EO big packet patch

endless.exe patch.txt

; Change packet substring index from 2 to 4
+9FA3D -> B9 02
edited -> B9 04

; Change packet substring bounds from (2, len-2) to (4, len-4)
+9FAA0 -> C1 FE BA 03
edited -> C1 FC BA 05

; more of the above...
+9FAE8 -> BA 03
edited -> BA 05

; even more of the above...
+9FAF9 -> C1 FE
edited -> C1 FC

; replace packet length calculation code to process three and four byte lengths
+A00B5 -> 83 FB 01 75 02 03 F0 83 FB 02 75 0C 8B C8 C1 E1 06 2B C8 8D 0C 88
edited -> 53 8B C8 83 FB 01 7E 0D 50 66 B8 FD 00 F7 E1 8B C8 58 4B EB EE 5B

; code before: 
	endless.exe+A00B5 - 83 FB 01              - cmp ebx,01 { 1 }
	endless.exe+A00B8 - 75 02                 - jne endless.exe+A00BC
	endless.exe+A00BA - 03 F0                 - add esi,eax
	endless.exe+A00BC - 83 FB 02              - cmp ebx,02 { 2 }
	endless.exe+A00BF - 75 0C                 - jne endless.exe+A00CD
	endless.exe+A00C1 - 8B C8                 - mov ecx,eax
	endless.exe+A00C3 - C1 E1 06              - shl ecx,06 { 6 }
	endless.exe+A00C6 - 2B C8                 - sub ecx,eax
	endless.exe+A00C8 - 8D 0C 88              - lea ecx,[eax+ecx*4]
	
; code after:
	endless.exe+A00B5 - 53                    - push ebx
	endless.exe+A00B6 - 8B C8                 - mov ecx,eax
	endless.exe+A00B8 - 83 FB 01              - cmp ebx,01 { 1 }
	endless.exe+A00BB - 7E 0D                 - jle endless.exe+A00CA
	endless.exe+A00BD - 50                    - push eax
	endless.exe+A00BE - 66 B8 FD00            - mov ax,00FD { 253 }
	endless.exe+A00C2 - F7 E1                 - mul ecx
	endless.exe+A00C4 - 8B C8                 - mov ecx,eax
	endless.exe+A00C6 - 58                    - pop eax
	endless.exe+A00C7 - 4B                    - dec ebx
	endless.exe+A00C8 - EB EE                 - jmp endless.exe+A00B8
	endless.exe+A00CA - 5B                    - pop ebx

eoserv patch.diff

diff --git a/src/packet.cpp b/src/packet.cpp
index f942b03..6a75401 100644
--- a/src/packet.cpp
+++ b/src/packet.cpp
@@ -176,19 +176,21 @@ std::string PacketProcessor::Decode(const std::string &str)
 
 std::string PacketProcessor::Encode(const std::string &rawstr)
 {
-	if (emulti_e == 0 || ((unsigned char)rawstr[2] == PACKET_A_INIT && (unsigned char)rawstr[3] == PACKET_F_INIT))
+	if (emulti_e == 0 || ((unsigned char)rawstr[4] == PACKET_A_INIT && (unsigned char)rawstr[5] == PACKET_F_INIT))
 		return rawstr;
 
 	std::string str = this->DickWinderE(rawstr);
 	std::string newstr;
 	int length = str.length();
-	int i = 2;
-	int ii = 2;
+	int i = 4;
+	int ii = 4;
 
 	newstr.resize(length);
 
-	newstr[0] = str[0];
-	newstr[1] = str[1];
+	newstr[0] = str[0];
+	newstr[1] = str[1];
+	newstr[2] = str[2];
+	newstr[3] = str[3];
 
 	while (i < length)
 	{
@@ -203,13 +205,13 @@ std::string PacketProcessor::Encode(const std::string &rawstr)
 		--i;
 	}
 
-	while (i >= 2)
+	while (i >= 4)
 	{
 		newstr[i] = (unsigned char)str[ii++] ^ 0x80;
 		i -= 2;
 	}
 
-	for (int i = 2; i < length; ++i)
+	for (int i = 4; i < length; ++i)
 	{
 		if (static_cast<unsigned char>(newstr[i]) == 128)
 		{
@@ -678,12 +680,14 @@ void PacketBuilder::Reset(std::size_t size_guess)
 std::string PacketBuilder::Get() const
 {
 	std::string retdata;
-	retdata.reserve(4 + this->data.length());
+	retdata.reserve(6 + this->data.length());
 	std::array<unsigned char, 2> id = PacketProcessor::EPID(this->id);
-	std::array<unsigned char, 4> length = PacketProcessor::ENumber(this->data.length() + 2 + this->add_size);
+	std::array<unsigned char, 4> length = PacketProcessor::ENumber(this->data.length() + 4 + this->add_size);
 
-	retdata += length[0];
-	retdata += length[1];
+	retdata += length[0];
+	retdata += length[1];
+	retdata += length[2];
+	retdata += length[3];
 	retdata += id[0];
 	retdata += id[1];
 	retdata += this->data;