reHLDS/rehlds
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Fix dos attack on connection challenges system

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This commit is contained in:
Asmodai 2021-01-26 02:13:34 +03:00
parent 83c0b6ea2b
commit 370dddb8b4
2 changed files with 41 additions and 0 deletions
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39
rehlds/engine/sv_main.cpp
View File

@ -1810,16 +1810,38 @@ challenge_t g_rg_sv_challenges[MAX_CHALLENGES];
int g_oldest_challenge = 0;
#endif
typedef struct challenge_buf_s
{
uint32_t ip;
uint16_t port;
uint32_t salt[14];
} challenge_buf_t;
challenge_buf_t g_raw_challenge_buf;
void SV_ChallengesInit()
{
#ifdef REHLDS_FIXES
static_assert(sizeof(g_raw_challenge_buf) == 64u, "Invalid g_raw_challenge_buf size");
for (uint32_t& s : g_raw_challenge_buf.salt)
s = __rdtsc() * rand();
#endif
}
bool EXT_FUNC SV_CheckChallenge_api(const netadr_t &adr, int nChallengeValue) {
if (NET_IsLocalAddress(adr))
return TRUE;
#ifdef REHLDS_FIXES
return SV_GetChallenge(adr) == nChallengeValue;
#else
for (int i = 0; i < MAX_CHALLENGES; i++) {
if (NET_CompareBaseAdr(adr, g_rg_sv_challenges[i].adr))
return nChallengeValue == g_rg_sv_challenges[i].challenge;
}
return FALSE;
#endif
}
int SV_CheckChallenge(netadr_t *adr, int nChallengeValue)
@ -1830,6 +1852,10 @@ int SV_CheckChallenge(netadr_t *adr, int nChallengeValue)
if (NET_IsLocalAddress(*adr))
return TRUE;
#ifdef REHLDS_FIXES
if (SV_GetChallenge(*adr) == nChallengeValue)
return TRUE;
#else
for (int i = 0; i < MAX_CHALLENGES; i++)
{
if (NET_CompareBaseAdr(net_from, g_rg_sv_challenges[i].adr))
@ -1842,6 +1868,7 @@ int SV_CheckChallenge(netadr_t *adr, int nChallengeValue)
return TRUE;
}
}
#endif
SV_RejectConnection(adr, "No challenge for your address.\n");
return FALSE;
}
@ -2499,6 +2526,16 @@ void SVC_Ping(void)
int EXT_FUNC SV_GetChallenge(const netadr_t& adr)
{
#ifdef REHLDS_FIXES
uint8_t digest[16];
g_raw_challenge_buf.ip = *(uint32_t*)adr.ip;
g_raw_challenge_buf.port = adr.port;
MD5Context_t ctx;
MD5Init(&ctx);
MD5Update(&ctx, (uint8_t *)&g_raw_challenge_buf, sizeof(g_raw_challenge_buf));
MD5Final(digest, &ctx);
return *(int *)digest & 0x7FFFFFFF;
#else
int i;
#ifndef REHLDS_OPT_PEDANTIC
int oldest = 0;
@ -2540,6 +2577,7 @@ int EXT_FUNC SV_GetChallenge(const netadr_t& adr)
}
return g_rg_sv_challenges[i].challenge;
#endif
}
void SVC_GetChallenge(void)
@ -7985,6 +8023,7 @@ void SV_Init(void)
PM_Init(&g_svmove);
SV_AllocClientFrames();
SV_InitDeltas();
SV_ChallengesInit();
}
void SV_Shutdown(void)

2
rehlds/public/rehlds/osconfig.h
View File

@ -136,6 +136,8 @@
VirtualFree(ptr, 0, MEM_RELEASE);
}
#else // _WIN32
#include <x86intrin.h>
#ifndef PAGESIZE
#define PAGESIZE 4096
#endif