check api version in corehttp

- add comments, trim api path prefix
- corehttp: add option to set HTTP header "Server"
- daemon: use new corehttp options

License: MIT
Signed-off-by: keks <keks@cryptoscope.co>

cmd/ipfs/daemon.go

@@ -17,6 +17,7 @@ import (
 	corehttp "github.com/ipfs/go-ipfs/core/corehttp"
 	corerepo "github.com/ipfs/go-ipfs/core/corerepo"
 	nodeMount "github.com/ipfs/go-ipfs/fuse/node"
+	config "github.com/ipfs/go-ipfs/repo/config"
 	fsrepo "github.com/ipfs/go-ipfs/repo/fsrepo"
 	migrate "github.com/ipfs/go-ipfs/repo/fsrepo/migrations"
 
@@ -432,6 +433,8 @@ func serveHTTPApi(req *cmds.Request, cctx *oldcmds.Context) (error, <-chan error
 	var opts = []corehttp.ServeOption{
 		corehttp.MetricsCollectionOption("api"),
 		corehttp.CommandsOption(*cctx),
+		corehttp.CheckVersionOption(),
+		corehttp.ServerNameOption("go-ipfs/" + config.CurrentVersionNumber),
 		corehttp.WebUIOption,
 		gatewayOpt,
 		corehttp.VersionOption(),
@@ -529,6 +532,7 @@ func serveHTTPGateway(req *cmds.Request, cctx *oldcmds.Context) (error, <-chan e
 		corehttp.VersionOption(),
 		corehttp.IPNSHostnameOption(),
 		corehttp.GatewayOption(writable, "/ipfs", "/ipns"),
+		corehttp.CheckVersionOption(),
 	}
 
 	if len(cfg.Gateway.RootRedirect) > 0 {

core/corehttp/commands.go

 package corehttp
 
 import (
+	"errors"
+	"fmt"
 	"net"
 	"net/http"
 	"os"
@@ -10,12 +12,18 @@ import (
 	oldcmds "github.com/ipfs/go-ipfs/commands"
 	core "github.com/ipfs/go-ipfs/core"
 	corecommands "github.com/ipfs/go-ipfs/core/commands"
+	path "github.com/ipfs/go-ipfs/path"
 	config "github.com/ipfs/go-ipfs/repo/config"
 
 	cmds "gx/ipfs/QmTwKPLyeRKuDawuy6CAn1kRj1FVoqBEM8sviAUWN7NW9K/go-ipfs-cmds"
 	cmdsHttp "gx/ipfs/QmTwKPLyeRKuDawuy6CAn1kRj1FVoqBEM8sviAUWN7NW9K/go-ipfs-cmds/http"
 )
 
+var (
+	errApiVersionMismatch = errors.New("api version mismatch")
+)
+
+const apiPath = "/api/v0"
 const originEnvKey = "API_ORIGIN"
 const originEnvKeyDeprecate = `You are using the ` + originEnvKey + `ENV Variable.
 This functionality is deprecated, and will be removed in future versions.
@@ -131,3 +139,42 @@ func CommandsOption(cctx oldcmds.Context) ServeOption {
 func CommandsROOption(cctx oldcmds.Context) ServeOption {
 	return commandsOption(cctx, corecommands.RootRO)
 }
+
+// CheckVersionOption returns a ServeOption that checks whether the client ipfs version matches. Does nothing when the user agent string does not contain `/go-ipfs/`
+func CheckVersionOption() ServeOption {
+	daemonVersion := config.ApiVersion
+
+	return ServeOption(func(n *core.IpfsNode, l net.Listener, next *http.ServeMux) (*http.ServeMux, error) {
+		mux := http.NewServeMux()
+		mux.HandleFunc(APIPath+"/", func(w http.ResponseWriter, r *http.Request) {
+			pth := path.SplitList(r.URL.Path[len(APIPath):])
+			// backwards compatibility to previous version check
+			if pth[1] != "version" {
+				clientVersion := r.UserAgent()
+				// skips check if client is not go-ipfs
+				if clientVersion != "" && strings.Contains(clientVersion, "/go-ipfs/") && daemonVersion != clientVersion {
+					http.Error(w, fmt.Sprintf("%s (%s != %s)", errApiVersionMismatch, daemonVersion, clientVersion), http.StatusBadRequest)
+					return
+				}
+			}
+
+			next.ServeHTTP(w, r)
+		})
+		mux.HandleFunc("/", next.ServeHTTP)
+
+		return mux, nil
+	})
+}
+
+// ServerNameOption returns a ServeOption that makes the http server set the Server HTTP header.
+func ServerNameOption(name string) ServeOption {
+	return ServeOption(func(n *core.IpfsNode, l net.Listener, next *http.ServeMux) (*http.ServeMux, error) {
+		mux := http.NewServeMux()
+		mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Server", name)
+			next.ServeHTTP(w, r)
+		})
+
+		return mux, nil
+	})
+}

core/corehttp/option_test.go

+package corehttp
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	config "github.com/ipfs/go-ipfs/repo/config"
+)
+
+type testcasecheckversion struct {
+	userAgent    string
+	uri          string
+	shouldHandle bool
+	responseBody string
+	responseCode int
+}
+
+func (tc testcasecheckversion) body() string {
+	if !tc.shouldHandle && tc.responseBody == "" {
+		return fmt.Sprintf("%s (%s != %s)\n", errApiVersionMismatch, config.ApiVersion, tc.userAgent)
+	}
+
+	return tc.responseBody
+}
+
+func TestCheckVersionOption(t *testing.T) {
+	tcs := []testcasecheckversion{
+		{"/go-ipfs/0.1/", APIPath + "/test/", false, "", http.StatusBadRequest},
+		{"/go-ipfs/0.1/", APIPath + "/version", true, "check!", http.StatusOK},
+		{config.ApiVersion, APIPath + "/test", true, "check!", http.StatusOK},
+		{"Mozilla Firefox/no go-ipfs node", APIPath + "/test", true, "check!", http.StatusOK},
+		{"/go-ipfs/0.1/", "/webui", true, "check!", http.StatusOK},
+	}
+
+	for _, tc := range tcs {
+		t.Logf("%#v", tc)
+		r := httptest.NewRequest("POST", tc.uri, nil)
+		r.Header.Add("User-Agent", tc.userAgent) // old version, should fail
+
+		called := false
+		inner := http.NewServeMux()
+		inner.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+			called = true
+			if !tc.shouldHandle {
+				t.Error("handler was called even though version didn't match")
+			} else {
+				io.WriteString(w, "check!")
+			}
+		})
+
+		mux, err := CheckVersionOption()(nil, nil, inner)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		w := httptest.NewRecorder()
+
+		mux.ServeHTTP(w, r)
+
+		if tc.shouldHandle && !called {
+			t.Error("handler wasn't called even though it should have")
+		}
+
+		if w.Code != tc.responseCode {
+			t.Errorf("expected code %d but got %d", tc.responseCode, w.Code)
+		}
+
+		if w.Body.String() != tc.body() {
+			t.Errorf("expected error message %q, got %q", tc.body(), w.Body.String())
+		}
+	}
+}
+
+func TestServerNameOption(t *testing.T) {
+	type testcase struct {
+		name string
+	}
+
+	tcs := []testcase{
+		{"go-ipfs/0.4.13"},
+		{"go-ipfs/" + config.CurrentVersionNumber},
+	}
+
+	assert := func(name string, exp, got interface{}) {
+		if got != exp {
+			t.Errorf("%s: got %q, expected %q", name, got, exp)
+		}
+	}
+
+	for _, tc := range tcs {
+		t.Logf("%#v", tc)
+		r := httptest.NewRequest("POST", "/", nil)
+
+		inner := http.NewServeMux()
+		inner.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+			// this block is intentionally left blank.
+		})
+
+		mux, err := ServerNameOption(tc.name)(nil, nil, inner)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		w := httptest.NewRecorder()
+
+		mux.ServeHTTP(w, r)
+		srvHdr := w.Header().Get("Server")
+		assert("Server header", tc.name, srvHdr)
+	}
+}