Mention of 404 error was removed from GET /:captcha_id description.

README.md

@@ -53,7 +53,6 @@ Responds with an empty body and one of the HTTP codes.
 #### HTTP codes
 - `202` if solved
 - `403` if not solved
-- `404` if doesn't exist
 
 ### Check if captcha is solved
 
@@ -63,8 +62,7 @@ Responds with an empty body and one of the HTTP codes.
 
 If an optional `remove` parameter without a value supplied CAPTCHA will be
 removed without checking and a HTTP code `204` will be sent. Otherwise, a `403`
-HTTP code will be sent if it is not solved. If a CAPTCHA doesn't exist a `404`
-HTTP code still will be returned.
+HTTP code will be sent if it is not solved.
 
 A `remove` parameter was added because browsers will print an error in a console
 if HTTP code is not within `2xx`, so to keep a console clean you can provide
@@ -76,7 +74,6 @@ to be expired. E.g. when a visitor requests for a new CAPTCHA or leaving a page.
 #### HTTP codes
 - `204` if solved
 - `403` if not solved
-- `404` if doesn't exist
 
 ### Example of interaction
 

internal/handlers/handlers.go

@@ -11,9 +11,7 @@ import (
 	"time"
 )
 
-const errMsgNotFound = "CAPTCHA with such ID doesn't exist"
 const errMsgWrongAnswer = "An answer provided was wrong"
-const errMsgFailedToGenImage = "failed to generate an image for a CAPTCHA"
 const errMsgImageNotFound = "cannot get an image for a non-existing CAPTCHA"
 
 type CaptchaHandlers struct {
@@ -36,16 +34,9 @@ func (h *CaptchaHandlers) Image(w http.ResponseWriter, r *http.Request) {
 	captchaID := captcha.ID(server.GetURLParam(r, "captcha"))
 	captchaStyle := r.URL.Query().Get("style")
 
-	captchaImage, err := inmemdb.Image(captchaID, captchaStyle)
-	if err != nil {
-		w.WriteHeader(http.StatusNotFound)
-		fmt.Fprint(w, errMsgImageNotFound)
-		return
-	}
-
+	captchaImage := inmemdb.Image(captchaID, captchaStyle)
 	if captchaImage == nil {
-		w.WriteHeader(http.StatusInternalServerError)
-		fmt.Fprint(w, errMsgFailedToGenImage)
+		http.Error(w, errMsgImageNotFound, http.StatusNotFound)
 		return
 	}
 
@@ -60,16 +51,8 @@ func (h *CaptchaHandlers) Solve(w http.ResponseWriter, r *http.Request) {
 	r.ParseForm()
 	answer := captcha.Answer(r.FormValue("answer"))
 
-	ok, err := inmemdb.Solve(captchaID, answer)
-	if err != nil {
-		w.WriteHeader(http.StatusNotFound)
-		fmt.Fprint(w, errMsgNotFound)
-		return
-	}
-
-	if !ok {
-		w.WriteHeader(http.StatusForbidden)
-		fmt.Fprint(w, errMsgWrongAnswer)
+	if ok := inmemdb.Solve(captchaID, answer); !ok {
+		http.Error(w, errMsgWrongAnswer, http.StatusForbidden)
 		return
 	}
 
@@ -80,22 +63,16 @@ func (h *CaptchaHandlers) IsSolved(w http.ResponseWriter, r *http.Request) {
 	captchaID := captcha.ID(server.GetURLParam(r, "captcha"))
 	isJustRemove := r.URL.Query().Has("remove")
 
-	w.WriteHeader(http.StatusNoContent)
-
 	if isJustRemove {
 		inmemdb.Remove(captchaID)
+		w.WriteHeader(http.StatusNoContent)
 		return
 	}
 
-	solved, err := inmemdb.IsSolved(captchaID)
-	if err != nil {
-		w.WriteHeader(http.StatusNotFound)
-		fmt.Fprint(w, errMsgNotFound)
+	if solved := inmemdb.IsSolved(captchaID); !solved {
+		http.Error(w, errMsgWrongAnswer, http.StatusForbidden)
 		return
 	}
 
-	if !solved {
-		w.WriteHeader(http.StatusForbidden)
-		fmt.Fprint(w, errMsgWrongAnswer)
-	}
+	w.WriteHeader(http.StatusNoContent)
 }

pkg/captcha/db.go

@@ -4,14 +4,11 @@ import (
 	"crypto/rand"
 	"crypto/sha256"
 	"encoding/base64"
-	"errors"
 	"image"
 	"strconv"
 	"time"
 )
 
-var ErrorNotFound = errors.New("captcha not found")
-
 const DefaultExpiredScanInterval = 60 * time.Second
 
 // ID is a CAPTCHA identifier.
@@ -38,8 +35,8 @@ type CaptchaDB interface {
 	New(data string, captcha Captcha) (Captcha, ID)
 	GetExpiry() time.Duration
 	SetExpiry(expiry time.Duration)
-	Image(id ID, style string) (*image.Image, error)
-	Solve(id ID, answer Answer) (bool, error)
-	IsSolved(id ID) (bool, error)
-	Remove(id ID) error
+	Image(id ID, style string) *image.Image
+	Solve(id ID, answer Answer) bool
+	IsSolved(id ID) bool
+	Remove(id ID)
 }

pkg/captcha/inmemdb/inmemdb.go

@@ -61,18 +61,18 @@ func (imcdb *InMemoryCaptchaDB) SetExpiry(expiry time.Duration) {
 }
 
 // Image returns a freshly generated image for a CAPTCHA.
-func (imcdb *InMemoryCaptchaDB) Image(id captcha.ID, style string) (*image.Image, error) {
+func (imcdb *InMemoryCaptchaDB) Image(id captcha.ID, style string) *image.Image {
 	imcdb.Lock()
 	defer imcdb.Unlock()
 	if c, ok := imcdb.db[id]; ok {
-		return c.Image(style), nil
+		return c.Image(style)
 	}
-	return nil, captcha.ErrorNotFound
+	return nil
 }
 
 // Solve compares given answer with a stored one and if failed
 // deletes a CAPTCHA from database.
-func (imcdb *InMemoryCaptchaDB) Solve(id captcha.ID, answer captcha.Answer) (bool, error) {
+func (imcdb *InMemoryCaptchaDB) Solve(id captcha.ID, answer captcha.Answer) bool {
 	imcdb.Lock()
 	defer imcdb.Unlock()
 	if c, ok := imcdb.db[id]; ok {
@@ -80,32 +80,30 @@ func (imcdb *InMemoryCaptchaDB) Solve(id captcha.ID, answer captcha.Answer) (boo
 		if !ok {
 			delete(imcdb.db, id)
 		}
-		return ok, nil
+		return ok
 	}
-	return false, captcha.ErrorNotFound
+	return false
 }
 
 // IsSolved checks if CAPTCHA was solved and removes it
 // from a database.
-func (imcdb *InMemoryCaptchaDB) IsSolved(id captcha.ID) (bool, error) {
+func (imcdb *InMemoryCaptchaDB) IsSolved(id captcha.ID) bool {
 	imcdb.Lock()
 	defer imcdb.Unlock()
 	if c, ok := imcdb.db[id]; ok {
 		delete(imcdb.db, id)
-		return c.IsSolved(), nil
+		return c.IsSolved()
 	}
-	return false, captcha.ErrorNotFound
+	return false
 }
 
 // Remove a CAPTCHA from a database.
-func (imcdb *InMemoryCaptchaDB) Remove(id captcha.ID) error {
+func (imcdb *InMemoryCaptchaDB) Remove(id captcha.ID) {
 	imcdb.Lock()
 	defer imcdb.Unlock()
 	if _, ok := imcdb.db[id]; ok {
 		delete(imcdb.db, id)
-		return nil
 	}
-	return captcha.ErrorNotFound
 }
 
 // cleanExpired removes expired CAPTCHAs in a loop.
@@ -140,18 +138,18 @@ func New(data string, captcha captcha.Captcha) (captcha.Captcha, captcha.ID) {
 	return imcdb.New(data, captcha)
 }
 
-func Image(id captcha.ID, style string) (*image.Image, error) {
+func Image(id captcha.ID, style string) *image.Image {
 	return imcdb.Image(id, style)
 }
 
-func Solve(id captcha.ID, answer captcha.Answer) (bool, error) {
+func Solve(id captcha.ID, answer captcha.Answer) bool {
 	return imcdb.Solve(id, answer)
 }
 
-func IsSolved(id captcha.ID) (bool, error) {
+func IsSolved(id captcha.ID) bool {
 	return imcdb.IsSolved(id)
 }
 
-func Remove(id captcha.ID) error {
-	return imcdb.Remove(id)
+func Remove(id captcha.ID) {
+	imcdb.Remove(id)
 }