Support Go dependency scanning for pull requests

examples/github/policies/pr_vuln_check.yaml

@@ -15,8 +15,8 @@ pull_request:
               vulnerability_database_endpoint: https://api.osv.dev/v1/query
               package_repository:
                 url: https://registry.npmjs.org
-            - name: go
+            - name: Go
               vulnerability_database_type: osv
-              vulnerability_database_endpoint: https://vuln.go.dev
+              vulnerability_database_endpoint: https://api.osv.dev/v1/query
               package_repository:
                 url: https://proxy.golang.org

examples/github/rule-types/pr_vulnerability_check.yaml

@@ -57,6 +57,8 @@ def:
       ecosystems:
         - name: npm
           depfile: package-lock.json
+        - name: go
+          depfile: go.sum
   # Defines the configuration for evaluating data ingested against the given policy
   eval:
     type: vulncheck

internal/engine/eval/vulncheck/config.go

@@ -82,6 +82,8 @@ func pbEcosystemAsString(ecosystem pb.DepEcosystem) string {
 	switch ecosystem {
 	case pb.DepEcosystem_DEP_ECOSYSTEM_NPM:
 		return "npm"
+	case pb.DepEcosystem_DEP_ECOSYSTEM_GO:
+		return "Go"
 	case pb.DepEcosystem_DEP_ECOSYSTEM_UNSPECIFIED:
 		// this shouldn't happen
 		return ""

internal/engine/ingester/diff/config.go

@@ -21,6 +21,8 @@ type DependencyEcosystem string
 const (
 	// DepEcosystemNPM is the npm dependency ecosystem
 	DepEcosystemNPM DependencyEcosystem = "npm"
+	// DepEcosystemGo is the go dependency ecosystem
+	DepEcosystemGo DependencyEcosystem = "go"
 	// DepEcosystemNone is the fallback value
 	DepEcosystemNone DependencyEcosystem = ""
 )

internal/engine/ingester/diff/parse.go

@@ -16,6 +16,7 @@
 package diff
 
 import (
+	"bufio"
 	"encoding/json"
 	"fmt"
 	"strings"
@@ -26,16 +27,47 @@ import (
 type ecosystemParser func(string) ([]*pb.Dependency, error)
 
 func newEcosystemParser(eco DependencyEcosystem) ecosystemParser {
-	switch eco {
-	case DepEcosystemNPM:
+	switch strings.ToLower(string(eco)) {
+	case string(DepEcosystemNPM):
 		return npmParse
-	case DepEcosystemNone:
+	case string(DepEcosystemGo):
+		return goParse
+	case string(DepEcosystemNone):
 		return nil
 	default:
 		return nil
 	}
 }
 
+func goParse(patch string) ([]*pb.Dependency, error) {
+	scanner := bufio.NewScanner(strings.NewReader(patch))
+	var deps []*pb.Dependency
+
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		if strings.HasPrefix(line, "+") {
+			fields := strings.Split(line, " ")
+			if len(fields) > 2 && !strings.HasSuffix(fields[1], "/go.mod") {
+				name, version := fields[0], fields[1]
+				dep := &pb.Dependency{
+					Ecosystem: pb.DepEcosystem_DEP_ECOSYSTEM_GO,
+					Name:      name[1:],
+					Version:   version,
+				}
+
+				deps = append(deps, dep)
+			}
+		}
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return deps, nil
+}
+
 type npmDependency struct {
 	Version      string                    `json:"version"`
 	Resolved     string                    `json:"resolved"`

internal/engine/ingester/diff/parse_test.go

@@ -0,0 +1,104 @@
+// Copyright 2023 Stacklok, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package diff provides the diff rule data ingest engine
+package diff
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/protobuf/proto"
+
+	pb "github.com/stacklok/mediator/pkg/api/protobuf/go/mediator/v1"
+)
+
+func TestGoParse(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		description          string
+		content              string
+		expectedCount        int
+		expectedDependencies []*pb.Dependency
+	}{
+		{
+			description: "Single addition",
+			content: `
++cloud.google.com/go/compute v1.23.0 h1:tP41Zoavr8ptEqaW6j+LQOnyBBhO7OkOMAGrgLopTwY=
++cloud.google.com/go/compute v1.23.0/go.mod h1:4tCnrn48xsqlwSAiLf1HXMQk8CONslYbdiEZc9FEIbM=
+cloud.google.com/go/compute/metadata v0.2.3 h1:mg4jlk7mCAj6xXp9UJ4fjI9VUI5rubuGBW5aJ7UnBMY=
+cloud.google.com/go/compute/metadata v0.2.3/go.mod h1:VAV5nSsACxMJvgaAuX6Pk2AawlZn8kiOGuCv6gTkwuA=`,
+			expectedCount: 1,
+			expectedDependencies: []*pb.Dependency{
+				{
+					Ecosystem: pb.DepEcosystem_DEP_ECOSYSTEM_GO,
+					Name:      "cloud.google.com/go/compute",
+					Version:   "v1.23.0",
+				},
+			},
+		},
+		{
+			description: "Single removal",
+			content: `
+-cloud.google.com/go/compute v1.23.0 h1:tP41Zoavr8ptEqaW6j+LQOnyBBhO7OkOMAGrgLopTwY=
+-cloud.google.com/go/compute v1.23.0/go.mod h1:4tCnrn48xsqlwSAiLf1HXMQk8CONslYbdiEZc9FEIbM=
+cloud.google.com/go/compute/metadata v0.2.3 h1:mg4jlk7mCAj6xXp9UJ4fjI9VUI5rubuGBW5aJ7UnBMY=
+cloud.google.com/go/compute/metadata v0.2.3/go.mod h1:VAV5nSsACxMJvgaAuX6Pk2AawlZn8kiOGuCv6gTkwuA=`,
+			expectedCount:        0,
+			expectedDependencies: nil,
+		},
+		{
+			description: "Mixed additions and removals",
+			content: `
+-cloud.google.com/go/compute v1.23.0 h1:tP41Zoavr8ptEqaW6j+LQOnyBBhO7OkOMAGrgLopTwY=
+-cloud.google.com/go/compute v1.23.0/go.mod h1:4tCnrn48xsqlwSAiLf1HXMQk8CONslYbdiEZc9FEIbM=
++cloud.google.com/go/compute/metadata v0.2.3 h1:mg4jlk7mCAj6xXp9UJ4fjI9VUI5rubuGBW5aJ7UnBMY=
++cloud.google.com/go/compute/metadata v0.2.3/go.mod h1:VAV5nSsACxMJvgaAuX6Pk2AawlZn8kiOGuCv6gTkwuA=
++dario.cat/mergo v1.0.0 h1:AGCNq9Evsj31mOgNPcLyXc+4PNABt905YmuqPYYpBWk=
++dario.cat/mergo v1.0.0/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=`,
+			expectedCount: 2,
+			expectedDependencies: []*pb.Dependency{
+				{
+					Ecosystem: pb.DepEcosystem_DEP_ECOSYSTEM_GO,
+					Name:      "cloud.google.com/go/compute/metadata",
+					Version:   "v0.2.3",
+				},
+				{
+					Ecosystem: pb.DepEcosystem_DEP_ECOSYSTEM_GO,
+					Name:      "dario.cat/mergo",
+					Version:   "v1.0.0",
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.description, func(t *testing.T) {
+			t.Parallel()
+			got, err := goParse(tt.content)
+			if err != nil {
+				t.Fatalf("goParse() returned error: %v", err)
+			}
+
+			assert.Equal(t, tt.expectedCount, len(got), "mismatched dependency count")
+
+			for i, expectedDep := range tt.expectedDependencies {
+				if !proto.Equal(expectedDep, got[i]) {
+					t.Errorf("mismatch at index %d: expected %v, got %v", i, expectedDep, got[i])
+				}
+			}
+		})
+	}
+}