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httputils.go
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httputils.go
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package httputils
import (
"encoding/json"
"fmt"
"io"
"net/http"
"strings"
"golang.org/x/net/context"
"github.com/Sirupsen/logrus"
"github.com/docker/distribution/registry/api/errcode"
"github.com/docker/docker/api"
"github.com/docker/docker/pkg/version"
"github.com/docker/docker/utils"
)
// APIVersionKey is the client's requested API version.
const APIVersionKey = "api-version"
// APIFunc is an adapter to allow the use of ordinary functions as Docker API endpoints.
// Any function that has the appropriate signature can be register as a API endpoint (e.g. getVersion).
type APIFunc func(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error
// HijackConnection interrupts the http response writer to get the
// underlying connection and operate with it.
func HijackConnection(w http.ResponseWriter) (io.ReadCloser, io.Writer, error) {
conn, _, err := w.(http.Hijacker).Hijack()
if err != nil {
return nil, nil, err
}
// Flush the options to make sure the client sets the raw mode
conn.Write([]byte{})
return conn, conn, nil
}
// CloseStreams ensures that a list for http streams are properly closed.
func CloseStreams(streams ...interface{}) {
for _, stream := range streams {
if tcpc, ok := stream.(interface {
CloseWrite() error
}); ok {
tcpc.CloseWrite()
} else if closer, ok := stream.(io.Closer); ok {
closer.Close()
}
}
}
// CheckForJSON makes sure that the request's Content-Type is application/json.
func CheckForJSON(r *http.Request) error {
ct := r.Header.Get("Content-Type")
// No Content-Type header is ok as long as there's no Body
if ct == "" {
if r.Body == nil || r.ContentLength == 0 {
return nil
}
}
// Otherwise it better be json
if api.MatchesContentType(ct, "application/json") {
return nil
}
return fmt.Errorf("Content-Type specified (%s) must be 'application/json'", ct)
}
// ParseForm ensures the request form is parsed even with invalid content types.
// If we don't do this, POST method without Content-type (even with empty body) will fail.
func ParseForm(r *http.Request) error {
if r == nil {
return nil
}
if err := r.ParseForm(); err != nil && !strings.HasPrefix(err.Error(), "mime:") {
return err
}
return nil
}
// ParseMultipartForm ensure the request form is parsed, even with invalid content types.
func ParseMultipartForm(r *http.Request) error {
if err := r.ParseMultipartForm(4096); err != nil && !strings.HasPrefix(err.Error(), "mime:") {
return err
}
return nil
}
// WriteError decodes a specific docker error and sends it in the response.
func WriteError(w http.ResponseWriter, err error) {
if err == nil || w == nil {
logrus.WithFields(logrus.Fields{"error": err, "writer": w}).Error("unexpected HTTP error handling")
return
}
statusCode := http.StatusInternalServerError
errMsg := err.Error()
// Based on the type of error we get we need to process things
// slightly differently to extract the error message.
// In the 'errcode.*' cases there are two different type of
// error that could be returned. errocode.ErrorCode is the base
// type of error object - it is just an 'int' that can then be
// used as the look-up key to find the message. errorcode.Error
// extends errorcode.Error by adding error-instance specific
// data, like 'details' or variable strings to be inserted into
// the message.
//
// Ideally, we should just be able to call err.Error() for all
// cases but the errcode package doesn't support that yet.
//
// Additionally, in both errcode cases, there might be an http
// status code associated with it, and if so use it.
switch err.(type) {
case errcode.ErrorCode:
daError, _ := err.(errcode.ErrorCode)
statusCode = daError.Descriptor().HTTPStatusCode
errMsg = daError.Message()
case errcode.Error:
// For reference, if you're looking for a particular error
// then you can do something like :
// import ( derr "github.com/docker/docker/errors" )
// if daError.ErrorCode() == derr.ErrorCodeNoSuchContainer { ... }
daError, _ := err.(errcode.Error)
statusCode = daError.ErrorCode().Descriptor().HTTPStatusCode
errMsg = daError.Message
default:
// This part of will be removed once we've
// converted everything over to use the errcode package
// FIXME: this is brittle and should not be necessary.
// If we need to differentiate between different possible error types,
// we should create appropriate error types with clearly defined meaning
errStr := strings.ToLower(err.Error())
for keyword, status := range map[string]int{
"not found": http.StatusNotFound,
"no such": http.StatusNotFound,
"bad parameter": http.StatusBadRequest,
"conflict": http.StatusConflict,
"impossible": http.StatusNotAcceptable,
"wrong login/password": http.StatusUnauthorized,
"hasn't been activated": http.StatusForbidden,
} {
if strings.Contains(errStr, keyword) {
statusCode = status
break
}
}
}
if statusCode == 0 {
statusCode = http.StatusInternalServerError
}
logrus.WithFields(logrus.Fields{"statusCode": statusCode, "err": utils.GetErrorMessage(err)}).Error("HTTP Error")
http.Error(w, errMsg, statusCode)
}
// WriteJSON writes the value v to the http response stream as json with standard json encoding.
func WriteJSON(w http.ResponseWriter, code int, v interface{}) error {
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(code)
return json.NewEncoder(w).Encode(v)
}
// VersionFromContext returns an API version from the context using APIVersionKey.
// It panics if the context value does not have version.Version type.
func VersionFromContext(ctx context.Context) (ver version.Version) {
if ctx == nil {
return
}
val := ctx.Value(APIVersionKey)
if val == nil {
return
}
return val.(version.Version)
}