parser.c

SDP文件解析代码

/*
  This file is part of FreeSDP
  Copyright (C) 2001,2002,2003 Federico Montesino Pouzols <[e-mail]>
  
  FreeSDP 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

  Benjamin Zores, (C) 2006
    added support in parser for the a=control: lines.
    added support in parser for the a=range: lines.
*/

/**
 * @file parser.c
 *
 * @short Parsing module implementation.
 *
 * This file implements the parsing routine <code>fsdp_parse</code>
 * and the <code>fsdp_get_xxxx</code> routines that allow to get the
 * session properties from a session description object build through
 * the application of <code>fsdp_parse</code> to a textual SDP session
 * description.
 **/

#include "parserpriv.h"

/**
 * \brief find the start of the next line
 * \param c pointer to current position in string
 * \return pointer to start of next line or NULL if illegal (i.e.
 *         a '\r' is not followed by a '\n'
 */
static const char *next_line(const char *c) {
  c += strcspn(c, "\n\r");
  if (*c == 0) return c;
  if (*c == '\r') c++;
  if (*c == '\n')
    return c + 1;
  return NULL;
}

/**
 * Moves the <code>c<code> pointer up to the beginning of the next
 * line.
 *
 * @param c char pointer to pointer
 * @retval FSDPE_ILLEGAL_CHARACTER, when an illegal '\r' character
 * (not followed by a '\n') is found, returns
 */
#define NEXT_LINE(c) do { if (!(c = next_line(c))) return FSDPE_ILLEGAL_CHARACTER; } while (0);

fsdp_error_t
fsdp_parse (const char *text_description, fsdp_description_t * dsc)
{
  fsdp_error_t result;
  const char *p = text_description, *p2;
  unsigned int index, j;
  /* temps for sscanf */
  const unsigned int TEMPCHARS = 6;
  char fsdp_buf[TEMPCHARS][MAXSHORTFIELDLEN];
  char longfsdp_buf[MAXLONGFIELDLEN];
  const unsigned int TEMPINTS = 2;
  unsigned long int wuint[TEMPINTS];

  if ((NULL == text_description) || (NULL == dsc))
    return FSDPE_INVALID_PARAMETER;

  /***************************************************************************/
  /* A) parse session-level description                                      */
  /***************************************************************************/

  /* `v=' line (protocol version) */
  /* according to the RFC, only `v=0' is valid */
  if (sscanf (p, "v=%1lu", &wuint[0]))
  {
    if (wuint[0] != 0)
      return FSDPE_INVALID_VERSION;
  }
  else
  {
    return FSDPE_MISSING_VERSION;
  }
  NEXT_LINE (p);

  /* `o=' line (owner/creator and session identifier) */
  /* o=<username> <session id> <version> <network type> <address type>
     <address> */
  if (!strncmp (p, "o=", 2))
  {
    p += 2;
    /* note that the following max lengths may vary in the future and
       are quite arbitary */
    if (sscanf
        (p,
         "%" MSFLENS "[\x21-\xFF] %" MSFLENS "[0-9] %" MSFLENS
         "[0-9] %2s %3s %" MSFLENS "s", fsdp_buf[0], fsdp_buf[1],
         fsdp_buf[2], fsdp_buf[3], fsdp_buf[4], fsdp_buf[5]) != 6)
      return FSDPE_INVALID_OWNER;
    dsc->o_username = strdup (fsdp_buf[0]);
    dsc->o_session_id = strdup (fsdp_buf[1]);
    dsc->o_announcement_version = strdup (fsdp_buf[2]);
    if (!strncmp (fsdp_buf[3], "IN", 2))
    {
      dsc->o_network_type = FSDP_NETWORK_TYPE_INET;
      if (!strncmp (fsdp_buf[4], "IP4", 3))
        dsc->o_address_type = FSDP_ADDRESS_TYPE_IPV4;
      else if (!strncmp (fsdp_buf[4], "IP6", 3))
        dsc->o_address_type = FSDP_ADDRESS_TYPE_IPV6;
      else
        return FSDPE_INVALID_OWNER;
    }
    else
    {
      return FSDPE_INVALID_OWNER;
    }
    /* TODO? check valid unicast address/FQDN */
    dsc->o_address = strdup (fsdp_buf[5]);
  }
  else
  {
    return FSDPE_MISSING_OWNER;
  }
  NEXT_LINE (p);

  /* `s=' line (session name) -note that the name string cannot be empty */
  /* s=<session name> */
  if (!strncmp (p, "s=", 2))
  {
    if (sscanf (p, "s=%" MLFLENS "[^\r\n]", longfsdp_buf) < 1)
      return FSDPE_EMPTY_NAME;
    dsc->s_name = strdup (longfsdp_buf);
  }
  else
  {
    return FSDPE_MISSING_NAME;
  }
  NEXT_LINE (p);

  /* `i=' line (session information) [optional] */
  /* i=<session description> */
  if (!strncmp (p, "i=", 2)
      && sscanf (p, "i=%" MLFLENS "[^\r\n]", longfsdp_buf))
  {
    dsc->i_information = strdup (longfsdp_buf);
    NEXT_LINE (p);
  }
  else
  {
    /* (optional) information absent */
  }

  /* `u=' line (URI of description)  [optional] */
  /* u=<URI> */
  if (!strncmp (p, "u=", 2)
      && sscanf (p, "u=%" MLFLENS "[^\r\n]", longfsdp_buf))
  {
    /* TODO? check valid uri */
    dsc->u_uri = strdup (longfsdp_buf);
    NEXT_LINE (p);
  }
  else
  {
    /* (optional) uri absent */
  }

  /* `e=' lines (email address) [zero or more] */
  /* e=<email address> */
  p2 = p;
  j = 0;
  while (!strncmp (p2, "e=", 2))
  {
    /* First, count how many emails are there */
    j++;
    NEXT_LINE (p2);
  }
  dsc->emails_count = j;
  if (dsc->emails_count > 0)
  {
    /* Then, build the array of emails */
    dsc->emails = calloc (j, sizeof (const char *));
    for (j = 0; j < dsc->emails_count; j++)
    {
      sscanf (p, "e=%" MLFLENS "[^\r\n]", longfsdp_buf);
      /* TODO? check valid email-address. */
      dsc->emails[j] = strdup (longfsdp_buf);
      NEXT_LINE (p);
    }
  }

  /* `p=' lines (phone number) [zero or more] */
  /*  p=<phone number> */
  j = 0;
  /* assert ( p2 == p ); */
  while (!strncmp (p2, "p=", 2))
  {
    j++;
    NEXT_LINE (p2);
  }
  dsc->phones_count = j;
  if (dsc->phones_count > 0)
  {
    dsc->phones = calloc (j, sizeof (const char *));
    for (j = 0; j < dsc->phones_count; j++)
    {
      sscanf (p, "p=%" MLFLENS "[^\r\n]", longfsdp_buf);
      /* TODO? check valid phone-number. */
      dsc->phones[j] = strdup (longfsdp_buf);
      NEXT_LINE (p);
    }
  }

  /* `c=' line (connection information - not required if included in all media) [optional] */
  /* c=<network type> <address type> <connection address> */
  result = fsdp_parse_c (&p, &(dsc->c_network_type), &(dsc->c_address_type),
			 &(dsc->c_address));
  if (FSDPE_OK != result)
    return result;

  /* `b=' lines (bandwidth information) [optional] */
  /* b=<modifier>:<bandwidth-value> */
  result =
    fsdp_parse_b (&p, &(dsc->bw_modifiers), &(dsc->bw_modifiers_count));
  if (FSDPE_OK != result)
    return result;

  /* A.1) Time descriptions: */

  /* `t=' lines (time the session is active) [1 or more] */
  /* t=<start time>  <stop time> */
  j = 0;
  p2 = p;
  while (!strncmp (p2, "t=", 2))
  {
    j++;
    NEXT_LINE (p2);
    while (!strncmp (p2, "r=", 2))
      NEXT_LINE (p2);
  }
  dsc->time_periods_count = j;
  if (dsc->time_periods_count == 0)
    return FSDPE_MISSING_TIME;
  dsc->time_periods = calloc (dsc->time_periods_count,
			      sizeof (fsdp_time_period_t *));
  index = 0;
  for (j = 0; j < dsc->time_periods_count; j++)
  {
    unsigned int h = 0;
    if (sscanf (p, "t=%10lu %10lu", &wuint[0], &wuint[1]) != 2)
    {
      /* not all periods have been successfully parsed */
      dsc->time_periods_count = j;
      return FSDPE_INVALID_TIME;
    }
    dsc->time_periods[j] = calloc (1, sizeof (fsdp_time_period_t));

    /* convert from NTP to time_t time */
    if (wuint[0] != 0)
      wuint[0] -= NTP_EPOCH_OFFSET;
    if (wuint[1] != 0)
      wuint[1] -= NTP_EPOCH_OFFSET;
    dsc->time_periods[j]->start = wuint[0];
    dsc->time_periods[j]->stop = wuint[1];
    NEXT_LINE (p);

    /* `r' lines [zero or more repeat times for each t=] */
    /*r=<repeat interval> <active duration> <list of offsets from
      start-time> */
    p2 = p;
    while (!strncmp (p2, "r=", 2))
    {
      h++;
      NEXT_LINE (p2);
    }
    dsc->time_periods[j]->repeats_count = h;
    if (h > 0)
    {
      unsigned int index2 = 0;
      dsc->time_periods[j]->repeats =
        calloc (h, sizeof (fsdp_repeat_t *));
      for (h = 0; h < dsc->time_periods[j]->repeats_count; h++)
      {
        /*
          get_repeat_values(p,&(dsc->time_periods[index].repeats[index2]));
          fsdp_error_t get_repeat_values (const char *r, fsdp_repeat_t
          *repeat);
          */
        if (sscanf (p, "r=%10s %10s %" MLFLENS "[^\r\n]",
                    fsdp_buf[0], fsdp_buf[1], longfsdp_buf) == 3)
        {
          fsdp_repeat_t *repeat;
          dsc->time_periods[j]->repeats[h] =
            calloc (1, sizeof (fsdp_repeat_t));
          repeat = dsc->time_periods[j]->repeats[h];
          /* get interval, duration and list of offsets */
          result =
            fsdp_repeat_time_to_uint (fsdp_buf[0],
                                      &(repeat->interval));
          if (result == FSDPE_OK)
          {
            result =
              fsdp_repeat_time_to_uint (fsdp_buf[1],
                                        &(repeat->duration));
            if (result == FSDPE_OK)
            {
              unsigned int k = 1;
              const char *i = longfsdp_buf;
              while (NULL != (i = strchr (i, ' ')))
              {
                k++;
                if (NULL != i)
                  i++;
              }
              repeat->offsets_count = k;
              repeat->offsets = calloc (k, sizeof (time_t));
              i = longfsdp_buf;
              for (k = 0;
                   (k < repeat->offsets_count)
                     && (result == FSDPE_OK); k++)
              {
                result =
                  fsdp_repeat_time_to_uint (i,
                                            &(repeat->
                                              offsets[k]));
                i = strchr (i, ' ');
                if (NULL != i)
                  i++;
              }
              if (k < repeat->offsets_count)
              {
                /* there where invalid repeat offsets */
                dsc->time_periods[j]->repeats_count = k;
                return FSDPE_INVALID_REPEAT;
              }
            }
          }
          if (result != FSDPE_OK)
          {
            /* not all repeats have been succesfully parsed */
            dsc->time_periods[j]->repeats_count = h;
            return FSDPE_INVALID_REPEAT;
          }
          NEXT_LINE (p);
        }
        else
        {
          /* not all repeats have been succesfully parsed */
          dsc->time_periods[j]->repeats_count = h;
          return FSDPE_INVALID_REPEAT;
        }
        index2++;
      }
    }
  }

  /* `z=' line (time zone adjustments) [zero or more] */
  /* z=<adjustment time> <offset> <adjustment time> <offset> .... */
  if (!strncmp (p, "z=", 2))
  {
    if (sscanf (p, "z=%" MLFLENS "[^\r\n]", longfsdp_buf))
    {
      /* TODO: guess how many pairs are there and process them */
      dsc->timezone_adj = strdup (longfsdp_buf);
      NEXT_LINE (p);
    }
    else
    {
      return FSDPE_INVALID_TIMEZONE;
    }
  }

  /* `k=' line (encryption key) [optional] */
  /* k=<method> 
     k=<method>:<encryption key> */
  result = fsdp_parse_k (&p, &(dsc->k_encryption_method),
			 &(dsc->k_encryption_content));
  if (result != FSDPE_OK)
    return result;

  /* A.2) Attributes */
  /* `a=' lines (session attribute) [0 or more] */
  /* a=<attribute>
     a=<attribute>:<value> */
  while (!strncmp (p, "a=", 2))
  {
    /* The "9" length specifier of the first string is subject to
       changes */
    if (sscanf
        (p, "a=%9[^:\r\n]:%" MSFLENS "[^\r\n]", fsdp_buf[0],
         fsdp_buf[1]) == 2)
    {
      /* session-level value attributes */
      if (!strncmp (fsdp_buf[0], "cat", 3))
        dsc->a_category = strdup (fsdp_buf[1]);
      else if (!strncmp (fsdp_buf[0], "keywds", 6))
        dsc->a_keywords = strdup (fsdp_buf[1]);
      else if (!strncmp (fsdp_buf[0], "tool", 4))
        dsc->a_keywords = strdup (fsdp_buf[1]);
      else if (!strncmp (fsdp_buf[0], "rtpmap", 6))
        fsdp_parse_rtpmap (&(dsc->a_rtpmaps),
                           &(dsc->a_rtpmaps_count), fsdp_buf[1]);
      else if (!strncmp (fsdp_buf[0], "type", 4))
      {
        if (!strncmp (fsdp_buf[1], "broadcast", 9))
          dsc->a_type = FSDP_SESSION_TYPE_BROADCAST;
        else if (!strncmp (fsdp_buf[1], "meeting", 7))
          dsc->a_type = FSDP_SESSION_TYPE_MEETING;
        else if (!strncmp (fsdp_buf[1], "moderated", 9))
          dsc->a_type = FSDP_SESSION_TYPE_MODERATED;
        else if (!strncmp (fsdp_buf[1], "test", 4))
          dsc->a_type = FSDP_SESSION_TYPE_TEST;
        else if (!strncmp (fsdp_buf[1], "H332", 4))
          dsc->a_type = FSDP_SESSION_TYPE_H332;
        else
          return FSDPE_INVALID_SESSION_TYPE;
      }
      else if (!strncmp (fsdp_buf[0], "charset", 7))
        dsc->a_charset = strdup (fsdp_buf[1]);
      else if (!strncmp (fsdp_buf[0], "sdplang", 7))
      {
        if (NULL == dsc->a_sdplangs)
        {
          dsc->a_sdplangs_count = 0;
          dsc->a_sdplangs =
            calloc (SDPLANGS_MAX_COUNT, sizeof (char *));
        }
        if (dsc->a_sdplangs_count < SDPLANGS_MAX_COUNT)
        {
          dsc->a_sdplangs[dsc->a_sdplangs_count] =
            strdup (fsdp_buf[1]);
          dsc->a_sdplangs_count++;
        }
      }
      else if (!strncmp (fsdp_buf[0], "lang", 4))
      {
        if (NULL == dsc->a_langs)
        {
          dsc->a_langs_count = 0;
          dsc->a_langs = calloc (SDPLANGS_MAX_COUNT, sizeof (char *));
        }
        if (dsc->a_langs_count < SDPLANGS_MAX_COUNT)
        {
          dsc->a_langs[dsc->a_langs_count] = strdup (fsdp_buf[1]);
          dsc->a_langs_count++;
        }
      }
      else if (!strncmp (fsdp_buf[0], "control", 7))
      {
        if (NULL == dsc->a_controls)
        {
          dsc->a_controls_count = 0;
          dsc->a_controls =
            calloc (SDPCONTROLS_MAX_COUNT, sizeof (char *));
        }
        if (dsc->a_controls_count < SDPCONTROLS_MAX_COUNT)
        {
          dsc->a_controls[dsc->a_controls_count] =
            strdup (fsdp_buf[1]);
          dsc->a_controls_count++;
        }
      }
      else if (!strncmp (fsdp_buf[0], "range", 5))
      {
        if (dsc->a_range)
          free (dsc->a_range);
        dsc->a_range = strdup (fsdp_buf[1]);
      }
      else
      {
        /* ignore unknown attributes, but provide access to them */
        *longfsdp_buf = '\0';
        strncat (longfsdp_buf, fsdp_buf[0], MAXLONGFIELDLEN-1);
        strncat (longfsdp_buf, ":", MAXLONGFIELDLEN-strlen(longfsdp_buf)-1);
        strncat (longfsdp_buf, fsdp_buf[1], MAXLONGFIELDLEN-strlen(longfsdp_buf)-1);
        if (NULL == dsc->unidentified_attributes)
        {
          dsc->unidentified_attributes_count = 0;
          dsc->unidentified_attributes =
            calloc (UNIDENTIFIED_ATTRIBUTES_MAX_COUNT,
                    sizeof (char *));