[PATCH v2 05/10] flow: Introduce struct flowside, space for uniform tracking of addresses

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

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 general abd robust handling, and more consistency 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 the address and ports of a
flow from a single "side" (guest or host).  Store two of these in the
common fields of a flow to track that information for both sides.

For now we just introduce the structure and fields themselves, along with
some simple helpers.  Later patches will actually use these to store useful
information.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 flow.c | 22 ++++++++++++++++++++++
 flow.h | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/flow.c b/flow.c
index 12ca8db..a93cf8c 100644
--- a/flow.c
+++ b/flow.c
@@ -7,6 +7,7 @@
 
 #include <unistd.h>
 #include <string.h>
+#include <arpa/inet.h>
 
 #include "util.h"
 #include "passt.h"
@@ -24,6 +25,27 @@ const char *flow_type_str[] = {
 /* Global Flow Table */
 union flow flowtab[FLOW_MAX];
 
+/** flowside_fmt - Format a flowside as a string
+ * @fs:		flowside to format
+ * @buf:	Buffer into which to store the formatted version
+ * @size:	Size of @buf
+ *
+ * Return: pointer to formatted string describing @fs, or NULL on error
+ */
+/* cppcheck-suppress unusedFunction */
+const char *flowside_fmt(const struct flowside *fs, char *buf, size_t size)
+{
+	char ebuf[INET6_ADDRSTRLEN], fbuf[INET6_ADDRSTRLEN];
+
+	if (!inet_ntop(AF_INET6, &fs->eaddr, ebuf, sizeof(ebuf))
+	    || !inet_ntop(AF_INET6, &fs->faddr, fbuf, sizeof(fbuf)))
+		return NULL;
+
+	snprintf(buf, size, "[%s]:%hu <-> [%s]:%hu", fbuf, fs->fport,
+		 ebuf, fs->eport);
+	return (const char *)buf;
+}
+
 /**
  * flow_table_compact() - Perform compaction on flow table
  * @c:		Execution context
diff --git a/flow.h b/flow.h
index e212796..9891fcb 100644
--- a/flow.h
+++ b/flow.h
@@ -18,11 +18,59 @@ extern const char *flow_type_str[];
 #define FLOW_TYPE(f)							\
         ((f)->type <= FLOW_MAX ? flow_type_str[(f)->type] : "?")
 
+/**
+ * struct flowside - Describes a logical packet flow as seen from one "side"
+ * @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, eport;
+};
+
+/** flowside_from_af - Initialize a flowside from addresses
+ * @fs:		flowside to initialize
+ * @af:		Address family (AF_INET or AF_INET6)
+ * @faddr:	Forwarding address (pointer to in_addr or in6_addr)
+ * @fport:	Forwarding port
+ * @eaddr:	Endpoint address (pointer to in_addr or in6_addr)
+ * @eport:	Endpoint port
+ */
+static inline void flowside_from_af(struct flowside *fs, int af,
+				    const void *faddr, in_port_t fport,
+				    const void *eaddr, in_port_t eport)
+{
+	inany_from_af(&fs->faddr, af, faddr);
+	inany_from_af(&fs->eaddr, af, eaddr);
+	fs->fport = fport;
+	fs->eport = eport;
+}
+
+/** flowside_complete - Check if flowside is fully initialized
+ * @fs:		flowside to check
+ */
+static inline bool flowside_complete(const struct flowside *fs)
+{
+	return !IN6_IS_ADDR_UNSPECIFIED(&fs->faddr) &&
+		!IN6_IS_ADDR_UNSPECIFIED(&fs->eaddr) &&
+		fs->fport != 0 && fs->eport != 0;
+}
+
+#define FLOWSIDE_STRLEN		(2*(INET6_ADDRSTRLEN+8) + 6)
+
+const char *flowside_fmt(const struct flowside *fs, char *buf, size_t size);
+
 /**
  * struct flow_common - Common fields for packet flows
+ * @side[]:	Information on the flow for each side.  Flow types can have
+ *		their own conventions about which side is which
  * @type:	Type of packet flow
  */
 struct flow_common {
+	struct flowside		side[2];
 	enum flow_type		type;
 };
 
-- 
@@ -18,11 +18,59 @@ extern const char *flow_type_str[];
 #define FLOW_TYPE(f)							\
         ((f)->type <= FLOW_MAX ? flow_type_str[(f)->type] : "?")
 
+/**
+ * struct flowside - Describes a logical packet flow as seen from one "side"
+ * @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, eport;
+};
+
+/** flowside_from_af - Initialize a flowside from addresses
+ * @fs:		flowside to initialize
+ * @af:		Address family (AF_INET or AF_INET6)
+ * @faddr:	Forwarding address (pointer to in_addr or in6_addr)
+ * @fport:	Forwarding port
+ * @eaddr:	Endpoint address (pointer to in_addr or in6_addr)
+ * @eport:	Endpoint port
+ */
+static inline void flowside_from_af(struct flowside *fs, int af,
+				    const void *faddr, in_port_t fport,
+				    const void *eaddr, in_port_t eport)
+{
+	inany_from_af(&fs->faddr, af, faddr);
+	inany_from_af(&fs->eaddr, af, eaddr);
+	fs->fport = fport;
+	fs->eport = eport;
+}
+
+/** flowside_complete - Check if flowside is fully initialized
+ * @fs:		flowside to check
+ */
+static inline bool flowside_complete(const struct flowside *fs)
+{
+	return !IN6_IS_ADDR_UNSPECIFIED(&fs->faddr) &&
+		!IN6_IS_ADDR_UNSPECIFIED(&fs->eaddr) &&
+		fs->fport != 0 && fs->eport != 0;
+}
+
+#define FLOWSIDE_STRLEN		(2*(INET6_ADDRSTRLEN+8) + 6)
+
+const char *flowside_fmt(const struct flowside *fs, char *buf, size_t size);
+
 /**
  * struct flow_common - Common fields for packet flows
+ * @side[]:	Information on the flow for each side.  Flow types can have
+ *		their own conventions about which side is which
  * @type:	Type of packet flow
  */
 struct flow_common {
+	struct flowside		side[2];
 	enum flow_type		type;
 };
 
-- 
2.41.0