Fix joold advertise, abandoned attempt

For #410.

I more or less finished the implementation (albeit not the testing),
but the unit tests revealed that one of my assumptions regarding Generic
Netlink is incorrect.

nla_put() cannot be trusted to respect the allocated packet size,
because alloc_skb() can reserve more tail area than it's requested.
This means ss-max-payload has to be enforced manually.

And this by itself wouldn't be enough to justify another rewrite, but
after thinking about it, I realized a more natural implementation would
also reduce the range of the spinlock... which is currently not the
best. Lots of performance to be gained from switching.

So checkpointing. I might have to return to this implementation if the
new one turns out unviable.

docs/en/usr-flags-global.md

@@ -670,7 +670,7 @@ If SS cannot keep up with the amount of traffic it needs to multicast, this maxi
 
 Watch out for this message in the kernel logs:
 
-	Too many sessions queued! I need to drop some; sorry.
+	Joold: Too many sessions deferred! I need to drop some; sorry.
 
 ### `ss-max-payload`
 

src/abbreviations.md

@@ -9,6 +9,7 @@ Some shortcuts used while naming variables and functions through the code or doc
 
 - 4to6 = translation from IPv4 to IPv6
 - 6to4 = translation from IPv6 to IPv4
+- ad = advertise (if verb), advertisement (if noun)
 - alloc = memory allocation
 - addr = address
 - ADF = Address-Dependent Filtering

src/common/types.h

@@ -88,6 +88,8 @@ const char *l3proto_to_string(l3_protocol proto);
  * We do not use IPPROTO_TCP and friends because I want the compiler to pester
  * me during defaultless `switch`s. Also, the zero-based index is convenient in
  * the Translate Packet module.
+ *
+ * Please don't change the order; there's at least one for that relies on it.
  */
 typedef enum l4_protocol {
 	/** Signals the presence of a TCP header. */
@@ -135,6 +137,11 @@ struct ipv4_transport_addr {
 	__u16 l4;
 };
 
+/* IPv4 Transport Address Prink Pattern */
+#define TA4PP "%pI4#%u"
+/* IPv4 Transport Address Prink Arguments */
+#define TA4PA(ta) &(ta).l3, (ta).l4
+
 /**
  * A layer-3 (IPv6) identifier attached to a layer-4 identifier.
  * Because they're paired all the time in this project.
@@ -146,6 +153,11 @@ struct ipv6_transport_addr {
 	__u16 l4;
 };
 
+/* IPv6 Transport Address Prink Pattern */
+#define TA6PP "%pI6c#%u"
+/* IPv6 Transport Address Prink Arguments */
+#define TA6PA(ta) &(ta).l3, (ta).l4
+
 struct taddr4_tuple {
 	struct ipv4_transport_addr src;
 	struct ipv4_transport_addr dst;
@@ -218,6 +230,12 @@ struct bib_entry {
 	bool is_static;
 };
 
+/* BIB Entry Printk Pattern */
+#define BEPP "[" TA6PP ", " TA4PP ", %s]"
+/* BIB Entry Printk Arguments */
+#define BEPA(b) TA6PA((b)->addr6), TA4PA((b)->addr4), \
+	l4proto_to_string((b)->l4_proto)
+
 bool port_range_equals(const struct port_range *r1,
 		const struct port_range *r2);
 bool port_range_touches(const struct port_range *r1,

src/mod/common/db/bib/db.c

@@ -477,12 +477,11 @@ static void log_bib(struct xlator *jool, struct tabled_bib *bib, char *action)
 
 	tsec = ktime_get_real_seconds();
 	time64_to_tm(tsec, 0, &time);
-	log_info("%s %ld/%d/%d %d:%d:%d (GMT) - %s %pI6c#%u to %pI4#%u (%s)",
+	log_info("%s %ld/%d/%d %d:%d:%d (GMT) - %s " TA6PP " to " TA4PP " (%s)",
 			jool->iname,
 			1900 + time.tm_year, time.tm_mon + 1, time.tm_mday,
 			time.tm_hour, time.tm_min, time.tm_sec, action,
-			&bib->src6.l3, bib->src6.l4,
-			&bib->src4.l3, bib->src4.l4,
+			TA6PA(bib->src6), TA4PA(bib->src4),
 			l4proto_to_string(bib->proto));
 }
 
@@ -503,14 +502,12 @@ static void log_session(struct xlator *jool,
 
 	tsec = ktime_get_real_seconds();
 	time64_to_tm(tsec, 0, &time);
-	log_info("%s %ld/%d/%d %d:%d:%d (GMT) - %s %pI6c#%u|%pI6c#%u|"
-			"%pI4#%u|%pI4#%u|%s", jool->iname,
+	log_info("%s %ld/%d/%d %d:%d:%d (GMT) - %s " TA6PP "|" TA6PP "|"
+			TA4PP "|" TA4PP "|%s", jool->iname,
 			1900 + time.tm_year, time.tm_mon + 1, time.tm_mday,
 			time.tm_hour, time.tm_min, time.tm_sec, action,
-			&session->bib->src6.l3, session->bib->src6.l4,
-			&session->dst6.l3, session->dst6.l4,
-			&session->bib->src4.l3, session->bib->src4.l4,
-			&session->dst4.l3, session->dst4.l4,
+			TA6PA(session->bib->src6), TA6PA(session->dst6),
+			TA4PA(session->bib->src4), TA4PA(session->dst4),
 			l4proto_to_string(session->bib->proto));
 }
 
@@ -2262,9 +2259,7 @@ static int __bib_add_static(struct xlator *jool, struct bib_entry *new,
 	struct tree_slot slot6;
 	struct tree_slot slot4;
 
-	__log_debug(jool, "Adding static BIB entry (%pI6c#%u, %pI4#%u).",
-			&new->addr6.l3, new->addr6.l4,
-			&new->addr4.l3, new->addr4.l4);
+	__log_debug(jool, "Adding static BIB entry " BEPP ".", BEPA(new));
 
 	table = get_table(jool->nat64.bib, new->l4_proto);
 	if (!table)
@@ -2328,11 +2323,8 @@ int bib_add_static(struct xlator *jool, struct bib_entry *new)
 	case 0:
 		break;
 	case -EEXIST:
-		log_err("Entry %pI4#%u|%pI6c#%u collides with %pI4#%u|%pI6c#%u.",
-				&new->addr4.l3, new->addr4.l4,
-				&new->addr6.l3, new->addr6.l4,
-				&old.addr4.l3, old.addr4.l4,
-				&old.addr6.l3, old.addr6.l4);
+		log_err("Entry " BEPP " collides with " BEPP ".",
+				BEPA(new), BEPA(&old));
 		break;
 	default:
 		log_err("Unknown error code: %d", error);
@@ -2452,9 +2444,8 @@ static void print_session(struct rb_node *node, int tabs, char *prefix)
 
 	session = node2session(node);
 	print_tabs(tabs);
-	pr_cont("[%s] %pI4#%u %pI6c#%u\n", prefix,
-			&session->dst4.l3, session->dst4.l4,
-			&session->dst6.l3, session->dst6.l4);
+	pr_cont("[%s] " TA4PP " " TA6PP "\n", prefix, TA4PA(session->dst4),
+			TA6PA(session->dst6));
 
 	print_session(node->rb_left, tabs + 1, "L"); /* "Left" */
 	print_session(node->rb_right, tabs + 1, "R"); /* "Right" */
@@ -2470,8 +2461,7 @@ static void print_bib(struct rb_node *node, int tabs)
 
 	bib = bib4_entry(node);
 	print_tabs(tabs);
-	pr_cont("%pI4#%u %pI6c#%u\n", &bib->src4.l3, bib->src4.l4,
-			&bib->src6.l3, bib->src6.l4);
+	pr_cont(TA4PP " " TA6PP "\n", TA4PA(bib->src4), TA6PA(bib->src6));
 
 	print_session(bib->sessions.rb_node, tabs + 1, "T"); /* "Tree" */
 	print_bib(node->rb_left, tabs + 1);

src/mod/common/db/bib/entry.h

@@ -27,9 +27,7 @@ struct session_entry {
 	 * unfortunate, as they only make sense in the 6-to-4 direction.
 	 *
 	 * @src6 is the remote IPv6 node's transport address.
-	 *     We used to call it "remote6".
 	 * @dst6 is the address the NAT64 is using to mask the IPv4 endpoint.
-	 *     We used to call it "local6".
 	 */
 	struct ipv6_transport_addr src6;
 	struct ipv6_transport_addr dst6;
@@ -41,9 +39,7 @@ struct session_entry {
 	 * unfortunate, as they only make sense in the 6-to-4 direction.
 	 *
 	 * @src4 is the address the NAT64 is using to mask the IPv6 endpoint.
-	 *     We used to call it "local4".
 	 * @dst4 is the remote IPv4 node's transport address.
-	 *     We used to call it "remote4".
 	 */
 	struct ipv4_transport_addr src4;
 	struct ipv4_transport_addr dst4;
@@ -66,6 +62,14 @@ struct session_entry {
 	bool has_stored;
 };
 
+/* Session Entry Printk Pattern */
+#define SEPP "[" TA6PP ", " TA6PP ", " TA4PP ", " TA4PP ", %s]"
+/* Session Entry Printk Arguments */
+#define SEPA(s) \
+	TA6PA((s)->src6), TA6PA((s)->dst6), \
+	TA4PA((s)->src4), TA4PA((s)->dst4), \
+	l4proto_to_string((s)->proto)
+
 struct bib_session {
 	/** Are @session.src6, @session.src4, @session.proto set? */
 	bool bib_set;