add basic command framework and apiserver

pkg/apiserver/httputils/httputils.go

@@ -0,0 +1,167 @@
+/*
+Copyright 2016 The GoStor Authors All rights reserved.
+
+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 httputils
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"mime"
+	"net/http"
+	"strings"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/gostor/gotgt/pkg/version"
+	"golang.org/x/net/context"
+)
+
+// 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()
+		}
+	}
+}
+
+// MatchesContentType validates the content type against the expected one
+func MatchesContentType(contentType, expectedType string) bool {
+	mimetype, _, err := mime.ParseMediaType(contentType)
+	if err != nil {
+		logrus.Errorf("Error parsing media type: %s error: %v", contentType, err)
+	}
+	return err == nil && mimetype == expectedType
+}
+
+// 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 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()
+
+	// 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
+	}
+
+	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) string {
+	if ctx == nil {
+		return version.VERSION
+	}
+	val := ctx.Value(APIVersionKey)
+	if val == nil {
+		return version.VERSION
+	}
+	return val.(string)
+}