Add the reverseproxy http service

changelog/unreleased/http-reverseproxy.md

@@ -0,0 +1,7 @@
+Enhancement: Add the reverseproxy http service
+
+This PR adds an HTTP service which does the job of authenticating incoming
+requests via the reva middleware before forwarding them to the respective
+backends.  This is useful for extensions which do not have the auth mechanisms.
+
+https://github.com/cs3org/reva/pull/2268

internal/http/services/loader/loader.go

@@ -32,6 +32,7 @@ import (
 	_ "github.com/cs3org/reva/internal/http/services/owncloud/ocdav"
 	_ "github.com/cs3org/reva/internal/http/services/owncloud/ocs"
 	_ "github.com/cs3org/reva/internal/http/services/prometheus"
+	_ "github.com/cs3org/reva/internal/http/services/reverseproxy"
 	_ "github.com/cs3org/reva/internal/http/services/siteacc"
 	_ "github.com/cs3org/reva/internal/http/services/sysinfo"
 	_ "github.com/cs3org/reva/internal/http/services/wellknown"

internal/http/services/reverseproxy/reverseproxy.go

@@ -0,0 +1,119 @@
+// Copyright 2018-2021 CERN
+//
+// 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.
+//
+// In applying this license, CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+
+package reverseproxy
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+
+	ctxpkg "github.com/cs3org/reva/pkg/ctx"
+	"github.com/cs3org/reva/pkg/rhttp/global"
+	"github.com/go-chi/chi/v5"
+	"github.com/mitchellh/mapstructure"
+	"github.com/rs/zerolog"
+)
+
+func init() {
+	global.Register("reverseproxy", New)
+}
+
+type proxyRule struct {
+	Endpoint string `mapstructure:"endpoint" json:"endpoint"`
+	Backend  string `mapstructure:"backend" json:"backend"`
+}
+
+type config struct {
+	ProxyRulesJSON string `mapstructure:"proxy_rules_json"`
+}
+
+func (c *config) init() {
+	if c.ProxyRulesJSON == "" {
+		c.ProxyRulesJSON = "/etc/revad/proxy_rules.json"
+	}
+}
+
+type svc struct {
+	router *chi.Mux
+}
+
+// New returns an instance of the reverse proxy service
+func New(m map[string]interface{}, log *zerolog.Logger) (global.Service, error) {
+	conf := &config{}
+	if err := mapstructure.Decode(m, conf); err != nil {
+		return nil, err
+	}
+	conf.init()
+
+	f, err := ioutil.ReadFile(conf.ProxyRulesJSON)
+	if err != nil {
+		return nil, err
+	}
+
+	var rules []proxyRule
+	err = json.Unmarshal(f, &rules)
+	if err != nil {
+		return nil, err
+	}
+
+	r := chi.NewRouter()
+
+	for _, rule := range rules {
+		remote, err := url.Parse(rule.Backend)
+		if err != nil {
+			// Skip the rule if the backend is not a valid URL
+			continue
+		}
+
+		proxy := httputil.NewSingleHostReverseProxy(remote)
+		handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			r.Host = remote.Host
+			if token, ok := ctxpkg.ContextGetToken(r.Context()); ok {
+				r.Header.Set(ctxpkg.TokenHeader, token)
+			}
+			proxy.ServeHTTP(w, r)
+		})
+		r.Mount(rule.Endpoint, handler)
+	}
+
+	return &svc{router: r}, nil
+}
+
+func (s *svc) Close() error {
+	return nil
+}
+
+func (s *svc) Prefix() string {
+	// This service will be served at root
+	return ""
+}
+
+func (s *svc) Unprotected() []string {
+	// TODO: If the services which will be served via the reverse proxy have unprotected endpoints,
+	// we won't be able to support those at the moment.
+	return []string{}
+}
+
+func (s *svc) Handler() http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		s.router.ServeHTTP(w, r)
+	})
+}