[PATCH v5 03/19] flow: Record the pifs for each side of each flow

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

Currently we have no generic information flows apart from the type and
state, everything else is specific to the flow type.  Start introducing
generic flow information by recording the pifs which the flow connects.

To keep track of what information is valid, introduce new flow states:
INI for when the initiating side information is complete, and FWD for when
both sides information is complete.  For now, these states seem like busy
work, but they'll become more important as we add more generic information.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 flow.c       | 56 +++++++++++++++++++++++++++++++++++++++++++++++-----
 flow.h       | 49 ++++++++++++++++++++++++++++++++++++++-------
 flow_table.h |  3 +++
 icmp.c       |  2 ++
 pif.h        |  1 -
 tcp.c        | 10 +++++++++-
 tcp_splice.c |  1 +
 7 files changed, 108 insertions(+), 14 deletions(-)

diff --git a/flow.c b/flow.c
index 7456021..aee2736 100644
--- a/flow.c
+++ b/flow.c
@@ -21,6 +21,8 @@
 const char *flow_state_str[] = {
 	[FLOW_STATE_FREE]	= "FREE",
 	[FLOW_STATE_NEW]	= "NEW",
+	[FLOW_STATE_INI]	= "INI",
+	[FLOW_STATE_FWD]	= "FWD",
 	[FLOW_STATE_TYPED]	= "TYPED",
 	[FLOW_STATE_ACTIVE]	= "ACTIVE",
 };
@@ -146,22 +148,63 @@ static void flow_set_state(struct flow_common *f, enum flow_state state)
 	f->state = state;
 	flow_log_(f, LOG_DEBUG, "%s -> %s", flow_state_str[oldstate],
 		  FLOW_STATE(f));
+
+	if (MAX(state, oldstate) >= FLOW_STATE_FWD)
+		flow_log_(f, LOG_DEBUG, "%s => %s", pif_name(f->pif[INISIDE]),
+			                            pif_name(f->pif[FWDSIDE]));
+	else if (MAX(state, oldstate) >= FLOW_STATE_INI)
+		flow_log_(f, LOG_DEBUG, "%s => ?", pif_name(f->pif[INISIDE]));
 }
 
 /**
- * flow_set_type() - Set type and mvoe to TYPED state
+ * flow_initiate() - Move flow to INI state, setting INISIDE details
  * @flow:	Flow to change state
- * @type:	Type for new flow
- *
- * Return: @flow
+ * @pif:	pif of the initiating side
+ */
+void flow_initiate(union flow *flow, uint8_t pif)
+{
+	struct flow_common *f = &flow->f;
+
+	ASSERT(pif != PIF_NONE);
+	ASSERT(flow_new_entry == flow && f->state == FLOW_STATE_NEW);
+	ASSERT(f->type == FLOW_TYPE_NONE);
+	ASSERT(f->pif[INISIDE] == PIF_NONE && f->pif[FWDSIDE] == PIF_NONE);
+
+	f->pif[INISIDE] = pif;
+	flow_set_state(f, FLOW_STATE_INI);
+}
+
+/**
+ * flow_forward() - Move flow to FWD state, setting FWDSIDE details
+ * @flow:	Flow to change state
+ * @pif:	pif of the forwarded side
+ */
+void flow_forward(union flow *flow, uint8_t pif)
+{
+	struct flow_common *f = &flow->f;
+
+	ASSERT(pif != PIF_NONE);
+	ASSERT(flow_new_entry == flow && f->state == FLOW_STATE_INI);
+	ASSERT(f->type == FLOW_TYPE_NONE);
+	ASSERT(f->pif[INISIDE] != PIF_NONE && f->pif[FWDSIDE] == PIF_NONE);
+
+	f->pif[FWDSIDE] = pif;
+	flow_set_state(f, FLOW_STATE_FWD);
+}
+
+/**
+ * flow_set_type() - Set type and move to TYPED state
+ * @flow:	Flow to change state
+ * @pif:	pif of the initiating side
  */
 union flow *flow_set_type(union flow *flow, enum flow_type type)
 {
 	struct flow_common *f = &flow->f;
 
 	ASSERT(type != FLOW_TYPE_NONE);
-	ASSERT(flow_new_entry == flow && f->state == FLOW_STATE_NEW);
+	ASSERT(flow_new_entry == flow && f->state == FLOW_STATE_FWD);
 	ASSERT(f->type == FLOW_TYPE_NONE);
+	ASSERT(f->pif[INISIDE] != PIF_NONE && f->pif[FWDSIDE] != PIF_NONE);
 
 	f->type = type;
 	flow_set_state(f, FLOW_STATE_TYPED);
@@ -175,6 +218,7 @@ union flow *flow_set_type(union flow *flow, enum flow_type type)
 void flow_activate(struct flow_common *f)
 {
 	ASSERT(&flow_new_entry->f == f && f->state == FLOW_STATE_TYPED);
+	ASSERT(f->pif[INISIDE] != PIF_NONE && f->pif[FWDSIDE] != PIF_NONE);
 
 	flow_set_state(f, FLOW_STATE_ACTIVE);
 	flow_new_entry = NULL;
@@ -234,6 +278,8 @@ void flow_alloc_cancel(union flow *flow)
 {
 	ASSERT(flow_new_entry == flow);
 	ASSERT(flow->f.state == FLOW_STATE_NEW ||
+	       flow->f.state == FLOW_STATE_INI ||
+	       flow->f.state == FLOW_STATE_FWD ||
 	       flow->f.state == FLOW_STATE_TYPED);
 	ASSERT(flow_first_free > FLOW_IDX(flow));
 
diff --git a/flow.h b/flow.h
index 28169a8..9871e3b 100644
--- a/flow.h
+++ b/flow.h
@@ -25,25 +25,56 @@
  *    NEW - Freshly allocated, uninitialised entry
  *        Operations:
  *            - flow_alloc_cancel() returns the entry to FREE state
+ *            - flow_initiate() sets the entry's INISIDE details and moves to
+ *              INI state
  *            - FLOW_SET_TYPE() sets the entry's type and moves to TYPED state
  *        Caveats:
  *            - No fields other than state may be accessed.
- *            - At most one entry may be in NEW or TYPED state at a time, so it's
- *              unsafe to use flow_alloc() again until this entry moves to
- *              ACTIVE or FREE state 
+ *            - At most one entry may be in NEW, INI, FWD or TYPED state at a
+ *              time, so it's unsafe to use flow_alloc() again until this entry
+ *              moves to ACTIVE or FREE state 
  *            - You may not return to the main epoll loop while an entry is in
  *              NEW state.
  *
+ *    INI - An entry with INISIDE common information completed
+ *        Operations:
+ *            - Common fields related to INISIDE may be read
+ *            - flow_alloc_cancel() returns the entry to FREE state
+ *            - flow_forward() sets the entry's FWDSIDE details and moves to FWD
+ *              state
+ *        Caveats:
+ *            - Other common fields may not be read
+ *            - Type specific fields may not be read or written
+ *            - At most one entry may be in NEW, INI, FWD or TYPED state at a
+ *              time, so it's unsafe to use flow_alloc() again until this entry
+ *              moves to ACTIVE or FREE state 
+ *            - You may not return to the main epoll loop while an entry is in
+ *              INI state.
+ *
+ *    FWD - An entry with only INISIDE and FWDSIDE common information completed
+ *        Operations:
+ *            - Common fields related to INISIDE & FWDSIDE may be read
+ *            - flow_alloc_cancel() returns the entry to FREE state
+ *            - FLOW_SET_TYPE() sets the entry's type and moves to TYPED state
+ *        Caveats:
+ *            - Other common fields may not be read
+ *            - Type specific fields may not be read or written
+ *            - At most one entry may be in NEW, INI, FWD or TYPED state at a
+ *              time, so it's unsafe to use flow_alloc() again until this entry
+ *              moves to ACTIVE or FREE state 
+ *            - You may not return to the main epoll loop while an entry is in
+ *              FWD state.
+ *
  *    TYPED - Generic info initialised, type specific initialisation underway
  *        Operations:
  *            - All common fields may be read
  *            - Type specific fields may be read and written
  *            - flow_alloc_cancel() returns the entry to FREE state
- *            - FLOW_ACTIVATE() moves the entry to ACTIVE STATE
+ *            - FLOW_ACTIVATE() moves the entry to ACTIVE state
  *        Caveats:
- *            - At most one entry may be in NEW or TYPED state at a time, so it's
- *              unsafe to use flow_alloc() again until this entry moves to
- *              ACTIVE or FREE state 
+ *            - At most one entry may be in NEW, INI, FWD or TYPED state at a
+ *              time, so it's unsafe to use flow_alloc() again until this entry
+ *              moves to ACTIVE or FREE state 
  *            - You may not return to the main epoll loop while an entry is in
  *              TYPED state.
  *
@@ -59,6 +90,8 @@
 enum flow_state {
 	FLOW_STATE_FREE,
 	FLOW_STATE_NEW,
+	FLOW_STATE_INI,
+	FLOW_STATE_FWD,
 	FLOW_STATE_TYPED,
 	FLOW_STATE_ACTIVE,
 
@@ -104,10 +137,12 @@ extern const uint8_t flow_proto[];
  * 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
  */
 struct flow_common {
 	uint8_t		state;
 	uint8_t		type;
+	uint8_t		pif[SIDES];
 };
 
 #define FLOW_INDEX_BITS		17	/* 128k - 1 */
diff --git a/flow_table.h b/flow_table.h
index 7c98195..01c9326 100644
--- a/flow_table.h
+++ b/flow_table.h
@@ -107,6 +107,9 @@ 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);
+void flow_forward(union flow *flow, uint8_t pif);
+
 union flow *flow_set_type(union flow *flow, enum flow_type type);
 #define FLOW_SET_TYPE(flow_, t_, var_)	(&flow_set_type((flow_), (t_))->var_)
 
diff --git a/icmp.c b/icmp.c
index 6df0989..f5b8405 100644
--- a/icmp.c
+++ b/icmp.c
@@ -163,6 +163,8 @@ static struct icmp_ping_flow *icmp_ping_new(const struct ctx *c,
 	if (!flow)
 		return NULL;
 
+	flow_initiate(flow, PIF_TAP);
+	flow_forward(flow, PIF_HOST);
 	pingf = FLOW_SET_TYPE(flow, flowtype, ping);
 
 	pingf->seq = -1;
diff --git a/pif.h b/pif.h
index bd52936..ca85b34 100644
--- a/pif.h
+++ b/pif.h
@@ -38,7 +38,6 @@ static inline const char *pif_type(enum pif_type pt)
 		return "?";
 }
 
-/* cppcheck-suppress unusedFunction */
 static inline const char *pif_name(uint8_t pif)
 {
 	return pif_type(pif);
diff --git a/tcp.c b/tcp.c
index 06401ba..48aae30 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1950,6 +1950,8 @@ static void tcp_conn_from_tap(struct ctx *c, sa_family_t af,
 	if (!(flow = flow_alloc()))
 		return;
 
+	flow_initiate(flow, PIF_TAP);
+
 	if (af == AF_INET) {
 		if (IN4_IS_ADDR_UNSPECIFIED(saddr) ||
 		    IN4_IS_ADDR_BROADCAST(saddr) ||
@@ -2002,6 +2004,7 @@ static void tcp_conn_from_tap(struct ctx *c, sa_family_t af,
 			goto cancel;
 	}
 
+	flow_forward(flow, PIF_HOST);
 	conn = FLOW_SET_TYPE(flow, FLOW_TCP, tcp);
 	conn->tapside = INISIDE;
 	conn->sock = s;
@@ -2722,7 +2725,10 @@ static void tcp_tap_conn_from_sock(struct ctx *c, in_port_t dstport,
 				   const union sockaddr_inany *sa,
 				   const struct timespec *now)
 {
-	struct tcp_tap_conn *conn = FLOW_SET_TYPE(flow, FLOW_TCP, tcp);
+	struct tcp_tap_conn *conn;
+
+	flow_forward(flow, PIF_TAP);
+	conn = FLOW_SET_TYPE(flow, FLOW_TCP, tcp);
 
 	conn->tapside = FWDSIDE;
 	conn->sock = s;
@@ -2771,6 +2777,8 @@ void tcp_listen_handler(struct ctx *c, union epoll_ref ref,
 	if (s < 0)
 		goto cancel;
 
+	flow_initiate(flow, ref.tcp_listen.pif);
+
 	if (sa.sa_family == AF_INET) {
 		const struct in_addr *addr = &sa.sa4.sin_addr;
 		in_port_t port = sa.sa4.sin_port;
diff --git a/tcp_splice.c b/tcp_splice.c
index 5da7021..0e02732 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -472,6 +472,7 @@ bool tcp_splice_conn_from_sock(const struct ctx *c,
 		return false;
 	}
 
+	flow_forward(flow, pif1);
 	conn = FLOW_SET_TYPE(flow, FLOW_TCP_SPLICE, tcp_splice);
 
 	conn->flags = af == AF_INET ? 0 : SPLICE_V6;
-- 
@@ -472,6 +472,7 @@ bool tcp_splice_conn_from_sock(const struct ctx *c,
 		return false;
 	}
 
+	flow_forward(flow, pif1);
 	conn = FLOW_SET_TYPE(flow, FLOW_TCP_SPLICE, tcp_splice);
 
 	conn->flags = af == AF_INET ? 0 : SPLICE_V6;
-- 
2.45.0