flow: Common address information for initiating side

Handling of each protocol needs some degree of tracking of the
addresses and ports at the end of each connection or flow.  Sometimes
that's explicit (as in the guest visible addresses for TCP
connections), sometimes implicit (the bound and connected addresses of
sockets).

To allow more consistent handling across protocols we want to
uniformly track the address and port at each end of the connection.
Furthermore, because we allow port remapping, and we sometimes need to
apply NAT, the addresses and ports can be different as seen by the
guest/namespace and as by the host.

Introduce 'struct flowside' to keep track of address and port
information related to one side of a flow. Store two of these in the
common fields of a flow to track that information for both sides.

For now we only populate the initiating side, requiring that
information be completed when a flows enter INI.  Later patches will
populate the target side.

For now this leaves some information redundantly recorded in both generic
and type specific fields.  We'll fix that in later patches.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

flow.c

@@ -108,6 +108,31 @@ static const union flow *flow_new_entry; /* = NULL */
 /* Last time the flow timers ran */
 static struct timespec flow_timer_run;
 
+/** flowside_from_af() - Initialise flowside from addresses
+ * @side:	flowside to initialise
+ * @af:		Address family (AF_INET or AF_INET6)
+ * @eaddr:	Endpoint address (pointer to in_addr or in6_addr)
+ * @eport:	Endpoint port
+ * @faddr:	Forwarding address (pointer to in_addr or in6_addr)
+ * @fport:	Forwarding port
+ */
+static void flowside_from_af(struct flowside *side, sa_family_t af,
+			     const void *eaddr, in_port_t eport,
+			     const void *faddr, in_port_t fport)
+{
+	if (faddr)
+		inany_from_af(&side->faddr, af, faddr);
+	else
+		side->faddr = inany_any6;
+	side->fport = fport;
+
+	if (eaddr)
+		inany_from_af(&side->eaddr, af, eaddr);
+	else
+		side->eaddr = inany_any6;
+	side->eport = eport;
+}
+
 /** flow_log_ - Log flow-related message
  * @f:		flow the message is related to
  * @pri:	Log priority
@@ -140,6 +165,8 @@ void flow_log_(const struct flow_common *f, int pri, const char *fmt, ...)
  */
 static void flow_set_state(struct flow_common *f, enum flow_state state)
 {
+	char estr[INANY_ADDRSTRLEN], fstr[INANY_ADDRSTRLEN];
+	const struct flowside *ini = &f->side[INISIDE];
 	uint8_t oldstate = f->state;
 
 	ASSERT(state < FLOW_NUM_STATES);
@@ -150,18 +177,28 @@ static void flow_set_state(struct flow_common *f, enum flow_state state)
 		  FLOW_STATE(f));
 
 	if (MAX(state, oldstate) >= FLOW_STATE_TGT)
-		flow_log_(f, LOG_DEBUG, "%s => %s", pif_name(f->pif[INISIDE]),
+		flow_log_(f, LOG_DEBUG, "%s [%s]:%hu -> [%s]:%hu => %s",
+			  pif_name(f->pif[INISIDE]),
+			  inany_ntop(&ini->eaddr, estr, sizeof(estr)),
+			  ini->eport,
+			  inany_ntop(&ini->faddr, fstr, sizeof(fstr)),
+			  ini->fport,
 			  pif_name(f->pif[TGTSIDE]));
 	else if (MAX(state, oldstate) >= FLOW_STATE_INI)
-		flow_log_(f, LOG_DEBUG, "%s => ?", pif_name(f->pif[INISIDE]));
+		flow_log_(f, LOG_DEBUG, "%s [%s]:%hu -> [%s]:%hu => ?",
+			  pif_name(f->pif[INISIDE]),
+			  inany_ntop(&ini->eaddr, estr, sizeof(estr)),
+			  ini->eport,
+			  inany_ntop(&ini->faddr, fstr, sizeof(fstr)),
+			  ini->fport);
 }
 
 /**
- * flow_initiate() - Move flow to INI, setting INISIDE details
+ * flow_initiate_() - Move flow to INI, setting pif[INISIDE]
  * @flow:	Flow to change state
  * @pif:	pif of the initiating side
  */
-void flow_initiate(union flow *flow, uint8_t pif)
+static void flow_initiate_(union flow *flow, uint8_t pif)
 {
 	struct flow_common *f = &flow->f;
 
@@ -174,6 +211,55 @@ void flow_initiate(union flow *flow, uint8_t pif)
 	flow_set_state(f, FLOW_STATE_INI);
 }
 
+/**
+ * flow_initiate_af() - Move flow to INI, setting INISIDE details
+ * @flow:	Flow to change state
+ * @pif:	pif of the initiating side
+ * @af:		Address family of @eaddr and @faddr
+ * @saddr:	Source address (pointer to in_addr or in6_addr)
+ * @sport:	Endpoint port
+ * @daddr:	Destination address (pointer to in_addr or in6_addr)
+ * @dport:	Destination port
+ *
+ * Return: pointer to the initiating flowside information
+ */
+const struct flowside *flow_initiate_af(union flow *flow, uint8_t pif,
+					sa_family_t af,
+					const void *saddr, in_port_t sport,
+					const void *daddr, in_port_t dport)
+{
+	struct flowside *ini = &flow->f.side[INISIDE];
+
+	flowside_from_af(ini, af, saddr, sport, daddr, dport);
+	flow_initiate_(flow, pif);
+	return ini;
+}
+
+/**
+ * flow_initiate_sa() - Move flow to INI, setting INISIDE details
+ * @flow:	Flow to change state
+ * @pif:	pif of the initiating side
+ * @ssa:	Source socket address
+ * @dport:	Destination port
+ *
+ * Return: pointer to the initiating flowside information
+ */
+const struct flowside *flow_initiate_sa(union flow *flow, uint8_t pif,
+					const union sockaddr_inany *ssa,
+					in_port_t dport)
+{
+	struct flowside *ini = &flow->f.side[INISIDE];
+
+	inany_from_sockaddr(&ini->eaddr, &ini->eport, ssa);
+	if (inany_v4(&ini->eaddr))
+		ini->faddr = inany_any4;
+	else
+		ini->faddr = inany_any6;
+	ini->fport = dport;
+	flow_initiate_(flow, pif);
+	return ini;
+}
+
 /**
  * flow_target() - Move flow to TGT, setting TGTSIDE details
  * @flow:	Flow to change state

flow.h

@@ -135,11 +135,26 @@ extern const uint8_t flow_proto[];
 #define INISIDE			0	/* Initiating side index */
 #define TGTSIDE			1	/* Target side index */
 
+/**
+ * struct flowside - Address information for one side of a flow
+ * @eaddr:	Endpoint address (remote address from passt's PoV)
+ * @faddr:	Forwarding address (local address from passt's PoV)
+ * @eport:	Endpoint port
+ * @fport:	Forwarding port
+ */
+struct flowside {
+	union inany_addr	faddr;
+	union inany_addr	eaddr;
+	in_port_t		fport;
+	in_port_t		eport;
+};
+
 /**
  * struct flow_common - Common fields for packet flows
  * @state:	State of the flow table entry
  * @type:	Type of packet flow
  * @pif[]:	Interface for each side of the flow
+ * @side[]:	Information for each side of the flow
  */
 struct flow_common {
 #ifdef __GNUC__
@@ -154,6 +169,7 @@ struct flow_common {
 		      "Not enough bits for type field");
 #endif
 	uint8_t		pif[SIDES];
+	struct flowside	side[SIDES];
 };
 
 #define FLOW_INDEX_BITS		17	/* 128k - 1 */

flow_table.h

@@ -127,7 +127,13 @@ static inline flow_sidx_t flow_sidx(const struct flow_common *f,
 union flow *flow_alloc(void);
 void flow_alloc_cancel(union flow *flow);
 
-void flow_initiate(union flow *flow, uint8_t pif);
+const struct flowside *flow_initiate_af(union flow *flow, uint8_t pif,
+					sa_family_t af,
+					const void *saddr, in_port_t sport,
+					const void *daddr, in_port_t dport);
+const struct flowside *flow_initiate_sa(union flow *flow, uint8_t pif,
+					const union sockaddr_inany *ssa,
+					in_port_t dport);
 void flow_target(union flow *flow, uint8_t pif);
 
 union flow *flow_set_type(union flow *flow, enum flow_type type);

icmp.c

@@ -162,12 +162,15 @@ static void icmp_ping_close(const struct ctx *c,
  * @id_sock:	Pointer to ping flow entry slot in icmp_id_map[] to update
  * @af:		Address family, AF_INET or AF_INET6
  * @id:		ICMP id for the new socket
+ * @saddr:	Source address
+ * @daddr:	Destination address
  *
  * Return: Newly opened ping flow, or NULL on failure
  */
 static struct icmp_ping_flow *icmp_ping_new(const struct ctx *c,
 					    struct icmp_ping_flow **id_sock,
-					    sa_family_t af, uint16_t id)
+					    sa_family_t af, uint16_t id,
+					    const void *saddr, const void *daddr)
 {
 	uint8_t flowtype = af == AF_INET ? FLOW_PING4 : FLOW_PING6;
 	union epoll_ref ref = { .type = EPOLL_TYPE_PING };
@@ -179,7 +182,7 @@ static struct icmp_ping_flow *icmp_ping_new(const struct ctx *c,
 	if (!flow)
 		return NULL;
 
-	flow_initiate(flow, PIF_TAP);
+	flow_initiate_af(flow, PIF_TAP, af, saddr, id, daddr, id);
 	flow_target(flow, PIF_HOST);
 	pingf = FLOW_SET_TYPE(flow, flowtype, ping);
 
@@ -285,7 +288,7 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 	}
 
 	if (!(pingf = *id_sock))
-		if (!(pingf = icmp_ping_new(c, id_sock, af, id)))
+		if (!(pingf = icmp_ping_new(c, id_sock, af, id, saddr, daddr)))
 			return 1;
 
 	pingf->ts = now->tv_sec;

passt.h

@@ -17,6 +17,9 @@ union epoll_ref;
 
 #include "pif.h"
 #include "packet.h"
+#include "siphash.h"
+#include "ip.h"
+#include "inany.h"
 #include "flow.h"
 #include "icmp.h"
 #include "fwd.h"

tcp.c

@@ -1666,7 +1666,7 @@ static void tcp_conn_from_tap(struct ctx *c, sa_family_t af,
 	if (!(flow = flow_alloc()))
 		return;
 
-	flow_initiate(flow, PIF_TAP);
+	flow_initiate_af(flow, PIF_TAP, af, saddr, srcport, daddr, dstport);
 
 	flow_target(flow, PIF_HOST);
 	conn = FLOW_SET_TYPE(flow, FLOW_TCP, tcp);
@@ -2351,7 +2351,9 @@ void tcp_listen_handler(struct ctx *c, union epoll_ref ref,
 	if (s < 0)
 		goto cancel;
 
-	flow_initiate(flow, ref.tcp_listen.pif);
+	/* FIXME: When listening port has a specific bound address, record that
+	 * as the forwarding address */
+	flow_initiate_sa(flow, ref.tcp_listen.pif, &sa, ref.tcp_listen.port);
 
 	if (sa.sa_family == AF_INET) {
 		const struct in_addr *addr = &sa.sa4.sin_addr;