1 files changed, 216 insertions, 0 deletions
diff --git a/pkg/auth/auth.go b/pkg/auth/auth.go
new file mode 100644
index 000000000..ffa65f7e5
--- /dev/null
+++ b/pkg/auth/auth.go
@@ -0,0 +1,216 @@
+package auth
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"strings"
+
+	imageAuth "github.com/containers/image/v5/pkg/docker/config"
+	"github.com/containers/image/v5/types"
+	dockerAPITypes "github.com/docker/docker/api/types"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+// XRegistryAuthHeader is the key to the encoded registry authentication
+// configuration in an http-request header.
+const XRegistryAuthHeader = "X-Registry-Auth"
+
+// GetCredentials extracts one or more DockerAuthConfigs from the request's
+// header.  The header could specify a single-auth config in which case the
+// first return value is set.  In case of a multi-auth header, the contents are
+// stored in a temporary auth file (2nd return value).  Note that the auth file
+// should be removed after usage.
+func GetCredentials(r *http.Request) (*types.DockerAuthConfig, string, error) {
+	authHeader := r.Header.Get(XRegistryAuthHeader)
+	if len(authHeader) == 0 {
+		return nil, "", nil
+	}
+
+	// First look for a multi-auth header (i.e., a map).
+	authConfigs, err := multiAuthHeader(r)
+	if err == nil {
+		authfile, err := authConfigsToAuthFile(authConfigs)
+		return nil, authfile, err
+	}
+
+	// Fallback to looking for a single-auth header (i.e., one config).
+	authConfigs, err = singleAuthHeader(r)
+	if err != nil {
+		return nil, "", err
+	}
+	var conf *types.DockerAuthConfig
+	for k := range authConfigs {
+		c := authConfigs[k]
+		conf = &c
+		break
+	}
+	return conf, "", nil
+}
+
+// Header returns a map with the XRegistryAuthHeader set which can
+// conveniently be used in the http stack.
+func Header(sys *types.SystemContext, authfile, username, password string) (map[string]string, error) {
+	var content string
+	var err error
+
+	if username != "" {
+		content, err = encodeSingleAuthConfig(types.DockerAuthConfig{Username: username, Password: password})
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		if sys == nil {
+			sys = &types.SystemContext{}
+		}
+		if authfile != "" {
+			sys.AuthFilePath = authfile
+		}
+		authConfigs, err := imageAuth.GetAllCredentials(sys)
+		if err != nil {
+			return nil, err
+		}
+		content, err = encodeMultiAuthConfigs(authConfigs)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	header := make(map[string]string)
+	header[XRegistryAuthHeader] = content
+
+	return header, nil
+}
+
+// RemoveAuthfile is a convenience function that is meant to be called in a
+// deferred statement. If non-empty, it removes the specified authfile and log
+// errors.  It's meant to reduce boilerplate code at call sites of
+// `GetCredentials`.
+func RemoveAuthfile(authfile string) {
+	if authfile == "" {
+		return
+	}
+	if err := os.Remove(authfile); err != nil {
+		logrus.Errorf("Error removing temporary auth file %q: %v", authfile, err)
+	}
+}
+
+// encodeSingleAuthConfig serializes the auth configuration as a base64 encoded JSON payload.
+func encodeSingleAuthConfig(authConfig types.DockerAuthConfig) (string, error) {
+	conf := imageAuthToDockerAuth(authConfig)
+	buf, err := json.Marshal(conf)
+	if err != nil {
+		return "", err
+	}
+	return base64.URLEncoding.EncodeToString(buf), nil
+}
+
+// encodeMultiAuthConfigs serializes the auth configurations as a base64 encoded JSON payload.
+func encodeMultiAuthConfigs(authConfigs map[string]types.DockerAuthConfig) (string, error) {
+	confs := make(map[string]dockerAPITypes.AuthConfig)
+	for registry, authConf := range authConfigs {
+		confs[registry] = imageAuthToDockerAuth(authConf)
+	}
+	buf, err := json.Marshal(confs)
+	if err != nil {
+		return "", err
+	}
+	return base64.URLEncoding.EncodeToString(buf), nil
+}
+
+// authConfigsToAuthFile stores the specified auth configs in a temporary files
+// and returns its path. The file can later be used an auth file for contacting
+// one or more container registries.  If tmpDir is empty, the system's default
+// TMPDIR will be used.
+func authConfigsToAuthFile(authConfigs map[string]types.DockerAuthConfig) (string, error) {
+	// Intitialize an empty temporary JSON file.
+	tmpFile, err := ioutil.TempFile("", "auth.json.")
+	if err != nil {
+		return "", err
+	}
+	if _, err := tmpFile.Write([]byte{'{', '}'}); err != nil {
+		return "", errors.Wrap(err, "error initializing temporary auth file")
+	}
+	if err := tmpFile.Close(); err != nil {
+		return "", errors.Wrap(err, "error closing temporary auth file")
+	}
+	authFilePath := tmpFile.Name()
+
+	// TODO: It would be nice if c/image could dump the map at once.
+	//
+	// Now use the c/image packages to store the credentials. It's battle
+	// tested, and we make sure to use the same code as the image backend.
+	sys := types.SystemContext{AuthFilePath: authFilePath}
+	for server, config := range authConfigs {
+		// Note that we do not validate the credentials here. Wassume
+		// that all credentials are valid. They'll be used on demand
+		// later.
+		if err := imageAuth.SetAuthentication(&sys, server, config.Username, config.Password); err != nil {
+			return "", errors.Wrapf(err, "error storing credentials in temporary auth file (server: %q, user: %q)", server, config.Username)
+		}
+	}
+
+	return authFilePath, nil
+}
+
+// dockerAuthToImageAuth converts a docker auth config to one we're using
+// internally from c/image.  Note that the Docker types look slightly
+// different, so we need to convert to be extra sure we're not running into
+// undesired side-effects when unmarhalling directly to our types.
+func dockerAuthToImageAuth(authConfig dockerAPITypes.AuthConfig) types.DockerAuthConfig {
+	return types.DockerAuthConfig{
+		Username:      authConfig.Username,
+		Password:      authConfig.Password,
+		IdentityToken: authConfig.IdentityToken,
+	}
+}
+
+// reverse conversion of `dockerAuthToImageAuth`.
+func imageAuthToDockerAuth(authConfig types.DockerAuthConfig) dockerAPITypes.AuthConfig {
+	return dockerAPITypes.AuthConfig{
+		Username:      authConfig.Username,
+		Password:      authConfig.Password,
+		IdentityToken: authConfig.IdentityToken,
+	}
+}
+
+// singleAuthHeader extracts a DockerAuthConfig from the request's header.
+// The header content is a single DockerAuthConfig.
+func singleAuthHeader(r *http.Request) (map[string]types.DockerAuthConfig, error) {
+	authHeader := r.Header.Get(XRegistryAuthHeader)
+	authConfig := dockerAPITypes.AuthConfig{}
+	if len(authHeader) > 0 {
+		authJSON := base64.NewDecoder(base64.URLEncoding, strings.NewReader(authHeader))
+		if err := json.NewDecoder(authJSON).Decode(&authConfig); err != nil {
+			return nil, err
+		}
+	}
+	authConfigs := make(map[string]types.DockerAuthConfig)
+	authConfigs["0"] = dockerAuthToImageAuth(authConfig)
+	return authConfigs, nil
+}
+
+// multiAuthHeader extracts a DockerAuthConfig from the request's header.
+// The header content is a map[string]DockerAuthConfigs.
+func multiAuthHeader(r *http.Request) (map[string]types.DockerAuthConfig, error) {
+	authHeader := r.Header.Get(XRegistryAuthHeader)
+	if len(authHeader) == 0 {
+		return nil, nil
+	}
+
+	dockerAuthConfigs := make(map[string]dockerAPITypes.AuthConfig)
+	authJSON := base64.NewDecoder(base64.URLEncoding, strings.NewReader(authHeader))
+	if err := json.NewDecoder(authJSON).Decode(&dockerAuthConfigs); err != nil {
+		return nil, err
+	}
+
+	// Now convert to the internal types.
+	authConfigs := make(map[string]types.DockerAuthConfig)
+	for server := range dockerAuthConfigs {
+		authConfigs[server] = dockerAuthToImageAuth(dockerAuthConfigs[server])
+	}
+	return authConfigs, nil
+}