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Don't return empty errcode.Errors slices

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If this slice ends up empty after parsing the HTTP response body, it
means the body is not well-formed. We've probably encountered an error
message produced by something that uses a different JSON schema, or
an error that just happens to validate as JSON.

An empty errcode.Errors slice is not a very useful thing to return,
since its Error() output is just `<nil>`. Detect this case, and instend
return an UnexpectedHTTPResponseError.

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
This commit is contained in:
Aaron Lehmann 2016-03-14 10:06:30 -07:00
parent 1d5d54978a
commit c94c2a47a3
2 changed files with 34 additions and 4 deletions
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19
docs/client/errors.go
View file

@ -2,6 +2,7 @@ package client
import (
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
@ -10,6 +11,10 @@ import (
"github.com/docker/distribution/registry/api/errcode"
)
// ErrNoErrorsInBody is returned when a HTTP response body parses to an empty
// errcode.Errors slice.
var ErrNoErrorsInBody = errors.New("no error details found in HTTP response body")
// UnexpectedHTTPStatusError is returned when an unexpected HTTP status is
// returned when making a registry api call.
type UnexpectedHTTPStatusError struct {
@ -17,7 +22,7 @@ type UnexpectedHTTPStatusError struct {
}
func (e *UnexpectedHTTPStatusError) Error() string {
return fmt.Sprintf("Received unexpected HTTP status: %s", e.Status)
return fmt.Sprintf("received unexpected HTTP status: %s", e.Status)
}
// UnexpectedHTTPResponseError is returned when an expected HTTP status code
@ -28,7 +33,7 @@ type UnexpectedHTTPResponseError struct {
}
func (e *UnexpectedHTTPResponseError) Error() string {
return fmt.Sprintf("Error parsing HTTP response: %s: %q", e.ParseErr.Error(), string(e.Response))
return fmt.Sprintf("error parsing HTTP response: %s: %q", e.ParseErr.Error(), string(e.Response))
}
func parseHTTPErrorResponse(statusCode int, r io.Reader) error {
@ -57,6 +62,16 @@ func parseHTTPErrorResponse(statusCode int, r io.Reader) error {
Response: body,
}
}
if len(errors) == 0 {
// If there was no error specified in the body, return
// UnexpectedHTTPResponseError.
return &UnexpectedHTTPResponseError{
ParseErr: ErrNoErrorsInBody,
Response: body,
}
}
return errors
}

19
docs/client/errors_test.go
View file

@ -59,6 +59,21 @@ func TestHandleErrorResponseExpectedStatusCode400ValidBody(t *testing.T) {
}
}
func TestHandleErrorResponseExpectedStatusCode404EmptyErrorSlice(t *testing.T) {
json := `{"randomkey": "randomvalue"}`
response := &http.Response{
Status: "404 Not Found",
StatusCode: 404,
Body: nopCloser{bytes.NewBufferString(json)},
}
err := HandleErrorResponse(response)
expectedMsg := `error parsing HTTP response: no error details found in HTTP response body: "{\"randomkey\": \"randomvalue\"}"`
if !strings.Contains(err.Error(), expectedMsg) {
t.Errorf("Expected \"%s\", got: \"%s\"", expectedMsg, err.Error())
}
}
func TestHandleErrorResponseExpectedStatusCode404InvalidBody(t *testing.T) {
json := "{invalid json}"
response := &http.Response{
@ -68,7 +83,7 @@ func TestHandleErrorResponseExpectedStatusCode404InvalidBody(t *testing.T) {
}
err := HandleErrorResponse(response)
expectedMsg := "Error parsing HTTP response: invalid character 'i' looking for beginning of object key string: \"{invalid json}\""
expectedMsg := "error parsing HTTP response: invalid character 'i' looking for beginning of object key string: \"{invalid json}\""
if !strings.Contains(err.Error(), expectedMsg) {
t.Errorf("Expected \"%s\", got: \"%s\"", expectedMsg, err.Error())
}
@ -82,7 +97,7 @@ func TestHandleErrorResponseUnexpectedStatusCode501(t *testing.T) {
}
err := HandleErrorResponse(response)
expectedMsg := "Received unexpected HTTP status: 501 Not Implemented"
expectedMsg := "received unexpected HTTP status: 501 Not Implemented"
if !strings.Contains(err.Error(), expectedMsg) {
t.Errorf("Expected \"%s\", got: \"%s\"", expectedMsg, err.Error())
}