LibC: Implement gethostbyname()

This is not a POSIX function, but curl seems to depend on it. It is
even deprecated on linux...

libc/CMakeLists.txt

@@ -10,6 +10,7 @@ set(LIBC_SOURCES
 	fcntl.cpp
 	grp.cpp
 	malloc.cpp
+	netdb.cpp
 	printf_impl.cpp
 	pwd.cpp
 	scanf_impl.cpp

libc/include/netdb.h

@@ -90,6 +90,7 @@ void				endservent(void);
 void				freeaddrinfo(struct addrinfo* ai);
 const char*			gai_strerror(int ecode);
 int					getaddrinfo(const char* __restrict nodename, const char* __restrict servname, const struct addrinfo* __restrict hints, struct addrinfo** __restrict res);
+struct hostent*		gethostbyname(const char* name);
 struct hostent*		gethostent(void);
 int					getnameinfo(const struct sockaddr* __restrict sa, socklen_t salen, char* __restrict node, socklen_t nodelen, char* __restrict service, socklen_t servicelen, int flags);
 struct netent*		getnetbyaddr(uint32_t net, int type);

libc/netdb.cpp

@@ -0,0 +1,69 @@
+#include <BAN/Bitcast.h>
+
+#include <arpa/inet.h>
+#include <limits.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+struct hostent* gethostbyname(const char* name)
+{
+	static char name_buffer[HOST_NAME_MAX + 1];
+	static in_addr_t addr_buffer;
+	static in_addr_t* addr_ptrs[2];
+	static struct hostent hostent;
+
+	if (strlen(name) > HOST_NAME_MAX)
+		return nullptr;
+	strcpy(name_buffer, name);
+	hostent.h_name = name_buffer;
+
+	hostent.h_aliases = nullptr;
+
+	hostent.h_addrtype = AF_INET;
+	hostent.h_length = sizeof(in_addr_t);
+
+	addr_ptrs[0] = &addr_buffer;
+	addr_ptrs[1] = nullptr;
+	hostent.h_addr_list = reinterpret_cast<char**>(addr_ptrs);
+
+	int socket = -1;
+
+	if (in_addr_t ipv4 = inet_addr(name); ipv4 != (in_addr_t)(-1))
+		addr_buffer = ipv4;
+	else
+	{
+		int socket = ::socket(AF_UNIX, SOCK_SEQPACKET, 0);
+		if (socket == -1)
+			return nullptr;
+
+		sockaddr_un addr;
+		addr.sun_family = AF_UNIX;
+		strcpy(addr.sun_path, "/tmp/resolver.sock");
+		if (connect(socket, (sockaddr*)&addr, sizeof(addr)) == -1)
+			goto error_close_socket;
+
+		if (send(socket, name, strlen(name), 0) == -1)
+			goto error_close_socket;
+
+		sockaddr_storage storage;
+		if (recv(socket, &storage, sizeof(storage), 0) == -1)
+			goto error_close_socket;
+
+		close(socket);
+
+		if (storage.ss_family != AF_INET)
+			return nullptr;
+
+		addr_buffer = *reinterpret_cast<in_addr_t*>(storage.ss_storage);
+	}
+
+	return &hostent;
+
+error_close_socket:
+	close(socket);
+	return nullptr;
+}