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refactor: Use functional errors

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Use well-defined server errors instead of hardcoded messages that could be
slightly different and spread accross the code base.

Signed-off-by: Julien Riou <julien@riou.xyz>
This commit is contained in:
Julien Riou 2025-10-02 06:35:27 +02:00
commit f721e56371
Signed by: jriou
GPG key ID: 9A099EDA51316854
3 changed files with 137 additions and 80 deletions
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24
src/server/errors.go Normal file
View file

@ -0,0 +1,24 @@
package server
import "errors"
var (
ErrCouldNotFindNote = errors.New("could not find note")
ErrNoteDoesNotExist = errors.New("note does not exist")
ErrCouldNotParseForm = errors.New("could not parse form")
ErrEncryptionKeyNotFound = errors.New("encryption key not found")
ErrCouldNotDecryptNote = errors.New("could not decrypt note")
ErrInvalidPassword = errors.New("invalid password")
ErrCouldNotParseFile = errors.New("could not parse file")
ErrFileTooLarge = errors.New("file too large")
ErrTextFileExpected = errors.New("text file expected")
ErrCouldNotReadFile = errors.New("could not read file")
ErrEmptyNote = errors.New("empty note")
ErrEncryptionRequired = errors.New("encryption is required")
ErrClientEncryptionKeyNotAllowed = errors.New("client encryption key is not allowed")
ErrInvalidExpiration = errors.New("invalid expiration")
ErrCouldNotCreateNote = errors.New("could not create note")
ErrCouldNotDecodePayload = errors.New("could not decode payload")
ErrCouldNotDecodeContent = errors.New("could not decode content")
ErrNoteIsPasswordProtected = errors.New("note is password protected")
)

63
src/server/handlers_api.go
View file

@ -24,29 +24,30 @@ func (e APIErrorResponse) ToJSON() string {
return fmt.Sprintf("{\"message\":\"could not serialize response to JSON\", \"error\":\"%v\"}", err)
}
func apiError(level int, w http.ResponseWriter, logger *slog.Logger, msg string, err error) {
func apiError(level int, w http.ResponseWriter, logger *slog.Logger, topLevelErr error, err error) {
// Wrap error for logging
if err != nil {
err = fmt.Errorf("%s: %w", msg, err)
err = fmt.Errorf("%v: %w", topLevelErr, err)
}
logger.Error(fmt.Sprintf("%v", err))
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(level)
fmt.Fprint(w, APIErrorResponse{
Message: msg,
Message: fmt.Sprintf("%v", topLevelErr),
}.ToJSON())
}
func APIError(w http.ResponseWriter, logger *slog.Logger, msg string, err error) {
apiError(http.StatusInternalServerError, w, logger, msg, err)
func APIError(w http.ResponseWriter, logger *slog.Logger, topLevelErr error, err error) {
apiError(http.StatusInternalServerError, w, logger, topLevelErr, err)
}
func APIErrorNotFound(w http.ResponseWriter, logger *slog.Logger, msg string, err error) {
apiError(http.StatusNotFound, w, logger, msg, err)
func APIErrorNotFound(w http.ResponseWriter, logger *slog.Logger, topLevelErr error, err error) {
apiError(http.StatusNotFound, w, logger, topLevelErr, err)
}
func APIErrorBadRequest(w http.ResponseWriter, logger *slog.Logger, msg string, err error) {
apiError(http.StatusBadRequest, w, logger, msg, err)
func APIErrorBadRequest(w http.ResponseWriter, logger *slog.Logger, topLevelErr error, err error) {
apiError(http.StatusBadRequest, w, logger, topLevelErr, err)
}
func HealthHandler(w http.ResponseWriter, r *http.Request) {
@ -61,6 +62,10 @@ type CreateNoteHandler struct {
allowNoEncryption bool
}
func (h *CreateNoteHandler) Name() string {
return "CreateNoteHandler"
}
type CreateNotePayload struct {
Content string `json:"content"`
Password string `json:"password"`
@ -78,7 +83,7 @@ type CreateNoteResponse struct {
func (h *CreateNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
logger := h.logger.With("handler", "CreateNoteHandler")
logger := h.logger.With("handler", h.Name())
bodyReader := http.MaxBytesReader(w, r.Body, h.maxUploadSize)
defer r.Body.Close()
@ -86,30 +91,30 @@ func (h *CreateNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
var body CreateNotePayload
err := json.NewDecoder(bodyReader).Decode(&body)
if err != nil {
APIError(w, logger, "could not decode payload", err)
APIError(w, logger, ErrCouldNotDecodePayload, err)
return
}
if !h.allowNoEncryption && !body.Encrypted {
APIError(w, logger, "encryption is mandatory", nil)
APIError(w, logger, ErrEncryptionRequired, nil)
return
}
if !h.allowClientEncryptionKey && body.EncryptionKey != "" {
APIError(w, logger, "client encryption key is not allowed", nil)
APIError(w, logger, ErrClientEncryptionKeyNotAllowed, nil)
return
}
content, err := internal.Decode(body.Content)
if err != nil {
APIError(w, logger, "could not decode content", err)
APIError(w, logger, ErrCouldNotDecodeContent, err)
return
}
note, err := h.db.Create(content, body.Password, body.EncryptionKey, body.Encrypted, body.Expiration, body.DeleteAfterRead, body.Language)
if err != nil {
APIError(w, logger, "could not create note", err)
APIError(w, logger, ErrCouldNotCreateNote, err)
return
}
@ -122,6 +127,10 @@ type GetNoteHandler struct {
db *Database
}
func (h *GetNoteHandler) Name() string {
return "GetNoteHandler"
}
func (h *GetNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain; charset=utf-8")
@ -129,14 +138,14 @@ func (h *GetNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
note, err := h.db.Get(id)
logger := h.logger.With("handler", "CreateNoteHandler", "note_id", id)
logger := h.logger.With("handler", h.Name(), "note_id", id)
if err != nil {
APIError(w, logger, "could not find note", err)
APIError(w, logger, ErrCouldNotFindNote, err)
} else if note == nil {
APIErrorNotFound(w, logger, "note does not exist", err)
APIErrorNotFound(w, logger, ErrNoteDoesNotExist, err)
} else if note.PasswordHash != nil {
APIErrorBadRequest(w, logger, "note is password protected", err)
APIErrorBadRequest(w, logger, ErrNoteIsPasswordProtected, err)
} else {
if note.Encrypted {
w.Header().Set("Content-Type", "application/octet-stream")
@ -157,13 +166,17 @@ type GetProtectedNotePayload struct {
Password string `json:"password"`
}
func (h *GetProtectedNoteHandler) Name() string {
return "GetProtectedNoteHandler"
}
func (h *GetProtectedNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain; charset=utf-8")
vars := mux.Vars(r)
id := vars["id"]
logger := h.logger.With("handler", "GetProtectedNoteHandler", "note_id", id)
logger := h.logger.With("handler", h.Name(), "note_id", id)
bodyReader := http.MaxBytesReader(w, r.Body, h.maxUploadSize)
defer r.Body.Close()
@ -171,14 +184,14 @@ func (h *GetProtectedNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Reque
var body GetProtectedNotePayload
err := json.NewDecoder(bodyReader).Decode(&body)
if err != nil {
APIError(w, logger, "could not decode payload", err)
APIError(w, logger, ErrCouldNotDecodePayload, err)
return
}
note, err := h.db.Get(id)
if err != nil {
APIError(w, logger, "could not find note", err)
APIError(w, logger, ErrCouldNotFindNote, err)
return
} else if note == nil {
w.WriteHeader(http.StatusNotFound)
@ -188,15 +201,15 @@ func (h *GetProtectedNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Reque
if body.EncryptionKey != "" && note.Encrypted {
note.Content, err = internal.Decrypt(note.Content, body.EncryptionKey)
if err != nil {
APIError(w, logger, "could not decrypt note", err)
APIError(w, logger, ErrCouldNotDecryptNote, err)
return
}
}
if body.Password == "" && (note.PasswordHash != nil || len(note.PasswordHash) > 0) {
if len(note.PasswordHash) > 0 {
err := bcrypt.CompareHashAndPassword(note.PasswordHash, []byte(body.Password))
if err != nil {
APIError(w, logger, "could not validate password", err)
APIError(w, logger, ErrInvalidPassword, err)
return
}
}

130
src/server/handlers_web.go
View file

@ -36,13 +36,13 @@ type PageData struct {
DisableEditor bool
}
func TemplateError(w http.ResponseWriter, pageData PageData, templates *template.Template, templateName string, logger *slog.Logger, msg string, err error) {
func WebError(w http.ResponseWriter, pageData PageData, templates *template.Template, templateName string, logger *slog.Logger, topLevelErr error, err error) {
// Only show the top-level error to users
pageData.Err = fmt.Errorf("%s", msg)
pageData.Err = topLevelErr
// Show full error in the logs
if err != nil {
err = fmt.Errorf("%s: %w", msg, err)
err = fmt.Errorf("%v: %w", topLevelErr, err)
} else {
err = pageData.Err
}
@ -71,19 +71,23 @@ func (h *CreateNoteWithFormHandler) TemplateName() string {
return "create"
}
func (h *CreateNoteWithFormHandler) TemplateError(w http.ResponseWriter, logger *slog.Logger, msg string, err error) {
TemplateError(w, h.PageData, h.Templates, h.TemplateName(), logger, msg, err)
func (h *CreateNoteWithFormHandler) Name() string {
return "CreateNoteWithFormHandler"
}
func (h *CreateNoteWithFormHandler) WebError(w http.ResponseWriter, logger *slog.Logger, topLevelErr error, err error) {
WebError(w, h.PageData, h.Templates, h.TemplateName(), logger, topLevelErr, err)
}
func (h *CreateNoteWithFormHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
h.PageData.Err = nil
logger := h.logger.With("handler", "CreateNoteWithFormHandler")
logger := h.logger.With("handler", h.Name())
logger.Debug("parsing multipart form")
err := r.ParseMultipartForm(h.maxUploadSize)
if err != nil {
h.TemplateError(w, logger, "could not parse form", err)
h.WebError(w, logger, ErrCouldNotParseForm, err)
return
}
@ -93,46 +97,46 @@ func (h *CreateNoteWithFormHandler) ServeHTTP(w http.ResponseWriter, r *http.Req
logger.Debug("parsing file")
file, handler, err := r.FormFile("file")
if err != nil && !errors.Is(err, http.ErrMissingFile) {
h.TemplateError(w, logger, "could not parse file", err)
h.WebError(w, logger, ErrCouldNotParseFile, err)
return
}
if !errors.Is(err, http.ErrMissingFile) {
defer file.Close()
h.logger.Debug("checking file size")
logger.Debug("checking file size")
if handler.Size > h.maxUploadSize {
h.TemplateError(w, logger, "file too large", err)
h.WebError(w, logger, ErrFileTooLarge, err)
return
}
h.logger.Debug("checking file content type")
logger.Debug("checking file content type")
if !strings.HasPrefix(handler.Header.Get("Content-Type"), "text/") {
h.TemplateError(w, logger, "text file expected", err)
h.WebError(w, logger, ErrTextFileExpected, err)
return
}
h.logger.Debug("reading uploaded file")
logger.Debug("reading uploaded file")
var fileContent bytes.Buffer
n, err := io.Copy(&fileContent, file)
if err != nil {
h.TemplateError(w, logger, "could not read file", err)
h.WebError(w, logger, ErrCouldNotReadFile, err)
return
}
h.logger.Debug("file uploaded", slog.Any("bytes", n))
logger.Debug("file uploaded", slog.Any("bytes", n))
if n != 0 {
content = fileContent.Bytes()
}
}
h.logger.Debug("checking content")
logger.Debug("checking content")
if content == nil || len(content) == 0 {
h.TemplateError(w, logger, "empty note", nil)
h.WebError(w, logger, ErrEmptyNote, nil)
return
}
h.logger.Debug("checking inputs")
logger.Debug("checking inputs")
password := r.FormValue("password")
noEncryption := r.FormValue("no-encryption")
encryptionKey := r.FormValue("encryption-key")
@ -141,11 +145,11 @@ func (h *CreateNoteWithFormHandler) ServeHTTP(w http.ResponseWriter, r *http.Req
language := r.FormValue("language")
if !h.PageData.AllowNoEncryption && noEncryption != "" {
h.TemplateError(w, logger, "encryption is required", nil)
h.WebError(w, logger, ErrEncryptionRequired, nil)
}
if !h.PageData.AllowClientEncryptionKey && encryptionKey != "" {
h.TemplateError(w, logger, "client encryption key is not allowed", nil)
h.WebError(w, logger, ErrClientEncryptionKeyNotAllowed, nil)
}
if !h.PageData.AllowClientEncryptionKey && encryptionKey == "" && noEncryption == "" {
@ -160,7 +164,7 @@ func (h *CreateNoteWithFormHandler) ServeHTTP(w http.ResponseWriter, r *http.Req
} else {
expirationInt, err = strconv.Atoi(expiration)
if err != nil {
h.TemplateError(w, logger, "invalid expiration", err)
h.WebError(w, logger, ErrInvalidExpiration, err)
return
}
}
@ -168,11 +172,11 @@ func (h *CreateNoteWithFormHandler) ServeHTTP(w http.ResponseWriter, r *http.Req
logger.Debug("saving note to the database")
note, err := h.db.Create(content, password, encryptionKey, encryptionKey != "", expirationInt, deleteAfterRead != "", language)
if err != nil {
h.TemplateError(w, logger, "could not create note", err)
h.WebError(w, logger, ErrCouldNotCreateNote, err)
return
}
h.logger.Debug("building note url")
logger.Debug("building note url")
var scheme = "http://"
if r.TLS != nil {
scheme = "https://"
@ -183,7 +187,7 @@ func (h *CreateNoteWithFormHandler) ServeHTTP(w http.ResponseWriter, r *http.Req
h.PageData.URL += "#" + encryptionKey
}
h.logger.Debug("rendering page")
logger.Debug("rendering page")
h.Templates.ExecuteTemplate(w, h.TemplateName(), h.PageData)
}
@ -198,8 +202,12 @@ func (h *GetRawWebNoteHandler) TemplateName() string {
return "unprotectedNote"
}
func (h *GetRawWebNoteHandler) TemplateError(w http.ResponseWriter, logger *slog.Logger, msg string, err error) {
TemplateError(w, h.PageData, h.Templates, h.TemplateName(), logger, msg, err)
func (h *GetRawWebNoteHandler) Name() string {
return "GetRawWebNoteHandler"
}
func (h *GetRawWebNoteHandler) WebError(w http.ResponseWriter, logger *slog.Logger, topLevelErr error, err error) {
WebError(w, h.PageData, h.Templates, h.TemplateName(), logger, topLevelErr, err)
}
func (h *GetRawWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@ -208,18 +216,18 @@ func (h *GetRawWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request)
vars := mux.Vars(r)
id := vars["id"]
logger := h.logger.With("handler", "GetRawWebNoteHandler", "note_id", id)
logger := h.logger.With("handler", h.Name(), "note_id", id)
logger.Debug("fetching note from the database")
note, err := h.db.Get(id)
if err != nil {
h.TemplateError(w, logger, "could not find note", err)
h.WebError(w, logger, ErrCouldNotFindNote, err)
return
}
if note == nil {
h.TemplateError(w, logger, "note does not exist", err)
h.WebError(w, logger, ErrNoteDoesNotExist, err)
return
}
@ -248,8 +256,12 @@ func (h *GetProtectedRawWebNoteHandler) TemplateName() string {
return "protectedNote"
}
func (h *GetProtectedRawWebNoteHandler) TemplateError(w http.ResponseWriter, logger *slog.Logger, msg string, err error) {
TemplateError(w, h.PageData, h.Templates, h.TemplateName(), logger, msg, err)
func (h *GetProtectedRawWebNoteHandler) Name() string {
return "GetProtectedRawWebNoteHandler"
}
func (h *GetProtectedRawWebNoteHandler) WebError(w http.ResponseWriter, logger *slog.Logger, topLevelErr error, err error) {
WebError(w, h.PageData, h.Templates, h.TemplateName(), logger, topLevelErr, err)
}
func (h *GetProtectedRawWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@ -258,12 +270,12 @@ func (h *GetProtectedRawWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http
vars := mux.Vars(r)
id := vars["id"]
logger := h.logger.With("handler", "GetProtectedRawWebNoteHandler", "note_id", id)
logger := h.logger.With("handler", h.Name(), "note_id", id)
logger.Debug("parsing multipart form")
err := r.ParseMultipartForm(h.maxUploadSize)
if err != nil {
h.TemplateError(w, logger, "could not parse form", err)
h.WebError(w, logger, ErrCouldNotParseForm, err)
return
}
@ -274,24 +286,24 @@ func (h *GetProtectedRawWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http
note, err := h.db.Get(id)
if err != nil {
h.TemplateError(w, logger, "could not find note", err)
h.WebError(w, logger, ErrCouldNotFindNote, err)
return
}
if note == nil {
h.TemplateError(w, logger, "note does not exist", nil)
h.WebError(w, logger, ErrNoteDoesNotExist, nil)
return
}
if note.Encrypted {
if encryptionKey == "" {
h.TemplateError(w, logger, "encryption key not found", nil)
h.WebError(w, logger, ErrEncryptionKeyNotFound, nil)
return
}
logger.Debug("decrypting content")
note.Content, err = internal.Decrypt(note.Content, encryptionKey)
if err != nil {
h.TemplateError(w, logger, "could not decrypt note", err)
h.WebError(w, logger, ErrCouldNotDecryptNote, err)
return
}
}
@ -299,7 +311,7 @@ func (h *GetProtectedRawWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http
if len(note.PasswordHash) > 0 {
logger.Debug("comparing password hashes")
if err := bcrypt.CompareHashAndPassword(note.PasswordHash, []byte(password)); err != nil {
h.TemplateError(w, logger, "invalid password", err)
h.WebError(w, logger, ErrInvalidPassword, err)
return
}
}
@ -321,8 +333,12 @@ func (h *GetWebNoteHandler) TemplateName() string {
return "unprotectedNote"
}
func (h *GetWebNoteHandler) TemplateError(w http.ResponseWriter, logger *slog.Logger, msg string, err error) {
TemplateError(w, h.PageData, h.Templates, h.TemplateName(), logger, msg, err)
func (h *GetWebNoteHandler) Name() string {
return "GetWebNoteHandler"
}
func (h *GetWebNoteHandler) WebError(w http.ResponseWriter, logger *slog.Logger, topLevelErr error, err error) {
WebError(w, h.PageData, h.Templates, h.TemplateName(), logger, topLevelErr, err)
}
func (h *GetWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@ -331,23 +347,23 @@ func (h *GetWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
id := vars["id"]
logger := h.logger.With("handler", "GetWebNoteHandler", "note_id", id)
logger := h.logger.With("handler", h.Name(), "note_id", id)
note, err := h.db.Get(id)
if err != nil {
h.TemplateError(w, logger, "could not find note", err)
h.WebError(w, logger, ErrCouldNotFindNote, err)
return
}
if note == nil {
h.TemplateError(w, logger, "note does not exist", nil)
h.WebError(w, logger, ErrNoteDoesNotExist, nil)
return
}
h.PageData.Note = note
h.logger.Debug("rendering page")
logger.Debug("rendering page")
h.Templates.ExecuteTemplate(w, h.TemplateName(), h.PageData)
}
@ -363,8 +379,12 @@ func (h *GetProtectedWebNoteHandler) TemplateName() string {
return "protectedNote"
}
func (h *GetProtectedWebNoteHandler) TemplateError(w http.ResponseWriter, logger *slog.Logger, msg string, err error) {
TemplateError(w, h.PageData, h.Templates, h.TemplateName(), logger, msg, err)
func (h *GetProtectedWebNoteHandler) Name() string {
return "GetProtectedWebNoteHandler"
}
func (h *GetProtectedWebNoteHandler) WebError(w http.ResponseWriter, logger *slog.Logger, topLevelErr error, err error) {
WebError(w, h.PageData, h.Templates, h.TemplateName(), logger, topLevelErr, err)
}
func (h *GetProtectedWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@ -373,12 +393,12 @@ func (h *GetProtectedWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Re
vars := mux.Vars(r)
id := vars["id"]
logger := h.logger.With("handler", "GetProtectedWebNoteHandler", "note_id", id)
logger := h.logger.With("handler", h.Name(), "note_id", id)
h.logger.Debug("parsing multipart form")
logger.Debug("parsing multipart form")
err := r.ParseMultipartForm(h.maxUploadSize)
if err != nil {
h.TemplateError(w, logger, "could not parse form", err)
h.WebError(w, logger, ErrCouldNotParseForm, err)
return
}
@ -388,37 +408,37 @@ func (h *GetProtectedWebNoteHandler) ServeHTTP(w http.ResponseWriter, r *http.Re
note, err := h.db.Get(id)
if err != nil {
h.TemplateError(w, logger, "could not find note", err)
h.WebError(w, logger, ErrCouldNotFindNote, err)
return
}
if note == nil {
h.TemplateError(w, logger, "note does not exist", nil)
h.WebError(w, logger, ErrNoteDoesNotExist, nil)
return
}
if note.Encrypted {
if encryptionKey == "" {
h.TemplateError(w, logger, "encryption key not found", nil)
h.WebError(w, logger, ErrEncryptionKeyNotFound, nil)
return
}
note.Content, err = internal.Decrypt(note.Content, encryptionKey)
if err != nil {
h.TemplateError(w, logger, "could not decrypt note", err)
h.WebError(w, logger, ErrCouldNotDecryptNote, err)
return
}
}
if len(note.PasswordHash) > 0 {
if err := bcrypt.CompareHashAndPassword(note.PasswordHash, []byte(password)); err != nil {
h.TemplateError(w, logger, "invalid password", err)
h.WebError(w, logger, ErrInvalidPassword, err)
return
}
}
h.PageData.Note = note
h.logger.Debug("rendering page")
logger.Debug("rendering page")
h.Templates.ExecuteTemplate(w, h.TemplateName(), h.PageData)
}