oracle: implement filters

go.mod

@@ -1,6 +1,7 @@
 module github.com/nspcc-dev/neo-go
 
 require (
+	github.com/PaesslerAG/jsonpath v0.1.1
 	github.com/Workiva/go-datastructures v1.0.50
 	github.com/abiosoft/readline v0.0.0-20180607040430-155bce2042db
 	github.com/alicebob/miniredis v2.5.0+incompatible

go.sum

@@ -8,6 +8,11 @@ github.com/DataDog/zstd v1.4.1 h1:3oxKN3wbHibqx897utPC2LTQU4J+IHWWJO+glkAkpFM=
 github.com/DataDog/zstd v1.4.1/go.mod h1:1jcaCB/ufaK+sKp1NBhlGmpz41jOoPQ35bpF36t7BBo=
 github.com/OneOfOne/xxhash v1.2.2 h1:KMrpdQIwFcEqXDklaen+P1axHaj9BSKzvpUUfnHldSE=
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
+github.com/PaesslerAG/gval v1.0.0 h1:GEKnRwkWDdf9dOmKcNrar9EA1bz1z9DqPIO1+iLzhd8=
+github.com/PaesslerAG/gval v1.0.0/go.mod h1:y/nm5yEyTeX6av0OfKJNp9rBNj2XrGhAf5+v24IBN1I=
+github.com/PaesslerAG/jsonpath v0.1.0/go.mod h1:4BzmtoM/PI8fPO4aQGIusjGxGir2BzcV0grWtFzq1Y8=
+github.com/PaesslerAG/jsonpath v0.1.1 h1:c1/AToHQMVsduPAa4Vh6xp2U0evy4t8SWp8imEsylIk=
+github.com/PaesslerAG/jsonpath v0.1.1/go.mod h1:lVboNxFGal/VwW6d9JzIy56bUsYAP6tH/x80vjnCseY=
 github.com/Workiva/go-datastructures v1.0.50 h1:slDmfW6KCHcC7U+LP3DDBbm4fqTwZGn1beOFPfGaLvo=
 github.com/Workiva/go-datastructures v1.0.50/go.mod h1:Z+F2Rca0qCsVYDS8z7bAGm8f3UkzuWYS/oBZz5a7VVA=
 github.com/abiosoft/ishell v2.0.0+incompatible h1:zpwIuEHc37EzrsIYah3cpevrIc8Oma7oZPxr03tlmmw=

pkg/core/oracle_test.go

@@ -140,6 +140,10 @@ func TestOracle(t *testing.T) {
 	putOracleRequest(t, cs.Hash, bc, "http://get.maxallowed", nil, "handle", []byte{}, 10_000_000)
 	putOracleRequest(t, cs.Hash, bc, "http://get.maxallowed", nil, "handle", []byte{}, 100_000_000)
 
+	flt := "Values[1]"
+	putOracleRequest(t, cs.Hash, bc, "http://get.filter", &flt, "handle", []byte{}, 10_000_000)
+	putOracleRequest(t, cs.Hash, bc, "http://get.filterinv", &flt, "handle", []byte{}, 10_000_000)
+
 	checkResp := func(t *testing.T, id uint64, resp *transaction.OracleResponse) *state.OracleRequest {
 		req, err := oracleCtr.GetRequestInternal(bc.dao, id)
 		require.NoError(t, err)
@@ -242,6 +246,19 @@ func TestOracle(t *testing.T) {
 			Result: make([]byte, transaction.MaxOracleResultSize),
 		})
 	})
+	t.Run("WithFilter", func(t *testing.T) {
+		checkResp(t, 10, &transaction.OracleResponse{
+			ID:     10,
+			Code:   transaction.Success,
+			Result: []byte(`[2]`),
+		})
+		t.Run("invalid response", func(t *testing.T) {
+			checkResp(t, 11, &transaction.OracleResponse{
+				ID:   11,
+				Code: transaction.Error,
+			})
+		})
+	})
 }
 
 func TestOracleFull(t *testing.T) {
@@ -354,6 +371,14 @@ func newDefaultHTTPClient() oracle.HTTPClient {
 				code: http.StatusOK,
 				body: make([]byte, transaction.MaxOracleResultSize),
 			},
+			"http://get.filter": {
+				code: http.StatusOK,
+				body: []byte(`{"Values":["one", 2, 3],"Another":null}`),
+			},
+			"http://get.filterinv": {
+				code: http.StatusOK,
+				body: []byte{0xFF},
+			},
 		},
 	}
 }

pkg/services/oracle/filter.go

@@ -0,0 +1,24 @@
+package oracle
+
+import (
+	"encoding/json"
+	"errors"
+	"unicode/utf8"
+
+	"github.com/PaesslerAG/jsonpath"
+)
+
+func filter(value []byte, path string) ([]byte, error) {
+	if !utf8.Valid(value) {
+		return nil, errors.New("not an UTF-8")
+	}
+	var v interface{}
+	if err := json.Unmarshal(value, &v); err != nil {
+		return nil, err
+	}
+	result, err := jsonpath.Get(path, v)
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal([]interface{}{result})
+}

pkg/services/oracle/filter_test.go

@@ -0,0 +1,50 @@
+package oracle
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFilter(t *testing.T) {
+	js := `{
+  	"Stores": [ "Lambton Quay",	"Willis Street" ],
+  	"Manufacturers": [
+		{
+			"Name": "Acme Co",
+			"Products": [
+		        { "Name": "Anvil", "Price": 50 }
+      		]
+    	},
+    	{
+      		"Name": "Contoso",
+      		"Products": [
+        		{ "Name": "Elbow Grease", "Price": 99.95 },
+        		{ "Name": "Headlight Fluid", "Price": 4 }
+      		]
+    	}
+  	]
+}`
+
+	testCases := []struct {
+		result, path string
+	}{
+		{`["Acme Co"]`, "Manufacturers[0].Name"},
+		{`[50]`, "Manufacturers[0].Products[0].Price"},
+		{`["Elbow Grease"]`, "Manufacturers[1].Products[0].Name"},
+		{`[{"Name":"Elbow Grease","Price":99.95}]`, "Manufacturers[1].Products[0]"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.path, func(t *testing.T) {
+			actual, err := filter([]byte(js), tc.path)
+			require.NoError(t, err)
+			require.Equal(t, tc.result, string(actual))
+		})
+	}
+
+	t.Run("not an UTF-8", func(t *testing.T) {
+		_, err := filter([]byte{0xFF}, "Manufacturers[0].Name")
+		require.Error(t, err)
+	})
+}

pkg/services/oracle/request.go

@@ -115,6 +115,14 @@ func (o *Oracle) processRequest(priv *keys.PrivateKey, req request) error {
 				}
 				break
 			}
+			if req.Req.Filter != nil {
+				res, err := filter(result, *req.Req.Filter)
+				if err != nil {
+					resp.Code = transaction.Error
+					break
+				}
+				result = res
+			}
 			resp.Code = transaction.Success
 			resp.Result = result
 		case r.StatusCode == http.StatusForbidden: