"
#define CRLF  "\015\012"
#define ALPHA "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
#define DIGIT "0123456789"

/* ========================================================================= */
/* Parsing functions */

static void post_session(sdp_parser_t *p, sdp_session_t *sdp);
static void parse_origin(sdp_parser_t *p, char *r, sdp_origin_t **result);
static void parse_subject(sdp_parser_t *p, char *r, sdp_text_t **result);
static void parse_information(sdp_parser_t *p, char *r, sdp_text_t **result);
static void parse_uri(sdp_parser_t *p, char *r, sdp_text_t **result);
static void parse_email(sdp_parser_t *p, char *r, sdp_list_t **result);
static void parse_phone(sdp_parser_t *p, char *r, sdp_list_t **result);
static void parse_connection(sdp_parser_t *p, char *r, sdp_connection_t **result);
static void parse_bandwidth(sdp_parser_t *p, char *r, sdp_bandwidth_t **result);
static void parse_time(sdp_parser_t *p, char *r, sdp_time_t **result);
static void parse_repeat(sdp_parser_t *p, char *r, sdp_repeat_t **result);
static void parse_zone(sdp_parser_t *p, char *r, sdp_zone_t **result);
static void parse_key(sdp_parser_t *p, char *r, sdp_key_t **result);
static void parse_session_attr(sdp_parser_t *p, char *r, sdp_attribute_t **result);
static void parse_media(sdp_parser_t *p, char *r, sdp_media_t **result);
static void parse_payload(sdp_parser_t *p, char *r, sdp_rtpmap_t **result);
static void parse_media_attr(sdp_parser_t *p, char *r, sdp_media_t *m, 
			     sdp_attribute_t **result);
static int parse_rtpmap(sdp_parser_t *p, char *r, sdp_media_t *m);
static int parse_fmtp(sdp_parser_t *p, char *r, sdp_media_t *m);
static void parse_text_list(sdp_parser_t *p, char *r, sdp_list_t **result);

static void parse_descs(sdp_parser_t *p, char *r, char *m, sdp_media_t **result);

static int parse_ul(sdp_parser_t *p, char **r, unsigned long *result, 
		    unsigned long max_value);
static int parse_ull(sdp_parser_t *p, char **r, uint64_t *result, 
		     uint64_t max_value);
static void parse_alloc_error(sdp_parser_t *p, const char *typename);
static char *next(char **message, const char *sep, const char *strip);
static char *token(char **message, const char *sep, const char *legal, 
		   const char *strip);
#if 0
static void check_mandatory(sdp_parser_t *p, sdp_session_t *sdp);
#endif

/* -------------------------------------------------------------------------
 * Macro PARSE_ALLOC
 *
 * Description:
 *   This macro declares a pointer (v) of given type (t). It then allocates
 *   an structure of given type (t). If allocation was succesful, it assigns
 *   the XX_size member with appropriate value.
 */
#define PARSE_ALLOC(p, t, v) \
 t *v = su_salloc(p->pr_home, sizeof(*v)); \
 if (!v && (parse_alloc_error(p, #t), 1)) return; 

/* -------------------------------------------------------------------------
 * Macro PARSE_CHECK_REST
 *
 * Description:
 *   This macro check if there is extra data at the end of field.
 */
#define PARSE_CHECK_REST(p, s, n)\
 if (*s && (parsing_error(p, "extra data after %s (\"%.04s\")", n, s), 1)) \
    return

/* -------------------------------------------------------------------------
 * Function parse_message() - parse an SDP message 
 *
 * Description:
 *   This function parses an SDP message, which is copied into the 
 *   p->pr_message. The p->pr_message is modified during the parsing,
 *   and parts of it are returned in p->pr_session.
 *
 * Parameters:
 *   p - pointer to SDP parser object
 */
static void parse_message(sdp_parser_t *p)
{
/*
   announcement =        proto-version
                         origin-field
                         session-name-field
                         information-field
                         uri-field
                         email-fields
                         phone-fields
                         connection-field
                         bandwidth-fields
                         time-fields
                         key-field
                         attribute-fields
                         media-descriptions
*/

  sdp_session_t *sdp = p->pr_session;
  char *record, *rest;
  char const *strip;
  char *message = p->pr_message;
  char field = '\0';
  sdp_list_t **emails = &sdp->sdp_emails;
  sdp_list_t **phones = &sdp->sdp_phones;
  sdp_bandwidth_t **bandwidths = &sdp->sdp_bandwidths;
  sdp_time_t **times = &sdp->sdp_time;
  sdp_repeat_t **repeats = NULL;
  sdp_zone_t **zones = NULL;
  sdp_attribute_t **attributes = &sdp->sdp_attributes;

  if (!STRICT(p))
    strip = SPACE TAB;		/* skip initial whitespace */
  else
    strip = "";

  p->pr_ok = 1;
  p->pr_session->sdp_size = sizeof(p->pr_session);

  /* Require that version comes first */
  record = next(&message, CRLF, strip);

  if (!record || strcmp(record, "v=0")) {
    if (!p->pr_config || !record || record[1] != '=') {
      parsing_error(p, "bad SDP message");
      return;
    }
  }
  else {
    record = next(&message, CRLF, strip);
  }

  /*
    XXX - the lines in SDP are in certain order, which we don't check here.
     For stricter parsing we might want to parse o= and s= next.
  */

  for (;
       record && p->pr_ok;
       record = next(&message, CRLF, strip)) {
    field = record[0]; 

    rest = record + 2; rest += strspn(rest, strip);

    if (record[1] != '=') {
      parsing_error(p, "bad line \"%s\"", record);
      return;
    }

    switch (field) {
    case 'o':
      parse_origin(p, rest, &sdp->sdp_origin);
      break;

    case 's':
      parse_subject(p, rest, &sdp->sdp_subject);
      break;

    case 'i':
      parse_information(p, rest, &sdp->sdp_information);
      break;

    case 'u':
      parse_uri(p, rest, &sdp->sdp_uri);
      break;

    case 'e':
      parse_email(p, rest, emails);
      emails = &(*emails)->l_next;
      break;

    case 'p':
      parse_phone(p, rest, phones);
      phones = &(*phones)->l_next;
      break;

    case 'c':
      parse_connection(p, rest, &sdp->sdp_connection);
      break;

    case 'b':
      parse_bandwidth(p, rest, bandwidths);
      bandwidths = &(*bandwidths)->b_next;
      break;

    case 't':
      parse_time(p, rest, times);
      repeats = &(*times)->t_repeat;
      zones = &(*times)->t_zone;
      times = &(*times)->t_next;
      break;

    case 'r':
      if (repeats)
	parse_repeat(p, rest, repeats);
      else
	parsing_error(p, "repeat field without time field");
      break;

    case 'z':
      if (zones)
	parse_zone(p, rest, zones), zones = NULL;
      else
	parsing_error(p, "zone field without time field");
      break;

    case 'k':
      parse_key(p, rest, &sdp->sdp_key);
      break;

    case 'a':
      parse_session_attr(p, rest, attributes);
      if (*attributes)
	attributes = &(*attributes)->a_next;
      break;

    case 'm':
      parse_descs(p, record, message, &sdp->sdp_media);
      post_session(p, sdp);
      return;

    default:
      parsing_error(p, "unknown field \"%s\"", record);
      return;
    }
  }