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https://github.com/OpenFusionProject/OpenFusion.git
synced 2024-11-22 13:30:06 +00:00
Implemented proper validation of variable-length packets.
Also changed output buffer in pcAttackNpcs() from dynamically to statically allocated. This in itself is temporary as I have a better idea as to how we can allocate buffers with a bit less boilerplate.
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@ -170,7 +170,7 @@ void CNSocket::step() {
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// we got out packet size!!!!
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readSize = *((int32_t*)readBuffer);
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// sanity check
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if (readSize > MAX_PACKETSIZE) {
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if (readSize > CN_PACKET_BUFFER_SIZE) {
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kill();
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return;
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}
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@ -1,6 +1,5 @@
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#pragma once
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#define MAX_PACKETSIZE 8192
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#define DEBUGLOG(x) if (settings::VERBOSITY) {x};
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#include <iostream>
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@ -56,7 +55,8 @@
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[4 bytes] - size of packet including the 4 byte packet type
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[size bytes] - Encrypted packet (byte swapped && xor'd with 8 byte key; see CNSocketEncryption)
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[4 bytes] - packet type (which is a combination of the first 4 bytes of the packet and a checksum in some versions)
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[structure]
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[structure] - one member contains length of trailing data (expressed in packet-dependant structures)
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[trailing data] - optional variable-length data that only some packets make use of
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*/
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// error checking calloc wrapper
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@ -71,6 +71,42 @@ inline void* xmalloc(size_t sz) {
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return res;
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}
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// overflow-safe validation of variable-length packets
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// for outbound packets
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inline bool validOutVarPacket(size_t base, int32_t npayloads, size_t plsize) {
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// check for multiplication overflow
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if (npayloads > 0 && CN_PACKET_BUFFER_SIZE / (size_t)npayloads < plsize)
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return false;
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// it's safe to multiply
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size_t trailing = npayloads * plsize;
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// does it fit in a packet?
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if (base + trailing <= CN_PACKET_BUFFER_SIZE)
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return false;
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// everything is a-ok!
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return true;
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}
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// for inbound packets
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inline bool validInVarPacket(size_t base, int32_t npayloads, size_t plsize, size_t datasize) {
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// check for multiplication overflow
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if (npayloads > 0 && CN_PACKET_BUFFER_SIZE / (size_t)npayloads < plsize)
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return false;
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// it's safe to multiply
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size_t trailing = npayloads * plsize;
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// make sure size is exact
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// datasize has already been validated against CN_PACKET_BUFFER_SIZE
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if (datasize != base + trailing)
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return false;
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// everything is a-ok!
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return true;
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}
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namespace CNSocketEncryption {
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// you won't believe how complicated they made it in the client :facepalm:
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static constexpr const char* defaultKey = "m@rQn~W#";
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@ -104,7 +140,7 @@ private:
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uint64_t EKey;
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uint64_t FEKey;
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int32_t readSize = 0;
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uint8_t readBuffer[MAX_PACKETSIZE];
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uint8_t readBuffer[CN_PACKET_BUFFER_SIZE];
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int readBufferIndex = 0;
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bool activelyReading = false;
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bool alive = true;
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@ -13,22 +13,31 @@ void CombatManager::init() {
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}
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void CombatManager::pcAttackNpcs(CNSocket *sock, CNPacketData *data) {
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// generic malformed packet checks are not applicable to variable-length packets
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sP_CL2FE_REQ_PC_ATTACK_NPCs* pkt = (sP_CL2FE_REQ_PC_ATTACK_NPCs*)data->buf;
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if (data->size != sizeof(sP_CL2FE_REQ_PC_ATTACK_NPCs) + pkt->iNPCCnt * 4) {
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std::cout << "bad sP_CL2FE_REQ_PC_ATTACK_NPCs packet size\n";
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// sanity check
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if (!validInVarPacket(sizeof(sP_CL2FE_REQ_PC_ATTACK_NPCs), pkt->iNPCCnt, sizeof(int32_t), data->size)) {
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std::cout << "[WARN] bad sP_CL2FE_REQ_PC_ATTACK_NPCs packet size\n";
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return;
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}
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int32_t *pktdata = (int32_t*)((uint8_t*)data->buf + sizeof(sP_CL2FE_REQ_PC_ATTACK_NPCs));
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std::printf("iNPCCnt: %d\n", pkt->iNPCCnt);
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/*
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* Due to the possibility of multiplication overflow (and regular buffer overflow),
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* both incoming and outgoing variable-length packets must be validated.
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*/
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if (!validOutVarPacket(sizeof(sP_FE2CL_PC_ATTACK_NPCs_SUCC), pkt->iNPCCnt, sizeof(sAttackResult))) {
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std::cout << "[WARN] bad sP_CL2FE_REQ_PC_ATTACK_NPCs packet size\n";
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return;
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}
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// initialize response struct
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// IMPORTANT TODO: verify that resplen doesn't overflow!!!
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size_t resplen = sizeof(sP_FE2CL_PC_ATTACK_NPCs_SUCC) + pkt->iNPCCnt * sizeof(sAttackResult);
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uint8_t *respbuf = (uint8_t*)xmalloc(resplen);
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uint8_t respbuf[4096];
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memset(respbuf, 0, resplen);
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sP_FE2CL_PC_ATTACK_NPCs_SUCC *resp = (sP_FE2CL_PC_ATTACK_NPCs_SUCC*)respbuf;
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sAttackResult *respdata = (sAttackResult*)(respbuf+sizeof(sP_FE2CL_PC_ATTACK_NPCs_SUCC));
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@ -45,7 +54,6 @@ void CombatManager::pcAttackNpcs(CNSocket *sock, CNPacketData *data) {
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BaseNPC& mob = NPCManager::NPCs[pktdata[i]];
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mob.appearanceData.iHP -= 100;
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std::cout << "mob health is now " << mob.appearanceData.iHP << std::endl;
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if (mob.appearanceData.iHP <= 0)
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giveReward(sock);
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@ -56,10 +64,7 @@ void CombatManager::pcAttackNpcs(CNSocket *sock, CNPacketData *data) {
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respdata[i].iHitFlag = 2;
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}
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std::cout << "sending packet of length " << resplen << std::endl;
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sock->sendPacket((void*)respbuf, P_FE2CL_PC_ATTACK_NPCs_SUCC, resplen);
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free(respbuf);
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}
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void CombatManager::combatBegin(CNSocket *sock, CNPacketData *data) {} // stub
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