[IPV6]: Generalise tcp_v6_search_req & tcp_v6_synq_add

More work is needed tho to introduce inet6_request_sock from
tcp6_request_sock, in the same layout considerations as ipv6_pinfo in
inet_sock, next changeset will do that.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/inet6_connection_sock.c

@@ -0,0 +1,96 @@
+/*
+ * INET        An implementation of the TCP/IP protocol suite for the LINUX
+ *             operating system.  INET is implemented using the  BSD Socket
+ *             interface as the means of communication with the user level.
+ *
+ *             Support for INET6 connection oriented protocols.
+ *
+ * Authors:    See the TCPv6 sources
+ *
+ *             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 <linux/config.h>
+#include <linux/module.h>
+#include <linux/in6.h>
+#include <linux/ipv6.h>
+#include <linux/jhash.h>
+
+#include <net/addrconf.h>
+#include <net/inet_connection_sock.h>
+#include <net/sock.h>
+
+/*
+ * request_sock (formerly open request) hash tables.
+ */
+static u32 inet6_synq_hash(const struct in6_addr *raddr, const u16 rport,
+			   const u32 rnd, const u16 synq_hsize)
+{
+	u32 a = raddr->s6_addr32[0];
+	u32 b = raddr->s6_addr32[1];
+	u32 c = raddr->s6_addr32[2];
+
+	a += JHASH_GOLDEN_RATIO;
+	b += JHASH_GOLDEN_RATIO;
+	c += rnd;
+	__jhash_mix(a, b, c);
+
+	a += raddr->s6_addr32[3];
+	b += (u32)rport;
+	__jhash_mix(a, b, c);
+
+	return c & (synq_hsize - 1);
+}
+
+struct request_sock *inet6_csk_search_req(const struct sock *sk,
+					  struct request_sock ***prevp,
+					  const __u16 rport,
+					  const struct in6_addr *raddr,
+					  const struct in6_addr *laddr,
+					  const int iif)
+{
+	const struct inet_connection_sock *icsk = inet_csk(sk);
+	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
+	struct request_sock *req, **prev;
+
+	for (prev = &lopt->syn_table[inet6_synq_hash(raddr, rport,
+						     lopt->hash_rnd,
+						     lopt->nr_table_entries)];
+	     (req = *prev) != NULL;
+	     prev = &req->dl_next) {
+		const struct tcp6_request_sock *treq = tcp6_rsk(req);
+
+		if (inet_rsk(req)->rmt_port == rport &&
+		    req->rsk_ops->family == AF_INET6 &&
+		    ipv6_addr_equal(&treq->rmt_addr, raddr) &&
+		    ipv6_addr_equal(&treq->loc_addr, laddr) &&
+		    (!treq->iif || treq->iif == iif)) {
+			BUG_TRAP(req->sk == NULL);
+			*prevp = prev;
+			return req;
+		}
+	}
+
+	return NULL;
+}
+
+EXPORT_SYMBOL_GPL(inet6_csk_search_req);
+
+void inet6_csk_reqsk_queue_hash_add(struct sock *sk,
+				    struct request_sock *req,
+				    const unsigned long timeout)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
+	const u32 h = inet6_synq_hash(&tcp6_rsk(req)->rmt_addr,
+				      inet_rsk(req)->rmt_port,
+				      lopt->hash_rnd, lopt->nr_table_entries);
+
+	reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
+	inet_csk_reqsk_queue_added(sk, timeout);
+}
+
+EXPORT_SYMBOL_GPL(inet6_csk_reqsk_queue_hash_add);