Rewrite DNS API from scratch into dedicated file(s)

From a functional point of view, the main improvement is that GetIP() now always prioritizes IPv6 over IPv4.
The previous implementation always returned an IPv4 address, unless not available: in such case it failed.
This means that now connections to hostnames should be established via IPv6 if available.

From a programmer point of view, getting rid of the insane wrappers is enough to justify a complete rewrite.

As an extra, several unrelated unused global variables are removed.

src/Cedar/Connection.c

@@ -21,6 +21,7 @@
 #include "UdpAccel.h"
 #include "Virtual.h"
 
+#include "Mayaqua/DNS.h"
 #include "Mayaqua/Kernel.h"
 #include "Mayaqua/Mayaqua.h"
 #include "Mayaqua/Memory.h"

src/Cedar/Hub.c

@@ -19,6 +19,7 @@
 #include "Server.h"
 
 #include "Mayaqua/Cfg.h"
+#include "Mayaqua/DNS.h"
 #include "Mayaqua/FileIO.h"
 #include "Mayaqua/Internat.h"
 #include "Mayaqua/Memory.h"

src/Cedar/Logging.c

@@ -17,6 +17,7 @@
 #include "SecureNAT.h"
 #include "Server.h"
 
+#include "Mayaqua/DNS.h"
 #include "Mayaqua/Internat.h"
 #include "Mayaqua/FileIO.h"
 #include "Mayaqua/Memory.h"

src/Cedar/Protocol.c

@@ -30,6 +30,7 @@
 #include "Wpc.h"
 
 #include "Mayaqua/Cfg.h"
+#include "Mayaqua/DNS.h"
 #include "Mayaqua/FileIO.h"
 #include "Mayaqua/Internat.h"
 #include "Mayaqua/Memory.h"

src/Cedar/Radius.c

@@ -11,6 +11,7 @@
 #include "IPC.h"
 #include "Server.h"
 
+#include "Mayaqua/DNS.h"
 #include "Mayaqua/Internat.h"
 #include "Mayaqua/Memory.h"
 #include "Mayaqua/Object.h"
@@ -1717,7 +1718,7 @@ bool RadiusLogin(CONNECTION *c, char *server, UINT port, UCHAR *secret, UINT sec
 		{
 			Add(ip_list, tmp_ip);
 		}
-		else if (GetIPEx(tmp_ip, token->Token[i], true))
+		else if (GetIP(tmp_ip, token->Token[i]))
 		{
 			Add(ip_list, tmp_ip);
 		}

src/Cedar/Server.c

@@ -25,6 +25,7 @@
 #include "WinUi.h"
 
 #include "Mayaqua/Cfg.h"
+#include "Mayaqua/DNS.h"
 #include "Mayaqua/FileIO.h"
 #include "Mayaqua/Internat.h"
 #include "Mayaqua/Memory.h"
@@ -312,8 +313,8 @@ UINT SiDebugProcGetCurrentGetIPThreadCount(SERVER *s, char *in_str, char *ret_st
 		return ERR_INVALID_PARAMETER;
 	}
 
-	ToStr3(tmp1, 0, GetCurrentGetIpThreadNum());
+	ToStr3(tmp1, 0, DnsThreadNum());
-	ToStr3(tmp2, 0, GetGetIpThreadMaxNum());
+	ToStr3(tmp2, 0, DnsThreadNumMax());
 
 	Format(ret_str, 0, 
 		"Current threads = %s\n"
@@ -5629,11 +5630,11 @@ void SiLoadServerCfg(SERVER *s, FOLDER *f)
 	i = CfgGetInt(f, "MaxConcurrentDnsClientThreads");
 	if (i != 0)
 	{
-		SetGetIpThreadMaxNum(i);
+		DnsThreadNumMaxSet(i);
 	}
 	else
 	{
-		SetGetIpThreadMaxNum(DEFAULT_GETIP_THREAD_MAX_NUM);
+		DnsThreadNumMaxSet(DNS_THREAD_DEFAULT_NUM_MAX);
 	}
 
 	s->DontBackupConfig = CfgGetBool(f, "DontBackupConfig");
@@ -6103,7 +6104,7 @@ void SiWriteServerCfg(FOLDER *f, SERVER *s)
 		return;
 	}
 
-	CfgAddInt(f, "MaxConcurrentDnsClientThreads", GetGetIpThreadMaxNum());
+	CfgAddInt(f, "MaxConcurrentDnsClientThreads", DnsThreadNumMax());
 
 	CfgAddInt(f, "CurrentBuild", s->Cedar->Build);
 
@@ -10766,7 +10767,7 @@ SERVER *SiNewServerEx(bool bridge, bool in_client_inner_server, bool relay_serve
 	LISTENER *azure;
 	LISTENER *rudp;
 
-	SetGetIpThreadMaxNum(DEFAULT_GETIP_THREAD_MAX_NUM);
+	DnsThreadNumMaxSet(DNS_THREAD_DEFAULT_NUM_MAX);
 
 	s = ZeroMalloc(sizeof(SERVER));
 

src/Cedar/UdpAccel.c

@@ -9,6 +9,7 @@
 
 #include "Connection.h"
 
+#include "Mayaqua/DNS.h"
 #include "Mayaqua/Kernel.h"
 #include "Mayaqua/Memory.h"
 #include "Mayaqua/Object.h"

src/Cedar/Virtual.c

@@ -15,6 +15,7 @@
 #include "NativeStack.h"
 #include "Server.h"
 
+#include "Mayaqua/DNS.h"
 #include "Mayaqua/FileIO.h"
 #include "Mayaqua/Memory.h"
 #include "Mayaqua/Object.h"

src/Cedar/Wpc.c

@@ -10,6 +10,7 @@
 #include "Command.h"
 #include "Protocol.h"
 
+#include "Mayaqua/DNS.h"
 #include "Mayaqua/Memory.h"
 #include "Mayaqua/Microsoft.h"
 #include "Mayaqua/Pack.h"

src/Mayaqua/DNS.c

@@ -0,0 +1,581 @@
+#include "DNS.h"
+
+#include "Memory.h"
+#include "Network.h"
+#include "Object.h"
+#include "Str.h"
+#include "Tick64.h"
+
+#ifdef OS_WIN32
+#include <WS2tcpip.h>
+#else
+#include <netdb.h>
+#include <sys/socket.h>
+#endif
+
+static bool cache_enabled;
+
+static LIST *cache;
+static LIST *cache_reverse;
+
+static COUNTER *threads_counter;
+static UINT threads_max;
+
+int DnsCacheCompare(void *p1, void *p2)
+{
+	if (p1 == NULL || p2 == NULL)
+	{
+		return (p1 == NULL && p2 == NULL ? 0 : (p1 == NULL ? -1 : 1));
+	}
+
+	const DNS_CACHE *c1 = *(DNS_CACHE **)p1;
+	const DNS_CACHE *c2 = *(DNS_CACHE **)p2;
+
+	return StrCmpi(c1->Hostname, c2->Hostname);
+}
+
+int DnsCacheReverseCompare(void *p1, void *p2)
+{
+	if (p1 == NULL || p2 == NULL)
+	{
+		return (p1 == NULL && p2 == NULL ? 0 : (p1 == NULL ? -1 : 1));
+	}
+
+	const DNS_CACHE_REVERSE *c1 = *(DNS_CACHE_REVERSE **)p1;
+	const DNS_CACHE_REVERSE *c2 = *(DNS_CACHE_REVERSE **)p2;
+
+	return CmpIpAddr(&c1->IP, &c2->IP);
+}
+
+void DnsInit()
+{
+	threads_counter = NewCounter();
+	DnsThreadNumMaxSet(DNS_THREAD_DEFAULT_NUM_MAX);
+
+	cache = NewList(DnsCacheCompare);
+	cache_reverse = NewList(DnsCacheReverseCompare);
+	DnsCacheToggle(true);
+}
+
+void DnsFree()
+{
+	DnsCacheToggle(false);
+
+	LockList(cache);
+	{
+		for (UINT i = 0; i < LIST_NUM(cache); ++i)
+		{
+			DNS_CACHE *entry = LIST_DATA(cache, i);
+			Free((void *)entry->Hostname);
+			Free(entry);
+		}
+	}
+	UnlockList(cache);
+
+	ReleaseList(cache);
+	cache = NULL;
+
+	LockList(cache_reverse);
+	{
+		for (UINT i = 0; i < LIST_NUM(cache_reverse); ++i)
+		{
+			DNS_CACHE_REVERSE *entry = LIST_DATA(cache, i);
+			Free(entry->Hostname);
+			Free(entry);
+		}
+	}
+	UnlockList(cache_reverse);
+
+	ReleaseList(cache_reverse);
+	cache_reverse = NULL;
+
+	DeleteCounter(threads_counter);
+	threads_counter = NULL;
+}
+
+UINT DnsThreadNum()
+{
+	return Count(threads_counter);
+}
+
+UINT DnsThreadNumMax()
+{
+	return threads_max;
+}
+
+void DnsThreadNumMaxSet(const UINT max)
+{
+	threads_max = max;
+}
+
+bool DnsCacheIsEnabled()
+{
+	return cache_enabled;
+}
+
+void DnsCacheToggle(const bool enabled)
+{
+	cache_enabled = enabled;
+}
+
+DNS_CACHE *DnsCacheFind(const char *hostname)
+{
+	if (DnsCacheIsEnabled() == false || IsEmptyStr(hostname))
+	{
+		return NULL;
+	}
+
+	DNS_CACHE *entry;
+
+	LockList(cache);
+	{
+		DNS_CACHE t;
+		t.Hostname = hostname;
+		entry = Search(cache, &t);
+	}
+	UnlockList(cache);
+
+	return entry;
+}
+
+DNS_CACHE *DnsCacheUpdate(const char *hostname, const IP *ipv6, const IP *ipv4)
+{
+	if (DnsCacheIsEnabled() == false || IsEmptyStr(hostname))
+	{
+		return NULL;
+	}
+
+	DNS_CACHE *entry;
+
+	LockList(cache);
+	{
+		DNS_CACHE t;
+		t.Hostname = hostname;
+		entry = Search(cache, &t);
+
+		if (ipv6 == NULL && ipv4 == NULL)
+		{
+			if (entry != NULL)
+			{
+				Delete(cache, entry);
+				Free(entry);
+				entry = NULL;
+			}
+		}
+		else
+		{
+			if (entry == NULL)
+			{
+				entry = ZeroMalloc(sizeof(DNS_CACHE));
+				entry->Hostname = CopyStr(hostname);
+
+				Add(cache, entry);
+			}
+
+			entry->Expiration = Tick64();
+
+			if (ipv6 != NULL)
+			{
+				if (CmpIpAddr(&entry->IPv6, ipv6) != 0)
+				{
+					Copy(&entry->IPv6, ipv6, sizeof(entry->IPv6));
+				}
+			}
+			else
+			{
+				if (CmpIpAddr(&entry->IPv4, ipv4) != 0)
+				{
+					Copy(&entry->IPv4, ipv4, sizeof(entry->IPv4));
+				}
+			}
+		}
+	}
+	UnlockList(cache);
+
+	return entry;
+}
+
+DNS_CACHE_REVERSE *DnsCacheReverseFind(const IP *ip)
+{
+	if (DnsCacheIsEnabled() == false || ip == NULL)
+	{
+		return NULL;
+	}
+
+	DNS_CACHE_REVERSE *entry;
+
+	LockList(cache_reverse);
+	{
+		DNS_CACHE_REVERSE t;
+		Copy(&t.IP, ip, sizeof(t.IP));
+		entry = Search(cache_reverse, &t);
+	}
+	UnlockList(cache_reverse);
+
+	return entry;
+}
+
+DNS_CACHE_REVERSE *DnsCacheReverseUpdate(const IP *ip, const char *hostname)
+{
+	if (DnsCacheIsEnabled() == false || IsZeroIP(&ip))
+	{
+		return NULL;
+	}
+
+	DNS_CACHE_REVERSE *entry;
+
+	LockList(cache_reverse);
+	{
+		DNS_CACHE_REVERSE t;
+		Copy(&t.IP, ip, sizeof(t.IP));
+		entry = Search(cache_reverse, &t);
+
+		if (IsEmptyStr(hostname))
+		{
+			if (entry != NULL)
+			{
+				Delete(cache, entry);
+				Free(entry);
+				entry = NULL;
+			}
+		}
+		else
+		{
+			if (entry == NULL)
+			{
+				entry = ZeroMalloc(sizeof(DNS_CACHE_REVERSE));
+				Copy(&entry->IP, ip, sizeof(entry->IP));
+
+				Add(cache, entry);
+			}
+
+			entry->Expiration = Tick64();
+
+			if (StrCmp(entry->Hostname, hostname) != 0)
+			{
+				Free(entry->Hostname);
+				entry->Hostname = CopyStr(hostname);
+			}
+		}
+	}
+	UnlockList(cache_reverse);
+
+	return entry;
+}
+
+bool DnsResolve(IP *ipv6, IP *ipv4, const char *hostname, UINT timeout, volatile const bool *cancel_flag)
+{
+	if ((ipv6 == NULL && ipv4 == NULL) || IsEmptyStr(hostname))
+	{
+		return false;
+	}
+
+	if (StrCmpi(hostname, "localhost") == 0)
+	{
+		GetLocalHostIP6(ipv6);
+		GetLocalHostIP4(ipv4);
+		return true;
+	}
+
+	IP ip;
+	if (StrToIP(&ip, hostname))
+	{
+		if (IsIP6(&ip))
+		{
+			if (ipv6 != NULL)
+			{
+				ZeroIP4(ipv4);
+				Copy(ipv6, &ip, sizeof(IP));
+				return true;
+			}
+		}
+		else
+		{
+			if (ipv4 != NULL)
+			{
+				Zero(ipv6, sizeof(IP));
+				Copy(ipv4, &ip, sizeof(IP));
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	if (DnsThreadNum() > DnsThreadNumMax())
+	{
+		Debug("DnsResolve(): Too many threads! Current: %u, Maximum: %u\n",
+			  DnsThreadNum(), DnsThreadNumMax());
+
+		goto CACHE;
+	}
+
+	if (cancel_flag != NULL && *cancel_flag)
+	{
+		return false;
+	}
+
+	if (timeout == 0)
+	{
+		timeout = DNS_RESOLVE_DEFAULT_TIMEOUT;
+	}
+
+	Inc(threads_counter);
+
+	DNS_RESOLVER resolver;
+	Zero(&resolver, sizeof(resolver));
+	ZeroIP4(&resolver.IPv4);
+	resolver.Hostname = hostname;
+
+	THREAD *worker = NewThread(DnsResolver, &resolver);
+	WaitThreadInit(worker);
+
+	if (cancel_flag == NULL)
+	{
+		WaitThread(worker, timeout);
+	}
+	else
+	{
+		const UINT64 end = Tick64() + timeout;
+
+		while (*cancel_flag == false)
+		{
+			const UINT64 now = Tick64();
+			if (now >= end)
+			{
+				break;
+			}
+
+			BYTE next = MIN(end - now, 100);
+			if (WaitThread(worker, next))
+			{
+				break;
+			}
+		}
+	}
+
+	ReleaseThread(worker);
+
+	Dec(threads_counter);
+
+	if (resolver.OK)
+	{
+		Copy(ipv6, &resolver.IPv6, sizeof(IP));
+		Copy(ipv4, &resolver.IPv4, sizeof(IP));
+
+		DnsCacheUpdate(hostname, ipv6, ipv4);
+
+		return true;
+	}
+CACHE:
+	Debug("DnsResolve(): Could not resolve \"%s\". Searching for it in the cache...\n", hostname);
+
+	const DNS_CACHE *cached = DnsCacheFind(hostname);
+	if (cached == NULL || cached->Expiration <= Tick64())
+	{
+		return false;
+	}
+
+	Copy(ipv6, &cached->IPv6, sizeof(IP));
+	Copy(ipv4, &cached->IPv4, sizeof(IP));
+
+	return true;
+}
+
+void DnsResolver(THREAD *t, void *param)
+{
+	if (t == NULL || param == NULL)
+	{
+		return;
+	}
+
+	DNS_RESOLVER *resolver = param;
+
+	NoticeThreadInit(t);
+	AddWaitThread(t);
+
+	struct addrinfo hints;
+	Zero(&hints, sizeof(hints));
+
+	hints.ai_family = AF_INET6;
+	hints.ai_flags = AI_ALL | AI_ADDRCONFIG | AI_V4MAPPED;
+
+	struct addrinfo *result;
+	const int ret = getaddrinfo(resolver->Hostname, NULL, &hints, &result);
+	if (ret == 0)
+	{
+		bool ipv6_ok = false;
+		bool ipv4_ok = false;
+		do
+		{
+			IP ip;
+			const struct sockaddr_in6 *in = (struct sockaddr_in6 *)result->ai_addr;
+			InAddrToIP6(&ip, &in->sin6_addr);
+			if (IsIP6(&ip) && ipv6_ok == false)
+			{
+				Copy(&resolver->IPv6, &ip, sizeof(resolver->IPv6));
+				resolver->IPv6.ipv6_scope_id = in->sin6_scope_id;
+				ipv6_ok = true;
+			}
+			else if (ipv4_ok == false)
+			{
+				Copy(&resolver->IPv4, &ip, sizeof(resolver->IPv4));
+				ipv4_ok = true;
+			}
+
+			result = result->ai_next;
+		} while (result != NULL && (ipv6_ok == false || ipv4_ok == false));
+
+		resolver->OK = true;
+	}
+	else if (ret != EAI_NONAME)
+	{
+		Debug("DnsResolver(): getaddrinfo() failed with error %d!\n", ret);
+	}
+
+	DelWaitThread(t);
+}
+
+bool DnsResolveReverse(char *dst, const UINT size, const IP *ip, UINT timeout, volatile const bool *cancel_flag)
+{
+	if (dst == NULL || size == 0 || IsZeroIP(ip))
+	{
+		return false;
+	}
+
+	if (DnsThreadNum() > DnsThreadNumMax())
+	{
+		Debug("DnsResolveReverse(): Too many threads! Current: %u, Maximum: %u\n",
+			  DnsThreadNum(), DnsThreadNumMax());
+
+		goto CACHE;
+	}
+
+	if (cancel_flag != NULL && *cancel_flag)
+	{
+		return false;
+	}
+
+	if (timeout == 0)
+	{
+		timeout = DNS_RESOLVE_REVERSE_DEFAULT_TIMEOUT;
+	}
+
+	Inc(threads_counter);
+
+	DNS_RESOLVER_REVERSE resolver;
+	Zero(&resolver, sizeof(resolver));
+	Copy(&resolver.IP, ip, sizeof(resolver.IP));
+
+	THREAD *worker = NewThread(DnsResolverReverse, &resolver);
+	WaitThreadInit(worker);
+
+	if (cancel_flag == NULL)
+	{
+		WaitThread(worker, timeout);
+	}
+	else
+	{
+		const UINT64 end = Tick64() + timeout;
+
+		while (*cancel_flag == false)
+		{
+			const UINT64 now = Tick64();
+			if (now >= end)
+			{
+				break;
+			}
+
+			BYTE next = MIN(end - now, 100);
+			if (WaitThread(worker, next))
+			{
+				break;
+			}
+		}
+	}
+
+	ReleaseThread(worker);
+
+	Dec(threads_counter);
+
+	if (resolver.OK)
+	{
+		StrCpy(dst, size, resolver.Hostname);
+		Free(resolver.Hostname);
+
+		DnsCacheReverseUpdate(ip, dst);
+
+		return true;
+	}
+CACHE:
+	Debug("DnsResolveReverse(): Could not resolve \"%r\". Searching for it in the cache...\n", ip);
+
+	const DNS_CACHE_REVERSE *cached = DnsCacheReverseFind(ip);
+	if (cached == NULL || cached->Expiration <= Tick64())
+	{
+		return false;
+	}
+
+	StrCpy(dst, size, cached->Hostname);
+
+	return true;
+}
+
+void DnsResolverReverse(THREAD *t, void *param)
+{
+	if (t == NULL || param == NULL)
+	{
+		return;
+	}
+
+	DNS_RESOLVER_REVERSE *resolver = param;
+
+	NoticeThreadInit(t);
+	AddWaitThread(t);
+
+	struct sockaddr_in6 in;
+	Zero(&in, sizeof(in));
+	in.sin6_family = AF_INET6;
+	IPToInAddr6(&in.sin6_addr, &resolver->IP);
+
+	char tmp[NI_MAXHOST];
+	const int ret = getnameinfo((struct sockaddr *)&in, sizeof(in), tmp, sizeof(tmp), NULL, 0, NI_NAMEREQD);
+	if (ret == 0)
+	{
+		resolver->Hostname = CopyStr(tmp);
+		resolver->OK = true;
+	}
+	else if (ret != EAI_NONAME)
+	{
+		Debug("DnsResolverReverse(): getnameinfo() failed with error %d!\n", ret);
+	}
+
+	DelWaitThread(t);
+}
+
+bool GetIPEx(IP *ip, const char *hostname, UINT timeout, volatile const bool *cancel_flag)
+{
+	if (ip == NULL || IsEmptyStr(hostname))
+	{
+		return false;
+	}
+
+	IP ipv6, ipv4;
+	if (DnsResolve(&ipv6, &ipv4, hostname, timeout, cancel_flag) == false)
+	{
+		return false;
+	}
+
+	if (IsZeroIP(&ipv6) == false)
+	{
+		Copy(ip, &ipv6, sizeof(IP));
+		return true;
+	}
+	else if (IsZeroIP(&ipv4) == false)
+	{
+		Copy(ip, &ipv4, sizeof(IP));
+		return true;
+	}
+
+	return false;
+}

src/Mayaqua/DNS.h

@@ -0,0 +1,78 @@
+#ifndef DNS_H
+#define DNS_H
+
+#include "Network.h"
+
+#define DNS_CACHE_EXPIRATION (10 * 60 * 1000)
+
+#ifndef USE_STRATEGY_LOW_MEMORY
+#define DNS_THREAD_DEFAULT_NUM_MAX (512)
+#else
+#define DNS_THREAD_DEFAULT_NUM_MAX (64)
+#endif
+
+#define DNS_RESOLVE_DEFAULT_TIMEOUT (2300)
+#define DNS_RESOLVE_REVERSE_DEFAULT_TIMEOUT (500)
+
+#define GetIP(ip, hostname) (GetIPEx(ip, hostname, 0, NULL))
+#define GetIP4(ip, hostname) (GetIP4Ex(ip, hostname, 0, NULL))
+#define GetIP6(ip, hostname) (GetIP6Ex(ip, hostname, 0, NULL))
+
+#define GetIP4Ex(ip, hostname, timeout, cancel_flag) (DnsResolve(NULL, ip, hostname, timeout, cancel_flag))
+#define GetIP6Ex(ip, hostname, timeout, cancel_flag) (DnsResolve(ip, NULL, hostname, timeout, cancel_flag))
+
+struct DNS_CACHE
+{
+	const char *Hostname;
+	IP IPv4;
+	IP IPv6;
+	UINT64 Expiration;
+};
+
+struct DNS_CACHE_REVERSE
+{
+	IP IP;
+	char *Hostname;
+	UINT64 Expiration;
+};
+
+struct DNS_RESOLVER
+{
+	const char *Hostname;
+	IP IPv4;
+	IP IPv6;
+	bool OK;
+};
+
+struct DNS_RESOLVER_REVERSE
+{
+	IP IP;
+	char *Hostname;
+	bool OK;
+};
+
+void DnsInit();
+void DnsFree();
+
+UINT DnsThreadNum();
+UINT DnsThreadNumMax();
+void DnsThreadNumMaxSet(const UINT num);
+
+bool DnsCacheIsEnabled();
+void DnsCacheToggle(const bool enabled);
+
+DNS_CACHE *DnsCacheFind(const char *hostname);
+DNS_CACHE *DnsCacheUpdate(const char *hostname, const IP *ipv6, const IP *ipv4);
+
+DNS_CACHE_REVERSE *DnsCacheReverseFind(const IP *ip);
+DNS_CACHE_REVERSE *DnsCacheReverseUpdate(const IP *ip, const char *hostname);
+
+bool DnsResolve(IP *ipv6, IP *ipv4, const char *hostname, UINT timeout, volatile const bool *cancel_flag);
+void DnsResolver(THREAD *t, void *param);
+
+bool DnsResolveReverse(char *dst, const UINT size, const IP *ip, UINT timeout, volatile const bool *cancel_flag);
+void DnsResolverReverse(THREAD *t, void *param);
+
+bool GetIPEx(IP *ip, const char *hostname, UINT timeout, volatile const bool *cancel_flag);
+
+#endif

src/Mayaqua/MayaType.h

@@ -352,7 +352,6 @@ typedef struct LANGLIST LANGLIST;
 
 // Network.h
 typedef struct IP IP;
-typedef struct DNSCACHE DNSCACHE;
 typedef struct SOCK_EVENT SOCK_EVENT;
 typedef struct SOCK SOCK;
 typedef struct SOCKSET SOCKSET;
@@ -362,7 +361,6 @@ typedef struct ROUTE_TABLE ROUTE_TABLE;
 typedef struct IP_CLIENT IP_CLIENT;
 typedef struct ROUTE_CHANGE ROUTE_CHANGE;
 typedef struct ROUTE_CHANGE_DATA ROUTE_CHANGE_DATA;
-typedef struct GETIP_THREAD_PARAM GETIP_THREAD_PARAM;
 typedef struct WIN32_RELEASEADDRESS_THREAD_PARAM WIN32_RELEASEADDRESS_THREAD_PARAM;
 typedef struct IPV6_ADDR IPV6_ADDR;
 typedef struct TUBE TUBE;
@@ -387,8 +385,6 @@ typedef struct TCP_PAIR_HEADER TCP_PAIR_HEADER;
 typedef struct NIC_ENTRY NIC_ENTRY;
 typedef struct HTTP_VALUE HTTP_VALUE;
 typedef struct HTTP_HEADER HTTP_HEADER;
-typedef struct DNSPROXY_CLIENT DNSPROXY_CLIENT;
-typedef struct DNSPROXY_CACHE DNSPROXY_CACHE;
 typedef struct QUERYIPTHREAD QUERYIPTHREAD;
 typedef struct IPBLOCK IPBLOCK;
 typedef struct SAFE_REQUEST SAFE_REQUEST;
@@ -464,4 +460,10 @@ typedef struct HTTP_MIME_TYPE HTTP_MIME_TYPE;
 typedef struct PROXY_PARAM_IN PROXY_PARAM_IN;
 typedef struct PROXY_PARAM_OUT PROXY_PARAM_OUT;
 
+// DNS.h
+typedef struct DNS_CACHE DNS_CACHE;
+typedef struct DNS_CACHE_REVERSE DNS_CACHE_REVERSE;
+typedef struct DNS_RESOLVER DNS_RESOLVER;
+typedef struct DNS_RESOLVER_REVERSE DNS_RESOLVER_REVERSE;
+
 #endif	// MAYATYPE_H

src/Mayaqua/Network.h

@@ -27,20 +27,14 @@ struct DYN_VALUE
 
 #define	MAX_HOST_NAME_LEN			255		// Maximum length of the host name
 
-#define	TIMEOUT_GETIP				2300
-
 #define	TIMEOUT_INFINITE			(0x7fffffff)
 #define	TIMEOUT_TCP_PORT_CHECK		(10 * 1000)
 #define	TIMEOUT_SSL_CONNECT			(15 * 1000)
 
-#define	TIMEOUT_HOSTNAME			(500)
 #define	TIMEOUT_NETBIOS_HOSTNAME	(100)
-#define	EXPIRES_HOSTNAME			(10 * 60 * 1000)
 
 #define	SOCKET_BUFFER_SIZE			0x10000000
 
-#define	IPV6_DUMMY_FOR_IPV4			0xFEFFFFDF
-
 #define	UDPLISTENER_CHECK_INTERVAL	1000ULL
 #define	UDPLISTENER_WAIT_INTERVAL	1234
 
@@ -48,12 +42,6 @@ struct DYN_VALUE
 
 #define	MAX_NUM_IGNORE_ERRORS		1024
 
-#ifndef	USE_STRATEGY_LOW_MEMORY
-#define	DEFAULT_GETIP_THREAD_MAX_NUM		512
-#else	// USE_STRATEGY_LOW_MEMORY
-#define	DEFAULT_GETIP_THREAD_MAX_NUM		64
-#endif	// USE_STRATEGY_LOW_MEMORY
-
 #define	DEFAULT_CIPHER_LIST			"ECDHE+AESGCM:ECDHE+CHACHA20:DHE+AESGCM:DHE+CHACHA20:ECDHE+AES256:DHE+AES256:RSA+AES"
 
 // SSL logging function
@@ -115,14 +103,6 @@ struct IPV6_ADDR
 #define	IPV6_ADDR_ZERO							128	// All zeros
 #define	IPV6_ADDR_LOOPBACK						256	// Loop-back
 
-
-// DNS cache list
-struct DNSCACHE
-{
-	char *HostName;
-	IP IpAddress;
-};
-
 // Client list
 struct IP_CLIENT
 {
@@ -328,15 +308,6 @@ struct ICMP_RESULT
 	IP IpAddress;									// IP address
 };
 
-
-// Host name cache list
-typedef struct HOSTCACHE
-{
-	UINT64 Expires;							// Expiration
-	IP IpAddress;							// IP address
-	char HostName[256];						// Host name
-} HOSTCACHE;
-
 // NETBIOS name requests
 typedef struct NBTREQUEST
 {
@@ -376,17 +347,6 @@ typedef struct SOCKET_TIMEOUT_PARAM {
 	bool unblocked;
 } SOCKET_TIMEOUT_PARAM;
 
-// Parameters for GetIP thread
-struct GETIP_THREAD_PARAM
-{
-	REF *Ref;
-	char HostName[MAX_PATH];
-	bool IPv6;
-	UINT Timeout;
-	IP Ip;
-	bool Ok;
-};
-
 // Parameters for the IP address release thread
 struct WIN32_RELEASEADDRESS_THREAD_PARAM
 {
@@ -900,7 +860,6 @@ bool GetSniNameFromSslPacket(UCHAR *packet_buf, UINT packet_size, char *sni, UIN
 
 void SetDhParam(DH_CTX *dh);
 
-bool IsUseDnsProxy();
 bool IsUseAlternativeHostname();
 
 #ifdef	OS_WIN32
@@ -1066,18 +1025,7 @@ void UnixSetSocketNonBlockingMode(int fd, bool nonblock);
 // Function prototype
 void InitNetwork();
 void FreeNetwork();
-void InitDnsCache();
+
-void FreeDnsCache();
-void LockDnsCache();
-void UnlockDnsCache();
-int CompareDnsCache(void *p1, void *p2);
-void GenDnsCacheKeyName(char *dst, UINT size, char *src, bool ipv6);
-void NewDnsCacheEx(char *hostname, IP *ip, bool ipv6);
-DNSCACHE *FindDnsCacheEx(char *hostname, bool ipv6);
-bool QueryDnsCacheEx(IP *ip, char *hostname, bool ipv6);
-void NewDnsCache(char *hostname, IP *ip);
-DNSCACHE *FindDnsCache(char *hostname);
-bool QueryDnsCache(IP *ip, char *hostname);
 void InAddrToIP(IP *ip, struct in_addr *addr);
 void InAddrToIP6(IP *ip, struct in6_addr *addr);
 void IPToInAddr(struct in_addr *addr, IP *ip);
@@ -1090,24 +1038,7 @@ void IPToStr32(char *str, UINT size, UINT ip);
 void IPToStr4or6(char *str, UINT size, UINT ip_4_uint, UCHAR *ip_6_bytes);
 void IPToUniStr(wchar_t *str, UINT size, IP *ip);
 void IPToUniStr32(wchar_t *str, UINT size, UINT ip);
-bool GetIPEx(IP *ip, char *hostname, bool ipv6);
-bool GetIP46Ex(IP *ip4, IP *ip6, char *hostname, UINT timeout, bool *cancel);
-bool GetIP(IP *ip, char *hostname);
-bool GetIP4(IP *ip, char *hostname);
-bool GetIP6(IP *ip, char *hostname);
-bool GetIP4Ex(IP *ip, char *hostname, UINT timeout, bool *cancel);
-bool GetIP6Ex(IP *ip, char *hostname, UINT timeout, bool *cancel);
-bool GetIP4Ex6Ex(IP *ip, char *hostname, UINT timeout, bool ipv6, bool *cancel);
-bool GetIP4Ex6Ex2(IP *ip, char *hostname, UINT timeout, bool ipv6, bool *cancel, bool only_direct_dns);
-void GetIP4Ex6ExThread(THREAD *t, void *param);
-void ReleaseGetIPThreadParam(GETIP_THREAD_PARAM *p);
-void CleanupGetIPThreadParam(GETIP_THREAD_PARAM *p);
-bool GetIP4Inner(IP *ip, char *hostname);
-bool GetIP6Inner(IP *ip, char *hostname);
-bool GetHostNameInner(char *hostname, UINT size, IP *ip);
-bool GetHostNameInner6(char *hostname, UINT size, IP *ip);
 bool GetHostName(char *hostname, UINT size, IP *ip);
-void GetHostNameThread(THREAD *t, void *p);
 void GetMachineName(char *name, UINT size);
 void GetMachineNameEx(char *name, UINT size, bool no_load_hosts);
 bool GetMachineNameFromHosts(char *name, UINT size);
@@ -1212,11 +1143,6 @@ void InitWaitThread();
 void FreeWaitThread();
 void AddWaitThread(THREAD *t);
 void DelWaitThread(THREAD *t);
-void InitHostCache();
-void FreeHostCache();
-int CompareHostCache(void *p1, void *p2);
-void AddHostCache(IP *ip, char *hostname);
-bool GetHostCache(char *hostname, UINT size, IP *ip);
 bool IsSubnetMask(IP *ip);
 bool IsSubnetMask4(IP *ip);
 bool IsSubnetMask32(UINT ip);
@@ -1245,9 +1171,6 @@ IP_CLIENT *SearchIpClient(IP *ip);
 UINT GetNumIpClient(IP *ip);
 void SetLinuxArpFilter();
 int connect_timeout(SOCKET s, struct sockaddr *addr, int size, int timeout, bool *cancel_flag);
-void EnableNetworkNameCache();
-void DisableNetworkNameCache();
-bool IsNetworkNameCacheEnabled();
 ROUTE_CHANGE *NewRouteChange();
 void FreeRouteChange(ROUTE_CHANGE *r);
 bool IsRouteChanged(ROUTE_CHANGE *r);
@@ -1466,10 +1389,6 @@ QUERYIPTHREAD *NewQueryIpThread(char *hostname, UINT interval_last_ok, UINT inte
 bool GetQueryIpThreadResult(QUERYIPTHREAD *t, IP *ip);
 void FreeQueryIpThread(QUERYIPTHREAD *t);
 
-void SetGetIpThreadMaxNum(UINT num);
-UINT GetGetIpThreadMaxNum();
-UINT GetCurrentGetIpThreadNum();
-
 #ifdef	OS_WIN32
 LIST *Win32GetNicList();
 #endif	// OS_WIN32

src/Mayaqua/Proxy.c

@@ -3,6 +3,7 @@
 // TODO: Mayaqua should not depend on Cedar.
 #include "Cedar/WinUi.h"
 
+#include "DNS.h"
 #include "Memory.h"
 #include "Str.h"
 
@@ -550,8 +551,8 @@ UINT ProxySocks4Connect(PROXY_PARAM_OUT *out, PROXY_PARAM_IN *in, volatile bool
 
 	Zero(out, sizeof(PROXY_PARAM_OUT));
 
-	// Get the IP address of the destination server
+	// Get the IPv4 address of the destination server (SOCKS4 does not support IPv6).
-	if (GetIP(&target_ip, in->TargetHostname) == false)
+	if (GetIP4(&target_ip, in->TargetHostname) == false)
 	{
 		return PROXY_ERROR_CONNECTION;
 	}

src/Mayaqua/Table.c

@@ -8,6 +8,7 @@
 #include "Table.h"
 
 #include "Cfg.h"
+#include "DNS.h"
 #include "FileIO.h"
 #include "Internat.h"
 #include "Mayaqua.h"
@@ -1206,9 +1207,9 @@ bool LoadUnicodeCache(wchar_t *strfilename, UINT strfilesize, UCHAR *hash)
 	Zero(&c, sizeof(c));
 	UniToStr(c.StrFileName, sizeof(c.StrFileName), strfilename);
 	c.StrFileSize = strfilesize;
-	DisableNetworkNameCache();
+	DnsCacheToggle(false);
 	GetMachineName(c.MachineName, sizeof(c.MachineName));
-	EnableNetworkNameCache();
+	DnsCacheToggle(true);
 	c.OsType = GetOsInfo()->OsType;
 	Copy(c.hash, hash, MD5_SIZE);