Refactor the codebase

.gitignore

@@ -0,0 +1 @@
+bagage

auth_basic.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"errors"
+	"net/http"
+)
+
+/*
+ * We extract the credentials from the Basic Auth headers
+ * (We may think to other ways to pass credentials such as a JWT)
+ */
+type BasicAuthExtract struct {
+	OnNotFound ErrorHandler
+	OnCreds    CredsHandler
+}
+
+func (b BasicAuthExtract) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	username, password, ok := r.BasicAuth()
+	if !ok {
+		b.OnNotFound.WithError(errors.New("LDAP. Missing Authentication Header")).ServeHTTP(w, r)
+		return
+	}
+	if username == "" || password == "" {
+		b.OnNotFound.WithError(errors.New("LDAP. Username or password cannot be empty")).ServeHTTP(w, r)
+		return
+	}
+	b.OnCreds.WithCreds(username, password).ServeHTTP(w, r)
+}

auth_ldap.go

@@ -0,0 +1,115 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+
+	"github.com/go-ldap/ldap/v3"
+)
+
+/* Check credentials against LDAP */
+type LdapPreAuth struct {
+	WithConfig      *Config
+	OnWrongPassword ErrorHandler
+	OnFailure       ErrorHandler
+	OnCreds         CredsHandler
+}
+
+func (l LdapPreAuth) WithCreds(username, password string) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+
+		// 1. Connect to the server
+		conn, err := ldapConnect(l.WithConfig)
+		if err != nil {
+			l.OnFailure.WithError(err).ServeHTTP(w, r)
+			return
+		}
+		defer conn.Close()
+
+		// 2. Authenticate with provided credentials
+		// @FIXME we should better check the error, it could also be due to an LDAP error
+		err = conn.auth(username, password)
+		if err != nil {
+			l.OnWrongPassword.WithError(err).ServeHTTP(w, r)
+			return
+		}
+
+		// 3. Fetch user's profile
+		profile, err := conn.profile()
+		if err != nil {
+			l.OnFailure.WithError(err).ServeHTTP(w, r)
+			return
+		}
+
+		// 4. Basic checks upon users' attributes
+		access_key := profile.GetAttributeValue("garage_s3_access_key")
+		secret_key := profile.GetAttributeValue("garage_s3_secret_key")
+		if access_key == "" || secret_key == "" {
+			err = errors.New(fmt.Sprintf("Either access key or secret key is missing in LDAP for %s", conn.userDn))
+			l.OnFailure.WithError(err).ServeHTTP(w, r)
+			return
+		}
+
+		// 5. Send fetched credentials to the next middleware
+		l.OnCreds.WithCreds(access_key, secret_key).ServeHTTP(w, r)
+	})
+}
+
+/**
+ * Private logic
+ */
+
+type ldapConnector struct {
+	conn   *ldap.Conn
+	config *Config
+	userDn string
+}
+
+func ldapConnect(c *Config) (ldapConnector, error) {
+	ldapSock, err := ldap.Dial("tcp", c.LdapServer)
+	if err != nil {
+		return ldapConnector{}, err
+	}
+
+	return ldapConnector{
+		conn:   ldapSock,
+		config: c,
+	}, nil
+}
+
+func (l *ldapConnector) auth(username, password string) error {
+	l.userDn = fmt.Sprintf("%s=%s,%s", l.config.UserNameAttr, username, l.config.UserBaseDN)
+	return l.conn.Bind(l.userDn, password)
+}
+
+func (l *ldapConnector) profile() (*ldap.Entry, error) {
+	searchRequest := ldap.NewSearchRequest(
+		l.userDn,
+		ldap.ScopeBaseObject,
+		ldap.NeverDerefAliases,
+		0,
+		0,
+		false,
+		"(objectClass=*)",
+		[]string{"garage_s3_access_key", "garage_s3_secret_key"},
+		nil)
+
+	sr, err := l.conn.Search(searchRequest)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(sr.Entries) != 1 {
+		return nil, errors.New(fmt.Sprintf("Wrong number of LDAP entries, expected 1, got", len(sr.Entries)))
+	}
+
+	return sr.Entries[0], nil
+}
+
+func (l *ldapConnector) Close() {
+	if l.conn != nil {
+		l.conn.Close()
+		l.conn = nil
+	}
+}

auth_s3.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"net/http"
+
+	"github.com/minio/minio-go/v7"
+	"github.com/minio/minio-go/v7/pkg/credentials"
+)
+
+/* Check credentials against Minio */
+type S3Auth struct {
+	WithConfig    *Config
+	OnMinioClient MinioClientHandler
+	OnFailure     ErrorHandler
+}
+
+func (s S3Auth) WithCreds(access_key, secret_key string) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		mc, err := minio.New(s.WithConfig.Endpoint, &minio.Options{
+			Creds:  credentials.NewStaticV4(access_key, secret_key, ""),
+			Secure: s.WithConfig.UseSSL,
+		})
+		if err != nil {
+			s.OnFailure.WithError(err).ServeHTTP(w, r)
+			return
+		}
+		s.OnMinioClient.WithMC(mc).ServeHTTP(w, r)
+	})
+}

config.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"reflect"
+)
+
+type Config struct {
+	HttpListen   string `env:"BAGAGE_HTTP_LISTEN" default:":8080"`
+	DavPath      string `env:"BAGAGE_WEBDAV_PREFIX" default:"/webdav"`
+	LdapServer   string `env:"BAGAGE_LDAP_ENDPOINT" default:"127.0.0.1:1389"`
+	UserBaseDN   string `env:"BAGAGE_LDAP_USER_BASE_DN" default:"ou=users,dc=deuxfleurs,dc=fr"`
+	UserNameAttr string `env:"BAGAGE_LDAP_USERNAME_ATTR" default:"cn"`
+	Endpoint     string `env:"BAGAGE_S3_ENDPOINT" default:"garage.deuxfleurs.fr"`
+	UseSSL       bool   `env:"BAGAGE_S3_SSL" default:"true"`
+}
+
+func (c *Config) LoadWithDefault() *Config {
+	c.iter(func(t reflect.StructField, v reflect.Value) {
+		tag := t.Tag.Get("default")
+		if tag == "" {
+			return
+		} else {
+			setKey(v, tag)
+		}
+	})
+
+	return c
+}
+
+func (c *Config) LoadWithEnv() *Config {
+	c.iter(func(t reflect.StructField, v reflect.Value) {
+		tag := t.Tag.Get("env")
+		if tag == "" {
+			return
+		} else if val, ok := os.LookupEnv(tag); ok {
+			setKey(v, val)
+		}
+	})
+
+	return c
+}
+
+func (c *Config) String() (rep string) {
+	rep = "Configuration:\n"
+
+	c.iter(func(t reflect.StructField, v reflect.Value) {
+		rep += "\t" + t.Name + ": "
+		if t.Type.Kind() == reflect.Bool {
+			rep += fmt.Sprintf("%v", v.Bool()) + "\n"
+		} else {
+			rep += "\"" + v.String() + "\"\n"
+		}
+	})
+
+	return
+}
+
+func (c *Config) iter(cb func(t reflect.StructField, v reflect.Value)) {
+	t := reflect.ValueOf(c).Elem()
+	for i := 0; i < t.Type().NumField(); i++ {
+		field := t.Field(i)
+		typeField := t.Type().Field(i)
+		cb(typeField, field)
+	}
+}
+
+func setKey(v reflect.Value, e string) {
+	if v.Type().Kind() == reflect.String {
+		v.SetString(e)
+	} else if v.Type().Kind() == reflect.Bool {
+		v.SetBool(e == "true")
+	} else {
+		panic("Unsupported type")
+	}
+}

error.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"net/http"
+)
+
+type NotAuthorized struct{}
+
+func (n NotAuthorized) WithError(err error) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("WWW-Authenticate", `Basic realm="Pour accéder à Bagage, veuillez entrer vos identifiants Deuxfleurs"`)
+		w.WriteHeader(401)
+		w.Write([]byte("401 Unauthorized\n"))
+	})
+}
+
+type InternalError struct{}
+
+func (i InternalError) WithError(err error) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(500)
+		w.Write([]byte("500 Internal Server Error\n"))
+	})
+}

main.go

@@ -1,567 +1,35 @@
 package main
 
 import (
-	"context"
-	"errors"
-	"fmt"
-	"io"
-	"io/fs"
 	"log"
-	"mime"
 	"net/http"
-	"os"
-	"path"
-	"strings"
-	"time"
-
-	"golang.org/x/net/webdav"
-
-	"github.com/go-ldap/ldap/v3"
-
-	"github.com/minio/minio-go/v7"
-	"github.com/minio/minio-go/v7/pkg/credentials"
 )
 
-type bagageCtxKey string
-
-const garageEntry = bagageCtxKey("garage")
-
-type garageCtx struct {
-	MC        *minio.Client
-	StatCache map[string]*GarageStat
-}
-
-func EnvOrDefault(key, def string) string {
-	if val, ok := os.LookupEnv(key); ok {
-		return val
-	}
-	return def
-}
-
 func main() {
 	log.Println("=== Starting Bagage ===")
-	HttpListen := EnvOrDefault("BAGAGE_HTTP_LISTEN", ":8080")
-	pathPrefix := EnvOrDefault("BAGAGE_WEBDAV_PREFIX", "/webdav")
-	LdapServer := EnvOrDefault("BAGAGE_LDAP_ENDPOINT", "127.0.0.1:1389")
-	UserBaseDN := EnvOrDefault("BAGAGE_LDAP_USER_BASE_DN", "ou=users,dc=deuxfleurs,dc=fr")
-	UserNameAttr := EnvOrDefault("BAGAGE_LDAP_USERNAME_ATTR", "cn")
-	Endpoint := EnvOrDefault("BAGAGE_S3_ENDPOINT", "garage.deuxfleurs.fr")
-	UseSSL := EnvOrDefault("BAGAGE_S3_SSL", "true") == "true"
-
-	srv := &webdav.Handler{
-		Prefix:     pathPrefix,
-		FileSystem: NewGarageFS(),
-		LockSystem: webdav.NewMemLS(),
-		Logger: func(r *http.Request, err error) {
-			log.Printf("INFO: %s %s %s\n", r.RemoteAddr, r.Method, r.URL)
-			if err != nil {
-				log.Printf("ERR: %v", err)
-			}
-		},
-	}
-
-	http.HandleFunc(pathPrefix+"/", func(w http.ResponseWriter, r *http.Request) {
-		username, password, ok := r.BasicAuth()
-
-		if !ok {
-			NotAuthorized(w, r)
-			return
-		}
-
-		ldapSock, err := ldap.Dial("tcp", LdapServer)
-		if err != nil {
-			log.Println(err)
-			InternalError(w, r)
-			return
-		}
-		defer ldapSock.Close()
-
-		// Check credential
-		userDn := fmt.Sprintf("%s=%s,%s", UserNameAttr, username, UserBaseDN)
-		err = ldapSock.Bind(userDn, password)
-		if err != nil {
-			log.Println(err)
-			NotAuthorized(w, r)
-			return
-		}
-
-		// Get S3 creds garage_s3_access_key garage_s3_secret_key
-		searchRequest := ldap.NewSearchRequest(
-			userDn,
-			ldap.ScopeBaseObject,
-			ldap.NeverDerefAliases,
-			0,
-			0,
-			false,
-			"(objectClass=*)",
-			[]string{"garage_s3_access_key", "garage_s3_secret_key"},
-			nil)
-
-		sr, err := ldapSock.Search(searchRequest)
-		if err != nil {
-			log.Println(err)
-			InternalError(w, r)
-			return
-		}
-
-		if len(sr.Entries) != 1 {
-			log.Println("Wrong number of LDAP entries, expected 1, got", len(sr.Entries))
-			InternalError(w, r)
-			return
-		}
-
-		access_key := sr.Entries[0].GetAttributeValue("garage_s3_access_key")
-		secret_key := sr.Entries[0].GetAttributeValue("garage_s3_secret_key")
-
-		if access_key == "" || secret_key == "" {
-			log.Println("Either access key or secret key is missing in LDAP for ", userDn)
-			InternalError(w, r)
-			return
-		}
-
-		mc, err := minio.New(Endpoint, &minio.Options{
-			Creds:  credentials.NewStaticV4(access_key, secret_key, ""),
-			Secure: UseSSL,
+	config := (&Config{}).LoadWithDefault().LoadWithEnv()
+
+	log.Println(config)
+
+	// Assemble components to handle WebDAV requests
+	http.Handle(config.DavPath+"/",
+		BasicAuthExtract{
+			OnNotFound: NotAuthorized{},
+			OnCreds: LdapPreAuth{
+				WithConfig:      config,
+				OnWrongPassword: NotAuthorized{},
+				OnFailure:       InternalError{},
+				OnCreds: S3Auth{
+					WithConfig: config,
+					OnFailure:  InternalError{},
+					OnMinioClient: WebDav{
+						WithConfig: config,
+					},
+				},
+			},
 		})
-		if err != nil {
-			log.Println(err)
-			InternalError(w, r)
-			return
-		}
-
-		nctx := context.WithValue(r.Context(), garageEntry, garageCtx{MC: mc, StatCache: make(map[string]*GarageStat)})
-		srv.ServeHTTP(w, r.WithContext(nctx))
-		return
-	})
 
-	if err := http.ListenAndServe(HttpListen, nil); err != nil {
+	if err := http.ListenAndServe(config.HttpListen, nil); err != nil {
 		log.Fatalf("Error with WebDAV server: %v", err)
 	}
 }
-
-func NotAuthorized(w http.ResponseWriter, r *http.Request) {
-	w.Header().Set("WWW-Authenticate", `Basic realm="Pour accéder à Bagage, veuillez entrer vos identifiants Deuxfleurs"`)
-	w.WriteHeader(401)
-	w.Write([]byte("401 Unauthorized\n"))
-}
-
-func InternalError(w http.ResponseWriter, r *http.Request) {
-	w.WriteHeader(500)
-	w.Write([]byte("500 Internal Server Error\n"))
-}
-
-/*
-  /////// Select Action
-  If no slash or one trailing slash
-    return ListBuckets
-  Else
-    obj := ListObjects
-    If obj.Length == 1
-      return GetObject
-    Else
-      return obj
-*/
-type GarageFS struct{}
-
-func NewGarageFS() *GarageFS {
-	grg := new(GarageFS)
-	return grg
-}
-
-func (s *GarageFS) Mkdir(ctx context.Context, name string, perm os.FileMode) error {
-	return errors.New("Not implemented Mkdir")
-}
-
-func (s *GarageFS) OpenFile(ctx context.Context, name string, flag int, perm os.FileMode) (webdav.File, error) {
-	//log.Println("Stat from GarageFS.OpenFile()", name)
-	NewGarageStatFromFile(ctx, name)
-	return NewGarageFile(ctx, name)
-}
-
-func (s *GarageFS) RemoveAll(ctx context.Context, name string) error {
-	return errors.New("Not implemented RemoveAll")
-}
-
-func (s *GarageFS) Rename(ctx context.Context, oldName, newName string) error {
-	return errors.New("Not implemented Rename")
-}
-
-func (s *GarageFS) Stat(ctx context.Context, name string) (os.FileInfo, error) {
-	//log.Println("Stat from GarageFS.Stat()", name)
-	return NewGarageStat(ctx, name)
-}
-
-type GarageFile struct {
-	ctx   context.Context
-	mc    *minio.Client
-	obj   *minio.Object
-	objw  *io.PipeWriter
-	donew chan error
-	pos   int64
-	path  S3Path
-}
-
-func NewGarageFile(ctx context.Context, path string) (webdav.File, error) {
-	gf := new(GarageFile)
-	gf.ctx = ctx
-	gf.pos = 0
-	gf.mc = ctx.Value(garageEntry).(garageCtx).MC
-	gf.path = NewS3Path(path)
-	return gf, nil
-}
-
-func (gf *GarageFile) Close() error {
-	err := make([]error, 0)
-
-	if gf.obj != nil {
-		err = append(err, gf.obj.Close())
-		gf.obj = nil
-	}
-
-	if gf.objw != nil {
-		// wait that minio completes its transfers in background
-		err = append(err, gf.objw.Close())
-		err = append(err, <-gf.donew)
-		gf.donew = nil
-		gf.objw = nil
-	}
-
-	count := 0
-	for _, e := range err {
-		if e != nil {
-			count++
-			log.Println(e)
-		}
-	}
-	if count > 0 {
-		return errors.New(fmt.Sprintf("%d errors when closing this WebDAV File. Read previous logs to know more.", count))
-	}
-	return nil
-}
-
-func (gf *GarageFile) loadObject() error {
-	if gf.obj == nil {
-		obj, err := gf.mc.GetObject(gf.ctx, gf.path.bucket, gf.path.key, minio.GetObjectOptions{})
-		if err != nil {
-			return err
-		}
-		gf.obj = obj
-	}
-	return nil
-}
-
-func (gf *GarageFile) Read(p []byte) (n int, err error) {
-	//if gf.Stat() & OBJECT == 0 { /* @FIXME Ideally we would check against OBJECT but we need a non OPAQUE_KEY */
-	//	return 0, os.ErrInvalid
-	//}
-	if err := gf.loadObject(); err != nil {
-		return 0, err
-	}
-
-	return gf.obj.Read(p)
-}
-
-func (gf *GarageFile) Write(p []byte) (n int, err error) {
-	/*if gf.path.class != OBJECT {
-		return 0, os.ErrInvalid
-	}*/
-
-	if gf.objw == nil {
-		if gf.pos != 0 {
-			return 0, errors.New("writing with an offset is not implemented")
-		}
-
-		r, w := io.Pipe()
-		gf.donew = make(chan error, 1)
-		gf.objw = w
-
-		contentType := mime.TypeByExtension(path.Ext(gf.path.key))
-		go func() {
-			_, err := gf.mc.PutObject(context.Background(), gf.path.bucket, gf.path.key, r, -1, minio.PutObjectOptions{ContentType: contentType})
-			gf.donew <- err
-		}()
-	}
-
-	return gf.objw.Write(p)
-}
-
-func (gf *GarageFile) Seek(offset int64, whence int) (int64, error) {
-	if err := gf.loadObject(); err != nil {
-		return 0, err
-	}
-
-	pos, err := gf.obj.Seek(offset, whence)
-	gf.pos += pos
-	return pos, err
-}
-
-/*
-ReadDir reads the contents of the directory associated with the file f and returns a slice of DirEntry values in directory order. Subsequent calls on the same file will yield later DirEntry records in the directory.
-
-If n > 0, ReadDir returns at most n DirEntry records. In this case, if ReadDir returns an empty slice, it will return an error explaining why. At the end of a directory, the error is io.EOF.
-
-If n <= 0, ReadDir returns all the DirEntry records remaining in the directory. When it succeeds, it returns a nil error (not io.EOF).
-*/
-func (gf *GarageFile) Readdir(count int) ([]fs.FileInfo, error) {
-	if count > 0 {
-		return nil, errors.New("returning a limited number of directory entry is not supported in readdir")
-	}
-
-	if gf.path.class == ROOT {
-		return gf.readDirRoot(count)
-	} else {
-		return gf.readDirChild(count)
-	}
-}
-
-func (gf *GarageFile) readDirRoot(count int) ([]fs.FileInfo, error) {
-	buckets, err := gf.mc.ListBuckets(gf.ctx)
-	if err != nil {
-		return nil, err
-	}
-
-	entries := make([]fs.FileInfo, 0, len(buckets))
-	for _, bucket := range buckets {
-		//log.Println("Stat from GarageFile.readDirRoot()", "/"+bucket.Name)
-		ngf, err := NewGarageStat(gf.ctx, "/"+bucket.Name)
-		if err != nil {
-			return nil, err
-		}
-		entries = append(entries, ngf)
-	}
-
-	return entries, nil
-}
-
-func (gf *GarageFile) readDirChild(count int) ([]fs.FileInfo, error) {
-	prefix := gf.path.key
-	if len(prefix) > 0 && prefix[len(prefix)-1:] != "/" {
-		prefix = prefix + "/"
-	}
-
-	objs_info := gf.mc.ListObjects(gf.ctx, gf.path.bucket, minio.ListObjectsOptions{
-		Prefix:    prefix,
-		Recursive: false,
-	})
-
-	entries := make([]fs.FileInfo, 0)
-	for object := range objs_info {
-		if object.Err != nil {
-			return nil, object.Err
-		}
-		//log.Println("Stat from GarageFile.readDirChild()", path.Join("/", gf.path.bucket, object.Key))
-		ngf, err := NewGarageStatFromObjectInfo(gf.ctx, gf.path.bucket, object)
-		if err != nil {
-			return nil, err
-		}
-		entries = append(entries, ngf)
-	}
-
-	return entries, nil
-}
-
-func (gf *GarageFile) Stat() (fs.FileInfo, error) {
-	//log.Println("Stat from GarageFile.Stat()", gf.path.path)
-	return NewGarageStatFromFile(gf.ctx, gf.path.path)
-}
-
-/* Implements */
-// StatObject???
-type GarageStat struct {
-	obj  minio.ObjectInfo
-	ctx  context.Context
-	path S3Path
-}
-
-/*
- * Stat a path
- */
-func NewGarageStatFromFile(ctx context.Context, path string) (*GarageStat, error) {
-	cache := ctx.Value(garageEntry).(garageCtx).StatCache
-
-	// Maybe this file is already in our cache?
-	if entry, ok := cache[path]; ok {
-		return entry, nil
-	}
-
-	// Create a placeholder in case we are creating the object
-	gs := new(GarageStat)
-	gs.ctx = ctx
-	gs.path = NewS3Path(path)
-	if gs.path.class == OPAQUE_KEY {
-		gs.path.class = OBJECT // known because called from GarageFile
-	}
-	gs.obj.Key = gs.path.key
-	gs.obj.LastModified = time.Now()
-
-	// Maybe this file exists in garage?
-	err := gs.Refresh()
-	if err != nil && !os.IsNotExist(err) {
-		// There is an error and this is not a 404, report it.
-		return nil, err
-	}
-
-	cache[path] = gs
-	return gs, nil
-}
-
-/*
- * Stat a path knowing its ObjectInfo
- */
-func NewGarageStatFromObjectInfo(ctx context.Context, bucket string, obj minio.ObjectInfo) (*GarageStat, error) {
-	gs := new(GarageStat)
-	gs.path = NewTrustedS3Path(bucket, obj)
-	gs.obj = obj
-
-	cache := ctx.Value(garageEntry).(garageCtx).StatCache
-	cache[gs.path.path] = gs
-	return gs, nil
-}
-
-/*
- * Stat a path without additional information
- */
-func NewGarageStat(ctx context.Context, path string) (*GarageStat, error) {
-	cache := ctx.Value(garageEntry).(garageCtx).StatCache
-	if entry, ok := cache[path]; ok {
-		return entry, nil
-	}
-
-	gs := new(GarageStat)
-	gs.ctx = ctx
-	gs.path = NewS3Path(path)
-	if err := gs.Refresh(); err != nil {
-		return nil, err
-	}
-
-	if gs.path.class&OPAQUE_KEY != 0 {
-		return nil, errors.New("Failed to precisely determine the key type, this a logic error.")
-	}
-
-	cache[path] = gs
-	cache[gs.path.path] = gs
-	return gs, nil
-}
-
-func (gs *GarageStat) Refresh() error {
-	if gs.path.class == ROOT || gs.path.class == BUCKET {
-		return nil
-	}
-
-	mc := gs.ctx.Value(garageEntry).(garageCtx).MC
-
-	// Compute the prefix to have the desired behaviour for our stat logic
-	prefix := gs.path.key
-	if prefix[len(prefix)-1:] == "/" {
-		prefix = prefix[:len(prefix)-1]
-	}
-
-	// Get info and check if the key exists
-	objs_info := mc.ListObjects(gs.ctx, gs.path.bucket, minio.ListObjectsOptions{
-		Prefix:    prefix,
-		Recursive: false,
-	})
-
-	found := false
-	for object := range objs_info {
-		if object.Err != nil {
-			return object.Err
-		}
-
-		if object.Key == prefix || object.Key == prefix+"/" {
-			gs.obj = object
-			gs.path = NewTrustedS3Path(gs.path.bucket, object)
-			found = true
-			break
-		}
-	}
-
-	if !found {
-		return fs.ErrNotExist
-	}
-
-	return nil
-}
-
-func (gs *GarageStat) Name() string {
-	if gs.path.class == ROOT {
-		return "/"
-	} else if gs.path.class == BUCKET {
-		return gs.path.bucket
-	} else {
-		return path.Base(gs.path.key)
-	}
-}
-
-func (gs *GarageStat) Size() int64 {
-	return gs.obj.Size
-}
-
-func (gs *GarageStat) Mode() fs.FileMode {
-	if gs.path.class == OBJECT {
-		return fs.ModePerm
-	} else {
-		return fs.ModeDir | fs.ModePerm
-	}
-}
-
-func (gs *GarageStat) ModTime() time.Time {
-	return gs.obj.LastModified
-}
-
-func (gs *GarageStat) IsDir() bool {
-	return gs.path.class != OBJECT
-}
-
-func (gs *GarageStat) Sys() interface{} {
-	return nil
-}
-
-type S3Class int
-
-const (
-	ROOT S3Class = 1 << iota
-	BUCKET
-	COMMON_PREFIX
-	OBJECT
-	OPAQUE_KEY
-
-	KEY = COMMON_PREFIX | OBJECT | OPAQUE_KEY
-)
-
-type S3Path struct {
-	path   string
-	class  S3Class
-	bucket string
-	key    string
-}
-
-func NewS3Path(path string) S3Path {
-	exploded_path := strings.SplitN(path, "/", 3)
-
-	// If there is no bucket name (eg. "/")
-	if len(exploded_path) < 2 || exploded_path[1] == "" {
-		return S3Path{path, ROOT, "", ""}
-	}
-
-	// If there is no key
-	if len(exploded_path) < 3 || exploded_path[2] == "" {
-		return S3Path{path, BUCKET, exploded_path[1], ""}
-	}
-
-	return S3Path{path, OPAQUE_KEY, exploded_path[1], exploded_path[2]}
-}
-
-func NewTrustedS3Path(bucket string, obj minio.ObjectInfo) S3Path {
-	cl := OBJECT
-	if obj.Key[len(obj.Key)-1:] == "/" {
-		cl = COMMON_PREFIX
-	}
-
-	return S3Path{
-		path:   path.Join("/", bucket, obj.Key),
-		bucket: bucket,
-		key:    obj.Key,
-		class:  cl,
-	}
-}

middleware.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"github.com/minio/minio-go/v7"
+	"net/http"
+)
+
+/* We define some interface to enable our middleware to communicate */
+type ErrorHandler interface {
+	WithError(err error) http.Handler
+}
+type CredsHandler interface {
+	WithCreds(username, password string) http.Handler
+}
+type MinioClientHandler interface {
+	WithMC(mc *minio.Client) http.Handler
+}

s3_file.go

@@ -0,0 +1,186 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"log"
+	"mime"
+	"path"
+
+	"github.com/minio/minio-go/v7"
+	"golang.org/x/net/webdav"
+)
+
+type S3File struct {
+	fs    *S3FS
+	obj   *minio.Object
+	objw  *io.PipeWriter
+	donew chan error
+	pos   int64
+	path  S3Path
+}
+
+func NewS3File(s *S3FS, path string) (webdav.File, error) {
+	f := new(S3File)
+	f.fs = s
+	f.pos = 0
+	f.path = NewS3Path(path)
+	return f, nil
+}
+
+func (f *S3File) Close() error {
+	err := make([]error, 0)
+
+	if f.obj != nil {
+		err = append(err, f.obj.Close())
+		f.obj = nil
+	}
+
+	if f.objw != nil {
+		// wait that minio completes its transfers in background
+		err = append(err, f.objw.Close())
+		err = append(err, <-f.donew)
+		f.donew = nil
+		f.objw = nil
+	}
+
+	count := 0
+	for _, e := range err {
+		if e != nil {
+			count++
+			log.Println(e)
+		}
+	}
+	if count > 0 {
+		return errors.New(fmt.Sprintf("%d errors when closing this WebDAV File. Read previous logs to know more.", count))
+	}
+	return nil
+}
+
+func (f *S3File) loadObject() error {
+	if f.obj == nil {
+		obj, err := f.fs.mc.GetObject(f.fs.ctx, f.path.bucket, f.path.key, minio.GetObjectOptions{})
+		if err != nil {
+			return err
+		}
+		f.obj = obj
+	}
+	return nil
+}
+
+func (f *S3File) Read(p []byte) (n int, err error) {
+	//if f.Stat() & OBJECT == 0 { /* @FIXME Ideally we would check against OBJECT but we need a non OPAQUE_KEY */
+	//	return 0, os.ErrInvalid
+	//}
+	if err := f.loadObject(); err != nil {
+		return 0, err
+	}
+
+	return f.obj.Read(p)
+}
+
+func (f *S3File) Write(p []byte) (n int, err error) {
+	/*if f.path.class != OBJECT {
+		return 0, os.ErrInvalid
+	}*/
+
+	if f.objw == nil {
+		if f.pos != 0 {
+			return 0, errors.New("writing with an offset is not implemented")
+		}
+
+		r, w := io.Pipe()
+		f.donew = make(chan error, 1)
+		f.objw = w
+
+		contentType := mime.TypeByExtension(path.Ext(f.path.key))
+		go func() {
+			_, err := f.fs.mc.PutObject(context.Background(), f.path.bucket, f.path.key, r, -1, minio.PutObjectOptions{ContentType: contentType})
+			f.donew <- err
+		}()
+	}
+
+	return f.objw.Write(p)
+}
+
+func (f *S3File) Seek(offset int64, whence int) (int64, error) {
+	if err := f.loadObject(); err != nil {
+		return 0, err
+	}
+
+	pos, err := f.obj.Seek(offset, whence)
+	f.pos += pos
+	return pos, err
+}
+
+/*
+ReadDir reads the contents of the directory associated with the file f and returns a slice of DirEntry values in directory order. Subsequent calls on the same file will yield later DirEntry records in the directory.
+
+If n > 0, ReadDir returns at most n DirEntry records. In this case, if ReadDir returns an empty slice, it will return an error explaining why. At the end of a directory, the error is io.EOF.
+
+If n <= 0, ReadDir returns all the DirEntry records remaining in the directory. When it succeeds, it returns a nil error (not io.EOF).
+*/
+func (f *S3File) Readdir(count int) ([]fs.FileInfo, error) {
+	if count > 0 {
+		return nil, errors.New("returning a limited number of directory entry is not supported in readdir")
+	}
+
+	if f.path.class == ROOT {
+		return f.readDirRoot(count)
+	} else {
+		return f.readDirChild(count)
+	}
+}
+
+func (f *S3File) readDirRoot(count int) ([]fs.FileInfo, error) {
+	buckets, err := f.fs.mc.ListBuckets(f.fs.ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	entries := make([]fs.FileInfo, 0, len(buckets))
+	for _, bucket := range buckets {
+		//log.Println("Stat from GarageFile.readDirRoot()", "/"+bucket.Name)
+		nf, err := NewS3Stat(f.fs, "/"+bucket.Name)
+		if err != nil {
+			return nil, err
+		}
+		entries = append(entries, nf)
+	}
+
+	return entries, nil
+}
+
+func (f *S3File) readDirChild(count int) ([]fs.FileInfo, error) {
+	prefix := f.path.key
+	if len(prefix) > 0 && prefix[len(prefix)-1:] != "/" {
+		prefix = prefix + "/"
+	}
+
+	objs_info := f.fs.mc.ListObjects(f.fs.ctx, f.path.bucket, minio.ListObjectsOptions{
+		Prefix:    prefix,
+		Recursive: false,
+	})
+
+	entries := make([]fs.FileInfo, 0)
+	for object := range objs_info {
+		if object.Err != nil {
+			return nil, object.Err
+		}
+		//log.Println("Stat from GarageFile.readDirChild()", path.Join("/", f.path.bucket, object.Key))
+		nf, err := NewS3StatFromObjectInfo(f.fs, f.path.bucket, object)
+		if err != nil {
+			return nil, err
+		}
+		entries = append(entries, nf)
+	}
+
+	return entries, nil
+}
+
+func (f *S3File) Stat() (fs.FileInfo, error) {
+	return NewS3Stat(f.fs, f.path.path)
+}

s3_fs.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"os"
+	"time"
+
+	"github.com/minio/minio-go/v7"
+	"golang.org/x/net/webdav"
+)
+
+/*
+ * S3FS lifetime is limited to a single request
+ * Conversely, Golang's abstraction has been thought to be shared between users
+ * Sharing an instance between users would be very dangerous (as we would need many checks between shared values)
+ */
+type S3FS struct {
+	cache map[string]*S3Stat
+	mc    *minio.Client
+	ctx   context.Context
+}
+
+func NewS3FS(mc *minio.Client) S3FS {
+	return S3FS{
+		cache: make(map[string]*S3Stat),
+		mc:    mc,
+	}
+}
+
+func (s S3FS) Mkdir(ctx context.Context, name string, perm os.FileMode) error {
+	s.ctx = ctx
+	return errors.New("Not implemented Mkdir")
+}
+
+func (s S3FS) OpenFile(ctx context.Context, name string, flag int, perm os.FileMode) (webdav.File, error) {
+	s.ctx = ctx
+
+	// If the file does not exist when opening it, we create a stub
+	if _, ok := s.cache[name]; !ok {
+		st := new(S3Stat)
+		st.fs = &s
+		st.path = NewS3Path(name)
+		st.path.class = OBJECT
+		st.obj.Key = st.path.key
+		st.obj.LastModified = time.Now()
+		s.cache[name] = st
+	}
+
+	return NewS3File(&s, name)
+}
+
+func (s S3FS) RemoveAll(ctx context.Context, name string) error {
+	s.ctx = ctx
+	return errors.New("Not implemented RemoveAll")
+}
+
+func (s S3FS) Rename(ctx context.Context, oldName, newName string) error {
+	s.ctx = ctx
+	return errors.New("Not implemented Rename")
+}
+
+func (s S3FS) Stat(ctx context.Context, name string) (os.FileInfo, error) {
+	s.ctx = ctx
+	return NewS3Stat(&s, name)
+}

s3_path.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"path"
+	"strings"
+
+	"github.com/minio/minio-go/v7"
+)
+
+type S3Class int
+
+const (
+	ROOT S3Class = 1 << iota
+	BUCKET
+	COMMON_PREFIX
+	OBJECT
+	OPAQUE_KEY
+
+	KEY = COMMON_PREFIX | OBJECT | OPAQUE_KEY
+)
+
+type S3Path struct {
+	path   string
+	class  S3Class
+	bucket string
+	key    string
+}
+
+func NewS3Path(path string) S3Path {
+	exploded_path := strings.SplitN(path, "/", 3)
+
+	// If there is no bucket name (eg. "/")
+	if len(exploded_path) < 2 || exploded_path[1] == "" {
+		return S3Path{path, ROOT, "", ""}
+	}
+
+	// If there is no key
+	if len(exploded_path) < 3 || exploded_path[2] == "" {
+		return S3Path{path, BUCKET, exploded_path[1], ""}
+	}
+
+	return S3Path{path, OPAQUE_KEY, exploded_path[1], exploded_path[2]}
+}
+
+func NewTrustedS3Path(bucket string, obj minio.ObjectInfo) S3Path {
+	cl := OBJECT
+	if obj.Key[len(obj.Key)-1:] == "/" {
+		cl = COMMON_PREFIX
+	}
+
+	return S3Path{
+		path:   path.Join("/", bucket, obj.Key),
+		bucket: bucket,
+		key:    obj.Key,
+		class:  cl,
+	}
+}

s3_stat.go

@@ -0,0 +1,128 @@
+package main
+
+import (
+	"errors"
+	"io/fs"
+	"path"
+	"time"
+
+	"github.com/minio/minio-go/v7"
+)
+
+type S3Stat struct {
+	fs   *S3FS
+	obj  minio.ObjectInfo
+	path S3Path
+}
+
+/*
+ * Stat a path knowing its ObjectInfo
+ */
+func NewS3StatFromObjectInfo(fs *S3FS, bucket string, obj minio.ObjectInfo) (*S3Stat, error) {
+	s := new(S3Stat)
+	s.path = NewTrustedS3Path(bucket, obj)
+	s.obj = obj
+	s.fs = fs
+
+	fs.cache[s.path.path] = s
+	return s, nil
+}
+
+/*
+ * Stat a path without additional information
+ */
+func NewS3Stat(fs *S3FS, path string) (*S3Stat, error) {
+	cache := fs.cache
+	if entry, ok := cache[path]; ok {
+		return entry, nil
+	}
+
+	s := new(S3Stat)
+	s.fs = fs
+	s.path = NewS3Path(path)
+	if err := s.Refresh(); err != nil {
+		return nil, err
+	}
+
+	if s.path.class&OPAQUE_KEY != 0 {
+		return nil, errors.New("Failed to precisely determine the key type, this a logic error.")
+	}
+
+	cache[path] = s
+	cache[s.path.path] = s
+	return s, nil
+}
+
+func (s *S3Stat) Refresh() error {
+	if s.path.class == ROOT || s.path.class == BUCKET {
+		return nil
+	}
+
+	mc := s.fs.mc
+
+	// Compute the prefix to have the desired behaviour for our stat logic
+	prefix := s.path.key
+	if prefix[len(prefix)-1:] == "/" {
+		prefix = prefix[:len(prefix)-1]
+	}
+
+	// Get info and check if the key exists
+	objs_info := mc.ListObjects(s.fs.ctx, s.path.bucket, minio.ListObjectsOptions{
+		Prefix:    prefix,
+		Recursive: false,
+	})
+
+	found := false
+	for object := range objs_info {
+		if object.Err != nil {
+			return object.Err
+		}
+
+		if object.Key == prefix || object.Key == prefix+"/" {
+			s.obj = object
+			s.path = NewTrustedS3Path(s.path.bucket, object)
+			found = true
+			break
+		}
+	}
+
+	if !found {
+		return fs.ErrNotExist
+	}
+
+	return nil
+}
+
+func (s *S3Stat) Name() string {
+	if s.path.class == ROOT {
+		return "/"
+	} else if s.path.class == BUCKET {
+		return s.path.bucket
+	} else {
+		return path.Base(s.path.key)
+	}
+}
+
+func (s *S3Stat) Size() int64 {
+	return s.obj.Size
+}
+
+func (s *S3Stat) Mode() fs.FileMode {
+	if s.path.class == OBJECT {
+		return fs.ModePerm
+	} else {
+		return fs.ModeDir | fs.ModePerm
+	}
+}
+
+func (s *S3Stat) ModTime() time.Time {
+	return s.obj.LastModified
+}
+
+func (s *S3Stat) IsDir() bool {
+	return s.path.class != OBJECT
+}
+
+func (s *S3Stat) Sys() interface{} {
+	return nil
+}

webdav.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"github.com/minio/minio-go/v7"
+	"golang.org/x/net/webdav"
+	"log"
+	"net/http"
+)
+
+type WebDav struct {
+	WithConfig *Config
+}
+
+func (wd WebDav) WithMC(mc *minio.Client) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		(&webdav.Handler{
+			Prefix:     wd.WithConfig.DavPath,
+			FileSystem: NewS3FS(mc),
+			LockSystem: webdav.NewMemLS(),
+			Logger: func(r *http.Request, err error) {
+				log.Printf("INFO: %s %s %s\n", r.RemoteAddr, r.Method, r.URL)
+				if err != nil {
+					log.Printf("ERR: %v", err)
+				}
+			},
+		}).ServeHTTP(w, r)
+	})
+}