libports: add libc_resolv

libc_resolv is a {free,get}addrinfo() plugin, mainly for use with NOUX.

We prefix the original libc functions to with 'libc_' so there is no
symbol conflict with file_operations.cc.

libports/lib/mk/libc_resolv.mk

@@ -0,0 +1,9 @@
+LIBS   = libc libc-resolv libc-isc libc-nameser libc-net libc-rpc
+
+SRC_CC = plugin.cc
+
+vpath %.cc $(REP_DIR)/src/lib/libc_resolv
+
+include $(REP_DIR)/lib/mk/libc-common.inc
+
+SHARED_LIB = yes

libports/src/lib/libc/patches/getaddrinfo_c.patch

@@ -0,0 +1,20 @@
+--- libc/net/getaddrinfo.c.orig
++++ libc/net/getaddrinfo.c
+@@ -329,7 +329,7 @@ do { \
+ 	((x) == (y) || (/*CONSTCOND*/(w) && ((x) == ANY || (y) == ANY)))
+ 
+ void
+-freeaddrinfo(struct addrinfo *ai)
++libc_freeaddrinfo(struct addrinfo *ai)
+ {
+ 	struct addrinfo *next;
+ 
+@@ -362,7 +362,7 @@ str2number(const char *p, int *portp)
+ }
+ 
+ int
+-getaddrinfo(const char *hostname, const char *servname,
++libc_getaddrinfo(const char *hostname, const char *servname,
+     const struct addrinfo *hints, struct addrinfo **res)
+ {
+ 	struct addrinfo sentinel;

libports/src/lib/libc_resolv/README

@@ -0,0 +1,6 @@
+This libc plugin uses libc's own resolv facilities to do DNS resolving
+etc. pp. It is much more advanced than the functions which lwip has to
+offer.
+
+Its current use is for noux-pkgs only. ``Native'' Genode programs should
+use getaddrinfo() provided by lwip for now.

libports/src/lib/libc_resolv/plugin.cc

@@ -0,0 +1,94 @@
+/*
+ * \brief  Libc resolv
+ * \author Josef Soentgen
+ * \date   2012-07-19
+ */
+
+/*
+ * Copyright (C) 2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+/* Genode includes */
+#include <base/printf.h>
+#include <base/env.h>
+
+/* libc plugin includes */
+#include <libc-plugin/plugin.h>
+#include <libc-plugin/fd_alloc.h>
+
+/* libc includes */
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+
+
+void *operator new (size_t, void *ptr) { return ptr; }
+
+extern "C" void libc_freeaddrinfo(struct ::addrinfo *);
+extern "C" int libc_getaddrinfo(const char *, const char *,
+                                const struct ::addrinfo *,
+                                struct ::addrinfo **);
+
+/************
+ ** Plugin **
+ ************/
+
+namespace {
+	
+	struct Plugin_context : Libc::Plugin_context { };
+
+	static inline Plugin_context *context(Libc::File_descriptor *fd)
+	{
+		return static_cast<Plugin_context *>(fd->context);
+	}
+
+	class Plugin : public Libc::Plugin
+	{
+		private:
+
+			Plugin_context _context;
+
+		public:
+
+			/**
+			 * Constructor
+			 */
+			Plugin() { }
+
+			bool supports_freeaddrinfo(struct ::addrinfo *res)
+			{
+				return true;
+			}
+			bool supports_getaddrinfo(const char *node, const char *service,
+			                          const struct ::addrinfo *hints,
+			                          struct ::addrinfo **res)
+			{
+				return true;
+			}
+
+			int getaddrinfo(const char *node, const char *service,
+			                const struct ::addrinfo *hints,
+			                struct ::addrinfo **res)
+			{
+				PDBG("libc_resolv getaddrinfo() called");
+				return ::libc_getaddrinfo(node, service, hints, res);
+			}
+
+			void freeaddrinfo(struct ::addrinfo *res)
+			{
+				PDBG("libc_resolv freeaddrinfo() called");
+
+				return ::libc_freeaddrinfo(res);
+			}
+
+	};
+
+} /* unnamed namespace */
+
+void __attribute__((constructor)) init_libc_resolv(void)
+{
+	static Plugin libc_resolv;
+}