vlmcsd/src/network.c

#ifndef CONFIG
#define CONFIG "config.h"
#endif // CONFIG
#include CONFIG

#ifndef USE_MSRPC

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include "types.h"

#if HAVE_GETIFADDR && _WIN32
#include <iphlpapi.h>
#endif

#include <string.h>

#ifndef _WIN32
#include <signal.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/types.h>

#if HAVE_GETIFADDR

#if __ANDROID__
#include "ifaddrs-android.h"
#elif defined(GETIFADDRS_MUSL)
#include "ifaddrs-musl.h"
#else // getifaddrs from OS
#include <ifaddrs.h>
#endif // getifaddrs from OS

#endif // HAVE_GETIFADDR
#endif // !WIN32

#include "network.h"
#include "endian.h"
//#include "output.h"
#include "helpers.h"
#include "shared_globals.h"
#include "rpc.h"

#ifndef _WIN32
typedef ssize_t(*sendrecv_t)(int, void*, size_t, int);
#else
typedef int (WINAPI *sendrecv_t)(SOCKET, void*, int, int);
#endif


// Send or receive a fixed number of bytes regardless if received in one or more chunks
int_fast8_t sendrecv(SOCKET sock, BYTE *data, int len, int_fast8_t do_send)
{
	int n;
	sendrecv_t  f = do_send
		? (sendrecv_t)send
		: (sendrecv_t)recv;

	do
	{
		n = f(sock, data, len, 0);
	} while (
		(n < 0 && socket_errno == SOCKET_EINTR) || (n > 0 && (data += n, (len -= n) > 0)));

	return !len;
}


static int_fast8_t ip2str(char *restrict result, const size_t resultLength, const struct sockaddr *const restrict socketAddress, const socklen_t socketLength)
{
	static const char *const fIPv4 = "%s:%s";
	static const char *const fIPv6 = "[%s]:%s";
	char ipAddress[64], portNumber[8];

	if (getnameinfo
	(
		socketAddress,
		socketLength,
		ipAddress,
		sizeof(ipAddress),
		portNumber,
		sizeof(portNumber),
		NI_NUMERICHOST | NI_NUMERICSERV
	))
	{
		return FALSE;
	}

	if ((unsigned int)vlmcsd_snprintf(result, resultLength, socketAddress->sa_family == AF_INET6 ? fIPv6 : fIPv4, ipAddress, portNumber) > resultLength) return FALSE;
	return TRUE;
}


static int_fast8_t getSocketList(struct addrinfo **saList, const char *const addr, const int flags, const int AddressFamily)
{
	int status;
	char *szHost, *szPort;
	const size_t len = strlen(addr) + 1;

	// Don't alloca too much
	if (len > 264) return FALSE;

	char *addrcopy = (char*)alloca(len);
	memcpy(addrcopy, addr, len);

	parseAddress(addrcopy, &szHost, &szPort);

	struct addrinfo hints;

	memset(&hints, 0, sizeof(struct addrinfo));

	hints.ai_family = AddressFamily;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = IPPROTO_TCP;
	hints.ai_flags = flags;

	if ((status = getaddrinfo(szHost, szPort, &hints, saList)))
	{
		printerrorf("Warning: %s: %s\n", addr, gai_strerror(status));
		return FALSE;
	}

	return TRUE;
}


static int_fast8_t setBlockingEnabled(SOCKET fd, int_fast8_t blocking)
{
	if (fd == INVALID_SOCKET) return FALSE;

#ifdef _WIN32

	unsigned long mode = blocking ? 0 : 1;
	return (ioctlsocket(fd, FIONBIO, &mode) == 0) ? TRUE : FALSE;

#else // POSIX

	int flags = fcntl(fd, F_GETFL, 0);

	if (flags < 0) return FALSE;

	flags = blocking ? (flags & ~O_NONBLOCK) : (flags | O_NONBLOCK);
	return (fcntl(fd, F_SETFL, flags) == 0) ? TRUE : FALSE;

#endif // POSIX
}


int_fast8_t isDisconnected(const SOCKET s)
{
	char buffer[1];

	if (!setBlockingEnabled(s, FALSE)) return TRUE;

	const int n = recv(s, buffer, 1, MSG_PEEK);

	if (!setBlockingEnabled(s, TRUE)) return TRUE;
	if (n == 0) return TRUE;

	return FALSE;
}


#if !defined(NO_PRIVATE_IP_DETECT)
// Check, if a sockaddr is a private IPv4 or IPv6 address
static int_fast8_t isPrivateIPAddress(struct sockaddr* addr, socklen_t* length)
{
	union v6addr
	{
		uint8_t bytes[16];
		uint16_t words[8];
		uint32_t dwords[4];
		uint64_t qwords[2];
	};

	if (addr == NULL) return FALSE;

	switch (addr->sa_family)
	{
	case AF_INET6:
	{
		union v6addr* ipv6addr = (union v6addr*)&((struct sockaddr_in6*)addr)->sin6_addr;

		if
			(
			(ipv6addr->qwords[0] != 0 || BE64(ipv6addr->qwords[1]) != 1) && // ::1 IPv6 localhost
				(BE16(ipv6addr->words[0]) & 0xe000) == 0x2000 // !2000::/3
				)
		{
			return FALSE;
		}

		if (length) *length = sizeof(struct sockaddr_in6);
		break;
	}

	case AF_INET:
	{
		const uint32_t ipv4addr = BE32(((struct sockaddr_in*)addr)->sin_addr.s_addr);

		if
			(
			(ipv4addr & 0xff000000) != 0x7f000000 && // 127.x.x.x localhost
				(ipv4addr & 0xffff0000) != 0xc0a80000 && // 192.168.x.x private routeable
				(ipv4addr & 0xffff0000) != 0xa9fe0000 && // 169.254.x.x link local
				(ipv4addr & 0xff000000) != 0x0a000000 && // 10.x.x.x private routeable
				(ipv4addr & 0xfff00000) != 0xac100000    // 172.16-31.x.x private routeable
				)
		{
			return FALSE;
		}

		if (length) *length = sizeof(struct sockaddr_in);
		break;
	}

	default:
		return FALSE;
	}

	return TRUE;
}
#endif // !defined(NO_PRIVATE_IP_DETECT)


// Connect to TCP address addr (e.g. "kms.example.com:1688") and return an
// open socket for the connection if successful or INVALID_SOCKET otherwise
SOCKET connectToAddress(const char *const addr, const int AddressFamily, int_fast8_t showHostName)
{
	struct addrinfo *saList, *sa;
	SOCKET s = INVALID_SOCKET;
	char szAddr[128];

	if (!getSocketList(&saList, addr, 0, AddressFamily)) return INVALID_SOCKET;

	for (sa = saList; sa; sa = sa->ai_next)
	{
		// struct sockaddr_in* addr4 = (struct sockaddr_in*)sa->ai_addr;
		// struct sockaddr_in6* addr6 = (struct sockaddr_in6*)sa->ai_addr;

		if (ip2str(szAddr, sizeof(szAddr), sa->ai_addr, (socklen_t)sa->ai_addrlen))
		{
			showHostName ? printf("Connecting to %s (%s) ... ", addr, szAddr) : printf("Connecting to %s ... ", szAddr);
			fflush(stdout);
		}

		s = socket(sa->ai_family, SOCK_STREAM, IPPROTO_TCP);

#		if !defined(NO_TIMEOUT) && !__minix__
#		ifndef _WIN32 // Standard Posix timeout structure

		struct timeval to;
		to.tv_sec = 10;
		to.tv_usec = 0;

#		else // Windows requires a DWORD with milliseconds

		DWORD to = 10000;

#		endif // _WIN32

		setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, (sockopt_t)&to, sizeof(to));
		setsockopt(s, SOL_SOCKET, SO_SNDTIMEO, (sockopt_t)&to, sizeof(to));
#		endif // !defined(NO_TIMEOUT) && !__minix__

		if (!connect(s, sa->ai_addr, (int)sa->ai_addrlen))
		{
			printf("successful\n");
			break;
		}

		printerrorf("%s: %s\n", szAddr, socket_errno == SOCKET_EINPROGRESS ? "Timed out" : vlmcsd_strerror(socket_errno));

		socketclose(s);
		s = INVALID_SOCKET;
	}

	freeaddrinfo(saList);
	return s;
}

// fix for lame tomato toolchain
#	if !defined(IPV6_V6ONLY) && defined(__linux__)
#	define IPV6_V6ONLY (26)
#	endif // !defined(IPV6_V6ONLY) && defined(__linux__)


#ifndef NO_SOCKETS

static int_fast8_t allowSocketReuse(SOCKET s)
{
#	if !__CYGWIN__

	BOOL socketOption = TRUE;

#	if !_WIN32
#	define VLMCSD_SOCKET_OPTION SO_REUSEADDR
#	else // _WIN32
#	define VLMCSD_SOCKET_OPTION SO_EXCLUSIVEADDRUSE
#	endif // _WIN32

	if (setsockopt(s, SOL_SOCKET, VLMCSD_SOCKET_OPTION, (sockopt_t)&socketOption, sizeof(socketOption)))
	{
#		ifdef _PEDANTIC
		printerrorf("Warning: Socket option SO_REUSEADDR unsupported: %s\n", vlmcsd_strerror(socket_errno));
#		endif // _PEDANTIC
	}

#	undef VLMCSD_SOCKET_OPTION
#	endif // !__CYGWIN__

	return 0;
}


#ifdef SIMPLE_SOCKETS

int listenOnAllAddresses()
{
	uint32_t port_listen;

	if (!stringToInt(defaultport, 1, 65535, &port_listen))
	{
		printerrorf("Fatal: Port must be numeric between 1 and 65535.\n");
		exit(VLMCSD_EINVAL);
	}

#	if defined(AF_INET6) && defined(IPV6_V6ONLY)

	struct sockaddr_in6 addr;
	memset(&addr, 0, sizeof(addr));
	addr.sin6_family = AF_INET6;
	addr.sin6_port = BE16((uint16_t)port_listen);
	addr.sin6_addr = in6addr_any;
	BOOL v6only = FALSE;
	s_server = socket(AF_INET6, SOCK_STREAM, 0);

	if (s_server == INVALID_SOCKET
		|| allowSocketReuse(s_server)
		|| setsockopt(s_server, IPPROTO_IPV6, IPV6_V6ONLY, (sockopt_t)&v6only, sizeof(v6only))
		|| bind(s_server, (struct sockaddr *)&addr, sizeof(addr))
		|| listen(s_server, SOMAXCONN))
	{
		socketclose(s_server);
#	endif // defined(AF_INET6) && defined(IPV6_V6ONLY)
		struct sockaddr_in addr4 = {
				.sin_family = AF_INET,
				.sin_port = BE16((uint16_t)port_listen),
				.sin_addr.s_addr = BE32(INADDR_ANY)
		};

		s_server = socket(AF_INET, SOCK_STREAM, 0);

		if (s_server == INVALID_SOCKET
			|| allowSocketReuse(s_server)
			|| bind(s_server, (struct sockaddr *)&addr4, sizeof(addr4))
			|| listen(s_server, SOMAXCONN))
		{
			int error = socket_errno;
			printerrorf("Fatal: Cannot bind to TCP port %u: %s\n", port_listen, vlmcsd_strerror(error));
			return error;
		}

#	if defined(AF_INET6) && defined(IPV6_V6ONLY)
	}
#	endif // defined(AF_INET6) && defined(IPV6_V6ONLY)

#ifndef NO_LOG
	logger("Listening on TCP port %u\n", port_listen);
#endif // NO_LOG

	return 0;
}

#else // !SIMPLE_SOCKETS


#if HAVE_GETIFADDR && !defined(NO_PRIVATE_IP_DETECT)
// Get list of private IP addresses.
// Returns 0 on success or an errno error code on failure
void getPrivateIPAddresses(int* numAddresses, char*** ipAddresses)
{
#	if _WIN32

	PIP_ADAPTER_ADDRESSES firstAdapter, currentAdapter;

	DWORD dwRetVal;
	ULONG outBufLen = 16384;
	const ULONG flags = GAA_FLAG_SKIP_MULTICAST | GAA_FLAG_SKIP_ANYCAST | GAA_FLAG_SKIP_DNS_SERVER | GAA_FLAG_SKIP_FRIENDLY_NAME;

	firstAdapter = (PIP_ADAPTER_ADDRESSES)vlmcsd_malloc(outBufLen);

	if ((dwRetVal = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, firstAdapter, &outBufLen)) == ERROR_BUFFER_OVERFLOW)
	{
		free(firstAdapter);
		firstAdapter = (PIP_ADAPTER_ADDRESSES)vlmcsd_malloc(outBufLen);
		dwRetVal = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, firstAdapter, &outBufLen);
	}

	if (dwRetVal != NO_ERROR)
	{
		printerrorf("FATAL: Could not get network address list: %s\n", vlmcsd_strerror(dwRetVal));
		exit(dwRetVal);
	}

	for (currentAdapter = firstAdapter, *numAddresses = 0; currentAdapter != NULL; currentAdapter = currentAdapter->Next)
	{
		PIP_ADAPTER_UNICAST_ADDRESS currentAddress;
		int length;

		if (currentAdapter->OperStatus != IfOperStatusUp) continue;

		for (currentAddress = currentAdapter->FirstUnicastAddress; currentAddress != NULL; currentAddress = currentAddress->Next)
		{
			if (isPrivateIPAddress(currentAddress->Address.lpSockaddr, &length)) (*numAddresses)++;
		}
	}

	*ipAddresses = (char**)vlmcsd_malloc(*numAddresses * sizeof(char*));

	for (currentAdapter = firstAdapter, *numAddresses = 0; currentAdapter != NULL; currentAdapter = currentAdapter->Next)
	{
		PIP_ADAPTER_UNICAST_ADDRESS currentAddress;
		int length;

		if (currentAdapter->OperStatus != IfOperStatusUp) continue;

		for (currentAddress = currentAdapter->FirstUnicastAddress; currentAddress != NULL; currentAddress = currentAddress->Next)
		{
			if (!isPrivateIPAddress(currentAddress->Address.lpSockaddr, &length)) continue;

			char *ipAddress = (char*)vlmcsd_malloc(64);
			const int error = getnameinfo(currentAddress->Address.lpSockaddr, currentAddress->Address.iSockaddrLength, ipAddress, 64, NULL, 0, NI_NUMERICHOST);

			if (error)
			{
				printerrorf("WARNING: Could not get IP address from interface list: %s\n", gai_strerror(error));
				*ipAddress = 0;
			}

			(*ipAddresses)[(*numAddresses)++] = ipAddress;
		}
	}

	free(firstAdapter);

#	else // !_WIN32

	struct ifaddrs *addrs, *addr;

	if (getifaddrs(&addrs))
	{
		printerrorf("FATAL: Could not get network address list: %s\n", vlmcsd_strerror(errno));
		exit(errno);
	}

	socklen_t length;

	for (addr = addrs, *numAddresses = 0; addr != NULL; addr = addr->ifa_next)
	{
		if (!isPrivateIPAddress(addr->ifa_addr, &length)) continue;
		(*numAddresses)++;
	}

	*ipAddresses = (char**)vlmcsd_malloc(*numAddresses * sizeof(char*));

	for (addr = addrs, *numAddresses = 0; addr != NULL; addr = addr->ifa_next)
	{
		if (!isPrivateIPAddress(addr->ifa_addr, &length)) continue;

		char *ipAddress = (char*)vlmcsd_malloc(64);
		int error = getnameinfo(addr->ifa_addr, length, ipAddress, 64, NULL, 0, NI_NUMERICHOST);

		if (error)
		{
			printerrorf("WARNING: Could not get IP address from interface list: %s\n", gai_strerror(error));
			*ipAddress = 0;
		}

#		if __UCLIBC__ || __gnu_hurd__

		size_t adrlen = strlen(ipAddress);

		if
			(
				addr->ifa_addr->sa_family == AF_INET6 &&
				adrlen > 5 &&
				!strchr(ipAddress, '%') &&
				(BE16(*(uint16_t*)&((struct sockaddr_in6*)addr->ifa_addr)->sin6_addr) & 0xffc0) == 0xfe80
				)
		{
			size_t ifnamelen = strlen(addr->ifa_name);
			char* workaroundIpAddress = (char*)vlmcsd_malloc(adrlen + ifnamelen + 2);
			strcpy(workaroundIpAddress, ipAddress);
			strcat(workaroundIpAddress, "%");
			strcat(workaroundIpAddress, addr->ifa_name);
			(*ipAddresses)[(*numAddresses)++] = workaroundIpAddress;
			free(ipAddress);
		}
		else
		{
			(*ipAddresses)[(*numAddresses)++] = ipAddress;
		}
#		else // !(__UCLIBC__ || __gnu_hurd__)

		(*ipAddresses)[(*numAddresses)++] = ipAddress;

#		endif // !(__UCLIBC__ || __gnu_hurd__)
	}

	freeifaddrs(addrs);

#	endif // !_WIN32
}
#endif // HAVE_GETIFADDR && !defined(NO_PRIVATE_IP_DETECT)



// Create a Listening socket for addrinfo sa and return socket s
// szHost and szPort are for logging only
static int listenOnAddress(const struct addrinfo *const ai, SOCKET *s)
{
	int error;
	char ipstr[64];

	ip2str(ipstr, sizeof(ipstr), ai->ai_addr, (socklen_t)ai->ai_addrlen);

	//*s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
	*s = socket(ai->ai_family, SOCK_STREAM, IPPROTO_TCP);

	if (*s == INVALID_SOCKET)
	{
		error = socket_errno;
		printerrorf("Warning: %s error. %s\n", ai->ai_family == AF_INET6 ? cIPv6 : cIPv4, vlmcsd_strerror(error));
		return error;
	}

#	if !defined(_WIN32) && !defined(NO_SIGHUP)

	int flags = fcntl(*s, F_GETFD, 0);

	if (flags != -1)
	{
		flags |= FD_CLOEXEC;
		fcntl(*s, F_SETFD, flags);
	}
#	ifdef _PEDANTIC
	else
	{
		printerrorf("Warning: Could not set FD_CLOEXEC flag on %s: %s\n", ipstr, vlmcsd_strerror(errno));
	}
#	endif // _PEDANTIC

#	endif // !defined(_WIN32) && !defined(NO_SIGHUP)

	BOOL socketOption = TRUE;

#	ifdef IPV6_V6ONLY
	if (ai->ai_family == AF_INET6 && setsockopt(*s, IPPROTO_IPV6, IPV6_V6ONLY, (sockopt_t)&socketOption, sizeof(socketOption)))
	{
#		ifdef _PEDANTIC
#		if defined(_WIN32) || defined(__CYGWIN__)
		//		if (IsWindowsVistaOrGreater()) //Doesn't work with older version of MingW32-w64 toolchain
		if ((GetVersion() & 0xff) > 5)
		{
#		endif // _WIN32
			printerrorf("Warning: %s does not support socket option IPV6_V6ONLY: %s\n", ipstr, vlmcsd_strerror(socket_errno));
#		if defined(_WIN32) || defined(__CYGWIN__)
		}
#		endif // _WIN32
#		endif // _PEDANTIC
	}
#	endif

	allowSocketReuse(*s);

#	if HAVE_FREEBIND
#	if (defined(IP_NONLOCALOK) || __FreeBSD_kernel__ || __FreeBSD__) && !defined(IPV6_BINDANY)
#	define IPV6_BINDANY 64
#	endif // (defined(IP_NONLOCALOK) || __FreeBSD_kernel__ || __FreeBSD__) && !defined(IPV6_BINDANY)

	if (freebind)
	{
#		if defined(IP_FREEBIND) // Linux
		if (setsockopt(*s, IPPROTO_IP, IP_FREEBIND, (sockopt_t)&socketOption, sizeof(socketOption)))
		{
			printerrorf("Warning: Cannot use FREEBIND on %s: %s\n", ipstr, vlmcsd_strerror(socket_errno));
		}
#		endif // defined(IP_FREEBIND)

#		if defined(IP_BINDANY) // FreeBSD IPv4
		if (ai->ai_family == AF_INET && setsockopt(*s, IPPROTO_IP, IP_BINDANY, (sockopt_t)&socketOption, sizeof(socketOption)))
		{
			printerrorf("Warning: Cannot use BINDANY on %s: %s\n", ipstr, vlmcsd_strerror(socket_errno));
		}
#		endif // defined(IP_BINDANY)

#		if defined(IPV6_BINDANY) // FreeBSD IPv6
		if (ai->ai_family == AF_INET6 && setsockopt(*s, IPPROTO_IP, IPV6_BINDANY, (sockopt_t)&socketOption, sizeof(socketOption)))
		{
#			ifdef _PEDANTIC // FreeBSD defines the symbol but doesn't have BINDANY in IPv6 (Kame stack doesn't have it)
			printerrorf("Warning: Cannot use BINDANY on %s: %s\n", ipstr, vlmcsd_strerror(socket_errno));
#			endif
		}
#		endif // defined(IPV6_BINDANY)

#		if defined(IP_NONLOCALOK) && !defined(IP_BINDANY) // FreeBSD with GNU userspace IPv4
		if (ai->ai_family == AF_INET && setsockopt(*s, IPPROTO_IP, IP_NONLOCALOK, (sockopt_t)&socketOption, sizeof(socketOption)))
		{
			printerrorf("Warning: Cannot use BINDANY on %s: %s\n", ipstr, vlmcsd_strerror(socket_errno));
		}
#		endif // defined(IP_NONLOCALOK) && !defined(IP_BINDANY)
	}

#	endif // HAVE_FREEBIND

	if (bind(*s, ai->ai_addr, (int)ai->ai_addrlen) || listen(*s, SOMAXCONN))
	{
		error = socket_errno;
		printerrorf("Warning: %s: %s\n", ipstr, vlmcsd_strerror(error));
		socketclose(*s);
		return error;
	}

#	ifndef NO_LOG
	logger("Listening on %s\n", ipstr);
#	endif

	return 0;
}

// Adds a listening socket for an address string,
// e.g. 127.0.0.1:1688 or [2001:db8:dead:beef::1]:1688
BOOL addListeningSocket(const char *const addr)
{
	struct addrinfo *aiList, *ai;
	int result = FALSE;
	SOCKET *s = SocketList + numsockets;

	if (getSocketList(&aiList, addr, AI_PASSIVE | AI_NUMERICHOST, AF_UNSPEC))
	{
		for (ai = aiList; ai; ai = ai->ai_next)
		{
			// struct sockaddr_in* addr4 = (struct sockaddr_in*)sa->ai_addr;
			// struct sockaddr_in6* addr6 = (struct sockaddr_in6*)sa->ai_addr;

			if (numsockets >= FD_SETSIZE)
			{
#ifdef _PEDANTIC // Do not report this error in normal builds to keep file size low
				printerrorf("Warning: Cannot listen on %s. Your OS only supports %u listening sockets in an FD_SET.\n", addr, FD_SETSIZE);
#endif
				break;
			}

			if (!listenOnAddress(ai, s))
			{
				numsockets++;
				result = TRUE;
			}
			else
			{
				exitOnWarningLevel(1);
			}
		}

		freeaddrinfo(aiList);
	}
	return result;
}


// Just create some dummy sockets to see if we have a specific protocol (IPv4 or IPv6)
__pure int_fast8_t checkProtocolStack(const int addressfamily)
{
	SOCKET s; // = INVALID_SOCKET;

	s = socket(addressfamily, SOCK_STREAM, 0);
	const int_fast8_t success = (s != INVALID_SOCKET);

	socketclose(s);
	return success;
}


// Build an fd_set of all listening socket then use select to wait for an incoming connection
static SOCKET network_accept_any()
{
	fd_set ListeningSocketsList;
	SOCKET maxSocket, sock;
	int i;
	int status;

	FD_ZERO(&ListeningSocketsList);
	maxSocket = 0;

	for (i = 0; i < numsockets; i++)
	{
		FD_SET(SocketList[i], &ListeningSocketsList);
		if (SocketList[i] > maxSocket) maxSocket = SocketList[i];
	}

	status = select((int)maxSocket + 1, &ListeningSocketsList, NULL, NULL, NULL);

	if (status < 0) return INVALID_SOCKET;

	sock = INVALID_SOCKET;

	for (i = 0; i < numsockets; i++)
	{
		if (FD_ISSET(SocketList[i], &ListeningSocketsList))
		{
			sock = SocketList[i];
			break;
		}
	}

	if (sock == INVALID_SOCKET)
		return INVALID_SOCKET;
	else
		return accept(sock, NULL, NULL);
}
#endif // !SIMPLE_SOCKETS


void closeAllListeningSockets()
{
#	ifdef SIMPLE_SOCKETS

	socketclose(s_server);

#	else // !SIMPLE_SOCKETS

	int i;

	for (i = 0; i < numsockets; i++)
	{
		socketclose(SocketList[i]);
	}

#endif // !SIMPLE_SOCKETS
}
#endif // NO_SOCKETS


static void serveClient(const SOCKET s_client, const DWORD RpcAssocGroup)
{
#	if !defined(NO_TIMEOUT) && !__minix__

#	ifndef _WIN32 // Standard Posix timeout structure

	struct timeval to;
	to.tv_sec = ServerTimeout;
	to.tv_usec = 0;

#else // Windows requires a DWORD with milliseconds

	DWORD to = ServerTimeout * 1000;

#	endif // _WIN32

#	if !defined(NO_LOG) && defined(_PEDANTIC)

	const int result =
		setsockopt(s_client, SOL_SOCKET, SO_RCVTIMEO, (sockopt_t)&to, sizeof(to)) ||
		setsockopt(s_client, SOL_SOCKET, SO_SNDTIMEO, (sockopt_t)&to, sizeof(to));

	if (result) logger("Warning: Set timeout failed: %s\n", vlmcsd_strerror(socket_errno));

#	else // !(!defined(NO_LOG) && defined(_PEDANTIC))

	setsockopt(s_client, SOL_SOCKET, SO_RCVTIMEO, (sockopt_t)&to, sizeof(to));
	setsockopt(s_client, SOL_SOCKET, SO_SNDTIMEO, (sockopt_t)&to, sizeof(to));

#   endif // !(!defined(NO_LOG) && defined(_PEDANTIC))

#	endif // !defined(NO_TIMEOUT) && !__minix__

	char ipstr[64];
	socklen_t len;
	struct sockaddr_storage addr;

	len = sizeof(addr);

	if (getpeername(s_client, (struct sockaddr*)&addr, &len) ||
		!ip2str(ipstr, sizeof(ipstr), (struct sockaddr*)&addr, len))
	{
#		if !defined(NO_LOG) && defined(_PEDANTIC)
		logger("Fatal: Cannot determine client's IP address: %s\n", vlmcsd_strerror(errno));
#		endif // !defined(NO_LOG) && defined(_PEDANTIC)
		socketclose(s_client);
		return;
	}


#	ifndef NO_LOG
	const char *const connection_type = addr.ss_family == AF_INET6 ? cIPv6 : cIPv4;
	static const char *const cAccepted = "accepted";
	static const char *const cClosed = "closed";
	static const char *const fIP = "%s connection %s: %s.\n";

	logger(fIP, connection_type, cAccepted, ipstr);
#endif // NO_LOG

#	if !defined(NO_PRIVATE_IP_DETECT)

	if (!(PublicIPProtectionLevel & 2) || isPrivateIPAddress((struct sockaddr*)&addr, NULL))
	{
		rpcServer(s_client, RpcAssocGroup, ipstr);
	}
#	ifndef NO_LOG
	else
	{
		logger("Client with public IP address rejected\n");
	}
#	endif // NO_LOG

#   else // defined(NO_PRIVATE_IP_DETECT)

	rpcServer(s_client, RpcAssocGroup, ipstr);

#	endif // defined(NO_PRIVATE_IP_DETECT)

#	ifndef NO_LOG
	logger(fIP, connection_type, cClosed, ipstr);
#	endif // NO_LOG

	socketclose(s_client);
}


#ifndef NO_SOCKETS
static void post_sem(void)
{
#if !defined(NO_LIMIT) && !__minix__
	if (!InetdMode && MaxTasks != SEM_VALUE_MAX)
	{
		semaphore_post(MaxTaskSemaphore);
	}
#endif // !defined(NO_LIMIT) && !__minix__
}


static void wait_sem(void)
{
#if !defined(NO_LIMIT) && !__minix__
	if (!InetdMode && MaxTasks != SEM_VALUE_MAX)
	{
		semaphore_wait(MaxTaskSemaphore);
	}
#endif // !defined(NO_LIMIT) && !__minix__
}
#endif // NO_SOCKETS

#if defined(USE_THREADS) && !defined(NO_SOCKETS)

#if defined(_WIN32) || defined(__CYGWIN__) // Win32 Threads
static DWORD WINAPI serveClientThreadProc(PCLDATA clData)
#else // Posix threads
static void *serveClientThreadProc(PCLDATA clData)
#endif // Thread proc is identical in WIN32 and Posix threads
{
	serveClient(clData->socket, clData->RpcAssocGroup);
	free(clData);
	post_sem();

	return 0;
}

#endif // USE_THREADS


#ifndef NO_SOCKETS

#if defined(USE_THREADS) && (defined(_WIN32) || defined(__CYGWIN__)) // Windows Threads
static int serveClientAsyncWinThreads(PCLDATA thr_CLData)
{
	wait_sem();

	HANDLE h = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)serveClientThreadProc, thr_CLData, 0, NULL);

	if (h)
	{
		CloseHandle(h);
		return NO_ERROR;
	}
	else
	{
		socketclose(thr_CLData->socket);
		free(thr_CLData);
		post_sem();
		return GetLastError();
	}
}
#endif // defined(USE_THREADS) && defined(_WIN32) // Windows Threads


#if defined(USE_THREADS) && !defined(_WIN32) && !defined(__CYGWIN__) // Posix Threads
static int ServeClientAsyncPosixThreads(const PCLDATA thr_CLData)
{
	pthread_t p_thr;
	pthread_attr_t attr;
	int error;

	wait_sem();

	// Must set detached state to avoid memory leak
	if ((error = pthread_attr_init(&attr)) ||
		(error = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED)) ||
		(error = pthread_create(&p_thr, &attr, (void * (*)(void *))serveClientThreadProc, thr_CLData)))
	{
		socketclose(thr_CLData->socket);
		free(thr_CLData);
		post_sem();
		return error;
	}

	return 0;
}
#endif //  defined(USE_THREADS) && !defined(_WIN32) // Posix Threads

#ifndef USE_THREADS // fork() implementation
static void ChildSignalHandler(const int signal)
{
	if (signal == SIGHUP) return;

	post_sem();

#ifndef NO_LOG
	logger("Warning: Child killed/crashed by %s\n", strsignal(signal));
#endif // NO_LOG

	exit(ECHILD);
}

static int ServeClientAsyncFork(const SOCKET s_client, const DWORD RpcAssocGroup)
{
	int pid;
	wait_sem();

	if ((pid = fork()) < 0)
	{
		return errno;
	}
	else if (pid)
	{
		// Parent process
		socketclose(s_client);
		return 0;
	}
	else
	{
		// Child process

		// Setup a Child Handler for most common termination signals
		struct sigaction sa;

		sa.sa_flags = 0;
		sa.sa_handler = ChildSignalHandler;

		static int signallist[] = { SIGHUP, SIGINT, SIGTERM, SIGSEGV, SIGILL, SIGFPE, SIGBUS };

		if (!sigemptyset(&sa.sa_mask))
		{
			uint_fast8_t i;

			for (i = 0; i < vlmcsd_countof(signallist); i++)
			{
				sigaction(signallist[i], &sa, NULL);
			}
		}

		serveClient(s_client, RpcAssocGroup);
		post_sem();
		exit(0);
	}
}
#endif


int serveClientAsync(const SOCKET s_client, const DWORD RpcAssocGroup)
{
#ifndef USE_THREADS // fork() implementation

	return ServeClientAsyncFork(s_client, RpcAssocGroup);

#else // threads implementation

	PCLDATA thr_CLData = (PCLDATA)vlmcsd_malloc(sizeof(CLDATA));
	thr_CLData->socket = s_client;
	thr_CLData->RpcAssocGroup = RpcAssocGroup;

#if defined(_WIN32) || defined (__CYGWIN__) // Windows threads

	return serveClientAsyncWinThreads(thr_CLData);

#else // Posix Threads

	return ServeClientAsyncPosixThreads(thr_CLData);

#endif // Posix Threads

#endif // USE_THREADS
}

#endif // NO_SOCKETS


int runServer()
{
	DWORD RpcAssocGroup = rand32();

	// If compiled for inetd-only mode just serve the stdin socket
#ifdef NO_SOCKETS
	serveClient(STDIN_FILENO, RpcAssocGroup);
	return 0;
#else
// In inetd mode just handle the stdin socket
	if (InetdMode)
	{
		serveClient(STDIN_FILENO, RpcAssocGroup);
		return 0;
	}

	for (;;)
	{
		int error;
		SOCKET s_client;

#		ifdef SIMPLE_SOCKETS
		if ((s_client = accept(s_server, NULL, NULL)) == INVALID_SOCKET)
#		else // Standalone mode fully featured sockets
		if ((s_client = network_accept_any()) == INVALID_SOCKET)
#		endif // Standalone mode fully featured sockets
		{
			error = socket_errno;
			if (error == SOCKET_EINTR || error == SOCKET_ECONNABORTED) continue;

#			ifdef _NTSERVICE
			if (ServiceShutdown) return 0;
#			endif

#			ifndef NO_LOG
			logger("Fatal: %s\n", vlmcsd_strerror(error));
#			endif

			return error;
		}

		RpcAssocGroup++;

#		if !defined(NO_LOG) && defined(_PEDANTIC)
		if ((error = serveClientAsync(s_client, RpcAssocGroup)))
		{
#			ifdef USE_THREADS
			logger("Warning: Could not create client thread: %s\n", vlmcsd_strerror(error));
#			else // !USE_THREADS
			logger("Warning: Could not fork client: %s\n", vlmcsd_strerror(error));
#			endif // !USE_THREADS
		}
#		else // NO_LOG || !_PEDANTIC
		serveClientAsync(s_client, RpcAssocGroup);
#		endif // NO_LOG || !_PEDANTIC
	}
#	endif // NO_SOCKETS
}

#endif // USE_MSRPC