[PATCH 3/3] fwd, fwd_rule: Implement configurable target address mapping

[David Gibson <david@gibson.dropbear.id.au>]

From: Stefano Brivio <sbrivio@redhat.com>

Add a 'taddr' field to forwarding rules, which controls the destination
address on the target side.  Since changing the structure alters the pesto
update protocol, bump the protocol version number

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
[dwg: Split from option parsing code, added protocol version bump,
 explicitly exclude splicing with target address for now]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 fwd.c      | 8 ++++++--
 fwd_rule.c | 9 +--------
 fwd_rule.h | 2 ++
 pesto.h    | 6 +++++-
 4 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/fwd.c b/fwd.c
index 659f8d9f..84400948 100644
--- a/fwd.c
+++ b/fwd.c
@@ -1023,7 +1023,9 @@ uint8_t fwd_nat_from_host(const struct ctx *c,
 	/* Common for spliced and non-spliced cases */
 	tgt->eport = rule->to + (ini->oport - rule->first);
 
-	if (!c->no_splice && inany_is_loopback(&ini->eaddr) &&
+	/* TODO: Allow splicing with specified target address */
+	if (!c->no_splice && inany_is_unspecified(&rule->taddr) &&
+	    inany_is_loopback(&ini->eaddr) &&
 	    (proto == IPPROTO_TCP || proto == IPPROTO_UDP)) {
 		/* spliceable */
 
@@ -1072,7 +1074,9 @@ uint8_t fwd_nat_from_host(const struct ctx *c,
 	}
 	tgt->oport = ini->eport;
 
-	if (inany_v4(&tgt->oaddr)) {
+	if (!inany_is_unspecified(&rule->taddr)) {
+		tgt->eaddr = rule->taddr;
+	} else if (inany_v4(&tgt->oaddr)) {
 		tgt->eaddr = inany_from_v4(c->ip4.addr_seen);
 	} else {
 		if (inany_is_linklocal6(&tgt->oaddr))
diff --git a/fwd_rule.c b/fwd_rule.c
index e8abc884..494d3fc3 100644
--- a/fwd_rule.c
+++ b/fwd_rule.c
@@ -393,6 +393,7 @@ static void fwd_rule_range_except(struct fwd_table *fwd, bool del,
 {
 	struct fwd_rule rule = {
 		.addr = addr ? *addr : inany_any6,
+		.taddr = tgt_addr ? *tgt_addr : inany_any6,
 		.ifname = { 0 },
 		.proto = proto,
 		.flags = flags,
@@ -401,14 +402,6 @@ static void fwd_rule_range_except(struct fwd_table *fwd, bool del,
 	unsigned delta = tgt_first - first;
 	unsigned base, i;
 
-	if (tgt_addr && !inany_is_unspecified(tgt_addr)) {
-		char astr[INANY_ADDRSTRLEN];
-
-		info("Target address: %s",
-		     inany_ntop(tgt_addr, astr, sizeof(astr)));
-		die("Target address remapping not yet implemented");
-	}
-
 	if (!addr)
 		rule.flags |= FWD_DUAL_STACK_ANY;
 	if (ifname) {
diff --git a/fwd_rule.h b/fwd_rule.h
index 435be5bd..c782f9d4 100644
--- a/fwd_rule.h
+++ b/fwd_rule.h
@@ -33,6 +33,7 @@
 /**
  * struct fwd_rule - Forwarding rule governing a range of ports
  * @addr:	Address to forward from
+ * @taddr:	Target side destination address
  * @ifname:	Interface to forward from
  * @first:	First port number to forward
  * @last:	Last port number to forward
@@ -45,6 +46,7 @@
  */
 struct fwd_rule {
 	union inany_addr addr;
+	union inany_addr taddr;
 	char ifname[IFNAMSIZ];
 	in_port_t first;
 	in_port_t last;
diff --git a/pesto.h b/pesto.h
index 980cc17d..8db701b4 100644
--- a/pesto.h
+++ b/pesto.h
@@ -15,7 +15,11 @@
 #define PESTO_SERVER_MAGIC	"basil:s"
 
 /* Version 0 is reserved for unreleased / unsupported experimental versions */
-#define PESTO_PROTOCOL_VERSION	1
+/* Version 1 had no target address field in struct fwd_rule.  It was released,
+ * but was little enough used that we decided not to implement backwards
+ * compatiblity code (i.e. a v2 pesto will not work with a v1 pasta)
+ */
+#define PESTO_PROTOCOL_VERSION	2
 
 /* Maximum size of a pif name, including \0 */
 #define	PIF_NAME_SIZE	(128)
-- 
2.54.0