[PATCH v2 06/15] fwd: Store forwarding tables indexed by (origin) pif

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

Currently we store the inbound (PIF_HOST) and outbound (PIF_SPLICE)
forwarding tables in separate fields of struct ctx.  In a number of places
this requires somewhat awkward if or switch constructs to select the
right table for updates.  Conceptually simplify that by using an index of
forwarding tables by pif, which as a bonus keeps track generically which
pifs have implemented forwarding tables so far.

For now this doesn't simplify a lot textually, because many places that
need this also have other special cases to apply by pif.  It does simplify
a few crucial places though, and we expect it will become more useful as
the flexibility of the forwarding table is improved.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 conf.c  | 53 +++++++++++++++++++++++++++-------------------
 flow.c  | 22 +++++++------------
 fwd.c   | 65 ++++++++++++++++++++++++++++++---------------------------
 fwd.h   |  4 ++--
 passt.h |  3 +--
 5 files changed, 77 insertions(+), 70 deletions(-)

diff --git a/conf.c b/conf.c
index 940fb9e9..6af3c8a5 100644
--- a/conf.c
+++ b/conf.c
@@ -1252,11 +1252,12 @@ dns6:
 		}
 	}
 
-	info("Inbound forwarding:");
-	fwd_rules_print(&c->fwd_in);
-	if (c->mode == MODE_PASTA) {
-		info("Outbound forwarding:");
-		fwd_rules_print(&c->fwd_out);
+	for (i = 0; i < PIF_NUM_TYPES; i++) {
+		if (!c->fwd[i])
+			continue;
+
+		info("Forwarding from %s:", pif_name(i));
+		fwd_rules_print(c->fwd[i]);
 	}
 }
 
@@ -2154,18 +2155,24 @@ void conf(struct ctx *c, int argc, char **argv)
 
 	/* Forwarding options can be parsed now, after IPv4/IPv6 settings */
 	fwd_probe_ephemeral();
+	fwd_rule_init(c);
 	optind = 0;
 	do {
 		name = getopt_long(argc, argv, optstring, options, NULL);
 
-		if (name == 't')
-			conf_ports(c, name, optarg, &c->fwd_in, &tcp_in_mode);
-		else if (name == 'u')
-			conf_ports(c, name, optarg, &c->fwd_in, &udp_in_mode);
-		else if (name == 'T')
-			conf_ports(c, name, optarg, &c->fwd_out, &tcp_out_mode);
-		else if (name == 'U')
-			conf_ports(c, name, optarg, &c->fwd_out, &udp_out_mode);
+		if (name == 't') {
+			conf_ports(c, name, optarg, c->fwd[PIF_HOST],
+				   &tcp_in_mode);
+		} else if (name == 'u') {
+			conf_ports(c, name, optarg, c->fwd[PIF_HOST],
+				   &udp_in_mode);
+		} else if (name == 'T') {
+			conf_ports(c, name, optarg, c->fwd[PIF_SPLICE],
+				   &tcp_out_mode);
+		} else if (name == 'U') {
+			conf_ports(c, name, optarg, c->fwd[PIF_SPLICE],
+				   &udp_out_mode);
+		}
 	} while (name != -1);
 
 	if (c->mode == MODE_PASTA)
@@ -2224,20 +2231,24 @@ void conf(struct ctx *c, int argc, char **argv)
 		udp_out_mode = fwd_default;
 
 	if (tcp_in_mode == FWD_MODE_AUTO) {
-		conf_ports_range_except(c, 't', "auto", &c->fwd_in, NULL, NULL,
-					1, NUM_PORTS - 1, NULL, 1, FWD_SCAN);
+		conf_ports_range_except(c, 't', "auto", c->fwd[PIF_HOST],
+					NULL, NULL, 1, NUM_PORTS - 1, NULL, 1,
+					FWD_SCAN);
 	}
 	if (tcp_out_mode == FWD_MODE_AUTO) {
-		conf_ports_range_except(c, 'T', "auto", &c->fwd_out, NULL, "lo",
-					1, NUM_PORTS - 1, NULL, 1, FWD_SCAN);
+		conf_ports_range_except(c, 'T', "auto", c->fwd[PIF_SPLICE],
+					NULL, "lo", 1, NUM_PORTS - 1, NULL, 1,
+					FWD_SCAN);
 	}
 	if (udp_in_mode == FWD_MODE_AUTO) {
-		conf_ports_range_except(c, 'u', "auto", &c->fwd_in, NULL, NULL,
-					1, NUM_PORTS - 1, NULL, 1, FWD_SCAN);
+		conf_ports_range_except(c, 'u', "auto", c->fwd[PIF_HOST],
+					NULL, NULL, 1, NUM_PORTS - 1, NULL, 1,
+					FWD_SCAN);
 	}
 	if (udp_out_mode == FWD_MODE_AUTO) {
-		conf_ports_range_except(c, 'U', "auto", &c->fwd_out, NULL, "lo",
-					1, NUM_PORTS - 1, NULL, 1, FWD_SCAN);
+		conf_ports_range_except(c, 'U', "auto", c->fwd[PIF_SPLICE],
+					NULL, "lo", 1, NUM_PORTS - 1, NULL, 1,
+					FWD_SCAN);
 	}
 
 	if (!c->quiet)
diff --git a/flow.c b/flow.c
index 81333dbc..11cd5752 100644
--- a/flow.c
+++ b/flow.c
@@ -503,10 +503,10 @@ struct flowside *flow_target(const struct ctx *c, union flow *flow,
 {
 	char estr[INANY_ADDRSTRLEN], ostr[INANY_ADDRSTRLEN];
 	struct flow_common *f = &flow->f;
+	const struct fwd_table *fwd = c->fwd[f->pif[INISIDE]];
 	const struct flowside *ini = &f->side[INISIDE];
 	struct flowside *tgt = &f->side[TGTSIDE];
 	const struct fwd_rule *rule = NULL;
-	const struct fwd_table *fwd;
 	uint8_t tgtpif = PIF_NONE;
 
 	assert(flow_new_entry == flow && f->state == FLOW_STATE_INI);
@@ -514,6 +514,11 @@ struct flowside *flow_target(const struct ctx *c, union flow *flow,
 	assert(f->pif[INISIDE] != PIF_NONE && f->pif[TGTSIDE] == PIF_NONE);
 	assert(flow->f.state == FLOW_STATE_INI);
 
+	if (fwd) {
+		if (!(rule = fwd_rule_search(fwd, ini, proto, rule_hint)))
+			goto norule;
+	}
+
 	switch (f->pif[INISIDE]) {
 	case PIF_TAP:
 		memcpy(f->tap_omac, MAC_UNDEF, ETH_ALEN);
@@ -521,20 +526,10 @@ struct flowside *flow_target(const struct ctx *c, union flow *flow,
 		break;
 
 	case PIF_SPLICE:
-		fwd = &c->fwd_out;
-
-		if (!(rule = fwd_rule_search(fwd, ini, proto, rule_hint)))
-			goto norule;
-
 		tgtpif = fwd_nat_from_splice(rule, proto, ini, tgt);
 		break;
 
 	case PIF_HOST:
-		fwd = &c->fwd_in;
-
-		if (!(rule = fwd_rule_search(fwd, ini, proto, rule_hint)))
-			goto norule;
-
 		tgtpif = fwd_nat_from_host(c, rule, proto, ini, tgt);
 		fwd_neigh_mac_get(c, &tgt->oaddr, f->tap_omac);
 		break;
@@ -1014,8 +1009,7 @@ static int flow_migrate_source_rollback(struct ctx *c, unsigned bound, int ret)
 
 	debug("...roll back migration");
 
-	if (fwd_listen_sync(c, &c->fwd_in, PIF_HOST,
-			    &c->tcp.scan_in, &c->udp.scan_in) < 0)
+	if (fwd_listen_sync(c, PIF_HOST, &c->tcp.scan_in, &c->udp.scan_in) < 0)
 		die("Failed to re-establish listening sockets");
 
 	foreach_established_tcp_flow(flow) {
@@ -1148,7 +1142,7 @@ int flow_migrate_source(struct ctx *c, const struct migrate_stage *stage,
 	 * fix that is to not allow local to local migration, which arguably we
 	 * should (use namespaces for testing instead). */
 	debug("Stop listen()s");
-	fwd_listen_close(&c->fwd_in);
+	fwd_listen_close(c->fwd[PIF_HOST]);
 
 	debug("Sending %u flows", count);
 
diff --git a/fwd.c b/fwd.c
index 7844a674..3395a28e 100644
--- a/fwd.c
+++ b/fwd.c
@@ -331,6 +331,21 @@ bool fwd_port_is_ephemeral(in_port_t port)
 	return (port >= fwd_ephemeral_min) && (port <= fwd_ephemeral_max);
 }
 
+/* Forwarding table storage, generally accessed via pointers in struct ctx */
+static struct fwd_table fwd_in;
+static struct fwd_table fwd_out;
+
+/**
+ * fwd_rule_init() - Initialise forwarding tables
+ * @c:		Execution context
+ */
+void fwd_rule_init(struct ctx *c)
+{
+	c->fwd[PIF_HOST] = &fwd_in;
+	if (c->mode == MODE_PASTA)
+		c->fwd[PIF_SPLICE] = &fwd_out;
+}
+
 /**
  * fwd_rule_add() - Add a rule to a forwarding table
  * @fwd:	Table to add to
@@ -505,19 +520,17 @@ void fwd_rules_print(const struct fwd_table *fwd)
 
 /** fwd_sync_one() - Create or remove listening sockets for a forward entry
  * @c:		Execution context
- * @fwd:	Forwarding table
- * @idx:	Rule index
  * @pif:	Interface to create listening sockets for
+ * @idx:	Rule index
  * @tcp:	Bitmap of TCP ports to listen for on FWD_SCAN entries
  * @udp:	Bitmap of UDP ports to listen for on FWD_SCAN entries
  *
  * Return: 0 on success, -1 on failure
  */
-static int fwd_sync_one(const struct ctx *c, const struct fwd_table *fwd,
-			unsigned idx, uint8_t pif,
+static int fwd_sync_one(const struct ctx *c, uint8_t pif, unsigned idx,
 			const uint8_t *tcp, const uint8_t *udp)
 {
-	const struct fwd_rule *rule = &fwd->rules[idx];
+	const struct fwd_rule *rule = &c->fwd[pif]->rules[idx];
 	const union inany_addr *addr = fwd_rule_addr(rule);
 	const char *ifname = rule->ifname;
 	const uint8_t *map = NULL;
@@ -598,7 +611,6 @@ static int fwd_sync_one(const struct ctx *c, const struct fwd_table *fwd,
 
 /** struct fwd_listen_args - arguments for fwd_listen_init_()
  * @c:		Execution context
- * @fwd:	Forwarding table
  * @tcpmap:	Bitmap of TCP ports to auto-forward
  * @udpmap:	Bitmap of TCP ports to auto-forward
  * @pif:	Interface to create listening sockets for
@@ -606,7 +618,6 @@ static int fwd_sync_one(const struct ctx *c, const struct fwd_table *fwd,
  */
 struct fwd_listen_args {
 	const struct ctx *c;
-	const struct fwd_table *fwd;
 	const uint8_t *tcpmap, *udpmap;
 	uint8_t pif;
 	int ret;
@@ -625,9 +636,8 @@ static int fwd_listen_sync_(void *arg)
 	if (a->pif == PIF_SPLICE)
 		ns_enter(a->c);
 
-	for (i = 0; i < a->fwd->count; i++) {
-		a->ret = fwd_sync_one(a->c, a->fwd, i, a->pif,
-				      a->tcpmap, a->udpmap);
+	for (i = 0; i < a->c->fwd[a->pif]->count; i++) {
+		a->ret = fwd_sync_one(a->c, a->pif, i, a->tcpmap, a->udpmap);
 		if (a->ret < 0)
 			break;
 	}
@@ -637,21 +647,17 @@ static int fwd_listen_sync_(void *arg)
 
 /** fwd_listen_sync() - Call fwd_listen_sync_() in correct namespace
  * @c:		Execution context
- * @fwd:	Forwarding information
  * @pif:	Interface to create listening sockets for
  * @tcp:	Scanning state for TCP
  * @udp:	Scanning state for UDP
  *
  * Return: 0 on success, -1 on failure
  */
-int fwd_listen_sync(const struct ctx *c, const struct fwd_table *fwd,
-		    uint8_t pif,
+int fwd_listen_sync(const struct ctx *c, uint8_t pif,
 		    const struct fwd_scan *tcp, const struct fwd_scan *udp)
 {
 	struct fwd_listen_args a = {
-		.c = c, .fwd = fwd,
-		.tcpmap = tcp->map, .udpmap = udp->map,
-		.pif = pif,
+		.c = c, .tcpmap = tcp->map, .udpmap = udp->map, .pif = pif,
 	};
 
 	if (pif == PIF_SPLICE)
@@ -695,12 +701,11 @@ void fwd_listen_close(const struct fwd_table *fwd)
  */
 int fwd_listen_init(const struct ctx *c)
 {
-	if (fwd_listen_sync(c, &c->fwd_in, PIF_HOST,
-			    &c->tcp.scan_in, &c->udp.scan_in) < 0)
+	if (fwd_listen_sync(c, PIF_HOST, &c->tcp.scan_in, &c->udp.scan_in) < 0)
 		return -1;
 
 	if (c->mode == MODE_PASTA) {
-		if (fwd_listen_sync(c, &c->fwd_out, PIF_SPLICE,
+		if (fwd_listen_sync(c, PIF_SPLICE,
 				    &c->tcp.scan_out, &c->udp.scan_out) < 0)
 			return -1;
 	}
@@ -851,16 +856,16 @@ static void fwd_scan_ports(struct ctx *c)
 	uint8_t excl_tcp_out[PORT_BITMAP_SIZE], excl_udp_out[PORT_BITMAP_SIZE];
 	uint8_t excl_tcp_in[PORT_BITMAP_SIZE], excl_udp_in[PORT_BITMAP_SIZE];
 
-	current_listen_map(excl_tcp_out, &c->fwd_in, IPPROTO_TCP);
-	current_listen_map(excl_tcp_in, &c->fwd_out, IPPROTO_TCP);
-	current_listen_map(excl_udp_out, &c->fwd_in, IPPROTO_UDP);
-	current_listen_map(excl_udp_in, &c->fwd_out, IPPROTO_UDP);
+	current_listen_map(excl_tcp_out, c->fwd[PIF_HOST], IPPROTO_TCP);
+	current_listen_map(excl_tcp_in, c->fwd[PIF_SPLICE], IPPROTO_TCP);
+	current_listen_map(excl_udp_out, c->fwd[PIF_HOST], IPPROTO_UDP);
+	current_listen_map(excl_udp_in, c->fwd[PIF_SPLICE], IPPROTO_UDP);
 
-	fwd_scan_ports_tcp(&c->fwd_out, &c->tcp.scan_out, excl_tcp_out);
-	fwd_scan_ports_tcp(&c->fwd_in, &c->tcp.scan_in, excl_tcp_in);
-	fwd_scan_ports_udp(&c->fwd_out, &c->udp.scan_out,
+	fwd_scan_ports_tcp(c->fwd[PIF_SPLICE], &c->tcp.scan_out, excl_tcp_out);
+	fwd_scan_ports_tcp(c->fwd[PIF_HOST], &c->tcp.scan_in, excl_tcp_in);
+	fwd_scan_ports_udp(c->fwd[PIF_SPLICE], &c->udp.scan_out,
 			   &c->tcp.scan_out, excl_udp_out);
-	fwd_scan_ports_udp(&c->fwd_in, &c->udp.scan_in,
+	fwd_scan_ports_udp(c->fwd[PIF_HOST], &c->udp.scan_in,
 			   &c->tcp.scan_in, excl_udp_in);
 }
 
@@ -912,10 +917,8 @@ void fwd_scan_ports_timer(struct ctx *c, const struct timespec *now)
 
 	fwd_scan_ports(c);
 
-	fwd_listen_sync(c, &c->fwd_in, PIF_HOST,
-			&c->tcp.scan_in, &c->udp.scan_in);
-	fwd_listen_sync(c, &c->fwd_out, PIF_SPLICE,
-			&c->tcp.scan_out, &c->udp.scan_out);
+	fwd_listen_sync(c, PIF_HOST, &c->tcp.scan_in, &c->udp.scan_in);
+	fwd_listen_sync(c, PIF_SPLICE, &c->tcp.scan_out, &c->udp.scan_out);
 }
 
 /**
diff --git a/fwd.h b/fwd.h
index 958eee25..b387d926 100644
--- a/fwd.h
+++ b/fwd.h
@@ -108,6 +108,7 @@ struct fwd_scan {
 
 #define FWD_PORT_SCAN_INTERVAL		1000	/* ms */
 
+void fwd_rule_init(struct ctx *c);
 void fwd_rule_add(struct fwd_table *fwd, uint8_t proto, uint8_t flags,
 		  const union inany_addr *addr, const char *ifname,
 		  in_port_t first, in_port_t last, in_port_t to);
@@ -119,8 +120,7 @@ void fwd_rules_print(const struct fwd_table *fwd);
 void fwd_scan_ports_init(struct ctx *c);
 void fwd_scan_ports_timer(struct ctx * c, const struct timespec *now);
 
-int fwd_listen_sync(const struct ctx *c, const struct fwd_table *fwd,
-		    uint8_t pif,
+int fwd_listen_sync(const struct ctx *c, uint8_t pif,
 		    const struct fwd_scan *tcp, const struct fwd_scan *udp);
 void fwd_listen_close(const struct fwd_table *fwd);
 int fwd_listen_init(const struct ctx *c);
diff --git a/passt.h b/passt.h
index b614bdf0..5fc4e07f 100644
--- a/passt.h
+++ b/passt.h
@@ -264,8 +264,7 @@ struct ctx {
 	unsigned int pasta_ifi;
 	int pasta_conf_ns;
 
-	struct fwd_table fwd_in;
-	struct fwd_table fwd_out;
+	struct fwd_table *fwd[PIF_NUM_TYPES];
 
 	int no_tcp;
 	struct tcp_ctx tcp;
-- 
2.53.0