Kernel: Fix unix domain socket close detection

Also rework resolver's send format and convert test-tcp and nslookup to
use getaddrinfo

kernel/kernel/Networking/UNIX/Socket.cpp

@@ -60,7 +60,10 @@ namespace Kernel
 		{
 			auto& connection_info = m_info.get<ConnectionInfo>();
 			if (auto connection = connection_info.connection.lock(); connection && connection->m_info.has<ConnectionInfo>())
+			{
 				connection->m_info.get<ConnectionInfo>().target_closed = true;
+				connection->m_packet_thread_blocker.unblock();
+			}
 		}
 	}
 
@@ -350,6 +353,9 @@ namespace Kernel
 	}
 
 	BAN::ErrorOr<size_t> UnixDomainSocket::recvfrom_impl(BAN::ByteSpan buffer, sockaddr*, socklen_t*)
+	{
+		auto state = m_packet_lock.lock();
+		while (m_packet_size_total == 0)
 		{
 			if (m_info.has<ConnectionInfo>())
 			{
@@ -361,9 +367,6 @@ namespace Kernel
 					return BAN::Error::from_errno(ENOTCONN);
 			}
 
-		auto state = m_packet_lock.lock();
-		while (m_packet_size_total == 0)
-		{
 			m_packet_lock.unlock(state);
 			TRY(Thread::current().block_or_eintr_indefinite(m_packet_thread_blocker));
 			state = m_packet_lock.lock();

userspace/libraries/LibC/netdb.cpp

@@ -107,7 +107,7 @@ int getaddrinfo(const char* __restrict nodename, const char* __restrict servname
 			goto error_close_socket;
 
 		sockaddr_storage storage;
-		if (recv(resolver_sock, &storage, sizeof(storage), 0) == -1)
+		if (recv(resolver_sock, &storage, sizeof(storage), 0) < static_cast<ssize_t>(sizeof(sockaddr_in)))
 			goto error_close_socket;
 
 		close(resolver_sock);
@@ -115,12 +115,12 @@ int getaddrinfo(const char* __restrict nodename, const char* __restrict servname
 		if (storage.ss_family != AF_INET)
 			return EAI_FAIL;
 
-		ipv4_addr = *reinterpret_cast<in_addr_t*>(storage.ss_storage);
+		ipv4_addr = reinterpret_cast<sockaddr_in&>(storage).sin_addr.s_addr;
 	}
 
 	{
 		addrinfo* ai = (addrinfo*)malloc(sizeof(addrinfo) + sizeof(sockaddr_in));
-		if (*res == nullptr)
+		if (ai == nullptr)
 			return EAI_MEMORY;
 
 		sockaddr_in* sa_in = reinterpret_cast<sockaddr_in*>(reinterpret_cast<uintptr_t>(ai) + sizeof(addrinfo));
@@ -193,7 +193,7 @@ struct hostent* gethostbyname(const char* name)
 			goto error_close_socket;
 
 		sockaddr_storage storage;
-		if (recv(socket, &storage, sizeof(storage), 0) == -1)
+		if (recv(socket, &storage, sizeof(storage), 0) < static_cast<ssize_t>(sizeof(sockaddr_in)))
 			goto error_close_socket;
 
 		close(socket);
@@ -201,7 +201,7 @@ struct hostent* gethostbyname(const char* name)
 		if (storage.ss_family != AF_INET)
 			return nullptr;
 
-		addr_buffer = *reinterpret_cast<in_addr_t*>(storage.ss_storage);
+		addr_buffer = reinterpret_cast<sockaddr_in&>(storage).sin_addr.s_addr;
 	}
 
 	return &hostent;

userspace/programs/nslookup/main.cpp

@@ -1,10 +1,7 @@
 #include <arpa/inet.h>
+#include <netdb.h>
 #include <netinet/in.h>
 #include <stdio.h>
-#include <string.h>
-#include <sys/socket.h>
-#include <sys/un.h>
-#include <unistd.h>
 
 #define MAX(a, b) ((a) < (b) ? (b) : (a))
 
@@ -16,39 +13,37 @@ int main(int argc, char** argv)
 		return 1;
 	}
 
-	int socket = ::socket(AF_UNIX, SOCK_SEQPACKET, 0);
-	if (socket == -1)
+	const addrinfo hints {
+		.ai_flags = 0,
+		.ai_family = AF_INET,
+		.ai_socktype = SOCK_STREAM,
+		.ai_protocol = 0,
+		.ai_addrlen = 0,
+		.ai_addr = nullptr,
+		.ai_canonname = nullptr,
+		.ai_next = nullptr,
+	};
+
+	addrinfo* result;
+	if (int ret = getaddrinfo(argv[1], nullptr, &hints, &result); ret != 0)
 	{
-		perror("socket");
+		fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(ret));
 		return 1;
 	}
 
-	sockaddr_un addr;
-	addr.sun_family = AF_UNIX;
-	strcpy(addr.sun_path, "/tmp/resolver.sock");
-	if (connect(socket, (sockaddr*)&addr, sizeof(addr)) == -1)
+	for (addrinfo* ai = result; ai; ai = ai->ai_next)
 	{
-		perror("connect");
-		return 1;
+		if (ai->ai_family != AF_INET)
+			continue;
+
+		char buffer[NI_MAXHOST];
+		if (inet_ntop(ai->ai_family, &reinterpret_cast<sockaddr_in*>(ai->ai_addr)->sin_addr, buffer, sizeof(buffer)) == nullptr)
+			continue;
+
+		printf("%s\n", buffer);
+		return 0;
 	}
 
-	if (send(socket, argv[1], strlen(argv[1]), 0) == -1)
-	{
-		perror("send");
-		return 1;
-	}
-
-	sockaddr_storage storage;
-	if (recv(socket, &storage, sizeof(storage), 0) == -1)
-	{
-		perror("recv");
-		return 1;
-	}
-
-	close(socket);
-
-	char buffer[MAX(INET_ADDRSTRLEN, INET6_ADDRSTRLEN)];
-	printf("%s\n", inet_ntop(storage.ss_family, storage.ss_storage, buffer, sizeof(buffer)));
-
+	fprintf(stderr, "no address information available\n");
 	return 0;
 }

userspace/programs/resolver/CMakeLists.txt

@@ -6,4 +6,6 @@ add_executable(resolver ${SOURCES})
 banan_link_library(resolver ban)
 banan_link_library(resolver libc)
 
+target_compile_options(resolver PRIVATE -Wno-maybe-uninitialized)
+
 install(TARGETS resolver OPTIONAL)

userspace/programs/resolver/main.cpp

@@ -43,6 +43,7 @@ static_assert(sizeof(DNSAnswer) == 12);
 
 enum QTYPE : uint16_t
 {
+	INVALID = 0x0000,
 	A		= 0x0001,
 	CNAME	= 0x0005,
 	AAAA	= 0x001C,
@@ -50,14 +51,83 @@ enum QTYPE : uint16_t
 
 struct DNSEntry
 {
-	time_t				valid_until	{ 0 };
-	BAN::IPv4Address	address 	{ 0 };
+	DNSEntry(BAN::IPv4Address&& address, time_t valid_until)
+		: type(QTYPE::A)
+		, valid_until(valid_until)
+		, address(BAN::move(address))
+	{}
+
+	DNSEntry(BAN::String&& cname, time_t valid_until)
+		: type(QTYPE::CNAME)
+		, valid_until(valid_until)
+		, cname(BAN::move(cname))
+	{}
+
+	DNSEntry(DNSEntry&& other)
+	{
+		*this = BAN::move(other);
+	}
+
+	~DNSEntry() { clear(); }
+
+	DNSEntry& operator=(DNSEntry&& other)
+	{
+		clear();
+		valid_until = other.valid_until;
+		switch (type = other.type)
+		{
+			case QTYPE::A:
+				new (&address) BAN::IPv4Address(BAN::move(other.address));
+				break;
+			case QTYPE::CNAME:
+				new (&cname) BAN::String(BAN::move(other.cname));
+				break;
+			case QTYPE::INVALID:
+			case QTYPE::AAAA:
+				ASSERT_NOT_REACHED();
+		}
+		other.clear();
+		return *this;
+	}
+
+	void clear()
+	{
+		switch (type)
+		{
+			case QTYPE::A:
+				using BAN::IPv4Address;
+				address.~IPv4Address();
+				break;
+			case QTYPE::CNAME:
+				using BAN::String;
+				cname.~String();
+				break;
+			case QTYPE::AAAA:
+				ASSERT_NOT_REACHED();
+			case QTYPE::INVALID:
+				break;
+		}
+		type = QTYPE::INVALID;
+	}
+
+	QTYPE type;
+	time_t valid_until;
+	union {
+		BAN::IPv4Address address;
+		BAN::String cname;
+	};
 };
 
 struct DNSResponse
 {
-	uint16_t id;
+	struct NameEntryPair
+	{
+		BAN::String name;
 		DNSEntry entry;
+	};
+
+	uint16_t id;
+	BAN::Vector<NameEntryPair> entries;
 };
 
 bool send_dns_query(int socket, BAN::StringView domain, uint16_t id)
@@ -110,36 +180,83 @@ BAN::Optional<DNSResponse> read_dns_response(int socket)
 	}
 
 	DNSPacket& reply = *reinterpret_cast<DNSPacket*>(buffer);
-	if (reply.flags & 0x0F)
-	{
-		dprintln("DNS error (rcode {})", (unsigned)(reply.flags & 0xF));
-		return {};
-	}
-
-	size_t idx = 0;
-	for (size_t i = 0; i < reply.question_count; i++)
-	{
-		while (reply.data[idx])
-			idx += reply.data[idx] + 1;
-		idx += 5;
-	}
-
-	DNSAnswer& answer = *reinterpret_cast<DNSAnswer*>(&reply.data[idx]);
-	if (answer.type() != QTYPE::A)
-	{
-		dprintln("Not A record, but {}", static_cast<uint16_t>(answer.type()));
-		return {};
-	}
-	if (answer.data_len() != 4)
-	{
-		dprintln("corrupted package");
-		return {};
-	}
 
 	DNSResponse result;
 	result.id = reply.identification;
-	result.entry.valid_until = time(nullptr) + answer.ttl();
-	result.entry.address = BAN::IPv4Address(*reinterpret_cast<uint32_t*>(answer.data));
+
+	if (reply.flags & 0x0F)
+	{
+		dprintln("DNS error (rcode {})", (unsigned)(reply.flags & 0xF));
+		return result;
+	}
+
+	size_t idx = reply.data - buffer;
+	for (size_t i = 0; i < reply.question_count; i++)
+	{
+		while (buffer[idx])
+			idx += buffer[idx] + 1;
+		idx += 5;
+	}
+
+	const auto read_name =
+		[](size_t idx) -> BAN::String
+		{
+			BAN::String result;
+			while (buffer[idx])
+			{
+				if ((buffer[idx] & 0xC0) == 0xC0)
+				{
+					idx = ((buffer[idx] & 0x3F) << 8) | buffer[idx + 1];
+					continue;
+				}
+
+				MUST(result.append(BAN::StringView(reinterpret_cast<const char*>(&buffer[idx + 1]), buffer[idx])));
+				MUST(result.push_back('.'));
+				idx += buffer[idx] + 1;
+			}
+
+			if (!result.empty())
+				result.pop_back();
+			return result;
+		};
+
+	for (size_t i = 0; i < reply.answer_count; i++)
+	{
+		auto& answer = *reinterpret_cast<DNSAnswer*>(&buffer[idx]);
+
+		auto name = read_name(answer.__storage - buffer);
+
+		if (answer.type() == QTYPE::A)
+		{
+			if (answer.data_len() != 4)
+			{
+				dprintln("Invalid A record size {}", (uint16_t)answer.data_len());
+				return result;
+			}
+
+			MUST(result.entries.push_back({
+				.name = BAN::move(name),
+				.entry = {
+					BAN::IPv4Address(*reinterpret_cast<uint32_t*>(answer.data)),
+					time(nullptr) + answer.ttl(),
+				},
+			}));
+		}
+		else if (answer.type() == QTYPE::CNAME)
+		{
+			auto target = read_name(answer.data - buffer);
+
+			MUST(result.entries.push_back({
+				.name = BAN::move(name),
+				.entry = {
+					BAN::move(target),
+					time(nullptr) + answer.ttl()
+				},
+			}));
+		}
+
+		idx += sizeof(DNSAnswer) + answer.data_len();
+	}
 
 	return result;
 }
@@ -193,6 +310,32 @@ BAN::Optional<BAN::String> read_service_query(int socket)
 	return BAN::String(buffer);
 }
 
+BAN::Optional<BAN::IPv4Address> resolve_from_dns_cache(BAN::HashMap<BAN::String, DNSEntry>& dns_cache, const BAN::String& domain)
+{
+	for (auto it = dns_cache.find(domain); it != dns_cache.end();)
+	{
+		if (time(nullptr) > it->value.valid_until)
+		{
+			dns_cache.remove(it);
+			return {};
+		}
+
+		switch (it->value.type)
+		{
+			case QTYPE::A:
+				return it->value.address;
+			case QTYPE::CNAME:
+				it = dns_cache.find(it->value.cname);
+				break;
+			case QTYPE::AAAA:
+			case QTYPE::INVALID:
+				ASSERT_NOT_REACHED();
+		}
+	}
+
+	return {};
+}
+
 int main(int, char**)
 {
 	srand(time(nullptr));
@@ -266,17 +409,42 @@ int main(int, char**)
 			if (!result.has_value())
 				continue;
 
+			for (auto&& [name, entry] : result->entries)
+				MUST(dns_cache.insert_or_assign(BAN::move(name), BAN::move(entry)));
+
 			for (auto& client : clients)
 			{
 				if (client.query_id != result->id)
 					continue;
 
-				(void)dns_cache.insert(client.query, result->entry);
+				auto resolved = resolve_from_dns_cache(dns_cache, client.query);
+				if (!resolved.has_value())
+				{
+					auto it = dns_cache.find(client.query);
+					if (it == dns_cache.end())
+					{
+						client.close = true;
+						break;
+					}
+					for (;;)
+					{
+						ASSERT(it->value.type == QTYPE::CNAME);
+						auto next = dns_cache.find(it->value.cname);
+						if (next == dns_cache.end())
+							break;
+						it = next;
+					}
+					send_dns_query(service_socket, it->value.cname, client.query_id);
+					break;
+				}
 
-				sockaddr_storage storage;
-				storage.ss_family = AF_INET;
-				memcpy(storage.ss_storage, &result->entry.address.raw, sizeof(result->entry.address.raw));
-				if (send(client.socket, &storage, sizeof(storage), 0) == -1)
+				const sockaddr_in addr {
+					.sin_family = AF_INET,
+					.sin_port = 0,
+					.sin_addr = { .s_addr = resolved->raw },
+				};
+
+				if (send(client.socket, &addr, sizeof(addr), 0) == -1)
 					dprintln("send: {}", strerror(errno));
 				client.close = true;
 				break;
@@ -308,30 +476,22 @@ int main(int, char**)
 				continue;
 			}
 
-			BAN::Optional<DNSEntry> result;
+			BAN::Optional<BAN::IPv4Address> result;
 
 			if (*hostname && strcmp(query->data(), hostname) == 0)
-			{
-				result = DNSEntry {
-					.valid_until = time(nullptr),
-					.address = ntohl(INADDR_LOOPBACK),
-				};
-			}
-			else if (dns_cache.contains(*query))
-			{
-				auto& cached = dns_cache[*query];
-				if (time(nullptr) <= cached.valid_until)
-					result = cached;
-				else
-					dns_cache.remove(*query);
-			}
+				result = BAN::IPv4Address(ntohl(INADDR_LOOPBACK));
+			else if (auto resolved = resolve_from_dns_cache(dns_cache, query.value()); resolved.has_value())
+				result = resolved.release_value();
 
 			if (result.has_value())
 			{
-				sockaddr_storage storage;
-				storage.ss_family = AF_INET;
-				memcpy(storage.ss_storage, &result->address.raw, sizeof(result->address.raw));
-				if (send(client.socket, &storage, sizeof(storage), 0) == -1)
+				const sockaddr_in addr {
+					.sin_family = AF_INET,
+					.sin_port = 0,
+					.sin_addr = { .s_addr = result->raw },
+				};
+
+				if (send(client.socket, &addr, sizeof(addr), 0) == -1)
 					dprintln("send: {}", strerror(errno));
 				client.close = true;
 				continue;

userspace/tests/test-tcp/main.cpp

@@ -1,4 +1,5 @@
 #include <arpa/inet.h>
+#include <netdb.h>
 #include <netinet/in.h>
 #include <stdio.h>
 #include <string.h>
@@ -8,44 +9,26 @@
 
 in_addr_t get_ipv4_address(const char* query)
 {
-	if (in_addr_t ipv4 = inet_addr(query); ipv4 != (in_addr_t)(-1))
-		return ipv4;
+	const addrinfo hints {
+		.ai_flags = 0,
+		.ai_family = AF_INET,
+		.ai_socktype = SOCK_STREAM,
+		.ai_protocol = 0,
+		.ai_addrlen = 0,
+		.ai_addr = nullptr,
+		.ai_canonname = nullptr,
+		.ai_next = nullptr,
+	};
 
-	int socket = ::socket(AF_UNIX, SOCK_SEQPACKET, 0);
-	if (socket == -1)
-	{
-		perror("socket");
+	addrinfo* result;
+	if (getaddrinfo(query, nullptr, &hints, &result) != 0)
 		return -1;
-	}
 
-	sockaddr_un addr;
-	addr.sun_family = AF_UNIX;
-	strcpy(addr.sun_path, "/tmp/resolver.sock");
-	if (connect(socket, (sockaddr*)&addr, sizeof(addr)) == -1)
-	{
-		perror("connect");
-		close(socket);
+	for (addrinfo* ai = result; ai; ai = ai->ai_next)
+		if (ai->ai_family != AF_INET)
+			return reinterpret_cast<sockaddr_in*>(ai->ai_addr)->sin_addr.s_addr;
+
 	return -1;
-	}
-
-	if (send(socket, query, strlen(query), 0) == -1)
-	{
-		perror("send");
-		close(socket);
-		return -1;
-	}
-
-	sockaddr_storage storage;
-	if (recv(socket, &storage, sizeof(storage), 0) == -1)
-	{
-		perror("recv");
-		close(socket);
-		return -1;
-	}
-
-	close(socket);
-
-	return *reinterpret_cast<in_addr_t*>(storage.ss_storage);
 }
 
 int main(int argc, char** argv)