RxRPC: Handle VERSION Rx protocol packets

Handle VERSION Rx protocol packets.  We should respond to a VERSION packet
with a string indicating the Rx version.  This is a maximum of 64 characters
and is padded out to 65 chars with NUL bytes.

Note that other AFS clients use the version request as a NAT keepalive so we
need to handle it rather than returning an abort.

The standard formulation seems to be:

	<project> <version> built <yyyy>-<mm>-<dd>

for example:

	" OpenAFS 1.6.2 built  2013-05-07 "

(note the three extra spaces) as obtained with:

	rxdebug grand.mit.edu -version

from the openafs package.
Signed-off-by: David Howells <dhowells@redhat.com>

include/rxrpc/packet.h

@@ -47,7 +47,8 @@ struct rxrpc_header {
 #define RXRPC_PACKET_TYPE_CHALLENGE	6	/* connection security challenge (SRVR->CLNT) */
 #define RXRPC_PACKET_TYPE_RESPONSE	7	/* connection secutity response (CLNT->SRVR) */
 #define RXRPC_PACKET_TYPE_DEBUG		8	/* debug info request */
-#define RXRPC_N_PACKET_TYPES		9	/* number of packet types (incl type 0) */
+#define RXRPC_PACKET_TYPE_VERSION	13	/* version string request */
+#define RXRPC_N_PACKET_TYPES		14	/* number of packet types (incl type 0) */
 
 	uint8_t		flags;		/* packet flags */
 #define RXRPC_CLIENT_INITIATED	0x01		/* signifies a packet generated by a client */

net/rxrpc/ar-input.c

@@ -28,7 +28,7 @@
 const char *rxrpc_pkts[] = {
 	"?00",
 	"DATA", "ACK", "BUSY", "ABORT", "ACKALL", "CHALL", "RESP", "DEBUG",
-	"?09", "?10", "?11", "?12", "?13", "?14", "?15"
+	"?09", "?10", "?11", "?12", "VERSION", "?14", "?15"
 };
 
 /*
@@ -593,6 +593,20 @@ static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
 	rxrpc_queue_conn(conn);
 }
 
+/*
+ * post endpoint-level events to the local endpoint
+ * - this includes debug and version messages
+ */
+static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
+				       struct sk_buff *skb)
+{
+	_enter("%p,%p", local, skb);
+
+	atomic_inc(&local->usage);
+	skb_queue_tail(&local->event_queue, skb);
+	rxrpc_queue_work(&local->event_processor);
+}
+
 static struct rxrpc_connection *rxrpc_conn_from_local(struct rxrpc_local *local,
 					       struct sk_buff *skb,
 					       struct rxrpc_skb_priv *sp)
@@ -699,6 +713,11 @@ void rxrpc_data_ready(struct sock *sk)
 		goto bad_message;
 	}
 
+	if (sp->hdr.type == RXRPC_PACKET_TYPE_VERSION) {
+		rxrpc_post_packet_to_local(local, skb);
+		goto out;
+	}
+	
 	if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
 	    (sp->hdr.callNumber == 0 || sp->hdr.seq == 0))
 		goto bad_message;
@@ -731,6 +750,8 @@ void rxrpc_data_ready(struct sock *sk)
 		else
 			goto cant_route_call;
 	}
+
+out:
 	rxrpc_put_local(local);
 	return;
 

net/rxrpc/ar-internal.h

@@ -152,11 +152,13 @@ struct rxrpc_local {
 	struct work_struct	destroyer;	/* endpoint destroyer */
 	struct work_struct	acceptor;	/* incoming call processor */
 	struct work_struct	rejecter;	/* packet reject writer */
+	struct work_struct	event_processor; /* endpoint event processor */
 	struct list_head	services;	/* services listening on this endpoint */
 	struct list_head	link;		/* link in endpoint list */
 	struct rw_semaphore	defrag_sem;	/* control re-enablement of IP DF bit */
 	struct sk_buff_head	accept_queue;	/* incoming calls awaiting acceptance */
 	struct sk_buff_head	reject_queue;	/* packets awaiting rejection */
+	struct sk_buff_head	event_queue;	/* endpoint event packets awaiting processing */
 	spinlock_t		lock;		/* access lock */
 	rwlock_t		services_lock;	/* lock for services list */
 	atomic_t		usage;

net/rxrpc/ar-local.c

@@ -13,16 +13,22 @@
 #include <linux/net.h>
 #include <linux/skbuff.h>
 #include <linux/slab.h>
+#include <linux/udp.h>
+#include <linux/ip.h>
 #include <net/sock.h>
 #include <net/af_rxrpc.h>
+#include <generated/utsrelease.h>
 #include "ar-internal.h"
 
+static const char rxrpc_version_string[65] = "linux-" UTS_RELEASE " AF_RXRPC";
+
 static LIST_HEAD(rxrpc_locals);
 DEFINE_RWLOCK(rxrpc_local_lock);
 static DECLARE_RWSEM(rxrpc_local_sem);
 static DECLARE_WAIT_QUEUE_HEAD(rxrpc_local_wq);
 
 static void rxrpc_destroy_local(struct work_struct *work);
+static void rxrpc_process_local_events(struct work_struct *work);
 
 /*
  * allocate a new local
@@ -37,11 +43,13 @@ struct rxrpc_local *rxrpc_alloc_local(struct sockaddr_rxrpc *srx)
 		INIT_WORK(&local->destroyer, &rxrpc_destroy_local);
 		INIT_WORK(&local->acceptor, &rxrpc_accept_incoming_calls);
 		INIT_WORK(&local->rejecter, &rxrpc_reject_packets);
+		INIT_WORK(&local->event_processor, &rxrpc_process_local_events);
 		INIT_LIST_HEAD(&local->services);
 		INIT_LIST_HEAD(&local->link);
 		init_rwsem(&local->defrag_sem);
 		skb_queue_head_init(&local->accept_queue);
 		skb_queue_head_init(&local->reject_queue);
+		skb_queue_head_init(&local->event_queue);
 		spin_lock_init(&local->lock);
 		rwlock_init(&local->services_lock);
 		atomic_set(&local->usage, 1);
@@ -264,10 +272,12 @@ static void rxrpc_destroy_local(struct work_struct *work)
 	ASSERT(list_empty(&local->services));
 	ASSERT(!work_pending(&local->acceptor));
 	ASSERT(!work_pending(&local->rejecter));
+	ASSERT(!work_pending(&local->event_processor));
 
 	/* finish cleaning up the local descriptor */
 	rxrpc_purge_queue(&local->accept_queue);
 	rxrpc_purge_queue(&local->reject_queue);
+	rxrpc_purge_queue(&local->event_queue);
 	kernel_sock_shutdown(local->socket, SHUT_RDWR);
 	sock_release(local->socket);
 
@@ -308,3 +318,91 @@ void __exit rxrpc_destroy_all_locals(void)
 
 	_leave("");
 }
+
+/*
+ * Reply to a version request
+ */
+static void rxrpc_send_version_request(struct rxrpc_local *local,
+				       struct rxrpc_header *hdr,
+				       struct sk_buff *skb)
+{
+	struct sockaddr_in sin;
+	struct msghdr msg;
+	struct kvec iov[2];
+	size_t len;
+	int ret;
+
+	_enter("");
+
+	sin.sin_family = AF_INET;
+	sin.sin_port = udp_hdr(skb)->source;
+	sin.sin_addr.s_addr = ip_hdr(skb)->saddr;
+
+	msg.msg_name	= &sin;
+	msg.msg_namelen	= sizeof(sin);
+	msg.msg_control	= NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags	= 0;
+
+	hdr->seq	= 0;
+	hdr->serial	= 0;
+	hdr->type	= RXRPC_PACKET_TYPE_VERSION;
+	hdr->flags	= RXRPC_LAST_PACKET | (~hdr->flags & RXRPC_CLIENT_INITIATED);
+	hdr->userStatus	= 0;
+	hdr->_rsvd	= 0;
+
+	iov[0].iov_base	= hdr;
+	iov[0].iov_len	= sizeof(*hdr);
+	iov[1].iov_base	= (char *)rxrpc_version_string;
+	iov[1].iov_len	= sizeof(rxrpc_version_string);
+
+	len = iov[0].iov_len + iov[1].iov_len;
+
+	_proto("Tx VERSION (reply)");
+
+	ret = kernel_sendmsg(local->socket, &msg, iov, 2, len);
+	if (ret < 0)
+		_debug("sendmsg failed: %d", ret);
+
+	_leave("");
+}
+
+/*
+ * Process event packets targetted at a local endpoint.
+ */
+static void rxrpc_process_local_events(struct work_struct *work)
+{
+	struct rxrpc_local *local = container_of(work, struct rxrpc_local, event_processor);
+	struct sk_buff *skb;
+	char v;
+
+	_enter("");
+
+	atomic_inc(&local->usage);
+	
+	while ((skb = skb_dequeue(&local->event_queue))) {
+		struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+
+		kdebug("{%d},{%u}", local->debug_id, sp->hdr.type);
+
+		switch (sp->hdr.type) {
+		case RXRPC_PACKET_TYPE_VERSION:
+			if (skb_copy_bits(skb, 0, &v, 1) < 0)
+				return;
+			_proto("Rx VERSION { %02x }", v);
+			if (v == 0)
+				rxrpc_send_version_request(local, &sp->hdr, skb);
+			break;
+
+		default:
+			/* Just ignore anything we don't understand */
+			break;
+		}
+
+		rxrpc_put_local(local);
+		rxrpc_free_skb(skb);
+	}
+
+	rxrpc_put_local(local);
+	_leave("");
+}