Darwin-Streaming-Server/RTPMetaInfoLib/RTPMetaInfoPacket.cpp

/*
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * Copyright (c) 1999-2008 Apple Inc.  All Rights Reserved.
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
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 */
//
// RTPMetaInfo.h:
//   Some defs for RTP-Meta-Info payloads.


#include "RTPMetaInfoPacket.h"
#include "MyAssert.h"
#include "StringParser.h"
#include "OS.h"
#include <string.h>

#ifndef __Win32__
#include <netinet/in.h>
#endif

const RTPMetaInfoPacket::FieldName RTPMetaInfoPacket::kFieldNameMap[] =
{
    TW0_CHARS_TO_INT('p', 'p'),
    TW0_CHARS_TO_INT('t', 't'),
    TW0_CHARS_TO_INT('f', 't'),
    TW0_CHARS_TO_INT('p', 'n'),
    TW0_CHARS_TO_INT('s', 'q'),
    TW0_CHARS_TO_INT('m', 'd')
};

const UInt32 RTPMetaInfoPacket::kFieldLengthValidator[] =
{
    8,  //pp
    8,  //tt
    2,  //ft
    8,  //pn
    2,  //sq
    0,  //md
    0   //illegal / unknown
};


RTPMetaInfoPacket::FieldIndex RTPMetaInfoPacket::GetFieldIndexForName(FieldName inName)
{
    for (int x = 0; x < kNumFields; x++)
    {
        if (inName == kFieldNameMap[x])
            return x;
    }
    return kIllegalField;
}

void RTPMetaInfoPacket::ConstructFieldIDArrayFromHeader(StrPtrLen* inHeader, FieldID* ioFieldIDArray)
{
    for (UInt32 x = 0; x < kNumFields; x++)
        ioFieldIDArray[x] = kFieldNotUsed;
    
    //
    // Walk through the fields in this header
    StringParser theParser(inHeader);
    
    UInt16 fieldNameValue = 0;

    while (theParser.GetDataRemaining() > 0)
    {
        StrPtrLen theFieldP;
        (void)theParser.GetThru(&theFieldP, ';');
        
        //
        // Corrupt or something... just bail
        if (theFieldP.Len < 2)
            break;
        
        //
        // Extract the Field Name and convert it to a Field Index
        ::memcpy (&fieldNameValue, theFieldP.Ptr, sizeof(UInt16));
        FieldIndex theIndex = RTPMetaInfoPacket::GetFieldIndexForName(ntohs(fieldNameValue));
//      FieldIndex theIndex = RTPMetaInfoPacket::GetFieldIndexForName(ntohs(*(UInt16*)theFieldP.Ptr));

        //
        // Get the Field ID if there is one.
        FieldID theID = kUncompressed;
        if (theFieldP.Len > 3)
        {
            StringParser theIDExtractor(&theFieldP);
            theIDExtractor.ConsumeLength(NULL, 3);
            theID = theIDExtractor.ConsumeInteger(NULL);
        }
        
        if (theIndex != kIllegalField)
            ioFieldIDArray[theIndex] = theID;
    }
}


Bool16 RTPMetaInfoPacket::ParsePacket(UInt8* inPacketBuffer, UInt32 inPacketLen, FieldID* inFieldIDArray)
{
    UInt8* theFieldP = inPacketBuffer + 12; // skip RTP header
    UInt8* theEndP = inPacketBuffer + inPacketLen;
    
    SInt64 sInt64Val = 0;
    UInt16 uInt16Val = 0;
    
    while (theFieldP < (theEndP - 2))
    {
        FieldIndex theFieldIndex = kIllegalField;
        UInt32 theFieldLen = 0;
        FieldName* theFieldName = (FieldName*)theFieldP;
        
        if (*theFieldName & 0x8000)
        {
            Assert(inFieldIDArray != NULL);
            
            // If this is a compressed field, find to which field the ID maps
            UInt8 theFieldID = *theFieldP & 0x7F;
             
            for (int x = 0; x < kNumFields; x++)
            {
                if (theFieldID == inFieldIDArray[x])
                {
                    theFieldIndex = x;
                    break;
                }
            }
            
            theFieldLen = *(theFieldP + 1);
            theFieldP += 2;
        }
        else
        {
            // This is not a compressed field. Make sure there is enough room
            // in the packet for this to make sense
            if (theFieldP >= (theEndP - 4))
                break;

            ::memcpy(&uInt16Val, theFieldP, sizeof(uInt16Val));
            theFieldIndex = this->GetFieldIndexForName(ntohs(uInt16Val));
            
            ::memcpy(&uInt16Val, theFieldP + 2, sizeof(uInt16Val));
            theFieldLen = ntohs(uInt16Val);
            theFieldP += 4;
        }
        
        //
        // Validate the length of this field if possible.
        // If the field is of the wrong length, return an error.
        if ((kFieldLengthValidator[theFieldIndex] > 0) &&
            (kFieldLengthValidator[theFieldIndex] != theFieldLen))
            return false;
        if ((theFieldP + theFieldLen) > theEndP)
            return false;
            
        //
        // We now know what field we are dealing with, so store off
        // the proper value depending on the field
        switch (theFieldIndex)
        {
            case kPacketPosField:
            {
                ::memcpy(&sInt64Val, theFieldP, sizeof(sInt64Val));
                fPacketPosition = (UInt64)OS::NetworkToHostSInt64(sInt64Val);
                break;
            }
            case kTransTimeField:
            {
                ::memcpy(&sInt64Val, theFieldP, sizeof(sInt64Val));
                fTransmitTime = (UInt64)OS::NetworkToHostSInt64(sInt64Val);
                break;
            }
            case kFrameTypeField:
            {
                fFrameType = ntohs(*((FrameTypeField*)theFieldP));
                break;
            }
            case kPacketNumField:
            {
                ::memcpy(&sInt64Val, theFieldP, sizeof(sInt64Val));
                fPacketNumber = (UInt64)OS::NetworkToHostSInt64(sInt64Val);
                break;
            }
            case kSeqNumField:
            {
                
                ::memcpy(&uInt16Val, theFieldP, sizeof(uInt16Val));
                fSeqNum = ntohs(uInt16Val);
                break;
            }
            case kMediaDataField:
            {
                fMediaDataP = theFieldP;
                fMediaDataLen = theFieldLen;
                break;
            }
            default:
                break;
        }
        
        //
        // Skip onto the next field
        theFieldP += theFieldLen;
    }
    return true;
}

UInt8* RTPMetaInfoPacket::MakeRTPPacket(UInt32* outPacketLen)
{
    if (fMediaDataP == NULL)
        return NULL;
    
    //
    // Just move the RTP header to right before the media data.
    ::memmove(fMediaDataP - 12, fPacketBuffer, 12);
    
    //
    // Report the length of the resulting RTP packet 
    if (outPacketLen != NULL)
        *outPacketLen = fMediaDataLen + 12;
        
    return fMediaDataP - 12;
}