Optimize pool4

Added a new by-address index so there's no need to iterate
sequentially over anything now.

The new pool4 is unit-tested and looking stable, but there are two
TODOs preventing the code from being usable:

1. The API changed a little and I still need to tweak the callers.
2. I can't use RCU anymore and all the locking code is commented out.

Progress on #214.

include/nat64/mod/common/tags.h

@@ -7,6 +7,7 @@
  * help me review the code.
  *
  * Feel free to purge this if the code leaves my care.
+ * TODO remove?
  */
 
 /**

include/nat64/mod/stateful/pool4/db.h

@@ -18,7 +18,7 @@ struct pool4;
  * Write functions (Caller must prevent concurrence)
  */
 
-int pool4db_init(struct pool4 **pool, unsigned int capacity);
+int pool4db_init(struct pool4 **pool);
 void pool4db_get(struct pool4 *pool);
 void pool4db_put(struct pool4 *pool);
 
@@ -29,19 +29,20 @@ int pool4db_add_str(struct pool4 *pool, char *prefix_strs[], int prefix_count);
 int pool4db_rm(struct pool4 *pool, const __u32 mark, enum l4_protocol proto,
 		struct ipv4_prefix *prefix, struct port_range *ports);
 int pool4db_rm_usr(struct pool4 *pool, struct pool4_entry_usr *entry);
-int pool4db_flush(struct pool4 *pool);
+void pool4db_flush(struct pool4 *pool);
 
 /*
  * Read functions (Legal to use anywhere)
  */
 
 bool pool4db_contains(struct pool4 *pool, struct net *ns,
 		enum l4_protocol proto, struct ipv4_transport_addr *addr);
-bool pool4db_is_empty(struct pool4 *pool);
+/* This doesn't need to be public now. */
+/* bool pool4db_is_empty(struct pool4 *pool); */
 void pool4db_count(struct pool4 *pool, __u32 *tables, __u64 *samples,
 		__u64 *taddrs);
 
-int pool4db_foreach_sample(struct pool4 *pool,
+int pool4db_foreach_sample(struct pool4 *pool, l4_protocol proto,
 		int (*cb)(struct pool4_sample *, void *), void *arg,
 		struct pool4_sample *offset);
 int pool4db_foreach_taddr4(struct pool4 *pool, struct net *ns,

include/nat64/mod/stateful/pool4/entry.h

@@ -3,27 +3,7 @@
 
 #include "nat64/common/types.h"
 
-struct pool4_ports {
-	struct port_range range;
-	/* Links this pool4_ports to its address's "ports" list. */
-	struct list_head list_hook;
-};
 
-/**
- * An address within the pool, along with its ports.
- */
-struct pool4_addr {
-	struct in_addr addr;
-	/**
-	 * The port ranges from the addresses the user reserved for Jool to use.
-	 * It links elements of type pool4_ports.
-	 * TODO (performance) maybe we could break some iterations early if
-	 * this was sorted.
-	 */
-	struct list_head ports;
-
-	struct list_head list_hook;
-};
 
 struct pool4_ports *pool4_ports_create(const __u16 min, const __u16 max);
 

mod/common/nl/pool4.c

@@ -82,25 +82,18 @@ static int handle_pool4_rm(struct xlator *jool, struct genl_info *info,
 static int handle_pool4_flush(struct xlator *jool, struct genl_info *info,
 		union request_pool4 *request)
 {
-	int error;
-
 	if (verify_superpriv())
 		return nlcore_respond(info, -EPERM);
 
 	log_debug("Flushing pool4.");
-	error = pool4db_flush(jool->nat64.pool4);
 
-	/*
-	 * Well, pool4db_flush() only errors on memory allocation failures,
-	 * so I guess clearing BIB and session even if pool4db_flush fails
-	 * is a good idea.
-	 */
+	pool4db_flush(jool->nat64.pool4);
 	if (xlat_is_nat64() && !request->flush.quick) {
 		sessiondb_flush(jool->nat64.session);
 		bibdb_flush(jool->nat64.bib);
 	}
 
-	return nlcore_respond(info, error);
+	return nlcore_respond(info, 0);
 }
 
 static int handle_pool4_count(struct pool4 *pool, struct genl_info *info)

mod/common/types.c

@@ -27,6 +27,12 @@ bool port_range_equals(const struct port_range *r1,
 	return (r1->min == r2->min) && (r1->max == r2->max);
 }
 
+/**
+ * Range [1,3] touches [2,6].
+ * Range [1,3] touches [3,6].
+ * Range [1,3] touches [4,6].
+ * Range [1,3] does not touch [5,6].
+ */
 bool port_range_touches(const struct port_range *r1,
 		const struct port_range *r2)
 {