liveMedia/RTSPCommon.cpp

/**********
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 3 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

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 Street, Fifth Floor, Boston, MA 02110-1301  USA
**********/
// "liveMedia"
// Copyright (c) 1996-2020 Live Networks, Inc.  All rights reserved.
// Common routines used by both RTSP clients and servers
// Implementation

#include "RTSPCommon.hh"
#include "Locale.hh"
#include <string.h>
#include <stdio.h>
#include <ctype.h> // for "isxdigit()
#include <time.h> // for "strftime()" and "gmtime()"

static void decodeURL(char* url) {
  // Replace (in place) any %<hex><hex> sequences with the appropriate 8-bit character.
  char* cursor = url;
  while (*cursor) {
    if ((cursor[0] == '%') &&
	cursor[1] && isxdigit(cursor[1]) &&
	cursor[2] && isxdigit(cursor[2])) {
      // We saw a % followed by 2 hex digits, so we copy the literal hex value into the URL, then advance the cursor past it:
      char hex[3];
      hex[0] = cursor[1];
      hex[1] = cursor[2];
      hex[2] = '\0';
      *url++ = (char)strtol(hex, NULL, 16);
      cursor += 3;
    } else {
      // Common case: This is a normal character or a bogus % expression, so just copy it
      *url++ = *cursor++;
    }
  }
  
  *url = '\0';
}

Boolean parseRTSPRequestString(char const* reqStr,
			       unsigned reqStrSize,
			       char* resultCmdName,
			       unsigned resultCmdNameMaxSize,
			       char* resultURLPreSuffix,
			       unsigned resultURLPreSuffixMaxSize,
			       char* resultURLSuffix,
			       unsigned resultURLSuffixMaxSize,
			       char* resultCSeq,
			       unsigned resultCSeqMaxSize,
                               char* resultSessionIdStr,
                               unsigned resultSessionIdStrMaxSize,
			       unsigned& contentLength) {
  // This parser is currently rather dumb; it should be made smarter #####

  // "Be liberal in what you accept": Skip over any whitespace at the start of the request:
  unsigned i;
  for (i = 0; i < reqStrSize; ++i) {
    char c = reqStr[i];
    if (!(c == ' ' || c == '\t' || c == '\r' || c == '\n' || c == '\0')) break;
  }
  if (i == reqStrSize) return False; // The request consisted of nothing but whitespace!

  // Then read everything up to the next space (or tab) as the command name:
  Boolean parseSucceeded = False;
  unsigned i1 = 0;
  for (; i1 < resultCmdNameMaxSize-1 && i < reqStrSize; ++i,++i1) {
    char c = reqStr[i];
    if (c == ' ' || c == '\t') {
      parseSucceeded = True;
      break;
    }

    resultCmdName[i1] = c;
  }
  resultCmdName[i1] = '\0';
  if (!parseSucceeded) return False;

  // Skip over the prefix of any "rtsp://" or "rtsp:/" URL that follows:
  unsigned j = i+1;
  while (j < reqStrSize && (reqStr[j] == ' ' || reqStr[j] == '\t')) ++j; // skip over any additional white space
  for (; (int)j < (int)(reqStrSize-8); ++j) {
    if ((reqStr[j] == 'r' || reqStr[j] == 'R')
	&& (reqStr[j+1] == 't' || reqStr[j+1] == 'T')
	&& (reqStr[j+2] == 's' || reqStr[j+2] == 'S')
	&& (reqStr[j+3] == 'p' || reqStr[j+3] == 'P')
	&& reqStr[j+4] == ':' && reqStr[j+5] == '/') {
      j += 6;
      if (reqStr[j] == '/') {
	// This is a "rtsp://" URL; skip over the host:port part that follows:
	++j;
	while (j < reqStrSize && reqStr[j] != '/' && reqStr[j] != ' ') ++j;
      } else {
	// This is a "rtsp:/" URL; back up to the "/":
	--j;
      }
      i = j;
      break;
    }
  }

  // Look for the URL suffix (before the following "RTSP/"):
  parseSucceeded = False;
  for (unsigned k = i+1; (int)k < (int)(reqStrSize-5); ++k) {
    if (reqStr[k] == 'R' && reqStr[k+1] == 'T' &&
	reqStr[k+2] == 'S' && reqStr[k+3] == 'P' && reqStr[k+4] == '/') {
      while (--k >= i && reqStr[k] == ' ') {} // go back over all spaces before "RTSP/"
      unsigned k1 = k;
      while (k1 > i && reqStr[k1] != '/') --k1;

      // ASSERT: At this point
      //   i: first space or slash after "host" or "host:port"
      //   k: last non-space before "RTSP/"
      //   k1: last slash in the range [i,k]

      // The URL suffix comes from [k1+1,k]
      // Copy "resultURLSuffix":
      unsigned n = 0, k2 = k1+1;
      if (k2 <= k) {
        if (k - k1 + 1 > resultURLSuffixMaxSize) return False; // there's no room
        while (k2 <= k) resultURLSuffix[n++] = reqStr[k2++];
      }
      resultURLSuffix[n] = '\0';

      // The URL 'pre-suffix' comes from [i+1,k1-1]
      // Copy "resultURLPreSuffix":
      n = 0; k2 = i+1;
      if (k2+1 <= k1) {
        if (k1 - i > resultURLPreSuffixMaxSize) return False; // there's no room
        while (k2 <= k1-1) resultURLPreSuffix[n++] = reqStr[k2++];
      }
      resultURLPreSuffix[n] = '\0';
      decodeURL(resultURLPreSuffix);

      i = k + 7; // to go past " RTSP/"
      parseSucceeded = True;
      break;
    }
  }
  if (!parseSucceeded) return False;

  // Look for "CSeq:" (mandatory, case insensitive), skip whitespace,
  // then read everything up to the next \r or \n as 'CSeq':
  parseSucceeded = False;
  for (j = i; (int)j < (int)(reqStrSize-5); ++j) {
    if (_strncasecmp("CSeq:", &reqStr[j], 5) == 0) {
      j += 5;
      while (j < reqStrSize && (reqStr[j] ==  ' ' || reqStr[j] == '\t')) ++j;
      unsigned n;
      for (n = 0; n < resultCSeqMaxSize-1 && j < reqStrSize; ++n,++j) {
	char c = reqStr[j];
	if (c == '\r' || c == '\n') {
	  parseSucceeded = True;
	  break;
	}

	resultCSeq[n] = c;
      }
      resultCSeq[n] = '\0';
      break;
    }
  }
  if (!parseSucceeded) return False;

  // Look for "Session:" (optional, case insensitive), skip whitespace,
  // then read everything up to the next \r or \n as 'Session':
  resultSessionIdStr[0] = '\0'; // default value (empty string)
  for (j = i; (int)j < (int)(reqStrSize-8); ++j) {
    if (_strncasecmp("Session:", &reqStr[j], 8) == 0) {
      j += 8;
      while (j < reqStrSize && (reqStr[j] ==  ' ' || reqStr[j] == '\t')) ++j;
      unsigned n;
      for (n = 0; n < resultSessionIdStrMaxSize-1 && j < reqStrSize; ++n,++j) {
	char c = reqStr[j];
	if (c == '\r' || c == '\n') {
	  break;
	}

	resultSessionIdStr[n] = c;
      }
      resultSessionIdStr[n] = '\0';
      break;
    }
  }

  // Also: Look for "Content-Length:" (optional, case insensitive)
  contentLength = 0; // default value
  for (j = i; (int)j < (int)(reqStrSize-15); ++j) {
    if (_strncasecmp("Content-Length:", &(reqStr[j]), 15) == 0) {
      j += 15;
      while (j < reqStrSize && (reqStr[j] ==  ' ' || reqStr[j] == '\t')) ++j;
      unsigned num;
      if (sscanf(&reqStr[j], "%u", &num) == 1) {
	contentLength = num;
      }
    }
  }
  return True;
}

Boolean parseRangeParam(char const* paramStr,
			double& rangeStart, double& rangeEnd,
			char*& absStartTime, char*& absEndTime,
			Boolean& startTimeIsNow) {
  delete[] absStartTime; delete[] absEndTime;
  absStartTime = absEndTime = NULL; // by default, unless "paramStr" is a "clock=..." string
  startTimeIsNow = False; // by default
  double start, end;
  int numCharsMatched1 = 0, numCharsMatched2 = 0, numCharsMatched3 = 0, numCharsMatched4 = 0;
  int startHour = 0, startMin = 0, endHour = 0, endMin = 0;
  double startSec = 0.0, endSec = 0.0;
  Locale l("C", Numeric);
  if (sscanf(paramStr, "npt = %d:%d:%lf - %d:%d:%lf", &startHour, &startMin, &startSec, &endHour, &endMin, &endSec) == 6) {
    rangeStart = startHour*3600 + startMin*60 + startSec;
    rangeEnd = endHour*3600 + endMin*60 + endSec;
  } else if (sscanf(paramStr, "npt =%lf - %d:%d:%lf", &start, &endHour, &endMin, &endSec) == 4) {
    rangeStart = start;
    rangeEnd = endHour*3600 + endMin*60 + endSec;
  } else if (sscanf(paramStr, "npt = %d:%d:%lf -", &startHour, &startMin, &startSec) == 3) {
    rangeStart = startHour*3600 + startMin*60 + startSec;
    rangeEnd = 0.0;
  } else if (sscanf(paramStr, "npt = %lf - %lf", &start, &end) == 2) {
    rangeStart = start;
    rangeEnd = end;
  } else if (sscanf(paramStr, "npt = %n%lf -", &numCharsMatched1, &start) == 1) {
    if (paramStr[numCharsMatched1] == '-') {
      // special case for "npt = -<endtime>", which matches here:
      rangeStart = 0.0; startTimeIsNow = True;
      rangeEnd = -start;
    } else {
      rangeStart = start;
      rangeEnd = 0.0;
    }
  } else if (sscanf(paramStr, "npt = now - %lf", &end) == 1) {
      rangeStart = 0.0; startTimeIsNow = True;
      rangeEnd = end;
  } else if (sscanf(paramStr, "npt = now -%n", &numCharsMatched2) == 0 && numCharsMatched2 > 0) {
    rangeStart = 0.0; startTimeIsNow = True;
    rangeEnd = 0.0;
  } else if (sscanf(paramStr, "clock = %n", &numCharsMatched3) == 0 && numCharsMatched3 > 0) {
    rangeStart = rangeEnd = 0.0;

    char const* utcTimes = &paramStr[numCharsMatched3];
    size_t len = strlen(utcTimes) + 1;
    char* as = new char[len];
    char* ae = new char[len];
    int sscanfResult = sscanf(utcTimes, "%[^-]-%[^\r\n]", as, ae);
    if (sscanfResult == 2) {
      absStartTime = as;
      absEndTime = ae;
    } else if (sscanfResult == 1) {
      absStartTime = as;
      delete[] ae;
    } else {
      delete[] as; delete[] ae;
      return False;
    }
  } else if (sscanf(paramStr, "smtpe = %n", &numCharsMatched4) == 0 && numCharsMatched4 > 0) {
    // We accept "smtpe=" parameters, but currently do not interpret them.
  } else {
    return False; // The header is malformed
  }

  return True;
}

Boolean parseRangeHeader(char const* buf,
			 double& rangeStart, double& rangeEnd,
			 char*& absStartTime, char*& absEndTime,
			 Boolean& startTimeIsNow) {
  // First, find "Range:"
  while (1) {
    if (*buf == '\0') return False; // not found
    if (_strncasecmp(buf, "Range: ", 7) == 0) break;
    ++buf;
  }

  char const* fields = buf + 7;
  while (*fields == ' ') ++fields;
  return parseRangeParam(fields, rangeStart, rangeEnd, absStartTime, absEndTime, startTimeIsNow);
}

Boolean parseScaleHeader(char const* buf, float& scale) {
  // Initialize the result parameter to a default value:
  scale = 1.0;

  // First, find "Scale:"
  while (1) {
    if (*buf == '\0') return False; // not found
    if (_strncasecmp(buf, "Scale:", 6) == 0) break;
    ++buf;
  }

  char const* fields = buf + 6;
  while (*fields == ' ') ++fields;
  float sc;
  if (sscanf(fields, "%f", &sc) == 1) {
    scale = sc;
  } else {
    return False; // The header is malformed
  }

  return True;
}

// Used to implement "RTSPOptionIsSupported()":
static Boolean isSeparator(char c) { return c == ' ' || c == ',' || c == ';' || c == ':'; }

Boolean RTSPOptionIsSupported(char const* commandName, char const* optionsResponseString) {
  do {
    if (commandName == NULL || optionsResponseString == NULL) break;

    unsigned const commandNameLen = strlen(commandName);
    if (commandNameLen == 0) break;

    // "optionsResponseString" is assumed to be a list of command names, separated by " " and/or ",", ";", or ":"
    // Scan through these, looking for "commandName".
    while (1) {
      // Skip over separators:
      while (*optionsResponseString != '\0' && isSeparator(*optionsResponseString)) ++optionsResponseString;
      if (*optionsResponseString == '\0') break;

      // At this point, "optionsResponseString" begins with a command name (with perhaps a separator afterwads).
      if (strncmp(commandName, optionsResponseString, commandNameLen) == 0) {
	// We have at least a partial match here.
	optionsResponseString += commandNameLen;
	if (*optionsResponseString == '\0' || isSeparator(*optionsResponseString)) return True;
      }

      // No match.  Skip over the rest of the command name:
      while (*optionsResponseString != '\0' && !isSeparator(*optionsResponseString)) ++optionsResponseString;
    }
  } while (0);

  return False;
}

char const* dateHeader() {
  static char buf[200];
#if !defined(_WIN32_WCE)
  time_t tt = time(NULL);
  strftime(buf, sizeof buf, "Date: %a, %b %d %Y %H:%M:%S GMT\r\n", gmtime(&tt));
#else
  // WinCE apparently doesn't have "time()", "strftime()", or "gmtime()",
  // so generate the "Date:" header a different, WinCE-specific way.
  // (Thanks to Pierre l'Hussiez for this code)
  // RSF: But where is the "Date: " string?  This code doesn't look quite right...
  SYSTEMTIME SystemTime;
  GetSystemTime(&SystemTime);
  WCHAR dateFormat[] = L"ddd, MMM dd yyyy";
  WCHAR timeFormat[] = L"HH:mm:ss GMT\r\n";
  WCHAR inBuf[200];
  DWORD locale = LOCALE_NEUTRAL;

  int ret = GetDateFormat(locale, 0, &SystemTime,
                          (LPTSTR)dateFormat, (LPTSTR)inBuf, sizeof inBuf);
  inBuf[ret - 1] = ' ';
  ret = GetTimeFormat(locale, 0, &SystemTime,
                      (LPTSTR)timeFormat,
                      (LPTSTR)inBuf + ret, (sizeof inBuf) - ret);
  wcstombs(buf, inBuf, wcslen(inBuf));
#endif
  return buf;
}