Mod protocol

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(→proces mod data example: removed parts that are not relevant for the capability exchange)
(Undo revision 2952 by Izegiwera (Talk))
 
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Line 1: Line 1:
−
=Under construction =
+
= Under construction =
 
THIS IS NOT FINAL.. feel free to edit.  
 
THIS IS NOT FINAL.. feel free to edit.  
  
 
== Introduction ==
 
== Introduction ==
  
−
Modprot is needed for more clean protocol extensions by eMule modders....
+
The Modprot is needed for more clean protocol extensions by eMule modders....
  
 +
The main idea is to set a bit in CT_EMULE_MISCOPTIONS2 in the initial hello packet. If that bit is set and received by an eMule mod that is capable of processing extensions, then that mod will send the options it is capable of in the response and the first client will also send back the protocol extensions it is capable of.
  
−
== Protocol ==
+
'''Important:'''
  
 +
Clients that are not capable of processing the mod protocol (like official eMule/aMule)  will not set the mod bit in CT_EMULE_MISCOPTIONS2 and will never receive extended protocol information.
 +
 +
== Documentation ==
 +
 +
All mod communication is to be done over the OP_MODPROT/OP_MODPACKEDPROT.
 +
When a hello(answer) with a set mod bit is received the ConnectionEstablished has to be delayed. Instead of that the mod info packet with the opcode OP_MODINFOPACKET is to be sent.
 +
ConnectionEstablished will be triggered when the mod info packet is received.
 +
<pre>
 +
A              B
 +
Hello  --->    MB Set (see if ModBit is set)
 +
MB Set  <---    Hello Answer
 +
ConEst  <---    MInfo (Mod Info)
 +
MInfo  --->    ConEst (call ConnectionEstablished)
 +
</pre>
 +
The mod info packet has to contain eMuleTags that announce the supported features. The packet is made up this way:
 +
<pre>
 +
<uint 32> tag count
 +
<emule tag 1>
 +
<emule tag 2>
 +
...
 +
<emule tag n>
 +
</pre>
 +
It's only allowed to use mod features it their capability was announced by both sides.
 +
After the capability exchange via OP_MODINFOPACKET all remaining opcodes are allowed to be used by clients in any way they want.
 +
All further communication is not part of this specification.
 +
 +
== Protocol ==
  
−
=== Hello ===  
+
=== Sending Hello(answer) packets ===  
  
−
Set the modbit ot in in CT_EMULE_MISCOPTIONS2
+
Setting the modbit in CT_EMULE_MISCOPTIONS2
  
 
in baseclient.cpp,  void CUpDownClient::SendHelloTypePacket(CSafeMemFile* data)
 
in baseclient.cpp,  void CUpDownClient::SendHelloTypePacket(CSafeMemFile* data)
Line 20: Line 48:
 
const UINT uSupportLargeFiles = 1;
 
const UINT uSupportLargeFiles = 1;
 
const UINT uExtMultiPacket = 1;
 
const UINT uExtMultiPacket = 1;
−
const UINT uReserved = 1; // mod bit  
+
// Set the Mod Bit
 +
const UINT uModProt = 1; // mod bit // NEO: NMP - [NeoModProt] <-- Xanatos --
 
const UINT uSupportsCryptLayer = thePrefs.IsClientCryptLayerSupported() ? 1 : 0;
 
const UINT uSupportsCryptLayer = thePrefs.IsClientCryptLayerSupported() ? 1 : 0;
 
const UINT uRequestsCryptLayer = thePrefs.IsClientCryptLayerRequested() ? 1 : 0;
 
const UINT uRequestsCryptLayer = thePrefs.IsClientCryptLayerRequested() ? 1 : 0;
Line 32: Line 61:
 
(uRequestsCryptLayer <<  8) |
 
(uRequestsCryptLayer <<  8) |
 
(uSupportsCryptLayer <<  7) |
 
(uSupportsCryptLayer <<  7) |
−
(uReserved <<  6) |
+
(uModProt <<  6) |
 
(uExtMultiPacket <<  5) |
 
(uExtMultiPacket <<  5) |
 
(uSupportLargeFiles <<  4) |
 
(uSupportLargeFiles <<  4) |
Line 40: Line 69:
 
</pre>
 
</pre>
  
 +
=== Processing hello(answer) packets ===
  
−
=== Process hello. ===
+
Read out the modbit from CT_EMULE_MISCOPTIONS2
  
 
baseclient.cpp bool CUpDownClient::ProcessHelloTypePacket(CSafeMemFile* data)
 
baseclient.cpp bool CUpDownClient::ProcessHelloTypePacket(CSafeMemFile* data)
Line 60: Line 90:
 
m_fRequestsCryptLayer = (temptag.GetInt() >>  8) & 0x01;
 
m_fRequestsCryptLayer = (temptag.GetInt() >>  8) & 0x01;
 
m_fSupportsCryptLayer = (temptag.GetInt() >>  7) & 0x01;
 
m_fSupportsCryptLayer = (temptag.GetInt() >>  7) & 0x01;
−
m_NeoModProtVersion = (temptag.GetInt() >>  6) & 0x01; // modbit NEO: NMP - [NeoModProt] <-- Xanatos --
+
// read the mod bit
 +
m_fSupportsModProt = (temptag.GetInt() >>  6) & 0x01; // NEO: NMP - [NeoModProt] <-- Xanatos --
 
m_fExtMultiPacket = (temptag.GetInt() >>  5) & 0x01;
 
m_fExtMultiPacket = (temptag.GetInt() >>  5) & 0x01;
 
m_fSupportsLargeFiles  = (temptag.GetInt() >>  4) & 0x01;
 
m_fSupportsLargeFiles  = (temptag.GetInt() >>  4) & 0x01;
Line 71: Line 102:
 
</pre>
 
</pre>
  
−
 
+
== Sending hello answer and modprot info ==
−
==Send hello answer and modprot info ==
+
−
 
+
  
 
Listensocket.cpp bool CClientReqSocket::ProcessPacket(const BYTE* packet, uint32 size, UINT opcode)
 
Listensocket.cpp bool CClientReqSocket::ProcessPacket(const BYTE* packet, uint32 size, UINT opcode)
Line 89: Line 118:
  
  
−
Example of sendmoinfopacket:
+
Example of SendModInfoPacket:
  
 
<pre>
 
<pre>
 
void CUpDownClient::SendModInfoPacket(){
 
void CUpDownClient::SendModInfoPacket(){
−
if (socket == NULL){
+
if (socket == NULL){ // first we check if we have a valid socket, actualy we was called form the socket so this check is rather unnesesery, but in case
 
ASSERT(0);
 
ASSERT(0);
 
return;
 
return;
Line 100: Line 129:
 
CSafeMemFile data(128);
 
CSafeMemFile data(128);
  
−
uint32 tagcount=2+1;
+
// write the amount of emule tags we intent to send
−
 
+
// !!! this value must be correct !!!
−
#ifdef NATTUNNELING // NEO: NATT - [NatTraversal]
+
uint32 tagcount=2;
−
if(theApp.IsFirewalled() && Kademlia::CKademlia::IsConnected())
+
−
tagcount += 1;  
+
−
#endif //NATTUNNELING // NEO: NATT END
+
  
 +
// write the first tag (Nr.1)
 +
// in this sample its an normal tag with an uint8 ID, its the modstring 0x55 = 'T'
 
data.WriteUInt32(tagcount); // nr. of tags
 
data.WriteUInt32(tagcount); // nr. of tags
−
 
+
CTag tagPartStatus(0x55,_T("TestMod"));
−
 
+
−
/************************************************************************************
+
−
* Note: The meaning of the bit fields in the current sample *
+
−
* have to be reworked for the final release version numbers are almost useless, *
+
−
* support (or newver version) should be anounced only by single bit flags *
+
−
************************************************************************************/
+
−
 
+
−
#ifdef NATTUNNELING // NEO: NATT - [NatTraversal]
+
−
const UINT uNatT = NeoPrefs.IsNatTraversalEnabled();
+
−
#endif //NATTUNNELING // NEO: NATT END
+
−
uint32 uNeoFeatures =
+
−
// ((0 & 0xff) << 24) | // Unused
+
−
// ((0 & 0x0f) << 20) | // Reserved
+
−
#ifdef NATTUNNELING // NEO: NATT - [NatTraversal]
+
−
// ((0 & 0x03) << 18) | // Reserved for nat-t
+
−
((1 & 0x01) << 17) | // NEO: RTP - [ReuseTCPPort]
+
−
((uNatT & 0x01) << 16) | // Support Nat Traversal
+
−
// ((0 & 0x01) << 15) | // NEO: XSB - [XSBuddy]
+
−
#endif //NATTUNNELING // NEO: NATT END
+
−
((1 & 0x07) << 12) | // NEO: NXS - [NeoXS]
+
−
// ((0 & 0x03) << 10) | // Reserved
+
−
((1 & 0x01) << 9 ) | // LowID UDP Ping Support (notifyes a fix form xman1 that allow the remote low ID to use udp reasks) // NEO: MOD - [NewUploadState]
+
−
((1 & 0x01) << 8 ) | // Unsolicited Part Status (allows our client ro recieve filestatus at any time) // NEO: USPS - [UnSolicitedPartStatus]
+
−
// ((0 & 0x0f) << 4 ) | // Reserved
+
−
((0 & 0x0f) << 0 ); 
+
−
CTag tagNeoModProt(CT_NEO_FEATURES, uNeoFeatures);
+
−
tagNeoModProt.WriteTagToFile(&data);
+
−
 
+
−
uint32 nSCT = NeoPrefs.UseSubChunkTransfer() ? 1 : 0; // version 4 bit
+
−
uint32 ICSv2 = NeoPrefs.UseIncompletePartStatus() ? 2 : 0; // version 3 bit
+
−
// X-ToDo:
+
−
//uint32 RPS = NeoPrefs.UseRealPartStatus() ? 1 : 0; // version 3 bit
+
−
//uint32 HPS = NeoPrefs.UseRealPartStatus() ? 1 : 0; // flag 1 bit
+
−
//uint32 BPS = NeoPrefs.UseRealPartStatus() ? 1 : 0; // flag 1 bit
+
−
 
+
−
uint32 uFileStatus =
+
−
// ((0    & 0xff) << 24) | // unused
+
−
// ((0    & 0xff) << 16) | // reserved
+
−
// ((BPS  & 0x01) << 15) | // RPS Flag Blocked Parts
+
−
// ((HPS  & 0x01) << 14) | // RPS Flag Hiden Parts
+
−
// ((RPS  & 0x07) << 11) | // RPS VErsion
+
−
((ICSv2 & 0x07) << 8 ) | // ICSv2 Version
+
−
// ((0    & 0x0f) << 4 ) | // reserved
+
−
((nSCT  & 0x0f) << 0 );  // SCT version
+
−
CTag tagPartStatus(CT_EXT_FILESTATUS,uFileStatus);
+
 
tagPartStatus.WriteNewEd2kTag(&data);
 
tagPartStatus.WriteNewEd2kTag(&data);
  
−
#ifdef NATTUNNELING // NEO: NATT - [NatTraversal]
+
// write the secund tag (Nr.2)
−
if(theApp.IsFirewalled() && Kademlia::CKademlia::IsConnected())
+
// in this sample its an custom named tag with an string as ID
−
{
+
CTag tagMyMail("Mod:eMail",_T("User@Domain.com"));
−
// Note: to connect a cleint over his buddy or to request a calback we need not only his buddy IP/Port but also his Buddy ID
+
−
// So to get this realy to work we need to transmitt the buddy ID to
+
−
Kademlia::CUInt128 uBuddyID(true);
+
−
uBuddyID.Xor(Kademlia::CKademlia::GetPrefs()->GetKadID());
+
−
byte cID[16];
+
−
uBuddyID.ToByteArray(cID);
+
−
CTag tagBuddyID(CT_EMULE_BUDDYID, cID);
+
−
tagBuddyID.WriteNewEd2kTag(&data);
+
−
}
+
−
#endif //NATTUNNELING // NEO: NATT END
+
−
 
+
−
// Named tag test begin
+
−
LPCTSTR FunnyStr[3];
+
−
FunnyStr[0] = _T("Vote for the Pirate Party of your country");
+
−
FunnyStr[1] = _T("Have a nice day ;)");
+
−
FunnyStr[2] = _T("Confucius says: If you dont upload 10 GB/day good will punish you");
+
−
CTag tagMyMail("Mod:Hello",FunnyStr[rand()%ARRSIZE(FunnyStr)]);
+
 
tagMyMail.WriteNewEd2kTag(&data);
 
tagMyMail.WriteNewEd2kTag(&data);
−
// Named tag test end
+
 +
// we are done writing tags
  
 +
// now we create a packet and put what we have writen in it
 
Packet* packet = new Packet(&data,OP_MODPROT);
 
Packet* packet = new Packet(&data,OP_MODPROT);
 
packet->opcode = OP_MODINFOPACKET;
 
packet->opcode = OP_MODINFOPACKET;
Line 184: Line 152:
 
DebugSend("OP__ModInfoPacket", this);
 
DebugSend("OP__ModInfoPacket", this);
 
theStats.AddUpDataOverheadOther(packet->size);
 
theStats.AddUpDataOverheadOther(packet->size);
−
socket->SendPacket(packet,true,true);
+
socket->SendPacket(packet,true,true); // we send the packet
 
}
 
}
 
</pre>
 
</pre>
  
−
=== process modinfo packet ===
+
=== Delaying ConnectionEstablished & sending the mod info packet ===
 +
 
 +
listensocket.cpp
 +
bool CClientReqSocket::ProcessPacket(const BYTE* packet, uint32 size, UINT opcode)
 +
<pre>
 +
case OP_HELLOANSWER:
 +
{
 +
theStats.AddDownDataOverheadOther(size);
 +
client->ProcessHelloAnswer(packet,size);
 +
if (thePrefs.GetDebugClientTCPLevel() > 0){
 +
DebugRecv("OP_HelloAnswer", client);
 +
Debug(_T("  %s\n"), client->DbgGetHelloInfo());
 +
}
 +
 
 +
// NEO: NMP - [NeoModProt] -- Xanatos -->
 +
if(client->SupportsModProt() == 0) // check for mod prot
 +
// we will start the SUI when we recieve the mod info packet
 +
// NEO: NMP END <-- Xanatos --
 +
{
 +
// start secure identification, if
 +
//  - we have received OP_EMULEINFO and OP_HELLOANSWER (old eMule)
 +
// - we have received eMule-OP_HELLOANSWER (new eMule)
 +
if (client->GetInfoPacketsReceived() == IP_BOTH)
 +
client->InfoPacketsReceived();
 +
}
 +
 
 +
if (client)
 +
{
 +
// NEO: NMP - [NeoModProt] -- Xanatos -->
 +
if (client->SupportsModProt()) // if this cleint uses mod protocol extensions
 +
client->SendModInfoPacket(); // we send him the mod info packet with our rxtensions
 +
else // we *dont* call ConnectionEstablished at this point,
 +
// when will call ConnectionEstablished when we recieve the Mod Info frm this cleint
 +
// NEO: NMP END <-- Xanatos --
 +
{
 +
client->ConnectionEstablished();
 +
theApp.emuledlg->transferwnd->clientlistctrl.RefreshClient(client);
 +
}
 +
}
 +
break;
 +
}
 +
</pre>
 +
 
 +
listensocket.cpp
 +
bool CClientReqSocket::ProcessPacket(const BYTE* packet, uint32 size, UINT opcode)
 +
<pre>
 +
case OP_HELLO:
 +
{
 +
[..................]
 +
 
 +
if (client)
 +
{
 +
// NEO: NMP - [NeoModProt] -- Xanatos -->
 +
if(client->SupportsModProt()) // if this cleint uses mod protocol extensions
 +
client->SendModInfoPacket(); // we send him the mod info packet with our rxtensions
 +
else // we *dont* call ConnectionEstablished at this point,
 +
// when will call ConnectionEstablished when we recieve the Mod Info frm this cleint
 +
// NEO: NMP END <-- Xanatos --
 +
client->ConnectionEstablished();
 +
}
 +
 
 +
ASSERT( client );
 +
if(client)
 +
{
 +
// NEO: NMP - [NeoModProt] -- Xanatos -->
 +
if(client->SupportsModProt() == 0) // check for mod prot
 +
// we will start the SUI when we recieve the mod info packet
 +
// NEO: NMP END <-- Xanatos --
 +
{
 +
 
 +
// start secure identification, if
 +
// - we have received eMule-OP_HELLO (new eMule)
 +
if (client->GetInfoPacketsReceived() == IP_BOTH)
 +
client->InfoPacketsReceived();
 +
}
 +
 
 +
if( client->GetKadPort() )
 +
Kademlia::CKademlia::Bootstrap(ntohl(client->GetIP()), client->GetKadPort(), (client->GetKadVersion() > 1));
 +
}
 +
break;
 +
}
 +
</pre>
 +
 
 +
=== Processing the modinfo packet ===
  
 
listensocket.cpp
 
listensocket.cpp
Line 247: Line 298:
 
CSafeMemFile data(pachPacket, nSize);
 
CSafeMemFile data(pachPacket, nSize);
  
 +
// we read now the amount of tags that the sender put in th epacket
 
uint32 tagcount = data.ReadUInt32();
 
uint32 tagcount = data.ReadUInt32();
 
if (bDbgInfo)
 
if (bDbgInfo)
 
m_strModInfo.AppendFormat(_T("  Tags=%u"), (UINT)tagcount);
 
m_strModInfo.AppendFormat(_T("  Tags=%u"), (UINT)tagcount);
 +
// now we are going to read all of them
 
for (uint32 i = 0; i < tagcount; i++)
 
for (uint32 i = 0; i < tagcount; i++)
 
{
 
{
 
CTag temptag(&data, false);
 
CTag temptag(&data, false);
−
switch (temptag.GetNameID())
+
switch (temptag.GetNameID()) // here we distinguish only tags with an uint8 ID, all named tags are handled below
 
{
 
{
−
case CT_NEO_FEATURES:
+
case 0x55:
−
if (temptag.IsInt()){
+
if (temptag.IsStr())
−
// = (uint8)(temptag.GetInt() >> 24) & 0xff;
+
Log(_T("ModString %s", temptag.GetStr()));
−
// = (uint8)(temptag.GetInt() >> 20) & 0x0f;
+
else if (bDbgInfo)
−
#ifdef NATTUNNELING // NEO: NATT - [NatTraversal]
+
m_strModInfo.AppendFormat(_T("\n  ***UnkType=%s"), temptag.GetFullInfo());
−
// = (uint8)(temptag.GetInt() >> 18) & 0x03;
+
−
m_PublicPortReport = (uint8)(temptag.GetInt() >> 17) & 0x01; // NEO: RTP - [ReuseTCPPort]
+
−
m_SupportsNatTraversal = (uint8)(temptag.GetInt() >> 16) & 0x01;
+
−
// = (uint8)(temptag.GetInt() >> 15) & 0x01; // NEO: XSB - [XSBuddy]
+
−
#endif //NATTUNNELING // NEO: NATT END
+
−
m_NeoXSVersion = (uint8)(temptag.GetInt() >> 12) & 0x07; // NEO: NXS - [NeoXS]
+
−
// = (uint8)(temptag.GetInt() >> 10) & 0x03;
+
−
m_LowIDUDPPingSupport = (uint8)(temptag.GetInt() >> 9 ) & 0x01;
+
−
m_UnsolicitedPartStatus = (uint8)(temptag.GetInt() >> 8 ) & 0x01;
+
−
// = (uint8)(temptag.GetInt() >> 4 ) & 0x0f;
+
−
// = (uint8)(temptag.GetInt() >> 0 ) & 0x0f;
+
−
}else if (bDbgInfo)
+
−
m_strHelloInfo.AppendFormat(_T("\n  ***UnkType=%s"), temptag.GetFullInfo());
+
 
break;
 
break;
  
−
case CT_EXT_FILESTATUS:
 
−
if (temptag.IsInt()){
 
−
 
−
// X-ToDo
 
−
// = (uint8)(temptag.GetInt() >> 24) & 0xff;
 
−
// = (uint8)(temptag.GetInt() >> 16) & 0xff;
 
−
//uint8 BlockedPartStatus = (uint8)(temptag.GetInt() >> 15) & 0x01;
 
−
//uint8 HidenPartStatus = (uint8)(temptag.GetInt() >> 14) & 0x01;
 
−
//uint8 RealPartStatusVer = (uint8)(temptag.GetInt() >> 11) & 0x07;
 
−
m_IncompletePartVer = (uint8)(temptag.GetInt() >> 8 ) & 0x07;
 
−
// = (uint8)(temptag.GetInt() >> 4 ) & 0x0f;
 
−
m_SubChunksVer = (uint8)(temptag.GetInt() >> 0 ) & 0x0f;
 
−
 
−
//ASSERT(BlockedPartStatus || HidenPartStatus || !RealPartStatusVer);
 
−
// Note: RPC version without one or booth RPS flags is invalid,
 
−
//      the cleint must always say wha is he doint gith the parts 'blocking and hiding' or 'only hiding',
 
−
//      or he can booth depanding on the situation
 
−
// Booth RPS versions have always teh same version as the writing functions are identical
 
−
// just other opcodes are used and other part states notifyed
 
−
//if(BlockedPartStatus)
 
−
// m_BlockedPartStatusVer = RealPartStatusVer;
 
−
//if(HidenPartStatus)
 
−
// m_HidenPartStatusVer = RealPartStatusVer;
 
−
 
−
}else if (bDbgInfo)
 
−
m_strModInfo.AppendFormat(_T("\n  ***UnkType=%s"), temptag.GetFullInfo());
 
−
break;
 
−
#ifdef NATTUNNELING // NEO: NATT - [NatTraversal]
 
−
case CT_EMULE_BUDDYID:
 
−
if(temptag.IsHash())
 
−
{
 
−
SetBuddyID(temptag.GetHash());
 
−
}
 
−
else{
 
−
if (bDbgInfo)
 
−
m_strModInfo.AppendFormat(_T("\n  ***UnkType=%s"), temptag.GetFullInfo());
 
−
}
 
−
break;
 
−
#endif //NATTUNNELING // NEO: NATT END
 
 
default:
 
default:
  
−
// Named tag test begin
+
// now we habdle custom named tags, we use a series of (else)if's and strcmp, note: this is *not* unicide!!!
 
if(strcmp(temptag.GetName(),"Mod:Hello") == 0)
 
if(strcmp(temptag.GetName(),"Mod:Hello") == 0)
 
{
 
{
Line 323: Line 324:
 
}
 
}
 
else
 
else
−
// Named tag test end
 
  
 
if (bDbgInfo)
 
if (bDbgInfo)
Line 329: Line 329:
 
}
 
}
 
}
 
}
 +
 +
// some debug output
 +
if (bDbgInfo && data.GetPosition() < data.GetLength()){
 +
m_strModInfo.AppendFormat(_T("\n  ***AddData: %u bytes"), data.GetLength() - data.GetPosition());
 +
}
 +
}
  
 
</pre>
 
</pre>
  
 +
=== Processing mod data example ===
  
−
 
+
EMSocket.cpp
−
 
+
void CEMSocket::OnReceive(int nErrorCode)
−
 
+
<pre>
−
 
+
switch (pendingPacket->prot){
−
 
+
case OP_EDONKEYPROT:
−
 
+
case OP_PACKEDPROT:
−
 
+
case OP_EMULEPROT:
−
 
+
// NEO: NMP - [NeoModProt] -- Xanatos -->
−
 
+
// We have to accept also mod packet
−
 
+
case OP_MODPACKEDPROT:
−
=== proces mod data example ===
+
case OP_MODPROT:
−
 
+
// NEO: NMP END <-- Xanatos --
−
 
+
break;
−
 
+
default:
−
 
+
EMTrace("CEMSocket::OnReceive ERROR Wrong header");
 +
delete pendingPacket;
 +
pendingPacket = NULL;
 +
OnError(ERR_WRONGHEADER);
 +
return;
 +
}
 +
</pre>
  
  
Line 354: Line 367:
 
<pre>
 
<pre>
 
// NEO: NMP - [NeoModProt] -- Xanatos -->
 
// NEO: NMP - [NeoModProt] -- Xanatos -->
 +
// dispatch mod packets to the right processing functions
 
case OP_MODPACKEDPROT:
 
case OP_MODPACKEDPROT:
 
if (!packet->UnPackPacket()){
 
if (!packet->UnPackPacket()){
Line 373: Line 387:
 
try
 
try
 
{
 
{
 +
// we must have a cleint at this point !always!
 
if (!client)
 
if (!client)
 
{
 
{
Line 381: Line 396:
 
ASSERT_VALID(client);
 
ASSERT_VALID(client);
  
−
switch(opcode)
+
switch(opcode) // dispatch particular packets
 
{
 
{
 +
// for the mod prot v1 (capability exchange) only this one packet is relevant, the mod info packet
 
case OP_MODINFOPACKET:
 
case OP_MODINFOPACKET:
 
{
 
{
Line 389: Line 405:
 
theStats.AddDownDataOverheadOther(uRawSize);
 
theStats.AddDownDataOverheadOther(uRawSize);
  
−
if(client->GetNeoModProtVersion() == 0)
+
if(client->SupportsModProt() == 0) // just pure formality
 
throw CString(_T("Recieved Neo Mod Info Packet from a cleint whitch doe snot support this feature!"));
 
throw CString(_T("Recieved Neo Mod Info Packet from a cleint whitch doe snot support this feature!"));
  
 +
// Process the packet
 
client->ProcessModInfoPacket(packet,size);
 
client->ProcessModInfoPacket(packet,size);
  
Line 404: Line 421:
 
}
 
}
  
−
default:
+
default: // handle unknown packets
 +
 
theStats.AddDownDataOverheadOther(uRawSize);
 
theStats.AddDownDataOverheadOther(uRawSize);
 
PacketToDebugLogLine(_T("ModProt"), packet, size, opcode);
 
PacketToDebugLogLine(_T("ModProt"), packet, size, opcode);
Line 431: Line 449:
 
}
 
}
 
return true;
 
return true;
−
}
+
 
 
// NEO: NMP END <-- Xanatos --
 
// NEO: NMP END <-- Xanatos --
 
</pre>
 
</pre>
  
−
== backward compatibility ==
+
=== Additional modifications ===
 +
 
 +
Packets.cpp
 +
void Packet::PackPacket()
 +
<pre>
 +
// NEO: NMP - [NeoModProt] -- Xanatos -->
 +
if( prot == OP_MODPROT )
 +
prot = OP_MODPACKEDPROT;
 +
else
 +
// NEO: NMP END <-- Xanatos --
 +
if( prot == OP_KADEMLIAHEADER )
 +
prot = OP_KADEMLIAPACKEDPROT;
 +
else
 +
prot = OP_PACKEDPROT;
 +
</pre>
 +
 
 +
Packets.cpp
 +
bool Packet::UnPackPacket(UINT uMaxDecompressedSize)
 +
<pre>
 +
// NEO: NMP - [NeoModProt] -- Xanatos -->
 +
if( prot == OP_MODPACKEDPROT )
 +
prot = OP_MODPROT;
 +
else
 +
// NEO: NMP END <-- Xanatos --
 +
if( prot == OP_KADEMLIAPACKEDPROT )
 +
prot = OP_KADEMLIAHEADER;
 +
else
 +
prot =  OP_EMULEPROT;
 +
</pre>
 +
 
 +
== Backward compatibility ==
 +
 
 +
The modstring is still send via hello(answer) packets but '''only''' if the remote client is using a mod and does not support the mod prot extension to maintain backward compatibility. Usage of CT_MOD_VERSION is proposed to move it to the mod protocol. A mod using the modbit MUST identify itself either via CT_MOD_VERSION in the hello(answer) packets or via modstring in the modinfo packet.
 +
'''NOTE:''' a mod that uses extensions but refuses to identify itself will most likely be considered a bad mod by some antileecher systems
 +
 
 +
The proposed check to use would be like
 +
<pre>
 +
void CUpDownClient::SendHelloTypePacket(CSafeMemFile* data)
 +
{
 +
...
 +
...
 +
uint32 tagcount = 6;
 +
 
 +
if( theApp.clientlist->GetBuddy() && theApp.IsFirewalled() )
 +
tagcount += 2;
 +
 
 +
//>>> MODPROT::Send Modstring to old mods only
 +
const bool bSendModString = !SupportsModProt() && (!m_strModVersion.IsEmpty() || !m_pszUsername);
 +
if(bSendModString)
 +
++tagcount;
 +
//<<< MODPROT::Send Modstring to old mods only
 +
 
 +
data->WriteUInt32(tagcount);
 +
...
 +
...
 +
tagMuleVersion.WriteTagToFile(data);
 +
 
 +
//>>> MODPROT::Send Modstring to old mods only
 +
if(bSendModString)
 +
{
 +
CTag tagMod(CT_MOD_VERSION, L"My Mod String");
 +
tagMod.WriteTagToFile(data);
 +
}
 +
//<<< MODPROT::Send Modstring to old mods only
 +
 
 +
uint32 dwIP;
 +
uint16 nPort;
 +
...
 +
...
 +
</pre>
 +
and similar for the info packet.
 +
 
 +
 
 +
== OPCODE defines ==
 +
<pre>
 +
OP_MODPROT      0x4D
 +
OP_MODPACKEDPROT 0x6D
 +
OP_MODINFOPACKET 0x01
 +
</pre>
 +
 
 +
== TAG defines ==
 +
 
 +
Tags used must be reserved in modprot topic at http://forum.emule-project.net/
 +
Sources must be published within 3 months after claiming a tag.
 +
 
 +
The range 0x01 - 0x1F is completely reserved.
 +
 
 +
Tags in the range from 0x20 - 0x7E are reserved for major features, possible objections can be:
 +
#Modder uses too many tags (if you need more than 5 tags you are most likely doing something wrong. Note that string tags are also available - those are not regulated)
 +
#Utterly useless or unimplementable feature (no other mod will ever use it)
 +
#Illegal feature (should be clear)
 +
 
 +
The range 0x7F-FF is open and you can claim any free tag you want, only objection can be the usage of too many tags (e.g. someone claims to need a range from 0x80 to 0xAF).
 +
 
 +
{| style="font-size: 85%; text-align: Left;Border="1";
 +
! rowspan=2 | TAGNAME
 +
! rowspan=2 | VALUE
 +
! rowspan=2 | Meaning
 +
! rowspan=2 | Reserved by / source code
 +
|-
 +
|
 +
|-
 +
|MISC_PROTOCOL_EXTENSIONS
 +
| 'M' 4D
 +
| used for full mod extensions like ICS, etc..
 +
| basic modprot
 +
|-
 +
|MISC_PROTOCOL_EXTENSIONS2
 +
| 'm' 6D
 +
| used for full mod extensions 2, reserved for future use
 +
| basic modprot
 +
|-
 +
|CT_MOD_VERSION
 +
| 'U' 0x55
 +
| Modstring
 +
| basic modprot
 +
|-
 +
|KAD_EMULE_BUDDYID
 +
| '@' 40
 +
| [[NatT_protocol|NatT]]
 +
| David Xanatos
 +
|-
 +
|XS_EMULE_BUDDYIP
 +
| 'B' 42
 +
| [[NatT_protocol|NatT]]
 +
| David Xanatos
 +
|-
 +
|XS_EMULE_BUDDYUDP
 +
| 'b' 62
 +
| [[NatT_protocol|NatT]]
 +
| David Xanatos
 +
|-
 +
|NEO_PROTOCOL_EXTENSIONS
 +
|'N' 4E
 +
| etc.
 +
| David Xanatos
 +
|-
 +
|NEO_PROTOCOL_EXTENSIONS2
 +
|'n' 6E
 +
| reserved for future Neo features
 +
| David Xanatos
 +
|-
 +
|}
 +
 
 +
 
 +
* MISC_PROTOCOL_EXTENSIONS:
 +
 
 +
  [bit 1]  // Unsolicited Part Status (idea from netfinity, allows our client ro recieve filestatus at any time)
 +
  [bit 2]  // LowID UDP Ping Support (notifyes a fix form xman1 that  allow the remote low ID to use udp reasks)
 +
  [bit 3]  // [[Mod_Multi_Packet#ICS|ICSv2]] New Official Version
 +
  [bit 4]  // UDP Mod File Status*
 +
  [bit 5]  // [[NatT_protocol|NATT]] - [NatTraversal], [[NatT_protocol#XS Callback|XSB]] - [XSBuddy], [[NatT_protocol#Port Reporting|RPT]] - [ReuseTCPPort]
 +
  [bit 6]  // [[NatT_protocol#Neo XS|NXS]] - [NeoXS]
 +
  [bit 7]  // [[CommentsV2|SF comments v2]]
 +
  [bit 8]  // [[Mod_Multi_Packet#SCT|SCT]]
 +
  [bit 9]  // [[L2HAC|L2HAC]]
  
−
Modstring is still send and replied in hello packet to maintain backward compatibility However a opcode for modstring will be defined for those who alos want to move it to the mod protocol
 
  
 +
<nowiki>*</nowiki> The UDP Mod File Status bit is not only used for ICS but used in general. It also tells whether Mod Multi Packet with extended mod status should be sent over UDP or not.
  
 +
== See also ==
  
−
== tags ==
+
References to emule protocol...
 +
[[category:Mod_protocol_extensions]]

Latest revision as of 12:54, 18 November 2010

Contents

Under construction

THIS IS NOT FINAL.. feel free to edit.

Introduction

The Modprot is needed for more clean protocol extensions by eMule modders....

The main idea is to set a bit in CT_EMULE_MISCOPTIONS2 in the initial hello packet. If that bit is set and received by an eMule mod that is capable of processing extensions, then that mod will send the options it is capable of in the response and the first client will also send back the protocol extensions it is capable of.

Important:

Clients that are not capable of processing the mod protocol (like official eMule/aMule) will not set the mod bit in CT_EMULE_MISCOPTIONS2 and will never receive extended protocol information.

Documentation

All mod communication is to be done over the OP_MODPROT/OP_MODPACKEDPROT. When a hello(answer) with a set mod bit is received the ConnectionEstablished has to be delayed. Instead of that the mod info packet with the opcode OP_MODINFOPACKET is to be sent. ConnectionEstablished will be triggered when the mod info packet is received. 

A               B
Hello   --->    MB Set (see if ModBit is set)
MB Set  <---    Hello Answer
ConEst  <---    MInfo (Mod Info)
MInfo   --->    ConEst (call ConnectionEstablished)

The mod info packet has to contain eMuleTags that announce the supported features. The packet is made up this way: 

<uint 32> tag count
<emule tag 1>
<emule tag 2>
...
<emule tag n>

It's only allowed to use mod features it their capability was announced by both sides. After the capability exchange via OP_MODINFOPACKET all remaining opcodes are allowed to be used by clients in any way they want. All further communication is not part of this specification.

Protocol

Sending Hello(answer) packets

Setting the modbit in CT_EMULE_MISCOPTIONS2

in baseclient.cpp, void CUpDownClient::SendHelloTypePacket(CSafeMemFile* data) 

	// eMule Misc. Options #2
	const UINT uKadVersion			= KADEMLIA_VERSION;
	const UINT uSupportLargeFiles	= 1;
	const UINT uExtMultiPacket		= 1;
	// Set the Mod Bit
	const UINT uModProt				= 1; // mod bit // NEO: NMP - [NeoModProt] <-- Xanatos --
	const UINT uSupportsCryptLayer	= thePrefs.IsClientCryptLayerSupported() ? 1 : 0;
	const UINT uRequestsCryptLayer	= thePrefs.IsClientCryptLayerRequested() ? 1 : 0;
	const UINT uRequiresCryptLayer	= thePrefs.IsClientCryptLayerRequired() ? 1 : 0;
	const UINT uSupportsSourceEx2	= 1;

	CTag tagMisOptions2(CT_EMULE_MISCOPTIONS2, 
//				(RESERVED				     )
				(uSupportsSourceEx2		<< 10) |
				(uRequiresCryptLayer	<<  9) |
				(uRequestsCryptLayer	<<  8) |
				(uSupportsCryptLayer	<<  7) |
				(uModProt				<<  6) |
				(uExtMultiPacket		<<  5) |
				(uSupportLargeFiles		<<  4) |
				(uKadVersion			<<  0) 
				);
	tagMisOptions2.WriteTagToFile(data);

Processing hello(answer) packets

Read out the modbit from CT_EMULE_MISCOPTIONS2

baseclient.cpp bool CUpDownClient::ProcessHelloTypePacket(CSafeMemFile* data) 

	case CT_EMULE_MISCOPTIONS2:
				//	21 Reserved
				//	 1 Supports SourceExachnge2 Packets, ignores SX1 Packet Version
				//	 1 Requires CryptLayer
				//	 1 Requests CryptLayer
				//	 1 Supports CryptLayer
				//	 1 Reserved (ModBit)
				//   1 Ext Multipacket (Hash+Size instead of Hash)
				//   1 Large Files (includes support for 64bit tags)
				//   4 Kad Version
				if (temptag.IsInt()) {
					m_fSupportsSourceEx2	= (temptag.GetInt() >>  10) & 0x01;
					m_fRequiresCryptLayer	= (temptag.GetInt() >>  9) & 0x01;
					m_fRequestsCryptLayer	= (temptag.GetInt() >>  8) & 0x01;
					m_fSupportsCryptLayer	= (temptag.GetInt() >>  7) & 0x01;
					// read the mod bit
					m_fSupportsModProt		= (temptag.GetInt() >>  6) & 0x01; // NEO: NMP - [NeoModProt] <-- Xanatos --
					m_fExtMultiPacket		= (temptag.GetInt() >>  5) & 0x01;
					m_fSupportsLargeFiles   = (temptag.GetInt() >>  4) & 0x01;
					m_byKadVersion			= (uint8)((temptag.GetInt() >>  0) & 0x0f);
					dwEmuleTags |= 8;
					if (bDbgInfo)
						m_strHelloInfo.AppendFormat(_T("\n  KadVersion=%u, LargeFiles=%u ExtMultiPacket=%u CryptLayerSupport=%u CryptLayerRequest=%u CryptLayerRequires=%u m_fSupportsSourceEx2=%u"), m_byKadVersion, m_fSupportsLargeFiles, m_fExtMultiPacket, m_fSupportsCryptLayer, m_fRequestsCryptLayer, m_fRequiresCryptLayer, m_fSupportsSourceEx2);
					m_fRequestsCryptLayer &= m_fSupportsCryptLayer;
					m_fRequiresCryptLayer &= m_fRequestsCryptLayer;

Sending hello answer and modprot info

Listensocket.cpp bool CClientReqSocket::ProcessPacket(const BYTE* packet, uint32 size, UINT opcode) 

if (client->GetHashType() == SO_EMULE && !bIsMuleHello)
						client->SendMuleInfoPacket(false);

					client->SendHelloAnswer();

					if (client)
					{
						// NEO: NMP - [NeoModProt] -- Xanatos -->
						if(client->GetNeoModProtVersion())
							client->SendModInfoPacket();


Example of SendModInfoPacket: 

void CUpDownClient::SendModInfoPacket(){
	if (socket == NULL){ // first we check if we have a valid socket, actualy we was called form the socket so this check is rather unnesesery, but in case
		ASSERT(0);
		return;
	}

	CSafeMemFile data(128);

	// write the amount of emule tags we intent to send
	// !!! this value must be correct !!! 
	uint32 tagcount=2;

	// write the first tag (Nr.1)
	// in this sample its an normal tag with an uint8 ID, its the modstring 0x55 = 'T'
	data.WriteUInt32(tagcount); // nr. of tags
	CTag tagPartStatus(0x55,_T("TestMod"));
	tagPartStatus.WriteNewEd2kTag(&data);

	// write the secund tag (Nr.2)
	// in this sample its an custom named tag with an string as ID
	CTag tagMyMail("Mod:eMail",_T("User@Domain.com"));
	tagMyMail.WriteNewEd2kTag(&data);
	
	// we are done writing tags

	// now we create a packet and put what we have writen in it
	Packet* packet = new Packet(&data,OP_MODPROT);
	packet->opcode = OP_MODINFOPACKET;
	if (thePrefs.GetDebugClientTCPLevel() > 0)
		DebugSend("OP__ModInfoPacket", this);
	theStats.AddUpDataOverheadOther(packet->size);
	socket->SendPacket(packet,true,true); // we send the packet
}

Delaying ConnectionEstablished & sending the mod info packet

listensocket.cpp bool CClientReqSocket::ProcessPacket(const BYTE* packet, uint32 size, UINT opcode) 

				case OP_HELLOANSWER:
				{
					theStats.AddDownDataOverheadOther(size);
					client->ProcessHelloAnswer(packet,size);
					if (thePrefs.GetDebugClientTCPLevel() > 0){
						DebugRecv("OP_HelloAnswer", client);
						Debug(_T("  %s\n"), client->DbgGetHelloInfo());
					}

					// NEO: NMP - [NeoModProt] -- Xanatos -->
					if(client->SupportsModProt() == 0)	// check for mod prot
					// we will start the SUI when we recieve the mod info packet
					// NEO: NMP END <-- Xanatos --
					{
						// start secure identification, if
						//  - we have received OP_EMULEINFO and OP_HELLOANSWER (old eMule)
						//	- we have received eMule-OP_HELLOANSWER (new eMule)
						if (client->GetInfoPacketsReceived() == IP_BOTH)
							client->InfoPacketsReceived();
					}

					if (client)
					{
						// NEO: NMP - [NeoModProt] -- Xanatos -->
						if (client->SupportsModProt()) // if this cleint uses mod protocol extensions
							client->SendModInfoPacket(); // we send him the mod info packet with our rxtensions
						else // we *dont* call ConnectionEstablished at this point,
							 // when will call ConnectionEstablished when we recieve the Mod Info frm this cleint
						// NEO: NMP END <-- Xanatos --
						{
							client->ConnectionEstablished();
							theApp.emuledlg->transferwnd->clientlistctrl.RefreshClient(client);
						}
					}
					break;
				}

listensocket.cpp bool CClientReqSocket::ProcessPacket(const BYTE* packet, uint32 size, UINT opcode) 

				case OP_HELLO:
				{
					[..................]

					if (client)
					{
						// NEO: NMP - [NeoModProt] -- Xanatos -->
						if(client->SupportsModProt()) // if this cleint uses mod protocol extensions
							client->SendModInfoPacket(); // we send him the mod info packet with our rxtensions
						else // we *dont* call ConnectionEstablished at this point,
							 // when will call ConnectionEstablished when we recieve the Mod Info frm this cleint
						// NEO: NMP END <-- Xanatos --
							client->ConnectionEstablished();
					}

					ASSERT( client );
					if(client)
					{
						// NEO: NMP - [NeoModProt] -- Xanatos -->
						if(client->SupportsModProt() == 0) // check for mod prot
						// we will start the SUI when we recieve the mod info packet
						// NEO: NMP END <-- Xanatos --
						{

							// start secure identification, if
							//	- we have received eMule-OP_HELLO (new eMule)
							if (client->GetInfoPacketsReceived() == IP_BOTH)
								client->InfoPacketsReceived();
						}

						if( client->GetKadPort() )
							Kademlia::CKademlia::Bootstrap(ntohl(client->GetIP()), client->GetKadPort(), (client->GetKadVersion() > 1));
					}
					break;
				}

Processing the modinfo packet

listensocket.cpp 

bool CClientReqSocket::ProcessModPacket(const BYTE* packet, uint32 size, UINT opcode, UINT uRawSize)
{
	try
	{
		try
		{
			if (!client)
			{
				theStats.AddDownDataOverheadOther(uRawSize);
				throw GetResString(IDS_ERR_UNKNOWNCLIENTACTION);
			}
			if (thePrefs.m_iDbgHeap >= 2)
				ASSERT_VALID(client);

			switch(opcode)
			{
				case OP_MODINFOPACKET:
				{
					if (thePrefs.GetDebugClientTCPLevel() > 0)
						DebugRecv("OP__ModInfoPacket", client);
					theStats.AddDownDataOverheadOther(uRawSize);

					if(client->GetNeoModProtVersion() == 0)
						throw CString(_T("Recieved Neo Mod Info Packet from a cleint whitch doe snot support this feature!"));

					client->ProcessModInfoPacket(packet,size);

					// Now after we have all informations about the cleint the connection is established
					client->ConnectionEstablished();

					// start secure identification, if
					//  - we have received OP_MODINFOPACKET, (Neo Compatible new eMule mods)
					if (client->GetInfoPacketsReceived() == IP_BOTH)
						client->InfoPacketsReceived();
					break;
				}	

				// NEO: NMPm - [NeoModProtMultiPacket]
				case OP_MODMULTIPACKET: 
				{
...



baseclient.cpp 

void CUpDownClient::ProcessModInfoPacket(const uchar* pachPacket, uint32 nSize)
{
	bool bDbgInfo = thePrefs.GetUseDebugDevice();
	CString m_strModInfo;
	CSafeMemFile data(pachPacket, nSize);

	// we read now the amount of tags that the sender put in th epacket
	uint32 tagcount = data.ReadUInt32();
	if (bDbgInfo)
		m_strModInfo.AppendFormat(_T("  Tags=%u"), (UINT)tagcount);
	// now we are going to read all of them
	for (uint32 i = 0; i < tagcount; i++)
	{
		CTag temptag(&data, false);
		switch (temptag.GetNameID()) // here we distinguish only tags with an uint8 ID, all named tags are handled below
		{
			case 0x55:
				if (temptag.IsStr())
					Log(_T("ModString %s", temptag.GetStr()));
				else if (bDbgInfo)
					m_strModInfo.AppendFormat(_T("\n  ***UnkType=%s"), temptag.GetFullInfo());
				break;

			default:

				// now we habdle custom named tags, we use a series of (else)if's and strcmp, note: this is *not* unicide!!!
				if(strcmp(temptag.GetName(),"Mod:Hello") == 0)
				{
					if(temptag.IsStr())
						Log(LOG_SUCCESS,_T("*** Greathings from %s: %s"),GetUserName(),temptag.GetStr());
				}
				else

				if (bDbgInfo)
					m_strModInfo.AppendFormat(_T("\n  ***UnkTag=%s"), temptag.GetFullInfo());
		}
	}

	// some debug output
	if (bDbgInfo && data.GetPosition() < data.GetLength()){
		m_strModInfo.AppendFormat(_T("\n  ***AddData: %u bytes"), data.GetLength() - data.GetPosition());
	}
}

Processing mod data example

EMSocket.cpp void CEMSocket::OnReceive(int nErrorCode) 

switch (pendingPacket->prot){
				case OP_EDONKEYPROT:
				case OP_PACKEDPROT:
				case OP_EMULEPROT:
				// NEO: NMP - [NeoModProt] -- Xanatos -->
				// We have to accept also mod packet
				case OP_MODPACKEDPROT:
				case OP_MODPROT:
				// NEO: NMP END <-- Xanatos --
					break;
				default:
					EMTrace("CEMSocket::OnReceive ERROR Wrong header");
					delete pendingPacket;
					pendingPacket = NULL;
					OnError(ERR_WRONGHEADER);
					return;
			}


listensocket.cpp bool CClientReqSocket::PacketReceivedCppEH(Packet* packet) 

		// NEO: NMP - [NeoModProt] -- Xanatos -->
		// dispatch mod packets to the right processing functions
		case OP_MODPACKEDPROT:
			if (!packet->UnPackPacket()){
				if (thePrefs.GetVerbose())
					AddDebugLogLine(false, _T("Failed to decompress client Mod TCP packet; %s; %s"), DbgGetClientTCPPacket(packet->prot, packet->opcode, packet->size), DbgGetClientInfo());
				bResult = false;
				break;
			}
		case OP_MODPROT:
			bResult = ProcessModPacket((const BYTE*)packet->pBuffer, packet->size, packet->opcode, uRawSize);
			break;

// NEO: NMP - [NeoModProt] -- Xanatos -->
bool CClientReqSocket::ProcessModPacket(const BYTE* packet, uint32 size, UINT opcode, UINT uRawSize)
{
	try
	{
		try
		{
			// we must have a cleint at this point !always!
			if (!client)
			{
				theStats.AddDownDataOverheadOther(uRawSize);
				throw GetResString(IDS_ERR_UNKNOWNCLIENTACTION);
			}
			if (thePrefs.m_iDbgHeap >= 2)
				ASSERT_VALID(client);

			switch(opcode) // dispatch particular packets
			{
				// for the mod prot v1 (capability exchange) only this one packet is relevant, the mod info packet
				case OP_MODINFOPACKET:
				{
					if (thePrefs.GetDebugClientTCPLevel() > 0)
						DebugRecv("OP__ModInfoPacket", client);
					theStats.AddDownDataOverheadOther(uRawSize);

					if(client->SupportsModProt() == 0) // just pure formality
						throw CString(_T("Recieved Neo Mod Info Packet from a cleint whitch doe snot support this feature!"));

					// Process the packet
					client->ProcessModInfoPacket(packet,size);

					// Now after we have all informations about the cleint the connection is established
					client->ConnectionEstablished();

					// start secure identification, if
					//  - we have received OP_MODINFOPACKET, (Neo Compatible new eMule mods)
					if (client->GetInfoPacketsReceived() == IP_BOTH)
						client->InfoPacketsReceived();
					break;
				}	

				default: // handle unknown packets
					
					theStats.AddDownDataOverheadOther(uRawSize);
					PacketToDebugLogLine(_T("ModProt"), packet, size, opcode);
			}
		}
		catch(CFileException* error)
		{
			error->Delete();
			throw GetResString(IDS_ERR_INVALIDPACKAGE);
		}
		catch(CMemoryException* error)
		{
			error->Delete();
			throw CString(_T("Memory exception"));
		}
	}
	catch(CString error)
	{
		if (thePrefs.GetVerbose() && !error.IsEmpty())
			DebugLogWarning(_T("Error: %s - while processing Mod packet: opcode=%s  size=%u; %s"), error, DbgGetMuleClientTCPOpcode(opcode), size, DbgGetClientInfo());
		// Note: don't disconnect cleints on mod prot errors, the extensions are just addons and if thay fail the client will work anyway
		//if (client)
		//	client->SetDownloadState(DS_ERROR, _T("ProcessModPacket error. ") + error);
		//Disconnect(_T("ProcessModPacket error. ") + error); 
		//return false;
	}
	return true;

// NEO: NMP END <-- Xanatos --

Additional modifications

Packets.cpp void Packet::PackPacket() 

	// NEO: NMP - [NeoModProt] -- Xanatos -->
	if( prot == OP_MODPROT )
		prot = OP_MODPACKEDPROT;
	else
	// NEO: NMP END <-- Xanatos --
	if( prot == OP_KADEMLIAHEADER )
		prot = OP_KADEMLIAPACKEDPROT;
	else
		prot = OP_PACKEDPROT;

Packets.cpp bool Packet::UnPackPacket(UINT uMaxDecompressedSize) 

		// NEO: NMP - [NeoModProt] -- Xanatos -->
		if( prot == OP_MODPACKEDPROT )
			prot = OP_MODPROT;
		else
		// NEO: NMP END <-- Xanatos --
		if( prot == OP_KADEMLIAPACKEDPROT )
			prot = OP_KADEMLIAHEADER;
		else
			prot =  OP_EMULEPROT;

Backward compatibility

The modstring is still send via hello(answer) packets but only if the remote client is using a mod and does not support the mod prot extension to maintain backward compatibility. Usage of CT_MOD_VERSION is proposed to move it to the mod protocol. A mod using the modbit MUST identify itself either via CT_MOD_VERSION in the hello(answer) packets or via modstring in the modinfo packet. NOTE: a mod that uses extensions but refuses to identify itself will most likely be considered a bad mod by some antileecher systems

The proposed check to use would be like 

void CUpDownClient::SendHelloTypePacket(CSafeMemFile* data)
{
...
...
	uint32 tagcount = 6;

	if( theApp.clientlist->GetBuddy() && theApp.IsFirewalled() )
		tagcount += 2;

//>>> MODPROT::Send Modstring to old mods only
	const bool bSendModString = !SupportsModProt() && (!m_strModVersion.IsEmpty() || !m_pszUsername); 
	if(bSendModString)
		++tagcount;
//<<< MODPROT::Send Modstring to old mods only

	data->WriteUInt32(tagcount);
...
...
	tagMuleVersion.WriteTagToFile(data);

//>>> MODPROT::Send Modstring to old mods only
	if(bSendModString)
	{
		CTag tagMod(CT_MOD_VERSION, L"My Mod String");
		tagMod.WriteTagToFile(data);
	}
//<<< MODPROT::Send Modstring to old mods only

	uint32 dwIP;
	uint16 nPort;
...
...

and similar for the info packet.


OPCODE defines 

OP_MODPROT       0x4D
OP_MODPACKEDPROT 0x6D
OP_MODINFOPACKET 0x01

TAG defines

Tags used must be reserved in modprot topic at http://forum.emule-project.net/ Sources must be published within 3 months after claiming a tag.

The range 0x01 - 0x1F is completely reserved.

Tags in the range from 0x20 - 0x7E are reserved for major features, possible objections can be:

  1. Modder uses too many tags (if you need more than 5 tags you are most likely doing something wrong. Note that string tags are also available - those are not regulated)
  2. Utterly useless or unimplementable feature (no other mod will ever use it)
  3. Illegal feature (should be clear)

The range 0x7F-FF is open and you can claim any free tag you want, only objection can be the usage of too many tags (e.g. someone claims to need a range from 0x80 to 0xAF).

TAGNAME VALUE Meaning Reserved by / source code
MISC_PROTOCOL_EXTENSIONS 'M' 4D used for full mod extensions like ICS, etc.. basic modprot
MISC_PROTOCOL_EXTENSIONS2 'm' 6D used for full mod extensions 2, reserved for future use basic modprot
CT_MOD_VERSION 'U' 0x55 Modstring basic modprot
KAD_EMULE_BUDDYID '@' 40 NatT David Xanatos
XS_EMULE_BUDDYIP 'B' 42 NatT David Xanatos
XS_EMULE_BUDDYUDP 'b' 62 NatT David Xanatos
NEO_PROTOCOL_EXTENSIONS 'N' 4E etc. David Xanatos
NEO_PROTOCOL_EXTENSIONS2 'n' 6E reserved for future Neo features David Xanatos


  • MISC_PROTOCOL_EXTENSIONS: 
  [bit 1]   // Unsolicited Part Status (idea from netfinity, allows our client ro recieve filestatus at any time)
  [bit 2]   // LowID UDP Ping Support (notifyes a fix form xman1 that  allow the remote low ID to use udp reasks)
  [bit 3]   // ICSv2 New Official Version
  [bit 4]   // UDP Mod File Status*
  [bit 5]   // NATT - [NatTraversal], XSB - [XSBuddy], RPT - [ReuseTCPPort]
  [bit 6]   // NXS - [NeoXS]
  [bit 7]   // SF comments v2
  [bit 8]   // SCT
  [bit 9]   // L2HAC


* The UDP Mod File Status bit is not only used for ICS but used in general. It also tells whether Mod Multi Packet with extended mod status should be sent over UDP or not.

See also

References to emule protocol...

Retrieved from "?title=Mod_protocol&oldid=2994"
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