added linter

engine/auth/auth.go

@@ -0,0 +1,122 @@
+// Copyright 2019 Drone.IO Inc. All rights reserved.
+// Use of this source code is governed by the Polyform License
+// that can be found in the LICENSE file.
+
+package auth
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"io"
+	"net/url"
+	"os"
+	"strings"
+
+	"github.com/drone-runners/drone-runner-docker/engine"
+)
+
+// config represents the Docker client configuration,
+// typically located at ~/.docker/config.json
+type config struct {
+	Auths map[string]auths `json:"auths"`
+}
+
+type auths struct {
+	Auth string `json:"auth"`
+}
+
+// Parse parses the registry credential from the reader.
+func Parse(r io.Reader) ([]*engine.Auth, error) {
+	c := new(config)
+	err := json.NewDecoder(r).Decode(c)
+	if err != nil {
+		return nil, err
+	}
+	var auths []*engine.Auth
+	for k, v := range c.Auths {
+		username, password := decode(v.Auth)
+		auths = append(auths, &engine.Auth{
+			Address:  hostname(k),
+			Username: username,
+			Password: password,
+		})
+	}
+	return auths, nil
+}
+
+// ParseFile parses the registry credential file.
+func ParseFile(filepath string) ([]*engine.Auth, error) {
+	f, err := os.Open(filepath)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	return Parse(f)
+}
+
+// ParseString parses the registry credential file.
+func ParseString(s string) ([]*engine.Auth, error) {
+	return Parse(strings.NewReader(s))
+}
+
+// encode returns the encoded credentials.
+func encode(username, password string) string {
+	return base64.StdEncoding.EncodeToString(
+		[]byte(username + ":" + password),
+	)
+}
+
+// decode returns the decoded credentials.
+func decode(s string) (username, password string) {
+	d, err := base64.StdEncoding.DecodeString(s)
+	if err != nil {
+		return
+	}
+	parts := strings.SplitN(string(d), ":", 2)
+	if len(parts) > 0 {
+		username = parts[0]
+	}
+	if len(parts) > 1 {
+		password = parts[1]
+	}
+	return
+}
+
+func hostname(s string) string {
+	uri, _ := url.Parse(s)
+	if uri.Host != "" {
+		s = uri.Host
+	}
+	return s
+}
+
+// Encode returns the json marshaled, base64 encoded
+// credential string that can be passed to the docker
+// registry authentication header.
+func Encode(username, password string) string {
+	v := struct {
+		Username string `json:"username,omitempty"`
+		Password string `json:"password,omitempty"`
+	}{
+		Username: username,
+		Password: password,
+	}
+	buf, _ := json.Marshal(&v)
+	return base64.URLEncoding.EncodeToString(buf)
+}
+
+// Marshal marshals the Auth credentials to a
+// .docker/config.json file.
+func Marshal(list []*engine.Auth) ([]byte, error) {
+	out := &config{}
+	out.Auths = map[string]auths{}
+	for _, item := range list {
+		out.Auths[item.Address] = auths{
+			Auth: encode(
+				item.Username,
+				item.Password,
+			),
+		}
+	}
+	return json.Marshal(out)
+}