1 files changed, 321 insertions, 0 deletions
diff --git a/lib/srcdest_table.c b/lib/srcdest_table.c
new file mode 100644
index 0000000..3247a03
--- /dev/null
+++ b/lib/srcdest_table.c
@@ -0,0 +1,321 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * SRC-DEST Routing Table
+ *
+ * Copyright (C) 2017 by David Lamparter & Christian Franke,
+ *                       Open Source Routing / NetDEF Inc.
+ *
+ * This file is part of FRRouting (FRR)
+ */
+
+#include <zebra.h>
+
+#include "srcdest_table.h"
+
+#include "memory.h"
+#include "prefix.h"
+#include "table.h"
+#include "printfrr.h"
+
+DEFINE_MTYPE_STATIC(LIB, ROUTE_SRC_NODE, "Route source node");
+
+/* ----- functions to manage rnodes _with_ srcdest table ----- */
+struct srcdest_rnode {
+	/* must be first in structure for casting to/from route_node */
+	ROUTE_NODE_FIELDS;
+
+	struct route_table *src_table;
+};
+
+static struct srcdest_rnode *srcdest_rnode_from_rnode(struct route_node *rn)
+{
+	assert(rnode_is_dstnode(rn));
+	return (struct srcdest_rnode *)rn;
+}
+
+static struct route_node *srcdest_rnode_to_rnode(struct srcdest_rnode *srn)
+{
+	return (struct route_node *)srn;
+}
+
+static struct route_node *srcdest_rnode_create(route_table_delegate_t *delegate,
+					       struct route_table *table)
+{
+	struct srcdest_rnode *srn;
+	srn = XCALLOC(MTYPE_ROUTE_NODE, sizeof(struct srcdest_rnode));
+	return srcdest_rnode_to_rnode(srn);
+}
+
+static void srcdest_rnode_destroy(route_table_delegate_t *delegate,
+				  struct route_table *table,
+				  struct route_node *rn)
+{
+	struct srcdest_rnode *srn = srcdest_rnode_from_rnode(rn);
+	struct route_table *src_table;
+
+	/* Clear route node's src_table here already, otherwise the
+	 * deletion of the last node in the src_table will trigger
+	 * another call to route_table_finish for the src_table.
+	 *
+	 * (Compare with srcdest_srcnode_destroy)
+	 */
+	src_table = srn->src_table;
+	srn->src_table = NULL;
+	route_table_finish(src_table);
+	XFREE(MTYPE_ROUTE_NODE, rn);
+}
+
+route_table_delegate_t _srcdest_dstnode_delegate = {
+	.create_node = srcdest_rnode_create,
+	.destroy_node = srcdest_rnode_destroy};
+
+/* ----- functions to manage rnodes _in_ srcdest table ----- */
+
+/* node creation / deletion for srcdest source prefix nodes.
+ * the route_node isn't actually different from the normal route_node,
+ * but the cleanup is special to free the table (and possibly the
+ * destination prefix's route_node) */
+
+static struct route_node *
+srcdest_srcnode_create(route_table_delegate_t *delegate,
+		       struct route_table *table)
+{
+	return XCALLOC(MTYPE_ROUTE_SRC_NODE, sizeof(struct route_node));
+}
+
+static void srcdest_srcnode_destroy(route_table_delegate_t *delegate,
+				    struct route_table *table,
+				    struct route_node *rn)
+{
+	struct srcdest_rnode *srn;
+
+	XFREE(MTYPE_ROUTE_SRC_NODE, rn);
+
+	srn = route_table_get_info(table);
+	if (srn->src_table && route_table_count(srn->src_table) == 0) {
+		/* deleting the route_table from inside destroy_node is ONLY
+		 * permitted IF table->count is 0!  see lib/table.c
+		 * route_node_delete()
+		 * for details */
+		route_table_finish(srn->src_table);
+		srn->src_table = NULL;
+
+		/* drop the ref we're holding in srcdest_node_get().  there
+		 * might be
+		 * non-srcdest routes, so the route_node may still exist.
+		 * hence, it's
+		 * important to clear src_table above. */
+		route_unlock_node(srcdest_rnode_to_rnode(srn));
+	}
+}
+
+route_table_delegate_t _srcdest_srcnode_delegate = {
+	.create_node = srcdest_srcnode_create,
+	.destroy_node = srcdest_srcnode_destroy};
+
+/* NB: read comments in code for refcounting before using! */
+static struct route_node *srcdest_srcnode_get(struct route_node *rn,
+					      const struct prefix_ipv6 *src_p)
+{
+	struct srcdest_rnode *srn;
+
+	if (!src_p || src_p->prefixlen == 0)
+		return rn;
+
+	srn = srcdest_rnode_from_rnode(rn);
+	if (!srn->src_table) {
+		/* this won't use srcdest_rnode, we're already on the source
+		 * here */
+		srn->src_table = route_table_init_with_delegate(
+			&_srcdest_srcnode_delegate);
+		route_table_set_info(srn->src_table, srn);
+
+		/* there is no route_unlock_node on the original rn here.
+		 * The reference is kept for the src_table. */
+	} else {
+		/* only keep 1 reference for the src_table, makes the
+		 * refcounting
+		 * more similar to the non-srcdest case.  Either way after
+		 * return from
+		 * function, the only reference held is the one on the return
+		 * value.
+		 *
+		 * We can safely drop our reference here because src_table is
+		 * holding
+		 * another reference, so this won't free rn */
+		route_unlock_node(rn);
+	}
+
+	return route_node_get(srn->src_table, (const struct prefix *)src_p);
+}
+
+static struct route_node *srcdest_srcnode_lookup(
+	struct route_node *rn,
+	const struct prefix_ipv6 *src_p)
+{
+	struct srcdest_rnode *srn;
+
+	if (!rn || !src_p || src_p->prefixlen == 0)
+		return rn;
+
+	/* We got this rn from a lookup, so its refcnt was incremented. As we
+	 * won't
+	 * return return rn from any point beyond here, we should decrement its
+	 * refcnt.
+	 */
+	route_unlock_node(rn);
+
+	srn = srcdest_rnode_from_rnode(rn);
+	if (!srn->src_table)
+		return NULL;
+
+	return route_node_lookup(srn->src_table, (const struct prefix *)src_p);
+}
+
+/* ----- exported functions ----- */
+
+struct route_table *srcdest_table_init(void)
+{
+	return route_table_init_with_delegate(&_srcdest_dstnode_delegate);
+}
+
+struct route_node *srcdest_route_next(struct route_node *rn)
+{
+	struct route_node *next, *parent;
+
+	/* For a non src-dest node, just return route_next */
+	if (!(rnode_is_dstnode(rn) || rnode_is_srcnode(rn)))
+		return route_next(rn);
+
+	if (rnode_is_dstnode(rn)) {
+		/* This means the route_node is part of the top hierarchy
+		 * and refers to a destination prefix. */
+		struct srcdest_rnode *srn = srcdest_rnode_from_rnode(rn);
+
+		if (srn->src_table)
+			next = route_top(srn->src_table);
+		else
+			next = NULL;
+
+		if (next) {
+			/* There is a source prefix. Return the node for it */
+			route_unlock_node(rn);
+			return next;
+		} else {
+			/* There is no source prefix, just continue as usual */
+			return route_next(rn);
+		}
+	}
+
+	/* This part handles the case of iterating source nodes. */
+	parent = route_lock_node(route_table_get_info(rn->table));
+	next = route_next(rn);
+
+	if (next) {
+		/* There is another source node, continue in the source table */
+		route_unlock_node(parent);
+		return next;
+	} else {
+		/* The source table is complete, continue in the parent table */
+		return route_next(parent);
+	}
+}
+
+struct route_node *srcdest_rnode_get(struct route_table *table,
+				     union prefixconstptr dst_pu,
+				     const struct prefix_ipv6 *src_p)
+{
+	const struct prefix_ipv6 *dst_p = dst_pu.p6;
+	struct route_node *rn;
+
+	rn = route_node_get(table, (const struct prefix *)dst_p);
+	return srcdest_srcnode_get(rn, src_p);
+}
+
+struct route_node *srcdest_rnode_lookup(struct route_table *table,
+					union prefixconstptr dst_pu,
+					const struct prefix_ipv6 *src_p)
+{
+	const struct prefix_ipv6 *dst_p = dst_pu.p6;
+	struct route_node *rn;
+	struct route_node *srn;
+
+	rn = route_node_lookup_maynull(table, (const struct prefix *)dst_p);
+	srn = srcdest_srcnode_lookup(rn, src_p);
+
+	if (rn != NULL && rn == srn && !rn->info) {
+		/* Match the behavior of route_node_lookup and don't return an
+		 * empty route-node for a dest-route */
+		route_unlock_node(rn);
+		return NULL;
+	}
+	return srn;
+}
+
+void srcdest_rnode_prefixes(const struct route_node *rn,
+			    const struct prefix **p,
+			    const struct prefix **src_p)
+{
+	if (rnode_is_srcnode(rn)) {
+		struct route_node *dst_rn = route_table_get_info(rn->table);
+		if (p)
+			*p = &dst_rn->p;
+		if (src_p)
+			*src_p = &rn->p;
+	} else {
+		if (p)
+			*p = &rn->p;
+		if (src_p)
+			*src_p = NULL;
+	}
+}
+
+const char *srcdest2str(const struct prefix *dst_p,
+			const struct prefix_ipv6 *src_p,
+			char *str, int size)
+{
+	char dst_buf[PREFIX_STRLEN], src_buf[PREFIX_STRLEN];
+
+	snprintf(str, size, "%s%s%s",
+		 prefix2str(dst_p, dst_buf, sizeof(dst_buf)),
+		 (src_p && src_p->prefixlen) ? " from " : "",
+		 (src_p && src_p->prefixlen)
+			 ? prefix2str(src_p, src_buf, sizeof(src_buf))
+			 : "");
+	return str;
+}
+
+const char *srcdest_rnode2str(const struct route_node *rn, char *str, int size)
+{
+	const struct prefix *dst_p, *src_p;
+
+	srcdest_rnode_prefixes(rn, &dst_p, &src_p);
+	return srcdest2str(dst_p, (const struct prefix_ipv6 *)src_p, str, size);
+}
+
+printfrr_ext_autoreg_p("RN", printfrr_rn);
+static ssize_t printfrr_rn(struct fbuf *buf, struct printfrr_eargs *ea,
+			   const void *ptr)
+{
+	const struct route_node *rn = ptr;
+	const struct prefix *dst_p, *src_p;
+	char cbuf[PREFIX_STRLEN * 2 + 6];
+
+	if (!rn)
+		return bputs(buf, "(null)");
+
+	srcdest_rnode_prefixes(rn, &dst_p, &src_p);
+	srcdest2str(dst_p, (const struct prefix_ipv6 *)src_p,
+		    cbuf, sizeof(cbuf));
+	return bputs(buf, cbuf);
+}
+
+struct route_table *srcdest_srcnode_table(struct route_node *rn)
+{
+	if (rnode_is_dstnode(rn)) {
+		struct srcdest_rnode *srn = srcdest_rnode_from_rnode(rn);
+
+		return srn->src_table;
+	}
+	return NULL;
+}