socket_util: added function sockaddr_to_string()

Create the socket_util.c library, the first function is
sockaddr_to_string(): it converts a sockaddr struct to a string
containing the IP address in a human-readable form.

Makefile.am

@@ -113,6 +113,7 @@ mpd_headers = \
 	src/song_save.h \
 	src/song_sticker.h \
 	src/songvec.h \
+	src/socket_util.h \
 	src/state_file.h \
 	src/stats.h \
 	src/sticker.h \
@@ -201,6 +202,7 @@ src_mpd_SOURCES = \
 	src/song_print.c \
 	src/song_save.c \
 	src/songvec.c \
+	src/socket_util.c \
 	src/state_file.c \
 	src/stats.c \
 	src/tag.c \

src/socket_util.c

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "socket_util.h"
+#include "config.h"
+
+#include <sys/socket.h>
+#include <netdb.h>
+
+#ifdef HAVE_IPV6
+#include <string.h>
+#endif
+
+char *
+sockaddr_to_string(const struct sockaddr *sa, size_t length, GError **error)
+{
+	int ret;
+	char host[NI_MAXHOST], serv[NI_MAXSERV];
+
+	ret = getnameinfo(sa, length, host, sizeof(host), serv, sizeof(serv),
+			  NI_NUMERICHOST|NI_NUMERICSERV);
+	if (ret != 0) {
+		g_set_error(error, g_quark_from_static_string("netdb"), ret,
+			    gai_strerror(ret));
+		return NULL;
+	}
+
+#ifdef HAVE_UN
+	if (sa->sa_family == AF_UNIX)
+		/* "serv" contains corrupt information with unix
+		   sockets */
+		return g_strdup(host);
+#endif
+
+#ifdef HAVE_IPV6
+	if (strchr(host, ':') != NULL)
+		return g_strconcat("[", host, "]:", serv, NULL);
+#endif
+
+	return g_strconcat(host, ":", serv, NULL);
+}

src/socket_util.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/*
+ * This library provides easy helper functions for working with
+ * sockets.
+ *
+ */
+
+#ifndef SOCKET_UTIL_H
+#define SOCKET_UTIL_H
+
+#include <glib.h>
+
+struct sockaddr;
+
+/**
+ * Converts the specified socket address into a string in the form
+ * "IP:PORT".  The return value must be freed with g_free() when you
+ * don't need it anymore.
+ *
+ * @param sa the sockaddr struct
+ * @param length the length of #sa in bytes
+ * @param error location to store the error occuring, or NULL to
+ * ignore errors
+ */
+char *
+sockaddr_to_string(const struct sockaddr *sa, size_t length, GError **error);
+
+#endif