libmpdclient: added resolver library

The resolver library provides unified access to all resolvers
(getaddrinfo(), gethostbyname(), Unix domain sockets).  Like
getaddrinfo(), it can return more than one address for a host name.
This fixes bug 1517 (http://www.musicpd.org/mantis/view.php?id=1517).

1 files changed, 195 insertions, 0 deletions

diff --git a/src/resolver.c b/src/resolver.c
new file mode 100644
index 000000000..e5df05ce5
--- /dev/null
+++ b/src/resolver.c
@@ -0,0 +1,195 @@
+/* libmpdclient
+   (c) 2008 Max Kellermann <max@duempel.org>
+   This project's homepage is: http://www.musicpd.org
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+   - Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+   - Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+   - Neither the name of the Music Player Daemon nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
+   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "resolver.h"
+
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef WIN32
+#  include <ws2tcpip.h>
+#  include <winsock.h>
+#else
+#  include <netinet/in.h>
+#  include <arpa/inet.h>
+#  include <sys/socket.h>
+#  include <sys/un.h>
+#  include <netdb.h>
+#endif
+
+#ifndef MPD_NO_GAI
+#  ifdef AI_ADDRCONFIG
+#    define MPD_HAVE_GAI
+#  endif
+#endif
+
+struct resolver {
+	enum {
+		TYPE_ZERO, TYPE_ONE, TYPE_ANY
+	} type;
+
+#ifdef MPD_HAVE_GAI
+	struct addrinfo *ai;
+	const struct addrinfo *next;
+#else
+	struct sockaddr_in sin;
+#endif
+
+	struct resolver_address current;
+
+#ifndef WIN32
+	struct sockaddr_un sun;
+#endif
+};
+
+struct resolver *
+resolver_new(const char *host, int port)
+{
+	struct resolver *resolver;
+
+	resolver = malloc(sizeof(*resolver));
+	if (resolver == NULL)
+		return NULL;
+
+#ifndef WIN32
+	if (host[0] == '/') {
+		size_t path_length = strlen(host);
+		if (path_length >= sizeof(resolver->sun.sun_path)) {
+			free(resolver);
+			return NULL;
+		}
+
+		resolver->sun.sun_family = AF_UNIX;
+		memcpy(resolver->sun.sun_path, host, path_length + 1);
+
+		resolver->current.family = PF_UNIX;
+		resolver->current.protocol = 0;
+		resolver->current.addrlen = sizeof(resolver->sun);
+		resolver->current.addr = (const struct sockaddr *)&resolver->sun;
+		resolver->type = TYPE_ONE;
+	} else {
+#endif
+#ifdef MPD_HAVE_GAI
+		struct addrinfo hints;
+		char service[20];
+		int ret;
+
+		memset(&hints, 0, sizeof(hints));
+		hints.ai_flags = AI_ADDRCONFIG;
+		hints.ai_family = PF_UNSPEC;
+		hints.ai_socktype = SOCK_STREAM;
+		hints.ai_protocol = IPPROTO_TCP;
+
+		snprintf(service, sizeof(service), "%d", port);
+
+		ret = getaddrinfo(host, service, &hints, &resolver->ai);
+		if (ret != 0) {
+			free(resolver);
+			return NULL;
+		}
+
+		resolver->next = resolver->ai;
+		resolver->type = TYPE_ANY;
+#else
+		const struct hostent *he;
+
+		he = gethostbyname(host);
+		if (he == NULL) {
+			free(resolver);
+			return NULL;
+		}
+
+		if (he->h_addrtype != AF_INET) {
+			free(resolver);
+			return NULL;
+		}
+
+
+		memset(&resolver->sin, 0, sizeof(resolver->sin));
+		resolver->sin.sin_family = AF_INET;
+		resolver->sin.sin_port = htons(port);
+		memcpy((char *)&resolver->sin.sin_addr.s_addr,
+		       (char *)he->h_addr, he->h_length);
+
+		resolver->current.family = PF_INET;
+		resolver->current.protocol = 0;
+		resolver->current.addrlen = sizeof(resolver->sin);
+		resolver->current.addr = (const struct sockaddr *)&resolver->sin;
+
+		resolver->type = TYPE_ONE;
+#endif
+#ifndef WIN32
+	}
+#endif
+
+	return resolver;
+}
+
+void
+resolver_free(struct resolver *resolver)
+{
+#ifdef MPD_HAVE_GAI
+	if (resolver->type == TYPE_ANY)
+		freeaddrinfo(resolver->ai);
+#endif
+	free(resolver);
+}
+
+const struct resolver_address *
+resolver_next(struct resolver *resolver)
+{
+	if (resolver->type == TYPE_ZERO)
+		return NULL;
+
+	if (resolver->type == TYPE_ONE) {
+		resolver->type = TYPE_ZERO;
+		return &resolver->current;
+	}
+
+#ifdef MPD_HAVE_GAI
+	if (resolver->next == NULL)
+		return NULL;
+
+	resolver->current.family = resolver->next->ai_family;
+	resolver->current.protocol = resolver->next->ai_protocol;
+	resolver->current.addrlen = resolver->next->ai_addrlen;
+	resolver->current.addr = resolver->next->ai_addr;
+
+	resolver->next = resolver->next->ai_next;
+
+	return &resolver->current;
+#else
+	return NULL;
+#endif
+}