From 8a6e75ac815a5bdfd9fdbd3528c985d5fdde9c1b Mon Sep 17 00:00:00 2001
From: Daniel Nephin <dnephin@hashicorp.com>
Date: Tue, 25 Jan 2022 18:41:15 -0500
Subject: [PATCH] rpc: add errNotFound to all Get queries

Any query that returns a list of items is not part of this commit.
---
 agent/consul/acl_endpoint.go              | 21 ++++++++++++++++-----
 agent/consul/coordinate_endpoint.go       |  1 +
 agent/consul/federation_state_endpoint.go |  2 +-
 agent/consul/kvs_endpoint.go              | 15 +++++----------
 agent/consul/session_endpoint.go          |  1 +
 5 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/agent/consul/acl_endpoint.go b/agent/consul/acl_endpoint.go
index 13799c3182..d19836466f 100644
--- a/agent/consul/acl_endpoint.go
+++ b/agent/consul/acl_endpoint.go
@@ -322,6 +322,9 @@ func (a *ACL) TokenRead(args *structs.ACLTokenGetRequest, reply *structs.ACLToke
 
 			reply.Index, reply.Token = index, token
 			reply.SourceDatacenter = args.Datacenter
+			if token == nil {
+				return errNotFound
+			}
 			return nil
 		})
 }
@@ -1045,6 +1048,9 @@ func (a *ACL) PolicyRead(args *structs.ACLPolicyGetRequest, reply *structs.ACLPo
 			}
 
 			reply.Index, reply.Policy = index, policy
+			if policy == nil {
+				return errNotFound
+			}
 			return nil
 		})
 }
@@ -1428,6 +1434,9 @@ func (a *ACL) RoleRead(args *structs.ACLRoleGetRequest, reply *structs.ACLRoleRe
 			}
 
 			reply.Index, reply.Role = index, role
+			if role == nil {
+				return errNotFound
+			}
 			return nil
 		})
 }
@@ -1795,12 +1804,14 @@ func (a *ACL) BindingRuleRead(args *structs.ACLBindingRuleGetRequest, reply *str
 	return a.srv.blockingQuery(&args.QueryOptions, &reply.QueryMeta,
 		func(ws memdb.WatchSet, state *state.Store) error {
 			index, rule, err := state.ACLBindingRuleGetByID(ws, args.BindingRuleID, &args.EnterpriseMeta)
-
 			if err != nil {
 				return err
 			}
 
 			reply.Index, reply.BindingRule = index, rule
+			if rule == nil {
+				return errNotFound
+			}
 			return nil
 		})
 }
@@ -2052,16 +2063,16 @@ func (a *ACL) AuthMethodRead(args *structs.ACLAuthMethodGetRequest, reply *struc
 	return a.srv.blockingQuery(&args.QueryOptions, &reply.QueryMeta,
 		func(ws memdb.WatchSet, state *state.Store) error {
 			index, method, err := state.ACLAuthMethodGetByName(ws, args.AuthMethodName, &args.EnterpriseMeta)
-
 			if err != nil {
 				return err
 			}
 
-			if method != nil {
-				_ = a.enterpriseAuthMethodTypeValidation(method.Type)
+			reply.Index, reply.AuthMethod = index, method
+			if method == nil {
+				return errNotFound
 			}
 
-			reply.Index, reply.AuthMethod = index, method
+			_ = a.enterpriseAuthMethodTypeValidation(method.Type)
 			return nil
 		})
 }
diff --git a/agent/consul/coordinate_endpoint.go b/agent/consul/coordinate_endpoint.go
index b35d8b2609..26aaa8536f 100644
--- a/agent/consul/coordinate_endpoint.go
+++ b/agent/consul/coordinate_endpoint.go
@@ -267,6 +267,7 @@ func (c *Coordinate) Node(args *structs.NodeSpecificRequest, reply *structs.Inde
 				})
 			}
 			reply.Index, reply.Coordinates = index, coords
+
 			return nil
 		})
 }
diff --git a/agent/consul/federation_state_endpoint.go b/agent/consul/federation_state_endpoint.go
index da1171a8b7..ac02ee469a 100644
--- a/agent/consul/federation_state_endpoint.go
+++ b/agent/consul/federation_state_endpoint.go
@@ -124,7 +124,7 @@ func (c *FederationState) Get(args *structs.FederationStateQuery, reply *structs
 
 			reply.Index = index
 			if fedState == nil {
-				return nil
+				return errNotFound
 			}
 
 			reply.State = fedState
diff --git a/agent/consul/kvs_endpoint.go b/agent/consul/kvs_endpoint.go
index 2023ea1ea7..9befae5d6a 100644
--- a/agent/consul/kvs_endpoint.go
+++ b/agent/consul/kvs_endpoint.go
@@ -160,18 +160,13 @@ func (k *KVS) Get(args *structs.KeyRequest, reply *structs.IndexedDirEntries) er
 			}
 
 			if ent == nil {
-				// Must provide non-zero index to prevent blocking
-				// Index 1 is impossible anyways (due to Raft internals)
-				if index == 0 {
-					reply.Index = 1
-				} else {
-					reply.Index = index
-				}
+				reply.Index = index
 				reply.Entries = nil
-			} else {
-				reply.Index = ent.ModifyIndex
-				reply.Entries = structs.DirEntries{ent}
+				return errNotFound
 			}
+
+			reply.Index = ent.ModifyIndex
+			reply.Entries = structs.DirEntries{ent}
 			return nil
 		})
 }
diff --git a/agent/consul/session_endpoint.go b/agent/consul/session_endpoint.go
index ae39a6fc54..bb65938fef 100644
--- a/agent/consul/session_endpoint.go
+++ b/agent/consul/session_endpoint.go
@@ -198,6 +198,7 @@ func (s *Session) Get(args *structs.SessionSpecificRequest,
 				reply.Sessions = structs.Sessions{session}
 			} else {
 				reply.Sessions = nil
+				return errNotFound
 			}
 			s.srv.filterACLWithAuthorizer(authz, reply)
 			return nil