From c80e62556cd9cf9e30b9eb48de72cadc41e1f4ff Mon Sep 17 00:00:00 2001
From: Nicolas Maquet <nicolas@movio.co>
Date: Sat, 13 Jun 2020 18:42:18 +1200
Subject: [PATCH 1/2] Fix SIGSEGV when client subs to multiple fields

---
 internal/exec/subscribe.go |  4 ++++
 subscription_test.go       | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/internal/exec/subscribe.go b/internal/exec/subscribe.go
index 6c7ea1a0..16cae69c 100644
--- a/internal/exec/subscribe.go
+++ b/internal/exec/subscribe.go
@@ -55,6 +55,10 @@ func (r *Request) Subscribe(ctx context.Context, s *resolvable.Schema, op *query
 		}
 	}()
 
+	if f == nil {
+		return sendAndReturnClosed(&Response{Errors: []*errors.QueryError{err}})
+	}
+
 	if err != nil {
 		if _, nonNullChild := f.field.Type.(*common.NonNull); nonNullChild {
 			return sendAndReturnClosed(&Response{Errors: []*errors.QueryError{err}})
diff --git a/subscription_test.go b/subscription_test.go
index 5b8c56ba..96649d94 100644
--- a/subscription_test.go
+++ b/subscription_test.go
@@ -56,6 +56,10 @@ func (r *helloSaidResolver) HelloSaid(ctx context.Context) (chan *helloSaidEvent
 	return c, nil
 }
 
+func (r *rootResolver) OtherField(ctx context.Context) <-chan int32 {
+	return make(chan int32)
+}
+
 func (r *helloSaidEventResolver) Msg() (string, error) {
 	return r.msg, r.err
 }
@@ -416,6 +420,36 @@ func TestRootOperations_validSubscriptionSchema(t *testing.T) {
 	})
 }
 
+func TestError_multiple_subscription_fields(t *testing.T) {
+	gqltesting.RunSubscribes(t, []*gqltesting.TestSubscription{
+		{
+			Name: "Explicit schema without subscription field",
+			Schema: graphql.MustParseSchema(`
+					schema {
+						query: Query
+						subscription: Subscription
+					}
+					type Query {
+						hello: String!
+					}
+					type Subscription {
+						helloSaid: HelloSaidEvent!
+						otherField: Int!
+					}
+					type HelloSaidEvent {
+						msg: String!
+					}
+			`, &rootResolver{helloSaidResolver: &helloSaidResolver{upstream: closedUpstream(&helloSaidEventResolver{msg: "Hello world!"})}}),
+			Query: `subscription { helloSaid { msg } otherField }`,
+			ExpectedResults: []gqltesting.TestResponse{
+				{
+					Errors: []*qerrors.QueryError{qerrors.Errorf("can subscribe to at most one subscription at a time")},
+				},
+			},
+		},
+	})
+}
+
 const schema = `
 	schema {
 		subscription: Subscription,

From 96ea6f07d73714de3b9cd645dc3a41e192cbcd9f Mon Sep 17 00:00:00 2001
From: Sean Sorrell <seansorr@twitch.tv>
Date: Wed, 17 Jun 2020 17:41:16 -0700
Subject: [PATCH 2/2] bugfix: correctly determine fragment usage

In previous versions of this code, this validation would exit when it
encountered a fragment legitimately used twice. This bugfix skips the recursion
but does not stop progress altogether allowing other fragments to be marked as
used.
---
 internal/validation/testdata/tests.json | 9 ++++++++-
 internal/validation/validation.go       | 3 ++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/internal/validation/testdata/tests.json b/internal/validation/testdata/tests.json
index 46df80d3..4687e8d1 100644
--- a/internal/validation/testdata/tests.json
+++ b/internal/validation/testdata/tests.json
@@ -1464,6 +1464,13 @@
       "query": "\n      query Foo($a: String, $b: String, $c: String) {\n        ... on Type {\n          field(a: $a) {\n            field(b: $b) {\n              ... on Type {\n                field(c: $c)\n              }\n            }\n          }\n        }\n      }\n    ",
       "errors": []
     },
+    {
+      "name": "Validate: fragments are used even when they are nested",
+      "rule": "NoUnusedFragments",
+      "schema": 1,
+      "query": "\n        query Foo() {\n ...StringFragment\n stringBox {\n ...StringFragment\n ...StringFragmentPrime\n}\n}\n\n\n fragment StringFragment on StringBox {\n scalar\n}\n\n fragment StringFragmentPrime on StringBox {\n unrelatedField\n}\n",
+      "errors": []
+    },
     {
       "name": "Validate: No unused variables/uses all variables in fragments",
       "rule": "NoUnusedVariables",
@@ -3853,4 +3860,4 @@
       ]
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/internal/validation/validation.go b/internal/validation/validation.go
index 94a9faf8..c8be7354 100644
--- a/internal/validation/validation.go
+++ b/internal/validation/validation.go
@@ -418,8 +418,9 @@ func markUsedFragments(c *context, sels []query.Selection, fragUsed map[*query.F
 			}
 
 			if _, ok := fragUsed[frag]; ok {
-				return
+				continue
 			}
+
 			fragUsed[frag] = struct{}{}
 			markUsedFragments(c, frag.Selections, fragUsed)