Move most of omegaup-update-problem's functionality to gitserver

This change is a huge refactor so that gitserver has all the
functionality that used to belong to omegaup-update-problem. Now the
protocol should be complete and the frontend should be able to stop
assuming that it is hosted in the same filesystem as the grader.

cmd/omegaup-gitserver/main.go

@@ -28,6 +28,7 @@ var (
 	pprofPort               = flag.Int("pprof-port", 33862, "Port in which the pprof server will listen")
 	libinteractivePath      = flag.String("libinteractive-path", "/usr/share/java/libinteractive.jar", "Path of libinteractive.jar")
 	allowDirectPushToMaster = flag.Bool("allow-direct-push-to-master", false, "Allow direct push to master")
+	verbose                 = flag.Bool("verbose", false, "Verbose logging")
 	log                     log15.Logger
 )
 
@@ -141,7 +142,12 @@ func (h *muxGitHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 func main() {
 	flag.Parse()
-	log = base.StderrLog()
+	if *verbose {
+		log = base.StderrLog()
+	} else {
+		log = log15.New()
+		log.SetHandler(base.ErrorCallerStackHandler(log15.LvlInfo, log15.StderrHandler))
+	}
 
 	stopChan := make(chan os.Signal)
 	signal.Notify(stopChan, os.Interrupt)

cmd/omegaup-gitserver/main_test.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"encoding/base64"
+	"fmt"
+	base "github.com/omegaup/go-base"
+	"golang.org/x/crypto/ed25519"
+	"testing"
+)
+
+const (
+	expiredToken = "v2.public.eyJwcm9ibGVtIjoiYTA5NGY3MWI0ZmEzZmY4YmVhZmY0MDZiNTQ1YTU1NzgiLCJleHAiOiIyMDE5LTAxLTA0VDA1OjAzOjA0KzAwOjAwIiwiaXNzIjoib21lZ2FVcCBmcm9udGVuZCIsInN1YiI6IjBiOGJhM2FjN2M2MzVkM2U2OTg5MWU4ODAzYzc4YTJmIn0VXEbZ414QQ7qEY9MFa2gGgeJqc-T1Ff7fPM3ZQ_YQudq5I05offZxG819gmdmq3Z1_HeV7bjMRWL5JIkfkHIK"
+)
+
+func TestParseBearerAuth(t *testing.T) {
+	log := base.StderrLog()
+	keyBytes, err := base64.StdEncoding.DecodeString(*publicKeyBase64)
+	if err != nil {
+		t.Fatalf("failed to parse shared key: %v", err)
+	}
+	auth := bearerAuthorization{
+		log:       log,
+		publicKey: ed25519.PublicKey(keyBytes),
+	}
+
+	_, _, ok := auth.parseBearerAuth(fmt.Sprintf("Bearer %s", expiredToken))
+	if ok {
+		t.Errorf("expired token was passed as valid")
+	}
+}

cmd/omegaup-migrate-problem/main.go

@@ -353,7 +353,7 @@ func convertCommitToPackfile(
 	return gitserver.CreatePackfile(
 		contents,
 		settings,
-		gitserver.ConvertZipUpdateAll,
+		gitserver.ZipMergeStrategyTheirs,
 		newRepo,
 		parentID,
 		originalCommit.Author(),