Codechange: Use null pointer literal instead of the NULL macro

16 files changed, 84 insertions, 84 deletions

diff --git a/src/network/core/address.cpp b/src/network/core/address.cpp
index 11b5d753f..3d5bd5d64 100644
--- a/src/network/core/address.cpp
+++ b/src/network/core/address.cpp
@@ -25,7 +25,7 @@ const char *NetworkAddress::GetHostname()
 {
 	if (StrEmpty(this->hostname) && this->address.ss_family != AF_UNSPEC) {
 		assert(this->address_length != 0);
-		getnameinfo((struct sockaddr *)&this->address, this->address_length, this->hostname, sizeof(this->hostname), NULL, 0, NI_NUMERICHOST);
+		getnameinfo((struct sockaddr *)&this->address, this->address_length, this->hostname, sizeof(this->hostname), nullptr, 0, NI_NUMERICHOST);
 	}
 	return this->hostname;
 }
@@ -131,7 +131,7 @@ const sockaddr_storage *NetworkAddress::GetAddress()
 		 * bothered to implement the specifications and allow '0' as value
 		 * that means "don't care whether it is SOCK_STREAM or SOCK_DGRAM".
 		 */
-		this->Resolve(this->address.ss_family, SOCK_STREAM, AI_ADDRCONFIG, NULL, ResolveLoopProc);
+		this->Resolve(this->address.ss_family, SOCK_STREAM, AI_ADDRCONFIG, nullptr, ResolveLoopProc);
 		this->resolved = true;
 	}
 	return &this->address;
@@ -145,7 +145,7 @@ const sockaddr_storage *NetworkAddress::GetAddress()
 bool NetworkAddress::IsFamily(int family)
 {
 	if (!this->IsResolved()) {
-		this->Resolve(family, SOCK_STREAM, AI_ADDRCONFIG, NULL, ResolveLoopProc);
+		this->Resolve(family, SOCK_STREAM, AI_ADDRCONFIG, nullptr, ResolveLoopProc);
 	}
 	return this->address.ss_family == family;
 }
@@ -167,7 +167,7 @@ bool NetworkAddress::IsInNetmask(const char *netmask)
 
 	/* Check for CIDR separator */
 	const char *chr_cidr = strchr(netmask, '/');
-	if (chr_cidr != NULL) {
+	if (chr_cidr != nullptr) {
 		int tmp_cidr = atoi(chr_cidr + 1);
 
 		/* Invalid CIDR, treat as single host */
@@ -232,7 +232,7 @@ SOCKET NetworkAddress::Resolve(int family, int socktype, int flags, SocketList *
 	seprintf(port_name, lastof(port_name), "%u", this->GetPort());
 
 	bool reset_hostname = false;
-	/* Setting both hostname to NULL and port to 0 is not allowed.
+	/* Setting both hostname to nullptr and port to 0 is not allowed.
 	 * As port 0 means bind to any port, the other must mean that
 	 * we want to bind to 'all' IPs. */
 	if (StrEmpty(this->hostname) && this->address_length == 0 && this->GetPort() == 0) {
@@ -242,7 +242,7 @@ SOCKET NetworkAddress::Resolve(int family, int socktype, int flags, SocketList *
 		strecpy(this->hostname, fam == AF_INET ? "0.0.0.0" : "::", lastof(this->hostname));
 	}
 
-	int e = getaddrinfo(StrEmpty(this->hostname) ? NULL : this->hostname, port_name, &hints, &ai);
+	int e = getaddrinfo(StrEmpty(this->hostname) ? nullptr : this->hostname, port_name, &hints, &ai);
 
 	if (reset_hostname) strecpy(this->hostname, "", lastof(this->hostname));
 
@@ -255,18 +255,18 @@ SOCKET NetworkAddress::Resolve(int family, int socktype, int flags, SocketList *
 	}
 
 	SOCKET sock = INVALID_SOCKET;
-	for (struct addrinfo *runp = ai; runp != NULL; runp = runp->ai_next) {
+	for (struct addrinfo *runp = ai; runp != nullptr; runp = runp->ai_next) {
 		/* When we are binding to multiple sockets, make sure we do not
 		 * connect to one with exactly the same address twice. That's
 		 * of course totally unneeded ;) */
-		if (sockets != NULL) {
+		if (sockets != nullptr) {
 			NetworkAddress address(runp->ai_addr, (int)runp->ai_addrlen);
 			if (sockets->Contains(address)) continue;
 		}
 		sock = func(runp);
 		if (sock == INVALID_SOCKET) continue;
 
-		if (sockets == NULL) {
+		if (sockets == nullptr) {
 			this->address_length = (int)runp->ai_addrlen;
 			assert(sizeof(this->address) >= runp->ai_addrlen);
 			memcpy(&this->address, runp->ai_addr, runp->ai_addrlen);
@@ -323,7 +323,7 @@ SOCKET NetworkAddress::Connect()
 {
 	DEBUG(net, 1, "Connecting to %s", this->GetAddressAsString());
 
-	return this->Resolve(AF_UNSPEC, SOCK_STREAM, AI_ADDRCONFIG, NULL, ConnectLoopProc);
+	return this->Resolve(AF_UNSPEC, SOCK_STREAM, AI_ADDRCONFIG, nullptr, ConnectLoopProc);
 }
 
 /**
@@ -386,9 +386,9 @@ static SOCKET ListenLoopProc(addrinfo *runp)
  */
 void NetworkAddress::Listen(int socktype, SocketList *sockets)
 {
-	assert(sockets != NULL);
+	assert(sockets != nullptr);
 
-	/* Setting both hostname to NULL and port to 0 is not allowed.
+	/* Setting both hostname to nullptr and port to 0 is not allowed.
 	 * As port 0 means bind to any port, the other must mean that
 	 * we want to bind to 'all' IPs. */
 	if (this->address_length == 0 && this->address.ss_family == AF_UNSPEC &&
diff --git a/src/network/core/address.h b/src/network/core/address.h
index bd1bab676..4dd0edbc0 100644
--- a/src/network/core/address.h
+++ b/src/network/core/address.h
@@ -84,7 +84,7 @@ public:
 		if (*hostname == '[') hostname++;
 		strecpy(this->hostname, StrEmpty(hostname) ? "" : hostname, lastof(this->hostname));
 		char *tmp = strrchr(this->hostname, ']');
-		if (tmp != NULL) *tmp = '\0';
+		if (tmp != nullptr) *tmp = '\0';
 
 		memset(&this->address, 0, sizeof(this->address));
 		this->address.ss_family = family;
diff --git a/src/network/core/host.cpp b/src/network/core/host.cpp
index 2bf862a4f..98a706e2f 100644
--- a/src/network/core/host.cpp
+++ b/src/network/core/host.cpp
@@ -45,7 +45,7 @@ static void NetworkFindBroadcastIPsInternal(NetworkAddressList *broadcast) // BE
 		return;
 	}
 
-	char *output_pointer = NULL;
+	char *output_pointer = nullptr;
 	int output_length = _netstat(sock, &output_pointer, 1);
 	if (output_length < 0) {
 		DEBUG(net, 0, "[core] error running _netstat");
@@ -94,9 +94,9 @@ static void NetworkFindBroadcastIPsInternal(NetworkAddressList *broadcast) // GE
 
 	if (getifaddrs(&ifap) != 0) return;
 
-	for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
+	for (ifa = ifap; ifa != nullptr; ifa = ifa->ifa_next) {
 		if (!(ifa->ifa_flags & IFF_BROADCAST)) continue;
-		if (ifa->ifa_broadaddr == NULL) continue;
+		if (ifa->ifa_broadaddr == nullptr) continue;
 		if (ifa->ifa_broadaddr->sa_family != AF_INET) continue;
 
 		NetworkAddress addr(ifa->ifa_broadaddr, sizeof(sockaddr));
@@ -116,7 +116,7 @@ static void NetworkFindBroadcastIPsInternal(NetworkAddressList *broadcast) // Wi
 	INTERFACE_INFO *ifo = CallocT<INTERFACE_INFO>(num);
 
 	for (;;) {
-		if (WSAIoctl(sock, SIO_GET_INTERFACE_LIST, NULL, 0, ifo, num * sizeof(*ifo), &len, NULL, NULL) == 0) break;
+		if (WSAIoctl(sock, SIO_GET_INTERFACE_LIST, nullptr, 0, ifo, num * sizeof(*ifo), &len, nullptr, nullptr) == 0) break;
 		free(ifo);
 		if (WSAGetLastError() != WSAEFAULT) {
 			closesocket(sock);
diff --git a/src/network/core/packet.cpp b/src/network/core/packet.cpp
index 8cecd9bd2..fda8fdfeb 100644
--- a/src/network/core/packet.cpp
+++ b/src/network/core/packet.cpp
@@ -24,10 +24,10 @@
  */
 Packet::Packet(NetworkSocketHandler *cs)
 {
-	assert(cs != NULL);
+	assert(cs != nullptr);
 
 	this->cs     = cs;
-	this->next   = NULL;
+	this->next   = nullptr;
 	this->pos    = 0; // We start reading from here
 	this->size   = 0;
 	this->buffer = MallocT<byte>(SEND_MTU);
@@ -39,8 +39,8 @@ Packet::Packet(NetworkSocketHandler *cs)
  */
 Packet::Packet(PacketType type)
 {
-	this->cs                   = NULL;
-	this->next                 = NULL;
+	this->cs                   = nullptr;
+	this->next                 = nullptr;
 
 	/* Skip the size so we can write that in before sending the packet */
 	this->pos                  = 0;
@@ -62,7 +62,7 @@ Packet::~Packet()
  */
 void Packet::PrepareToSend()
 {
-	assert(this->cs == NULL && this->next == NULL);
+	assert(this->cs == nullptr && this->next == nullptr);
 
 	this->buffer[0] = GB(this->size, 0, 8);
 	this->buffer[1] = GB(this->size, 8, 8);
@@ -149,7 +149,7 @@ void Packet::Send_uint64(uint64 data)
  */
 void Packet::Send_string(const char *data)
 {
-	assert(data != NULL);
+	assert(data != nullptr);
 	/* The <= *is* valid due to the fact that we are comparing sizes and not the index. */
 	assert(this->size + strlen(data) + 1 <= SEND_MTU);
 	while ((this->buffer[this->size++] = *data++) != '\0') {}
@@ -187,7 +187,7 @@ bool Packet::CanReadFromPacket(uint bytes_to_read)
  */
 void Packet::ReadRawPacketSize()
 {
-	assert(this->cs != NULL && this->next == NULL);
+	assert(this->cs != nullptr && this->next == nullptr);
 	this->size  = (PacketSize)this->buffer[0];
 	this->size += (PacketSize)this->buffer[1] << 8;
 }
diff --git a/src/network/core/tcp.cpp b/src/network/core/tcp.cpp
index 33b61688d..63d004a8f 100644
--- a/src/network/core/tcp.cpp
+++ b/src/network/core/tcp.cpp
@@ -24,7 +24,7 @@
  */
 NetworkTCPSocketHandler::NetworkTCPSocketHandler(SOCKET s) :
 		NetworkSocketHandler(),
-		packet_queue(NULL), packet_recv(NULL),
+		packet_queue(nullptr), packet_recv(nullptr),
 		sock(s), writable(false)
 {
 }
@@ -43,13 +43,13 @@ NetworkRecvStatus NetworkTCPSocketHandler::CloseConnection(bool error)
 	NetworkSocketHandler::CloseConnection(error);
 
 	/* Free all pending and partially received packets */
-	while (this->packet_queue != NULL) {
+	while (this->packet_queue != nullptr) {
 		Packet *p = this->packet_queue->next;
 		delete this->packet_queue;
 		this->packet_queue = p;
 	}
 	delete this->packet_recv;
-	this->packet_recv = NULL;
+	this->packet_recv = nullptr;
 
 	return NETWORK_RECV_STATUS_OKAY;
 }
@@ -63,7 +63,7 @@ NetworkRecvStatus NetworkTCPSocketHandler::CloseConnection(bool error)
 void NetworkTCPSocketHandler::SendPacket(Packet *packet)
 {
 	Packet *p;
-	assert(packet != NULL);
+	assert(packet != nullptr);
 
 	packet->PrepareToSend();
 
@@ -74,12 +74,12 @@ void NetworkTCPSocketHandler::SendPacket(Packet *packet)
 
 	/* Locate last packet buffered for the client */
 	p = this->packet_queue;
-	if (p == NULL) {
+	if (p == nullptr) {
 		/* No packets yet */
 		this->packet_queue = packet;
 	} else {
 		/* Skip to the last packet */
-		while (p->next != NULL) p = p->next;
+		while (p->next != nullptr) p = p->next;
 		p->next = packet;
 	}
 }
@@ -104,7 +104,7 @@ SendPacketsState NetworkTCPSocketHandler::SendPackets(bool closing_down)
 	if (!this->IsConnected()) return SPS_CLOSED;
 
 	p = this->packet_queue;
-	while (p != NULL) {
+	while (p != nullptr) {
 		res = send(this->sock, (const char*)p->buffer + p->pos, p->size - p->pos, 0);
 		if (res == -1) {
 			int err = GET_LAST_ERROR();
@@ -142,15 +142,15 @@ SendPacketsState NetworkTCPSocketHandler::SendPackets(bool closing_down)
 
 /**
  * Receives a packet for the given client
- * @return The received packet (or NULL when it didn't receive one)
+ * @return The received packet (or nullptr when it didn't receive one)
  */
 Packet *NetworkTCPSocketHandler::ReceivePacket()
 {
 	ssize_t res;
 
-	if (!this->IsConnected()) return NULL;
+	if (!this->IsConnected()) return nullptr;
 
-	if (this->packet_recv == NULL) {
+	if (this->packet_recv == nullptr) {
 		this->packet_recv = new Packet(this);
 	}
 
@@ -167,15 +167,15 @@ Packet *NetworkTCPSocketHandler::ReceivePacket()
 					/* Something went wrong... (104 is connection reset by peer) */
 					if (err != 104) DEBUG(net, 0, "recv failed with error %d", err);
 					this->CloseConnection();
-					return NULL;
+					return nullptr;
 				}
 				/* Connection would block, so stop for now */
-				return NULL;
+				return nullptr;
 			}
 			if (res == 0) {
 				/* Client/server has left */
 				this->CloseConnection();
-				return NULL;
+				return nullptr;
 			}
 			p->pos += res;
 		}
@@ -185,7 +185,7 @@ Packet *NetworkTCPSocketHandler::ReceivePacket()
 
 		if (p->size > SEND_MTU) {
 			this->CloseConnection();
-			return NULL;
+			return nullptr;
 		}
 	}
 
@@ -198,22 +198,22 @@ Packet *NetworkTCPSocketHandler::ReceivePacket()
 				/* Something went wrong... (104 is connection reset by peer) */
 				if (err != 104) DEBUG(net, 0, "recv failed with error %d", err);
 				this->CloseConnection();
-				return NULL;
+				return nullptr;
 			}
 			/* Connection would block */
-			return NULL;
+			return nullptr;
 		}
 		if (res == 0) {
 			/* Client/server has left */
 			this->CloseConnection();
-			return NULL;
+			return nullptr;
 		}
 
 		p->pos += res;
 	}
 
 	/* Prepare for receiving a new packet */
-	this->packet_recv = NULL;
+	this->packet_recv = nullptr;
 
 	p->PrepareToRead();
 	return p;
@@ -236,7 +236,7 @@ bool NetworkTCPSocketHandler::CanSendReceive()
 	FD_SET(this->sock, &write_fd);
 
 	tv.tv_sec = tv.tv_usec = 0; // don't block at all.
-	if (select(FD_SETSIZE, &read_fd, &write_fd, NULL, &tv) < 0) return false;
+	if (select(FD_SETSIZE, &read_fd, &write_fd, nullptr, &tv) < 0) return false;
 
 	this->writable = !!FD_ISSET(this->sock, &write_fd);
 	return FD_ISSET(this->sock, &read_fd) != 0;
diff --git a/src/network/core/tcp.h b/src/network/core/tcp.h
index f9e1e00cb..451b93071 100644
--- a/src/network/core/tcp.h
+++ b/src/network/core/tcp.h
@@ -52,7 +52,7 @@ public:
 	 * Whether there is something pending in the send queue.
 	 * @return true when something is pending in the send queue.
 	 */
-	bool HasSendQueue() { return this->packet_queue != NULL; }
+	bool HasSendQueue() { return this->packet_queue != nullptr; }
 
 	NetworkTCPSocketHandler(SOCKET s = INVALID_SOCKET);
 	~NetworkTCPSocketHandler();
diff --git a/src/network/core/tcp_admin.cpp b/src/network/core/tcp_admin.cpp
index 226bae024..98ef0f0a0 100644
--- a/src/network/core/tcp_admin.cpp
+++ b/src/network/core/tcp_admin.cpp
@@ -115,7 +115,7 @@ NetworkRecvStatus NetworkAdminSocketHandler::HandlePacket(Packet *p)
 NetworkRecvStatus NetworkAdminSocketHandler::ReceivePackets()
 {
 	Packet *p;
-	while ((p = this->ReceivePacket()) != NULL) {
+	while ((p = this->ReceivePacket()) != nullptr) {
 		NetworkRecvStatus res = this->HandlePacket(p);
 		if (res != NETWORK_RECV_STATUS_OKAY) return res;
 	}
diff --git a/src/network/core/tcp_connect.cpp b/src/network/core/tcp_connect.cpp
index d923688b1..13330108a 100644
--- a/src/network/core/tcp_connect.cpp
+++ b/src/network/core/tcp_connect.cpp
@@ -33,7 +33,7 @@ TCPConnecter::TCPConnecter(const NetworkAddress &address) :
 	address(address)
 {
 	_tcp_connecters.push_back(this);
-	if (!StartNewThread(NULL, "ottd:tcp", &TCPConnecter::ThreadEntry, this)) {
+	if (!StartNewThread(nullptr, "ottd:tcp", &TCPConnecter::ThreadEntry, this)) {
 		this->Connect();
 	}
 }
diff --git a/src/network/core/tcp_content.cpp b/src/network/core/tcp_content.cpp
index 8257a7252..ee8baf48e 100644
--- a/src/network/core/tcp_content.cpp
+++ b/src/network/core/tcp_content.cpp
@@ -47,8 +47,8 @@ void ContentInfo::TransferFrom(ContentInfo *other)
 		free(this->dependencies);
 		free(this->tags);
 		memcpy(this, other, sizeof(ContentInfo));
-		other->dependencies = NULL;
-		other->tags = NULL;
+		other->dependencies = nullptr;
+		other->tags = nullptr;
 	}
 }
 
@@ -98,11 +98,11 @@ bool ContentInfo::IsValid() const
 /**
  * Search a textfile file next to this file in the content list.
  * @param type The type of the textfile to search for.
- * @return The filename for the textfile, \c NULL otherwise.
+ * @return The filename for the textfile, \c nullptr otherwise.
  */
 const char *ContentInfo::GetTextfile(TextfileType type) const
 {
-	if (this->state == INVALID) return NULL;
+	if (this->state == INVALID) return nullptr;
 	const char *tmp;
 	switch (this->type) {
 		default: NOT_REACHED();
@@ -120,7 +120,7 @@ const char *ContentInfo::GetTextfile(TextfileType type) const
 			break;
 		case CONTENT_TYPE_NEWGRF: {
 			const GRFConfig *gc = FindGRFConfig(BSWAP32(this->unique_id), FGCM_EXACT, this->md5sum);
-			tmp = gc != NULL ? gc->filename : NULL;
+			tmp = gc != nullptr ? gc->filename : nullptr;
 			break;
 		}
 		case CONTENT_TYPE_BASE_GRAPHICS:
@@ -138,7 +138,7 @@ const char *ContentInfo::GetTextfile(TextfileType type) const
 			tmp = FindScenario(this, true);
 			break;
 	}
-	if (tmp == NULL) return NULL;
+	if (tmp == nullptr) return nullptr;
 	return ::GetTextfile(type, GetContentInfoSubDir(this->type), tmp);
 }
 #endif /* OPENTTD_MSU */
@@ -209,7 +209,7 @@ bool NetworkContentSocketHandler::ReceivePackets()
 	Packet *p;
 	static const int MAX_PACKETS_TO_RECEIVE = 42;
 	int i = MAX_PACKETS_TO_RECEIVE;
-	while (--i != 0 && (p = this->ReceivePacket()) != NULL) {
+	while (--i != 0 && (p = this->ReceivePacket()) != nullptr) {
 		bool cont = this->HandlePacket(p);
 		delete p;
 		if (!cont) return true;
diff --git a/src/network/core/tcp_game.cpp b/src/network/core/tcp_game.cpp
index 2d8a74a11..6d69d10d2 100644
--- a/src/network/core/tcp_game.cpp
+++ b/src/network/core/tcp_game.cpp
@@ -26,7 +26,7 @@
  * Create a new socket for the game connection.
  * @param s The socket to connect with.
  */
-NetworkGameSocketHandler::NetworkGameSocketHandler(SOCKET s) : info(NULL), client_id(INVALID_CLIENT_ID),
+NetworkGameSocketHandler::NetworkGameSocketHandler(SOCKET s) : info(nullptr), client_id(INVALID_CLIENT_ID),
 		last_frame(_frame_counter), last_frame_server(_frame_counter), last_packet(_realtime_tick)
 {
 	this->sock = s;
@@ -134,7 +134,7 @@ NetworkRecvStatus NetworkGameSocketHandler::HandlePacket(Packet *p)
 NetworkRecvStatus NetworkGameSocketHandler::ReceivePackets()
 {
 	Packet *p;
-	while ((p = this->ReceivePacket()) != NULL) {
+	while ((p = this->ReceivePacket()) != nullptr) {
 		NetworkRecvStatus res = HandlePacket(p);
 		delete p;
 		if (res != NETWORK_RECV_STATUS_OKAY) return res;
diff --git a/src/network/core/tcp_game.h b/src/network/core/tcp_game.h
index b392cf717..eb8881adc 100644
--- a/src/network/core/tcp_game.h
+++ b/src/network/core/tcp_game.h
@@ -130,12 +130,12 @@ struct CommandPacket;
 /** A queue of CommandPackets. */
 class CommandQueue {
 	CommandPacket *first; ///< The first packet in the queue.
-	CommandPacket *last;  ///< The last packet in the queue; only valid when first != NULL.
+	CommandPacket *last;  ///< The last packet in the queue; only valid when first != nullptr.
 	uint count;           ///< The number of items in the queue.
 
 public:
 	/** Initialise the command queue. */
-	CommandQueue() : first(NULL), last(NULL), count(0) {}
+	CommandQueue() : first(nullptr), last(nullptr), count(0) {}
 	/** Clear the command queue. */
 	~CommandQueue() { this->Free(); }
 	void Append(CommandPacket *p);
@@ -537,7 +537,7 @@ public:
 	 */
 	inline void SetInfo(NetworkClientInfo *info)
 	{
-		assert(info != NULL && this->info == NULL);
+		assert(info != nullptr && this->info == nullptr);
 		this->info = info;
 	}
 
diff --git a/src/network/core/tcp_http.cpp b/src/network/core/tcp_http.cpp
index 3e9cc8141..116232402 100644
--- a/src/network/core/tcp_http.cpp
+++ b/src/network/core/tcp_http.cpp
@@ -43,11 +43,11 @@ NetworkHTTPSocketHandler::NetworkHTTPSocketHandler(SOCKET s,
 	redirect_depth(depth),
 	sock(s)
 {
-	size_t bufferSize = strlen(url) + strlen(host) + strlen(GetNetworkRevisionString()) + (data == NULL ? 0 : strlen(data)) + 128;
+	size_t bufferSize = strlen(url) + strlen(host) + strlen(GetNetworkRevisionString()) + (data == nullptr ? 0 : strlen(data)) + 128;
 	char *buffer = AllocaM(char, bufferSize);
 
 	DEBUG(net, 7, "[tcp/http] requesting %s%s", host, url);
-	if (data != NULL) {
+	if (data != nullptr) {
 		seprintf(buffer, buffer + bufferSize - 1, "POST %s HTTP/1.0\r\nHost: %s\r\nUser-Agent: OpenTTD/%s\r\nContent-Type: text/plain\r\nContent-Length: %d\r\n\r\n%s\r\n", url, host, GetNetworkRevisionString(), (int)strlen(data), data);
 	} else {
 		seprintf(buffer, buffer + bufferSize - 1, "GET %s HTTP/1.0\r\nHost: %s\r\nUser-Agent: OpenTTD/%s\r\n\r\n", url, host, GetNetworkRevisionString());
@@ -108,7 +108,7 @@ static const char * const LOCATION       = "Location: ";       ///< Header for l
 int NetworkHTTPSocketHandler::HandleHeader()
 {
 	assert(strlen(HTTP_1_0) == strlen(HTTP_1_1));
-	assert(strstr(this->recv_buffer, END_OF_HEADER) != NULL);
+	assert(strstr(this->recv_buffer, END_OF_HEADER) != nullptr);
 
 	/* We expect a HTTP/1.[01] reply */
 	if (strncmp(this->recv_buffer, HTTP_1_0, strlen(HTTP_1_0)) != 0 &&
@@ -122,7 +122,7 @@ int NetworkHTTPSocketHandler::HandleHeader()
 
 		/* Get the length of the document to receive */
 		char *length = strcasestr(this->recv_buffer, CONTENT_LENGTH);
-		if (length == NULL) return_error("[tcp/http] missing 'content-length' header");
+		if (length == nullptr) return_error("[tcp/http] missing 'content-length' header");
 
 		/* Skip the header */
 		length += strlen(CONTENT_LENGTH);
@@ -163,7 +163,7 @@ int NetworkHTTPSocketHandler::HandleHeader()
 
 	/* Redirect to other URL */
 	char *uri = strcasestr(this->recv_buffer, LOCATION);
-	if (uri == NULL) return_error("[tcp/http] missing 'location' header for redirect");
+	if (uri == nullptr) return_error("[tcp/http] missing 'location' header for redirect");
 
 	uri += strlen(LOCATION);
 
@@ -178,7 +178,7 @@ int NetworkHTTPSocketHandler::HandleHeader()
 	if (ret != 0) return ret;
 
 	/* We've relinquished control of data now. */
-	this->data = NULL;
+	this->data = nullptr;
 
 	/* Restore the header. */
 	*end_of_line = '\r';
@@ -195,22 +195,22 @@ int NetworkHTTPSocketHandler::HandleHeader()
 /* static */ int NetworkHTTPSocketHandler::Connect(char *uri, HTTPCallback *callback, const char *data, int depth)
 {
 	char *hname = strstr(uri, "://");
-	if (hname == NULL) return_error("[tcp/http] invalid location");
+	if (hname == nullptr) return_error("[tcp/http] invalid location");
 
 	hname += 3;
 
 	char *url = strchr(hname, '/');
-	if (url == NULL) return_error("[tcp/http] invalid location");
+	if (url == nullptr) return_error("[tcp/http] invalid location");
 
 	*url = '\0';
 
 	/* Fetch the hostname, and possible port number. */
-	const char *company = NULL;
-	const char *port = NULL;
+	const char *company = nullptr;
+	const char *port = nullptr;
 	ParseConnectionString(&company, &port, hname);
-	if (company != NULL) return_error("[tcp/http] invalid hostname");
+	if (company != nullptr) return_error("[tcp/http] invalid hostname");
 
-	NetworkAddress address(hname, port == NULL ? 80 : atoi(port));
+	NetworkAddress address(hname, port == nullptr ? 80 : atoi(port));
 
 	/* Restore the URL. */
 	*url = '/';
@@ -246,7 +246,7 @@ int NetworkHTTPSocketHandler::Receive()
 		if (res == 0) {
 			if (this->recv_length != 0) return -1;
 
-			this->callback->OnReceiveData(NULL, 0);
+			this->callback->OnReceiveData(nullptr, 0);
 			return 0;
 		}
 
@@ -261,7 +261,7 @@ int NetworkHTTPSocketHandler::Receive()
 			char *end_of_header = strstr(this->recv_buffer, END_OF_HEADER);
 			this->recv_buffer[end] = prev;
 
-			if (end_of_header == NULL) {
+			if (end_of_header == nullptr) {
 				if (read == lengthof(this->recv_buffer)) {
 					DEBUG(net, 0, "[tcp/http] header too big");
 					return -1;
@@ -308,7 +308,7 @@ int NetworkHTTPSocketHandler::Receive()
 	}
 
 	tv.tv_sec = tv.tv_usec = 0; // don't block at all.
-	int n = select(FD_SETSIZE, &read_fd, NULL, NULL, &tv);
+	int n = select(FD_SETSIZE, &read_fd, nullptr, nullptr, &tv);
 	if (n == -1) return;
 
 	for (auto iter = _http_connections.begin(); iter < _http_connections.end(); /* nothing */) {
diff --git a/src/network/core/tcp_http.h b/src/network/core/tcp_http.h
index 5a5cdd9f2..001942ffb 100644
--- a/src/network/core/tcp_http.h
+++ b/src/network/core/tcp_http.h
@@ -26,9 +26,9 @@ struct HTTPCallback {
 
 	/**
 	 * We're receiving data.
-	 * @param data   the received data, NULL when all data has been received.
+	 * @param data   the received data, nullptr when all data has been received.
 	 * @param length the amount of received data, 0 when all data has been received.
-	 * @note When NULL is sent the HTTP socket handler is closed/freed.
+	 * @note When nullptr is sent the HTTP socket handler is closed/freed.
 	 */
 	virtual void OnReceiveData(const char *data, size_t length) = 0;
 
@@ -68,7 +68,7 @@ public:
 	~NetworkHTTPSocketHandler();
 
 	static int Connect(char *uri, HTTPCallback *callback,
-			const char *data = NULL, int depth = 0);
+			const char *data = nullptr, int depth = 0);
 
 	static void HTTPReceive();
 };
@@ -91,7 +91,7 @@ public:
 	 */
 	NetworkHTTPContentConnecter(const NetworkAddress &address,
 			HTTPCallback *callback, const char *url,
-			const char *data = NULL, int depth = 0) :
+			const char *data = nullptr, int depth = 0) :
 		TCPConnecter(address),
 		callback(callback),
 		url(stredup(url)),
@@ -116,7 +116,7 @@ public:
 	{
 		new NetworkHTTPSocketHandler(s, this->callback, this->address.GetHostname(), this->url, this->data, this->depth);
 		/* We've relinquished control of data now. */
-		this->data = NULL;
+		this->data = nullptr;
 	}
 };
 
diff --git a/src/network/core/tcp_listen.h b/src/network/core/tcp_listen.h
index 5668e48b2..28b6de8ac 100644
--- a/src/network/core/tcp_listen.h
+++ b/src/network/core/tcp_listen.h
@@ -116,7 +116,7 @@ public:
 		}
 
 		tv.tv_sec = tv.tv_usec = 0; // don't block at all.
-		if (select(FD_SETSIZE, &read_fd, &write_fd, NULL, &tv) < 0) return false;
+		if (select(FD_SETSIZE, &read_fd, &write_fd, nullptr, &tv) < 0) return false;
 
 		/* accept clients.. */
 		for (auto &s : sockets) {
diff --git a/src/network/core/udp.cpp b/src/network/core/udp.cpp
index 70bb0b9f0..853b19e1a 100644
--- a/src/network/core/udp.cpp
+++ b/src/network/core/udp.cpp
@@ -24,12 +24,12 @@
  */
 NetworkUDPSocketHandler::NetworkUDPSocketHandler(NetworkAddressList *bind)
 {
-	if (bind != NULL) {
+	if (bind != nullptr) {
 		for (NetworkAddress &addr : *bind) {
 			this->bind.push_back(addr);
 		}
 	} else {
-		/* As hostname NULL and port 0/NULL don't go well when
+		/* As hostname nullptr and port 0/nullptr don't go well when
 		 * resolving it we need to add an address for each of
 		 * the address families we support. */
 		this->bind.emplace_back(nullptr, 0, AF_INET);
@@ -176,13 +176,13 @@ void NetworkUDPSocketHandler::SendNetworkGameInfo(Packet *p, const NetworkGameIn
 		uint count = 0;
 
 		/* Count number of GRFs to send information about */
-		for (c = info->grfconfig; c != NULL; c = c->next) {
+		for (c = info->grfconfig; c != nullptr; c = c->next) {
 			if (!HasBit(c->flags, GCF_STATIC)) count++;
 		}
 		p->Send_uint8 (count); // Send number of GRFs
 
 		/* Send actual GRF Identifications */
-		for (c = info->grfconfig; c != NULL; c = c->next) {
+		for (c = info->grfconfig; c != nullptr; c = c->next) {
 			if (!HasBit(c->flags, GCF_STATIC)) this->SendGRFIdentifier(p, &c->ident);
 		}
 	}
diff --git a/src/network/core/udp.h b/src/network/core/udp.h
index fab232492..9ed2705ef 100644
--- a/src/network/core/udp.h
+++ b/src/network/core/udp.h
@@ -229,7 +229,7 @@ protected:
 	 */
 	virtual void HandleIncomingNetworkGameInfoGRFConfig(GRFConfig *config) { NOT_REACHED(); }
 public:
-	NetworkUDPSocketHandler(NetworkAddressList *bind = NULL);
+	NetworkUDPSocketHandler(NetworkAddressList *bind = nullptr);
 
 	/** On destructing of this class, the socket needs to be closed */
 	virtual ~NetworkUDPSocketHandler() { this->Close(); }