MEDIUM: protocol: add minimalist UDP protocol client

Basic introduction of a UDP layer in HAProxy. It can be used as a
client only and manages UDP exchanges with servers.

It can't be used to load-balance UDP protocols, but only used by
internal features such as DNS resolution.

Makefile

@@ -731,7 +731,7 @@ OBJS = src/haproxy.o src/sessionhash.o src/base64.o src/protocol.o \
        src/lb_chash.o src/lb_fwlc.o src/lb_fwrr.o src/lb_map.o src/lb_fas.o \
        src/stream_interface.o src/dumpstats.o src/proto_tcp.o src/applet.o \
        src/session.o src/stream.o src/hdr_idx.o src/ev_select.o src/signal.o \
-       src/acl.o src/sample.o src/memory.o src/freq_ctr.o src/auth.o \
+       src/acl.o src/sample.o src/memory.o src/freq_ctr.o src/auth.o src/proto_udp.o \
        src/compression.o src/payload.o src/hash.o src/pattern.o src/map.o \
        src/namespace.o src/mailers.o
 

include/proto/proto_udp.h

@@ -0,0 +1,27 @@
+/*
+ * include/proto/proto_udp.h
+ * This file provides functions related to UDP protocol.
+ *
+ * Copyright (C) 2014 Baptiste Assmann <bedis9@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, version 2.1
+ * exclusively.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef _PROTO_PROTO_UDP_H
+#define _PROTO_PROTO_UDP_H
+
+int dgram_fd_handler(int);
+
+#endif // _PROTO_PROTO_UDP_H

include/types/proto_udp.h

@@ -0,0 +1,52 @@
+/*
+ * include/types/proto_udp.h
+ * This file provides structures and types for UDP protocol.
+ *
+ * Copyright (C) 2014 Baptiste Assmann <bedis9@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, version 2.1
+ * exclusively.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef _TYPES_PROTO_UDP_H
+#define _TYPES_PROTO_UDP_H
+
+#include <arpa/inet.h>
+
+/*
+ * datagram related structure
+ */
+struct dgram_conn {
+	const struct dgram_data_cb *data;	/* data layer callbacks. Must be set before */
+	void *owner;				/* pointer to upper layer's entity */
+	union {					/* definitions which depend on connection type */
+		struct {			/*** information used by socket-based dgram ***/
+			int fd;			/* file descriptor */
+		} sock;
+	} t;
+	struct {
+		struct sockaddr_storage from;	/* client address, or address to spoof when connecting to the server */
+		struct sockaddr_storage to;	/* address reached by the client, or address to connect to */
+	} addr;					/* addresses of the remote side, client for producer and server for consumer */
+};
+
+/*
+ * datagram callback structure
+ */
+struct dgram_data_cb {
+	void (*recv)(struct dgram_conn *dgram); /* recv callback */
+	void (*send)(struct dgram_conn *dgram); /* send callback */
+};
+
+#endif /* _TYPES_PROTO_UDP_H */

src/proto_udp.c

@@ -0,0 +1,33 @@
+/*
+ * UDP protocol related functions
+ *
+ * Copyright 2014 Baptiste Assmann <bedis9@gmail.com>
+ *
+ * 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.
+ *
+ */
+
+#include <types/global.h>
+#include <types/fd.h>
+#include <types/proto_udp.h>
+
+#include <proto/fd.h>
+
+/* datagram handler callback */
+int dgram_fd_handler(int fd)
+{
+	struct dgram_conn *dgram = fdtab[fd].owner;
+
+	if (unlikely(!dgram))
+		return 0;
+
+	if (fd_recv_ready(fd))
+		dgram->data->recv(dgram);
+	else if (fd_send_ready(fd))
+		dgram->data->send(dgram);
+
+	return 0;
+}