lpm: check rule existence

Added API function for LPM IPv4 and IPv6 to query for the existence
of a rule/route and return the next hop ID associated with the route
if route is present.
This is used by the Packet Framework LPM table for implementing a
routing table.

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
Acked-by: Pablo de Lara Guarch <pablo.de.lara.guarch@intel.com>
Acked by: Ivan Boule <ivan.boule@6wind.com>

lib/librte_lpm/rte_lpm.c

@@ -619,6 +619,35 @@ rte_lpm_add(struct rte_lpm *lpm, uint32_t ip, uint8_t depth,
 	return 0;
 }
 
+/*
+ * Look for a rule in the high-level rules table
+ */
+int
+rte_lpm_is_rule_present(struct rte_lpm *lpm, uint32_t ip, uint8_t depth,
+uint8_t *next_hop)
+{
+	uint32_t ip_masked;
+	int32_t rule_index;
+
+	/* Check user arguments. */
+	if ((lpm == NULL) ||
+		(next_hop == NULL) ||
+		(depth < 1) || (depth > RTE_LPM_MAX_DEPTH))
+		return -EINVAL;
+
+	/* Look for the rule using rule_find. */
+	ip_masked = ip & depth_to_mask(depth);
+	rule_index = rule_find(lpm, ip_masked, depth);
+
+	if (rule_index >= 0) {
+		*next_hop = lpm->rules_tbl[rule_index].next_hop;
+		return 1;
+	}
+
+	/* If rule is not found return 0. */
+	return 0;
+}
+
 static inline int32_t
 find_previous_rule(struct rte_lpm *lpm, uint32_t ip, uint8_t depth, uint8_t *sub_rule_depth)
 {

lib/librte_lpm/rte_lpm.h

@@ -215,6 +215,25 @@ rte_lpm_free(struct rte_lpm *lpm);
 int
 rte_lpm_add(struct rte_lpm *lpm, uint32_t ip, uint8_t depth, uint8_t next_hop);
 
+/**
+ * Check if a rule is present in the LPM table,
+ * and provide its next hop if it is.
+ *
+ * @param lpm
+ *   LPM object handle
+ * @param ip
+ *   IP of the rule to be searched
+ * @param depth
+ *   Depth of the rule to searched
+ * @param next_hop
+ *   Next hop of the rule (valid only if it is found)
+ * @return
+ *   1 if the rule exists, 0 if it does not, a negative value on failure
+ */
+int
+rte_lpm_is_rule_present(struct rte_lpm *lpm, uint32_t ip, uint8_t depth,
+uint8_t *next_hop);
+
 /**
  * Delete a rule from the LPM table.
  *

lib/librte_lpm/rte_lpm6.c

@@ -663,6 +663,37 @@ rule_find(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth)
 	return -ENOENT;
 }
 
+/*
+ * Look for a rule in the high-level rules table
+ */
+int
+rte_lpm6_is_rule_present(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
+uint8_t *next_hop)
+{
+	uint8_t ip_masked[RTE_LPM6_IPV6_ADDR_SIZE];
+	int32_t rule_index;
+
+	/* Check user arguments. */
+	if ((lpm == NULL) || next_hop == NULL || ip == NULL ||
+			(depth < 1) || (depth > RTE_LPM6_MAX_DEPTH))
+		return -EINVAL;
+
+	/* Copy the IP and mask it to avoid modifying user's input data. */
+	memcpy(ip_masked, ip, RTE_LPM6_IPV6_ADDR_SIZE);
+	mask_ip(ip_masked, depth);
+
+	/* Look for the rule using rule_find. */
+	rule_index = rule_find(lpm, ip_masked, depth);
+
+	if (rule_index >= 0) {
+		*next_hop = lpm->rules_tbl[rule_index].next_hop;
+		return 1;
+	}
+
+	/* If rule is not found return 0. */
+	return 0;
+}
+
 /*
  * Delete a rule from the rule table.
  * NOTE: Valid range for depth parameter is 1 .. 128 inclusive.

lib/librte_lpm/rte_lpm6.h

@@ -124,6 +124,25 @@ int
 rte_lpm6_add(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
 		uint8_t next_hop);
 
+/**
+ * Check if a rule is present in the LPM table,
+ * and provide its next hop if it is.
+ *
+ * @param lpm
+ *   LPM object handle
+ * @param ip
+ *   IP of the rule to be searched
+ * @param depth
+ *   Depth of the rule to searched
+ * @param next_hop
+ *   Next hop of the rule (valid only if it is found)
+ * @return
+ *   1 if the rule exists, 0 if it does not, a negative value on failure
+ */
+int
+rte_lpm6_is_rule_present(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
+uint8_t *next_hop);
+
 /**
  * Delete a rule from the LPM table.
  *