Handlers are edited to work with modified interfaces. Status codes are changed. Now 404 is not being returned if parameter ?remove was set.

Makefile

@@ -6,7 +6,7 @@ SYSDDIR_=${shell pkg-config systemd --variable=systemdsystemunitdir}
 SYSDDIR=${SYSDDIR_:/%=%}
 DESTDIR=/
 
-LDFLAGS=-ldflags "-s -w -X main.version=1.2.0" -tags osusergo,netgo
+LDFLAGS=-ldflags "-s -w -X main.version=2.0.0" -tags osusergo,netgo
 
 all: ${TARGET}
 

README.md

@@ -1,11 +1,11 @@
-justcaptcha ver. 1.2.0
+justcaptcha ver. 2.0.0
 ======================
 
 A simple CAPTCHA service implementation.
 
 ## Usage
 
-    justcaptchad -expiry 5m -listen /var/run/justcaptchad/j.sock
+    justcaptchad -expiry 5m -listen /var/run/justcaptcha/c.sock
 
 `-expiry` takes time for CAPTCHA to be valid for in format X{s,m,h}.
 
@@ -13,22 +13,26 @@ A simple CAPTCHA service implementation.
 
 ## API
 
-### Get a new CAPTCHA
+### Errors
 
-    GET /
+All error codes are returned with an error message in `text/plain`.
 
-It will return an ID of a new CAPTCHA in plain text.
+### Create a new CAPTCHA
+
+    POST /
+
+It will return an ID of a new CAPTCHA in `text/plain`.
 
 #### HTTP codes
-- `200` if created (and it always being created)
+- `201` if created (always being created)
 
 ### Get an image for a CAPTCHA
 
     GET /:captcha_id/image?style=
 
-Responds with an image in JPEG format.
+Responds with an image in JPEG format (`image/jpeg`).
 
-An optional URL query parameter `style=` set a name of a CAPTCHA style if
+An optional URL parameter `style=` set a name of a CAPTCHA style if it is
 implemented by used CAPTCHA implementation.
 
 #### HTTP codes
@@ -47,7 +51,7 @@ It takes one parameter `answer=123456`.
 Responds with an empty body and one of the HTTP codes.
 
 #### HTTP codes
-- `200` if solved
+- `202` if solved
 - `403` if not solved
 - `404` if doesn't exist
 
@@ -57,17 +61,41 @@ Responds with an empty body and one of the HTTP codes.
 
 Responds with an empty body and one of the HTTP codes.
 
-If an optional `remove` URL query parameter without a value supplied. CAPTCHA
-will be removed without check if it is solved and a HTTP code `200` will be sent.
-Otherwise, a `403` HTTP code will be sent, and, e.g. browser will print an error
-message to console. So, in this case it helps to keep a browser's console cleaner.
-If CAPTCHA doesn't exist a `404` HTTP code still will be returned.
+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.
+
+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
+this parameter.
 
 This can be useful to remove an unused CAPTCHA from a DB without waiting for it
-to be expired. E.g. when a visitor requests for a new CAPTCHA because he struggle
-to solve it.
+to be expired. E.g. when a visitor requests for a new CAPTCHA or leaving a page.
 
 #### HTTP codes
-- `200` if solved
+- `204` if solved
 - `403` if not solved
-- `404` if doesn't exist
+- `404` if doesn't exist
+
+### Example of interaction
+
+First a client makes a POST request with empty body to create a new CAPTCHA and obtains an ID for it.
+
+    POST /
+
+As a result we get an ID `n60f2K9JiD5c4qX9MYe90A54nT0nnJrtgfhAjfaWtBg`.
+
+Then a client requests an image for a new CAPTCHA. E.g. with a dark style.
+
+    GET /n60f2K9JiD5c4qX9MYe90A54nT0nnJrtgfhAjfaWtBg/image?style=dark
+
+Then a client submits an answer for a CAPTCHA.
+
+    POST 'answer=198807' /n60f2K9JiD5c4qX9MYe90A54nT0nnJrtgfhAjfaWtBg
+
+And if answer was correct a client gets a HTTP code 202. Or 403 otherwise.
+
+Then a server checks if CAPTCHA was solved with following request.
+
+    GET /n60f2K9JiD5c4qX9MYe90A54nT0nnJrtgfhAjfaWtBg

build/archlinux/PKGBUILD

@@ -1,6 +1,6 @@
 # Maintainer: Alexander "Arav" Andreev <me@arav.top>
 pkgname=justcaptcha
-pkgver=1.2.0
+pkgver=2.0.0
 pkgrel=1
 pkgdesc="Just a CAPTCHA service"
 arch=('i686' 'x86_64' 'arm' 'armv6h' 'armv7h' 'aarch64')
@@ -15,7 +15,7 @@ replaces=()
 backup=()
 options=()
 install=
-source=('https://git.arav.top/Arav/justcaptcha/archive/1.2.0.tar.gz')
+source=('https://git.arav.top/Arav/justcaptcha/archive/2.0.0.tar.gz')
 noextract=()
 md5sums=('SKIP')
 

cmd/justcaptchad/main.go

@@ -3,7 +3,6 @@ package main
 import (
 	"flag"
 	"fmt"
-	"justcaptcha/internal/captcha"
 	"justcaptcha/internal/handlers"
 	"justcaptcha/pkg/server"
 	"log"
@@ -30,12 +29,10 @@ func main() {
 		return
 	}
 
-	captcha.Init(*captchaExpiry)
-
-	hand := handlers.New()
+	hand := handlers.New(*captchaExpiry)
 	srv := server.NewHttpServer()
 
-	srv.GET("/", hand.New)
+	srv.POST("/", hand.New)
 	srv.POST("/:captcha", hand.Solve)
 	srv.GET("/:captcha", hand.IsSolved)
 	srv.GET("/:captcha/image", hand.Image)

go.mod

@@ -1,6 +1,6 @@
 module justcaptcha
 
-go 1.18
+go 1.19
 
 require (
 	github.com/fogleman/gg v1.3.0
@@ -9,5 +9,5 @@ require (
 
 require (
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
-	golang.org/x/image v0.0.0-20220722155232-062f8c9fd539 // indirect
+	golang.org/x/image v0.1.0 // indirect
 )

go.sum

@@ -4,7 +4,29 @@ github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF0
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
 github.com/julienschmidt/httprouter v1.3.0 h1:U0609e9tgbseu3rBINet9P48AI/D3oJs4dN7jwJOQ1U=
 github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
-golang.org/x/image v0.0.0-20220722155232-062f8c9fd539 h1:/eM0PCrQI2xd471rI+snWuu251/+/jpBpZqir2mPdnU=
-golang.org/x/image v0.0.0-20220722155232-062f8c9fd539/go.mod h1:doUCurBvlfPMKfmIpRIywoHmhN3VyhnoFDbvIEWF4hY=
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/image v0.1.0 h1:r8Oj8ZA2Xy12/b5KZYj3tuv7NG/fBz3TwQVvpJ9l8Rk=
+golang.org/x/image v0.1.0/go.mod h1:iyPr49SD/G/TBxYVB/9RRtGUT5eNbo2u4NamWeQcD5c=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.4.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

internal/captcha/instance.go

@@ -1,38 +0,0 @@
-package captcha
-
-import (
-	"image"
-	"justcaptcha/pkg/captcha"
-	"time"
-)
-
-var captchaDb captcha.CaptchaDB
-
-func Init(expiry time.Duration) {
-	captchaDb = captcha.NewInMemoryCaptchaDB(expiry)
-}
-
-func New(data string) (captcha.Captcha, captcha.ID) {
-	dc := NewDwellingCaptcha(captchaDb.GetExpiry())
-	return captchaDb.New(data, dc)
-}
-
-func Image(id captcha.ID, style string) (*image.Image, error) {
-	return captchaDb.Image(id, style)
-}
-
-func Solve(id captcha.ID, answer captcha.Answer) (bool, error) {
-	return captchaDb.Solve(id, answer)
-}
-
-func IsSolved(id captcha.ID) (bool, error) {
-	return captchaDb.IsSolved(id)
-}
-
-func Remove(id captcha.ID) error {
-	return captchaDb.Remove(id)
-}
-
-func GetExpiry() time.Duration {
-	return captchaDb.GetExpiry()
-}

internal/dwcaptcha/dwelling_captcha.go

@@ -1,4 +1,4 @@
-package captcha
+package dwcaptcha
 
 import (
 	"image"

internal/handlers/handlers.go

@@ -3,36 +3,49 @@ package handlers
 import (
 	"fmt"
 	"image/jpeg"
-	"justcaptcha/internal/captcha"
-	pcaptcha "justcaptcha/pkg/captcha"
+	"justcaptcha/internal/dwcaptcha"
+	"justcaptcha/pkg/captcha"
+	"justcaptcha/pkg/captcha/inmemdb"
 	"justcaptcha/pkg/server"
 	"net/http"
+	"time"
 )
 
-type CaptchaHandlers struct{}
+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"
 
-func New() *CaptchaHandlers {
-	return &CaptchaHandlers{}
+type CaptchaHandlers struct {
+	expiry time.Duration
+}
+
+func New(expiry time.Duration) *CaptchaHandlers {
+	inmemdb.SetExpiry(expiry)
+	return &CaptchaHandlers{expiry: expiry}
 }
 
 func (h *CaptchaHandlers) New(w http.ResponseWriter, r *http.Request) {
-	_, id := captcha.New(r.RemoteAddr)
-
+	dc := dwcaptcha.NewDwellingCaptcha(h.expiry)
+	_, id := inmemdb.New(r.RemoteAddr, dc)
+	w.WriteHeader(http.StatusCreated)
 	fmt.Fprint(w, id)
 }
 
 func (h *CaptchaHandlers) Image(w http.ResponseWriter, r *http.Request) {
-	captchaID := pcaptcha.ID(server.GetURLParam(r, "captcha"))
+	captchaID := captcha.ID(server.GetURLParam(r, "captcha"))
 	captchaStyle := r.URL.Query().Get("style")
 
-	captchaImage, err := captcha.Image(captchaID, captchaStyle)
+	captchaImage, err := inmemdb.Image(captchaID, captchaStyle)
 	if err != nil {
 		w.WriteHeader(http.StatusNotFound)
+		fmt.Fprint(w, errMsgImageNotFound)
 		return
 	}
 
 	if captchaImage == nil {
 		w.WriteHeader(http.StatusInternalServerError)
+		fmt.Fprint(w, errMsgFailedToGenImage)
 		return
 	}
 
@@ -42,41 +55,47 @@ func (h *CaptchaHandlers) Image(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *CaptchaHandlers) Solve(w http.ResponseWriter, r *http.Request) {
+	captchaID := captcha.ID(server.GetURLParam(r, "captcha"))
+
 	r.ParseForm()
+	answer := captcha.Answer(r.FormValue("answer"))
 
-	captchaID := pcaptcha.ID(server.GetURLParam(r, "captcha"))
-	answer := pcaptcha.Answer(r.FormValue("answer"))
-
-	ok, err := captcha.Solve(captchaID, 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)
-	}
-}
-
-func (h *CaptchaHandlers) IsSolved(w http.ResponseWriter, r *http.Request) {
-	captchaID := pcaptcha.ID(server.GetURLParam(r, "captcha"))
-	isJustRemove := r.URL.Query().Has("remove")
-
-	if isJustRemove {
-		err := captcha.Remove(captchaID)
-		if err != nil {
-			w.WriteHeader(http.StatusNotFound)
-		}
+		fmt.Fprint(w, errMsgWrongAnswer)
 		return
 	}
 
-	solved, err := captcha.IsSolved(captchaID)
+	w.WriteHeader(http.StatusAccepted)
+}
+
+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)
+		return
+	}
+
+	solved, err := inmemdb.IsSolved(captchaID)
 	if err != nil {
 		w.WriteHeader(http.StatusNotFound)
+		fmt.Fprint(w, errMsgNotFound)
 		return
 	}
 
 	if !solved {
 		w.WriteHeader(http.StatusForbidden)
+		fmt.Fprint(w, errMsgWrongAnswer)
 	}
 }

pkg/captcha/captcha.go

@@ -20,7 +20,8 @@ func NewIntAnswer() Answer {
 
 // Captcha interface that should be implemented by a CAPTCHA.
 type Captcha interface {
-	// Image generates and returns a pointer to an image of CAPTCHA.
+	// Image generates an image of a CAPTCHA according to a passed style
+	// and returns a pointer to it.
 	Image(style string) *image.Image
 	// Answer returns a pregenerated answer.
 	Answer() Answer
@@ -37,14 +38,14 @@ type Captcha interface {
 // All derivatives that embed this struct only need to implement
 // an Image() method.
 type BaseCaptcha struct {
-	answer   Answer
-	solved   bool
-	expireIn time.Time
+	answer Answer
+	solved bool
+	expiry time.Time
 }
 
 func NewBaseCaptcha(expiry time.Duration) *BaseCaptcha {
 	return &BaseCaptcha{
-		expireIn: ExpiryDate(expiry),
+		expiry: ExpiryDate(expiry),
 	}
 }
 
@@ -52,8 +53,6 @@ func (c *BaseCaptcha) Image(style string) *image.Image {
 	return nil
 }
 
-// Answer generates an integer answer for a CAPTCHA or just returns
-// an existing one.
 func (c *BaseCaptcha) Answer() Answer {
 	if c.answer == "" {
 		c.answer = NewIntAnswer()
@@ -61,8 +60,6 @@ func (c *BaseCaptcha) Answer() Answer {
 	return c.answer
 }
 
-// Solve sets solved field to true if given answer is right and returns a result
-// of a check.
 func (c *BaseCaptcha) Solve(answer Answer) bool {
 	c.solved = c.answer == answer
 	return c.solved
@@ -73,7 +70,7 @@ func (c *BaseCaptcha) IsSolved() bool {
 }
 
 func (c *BaseCaptcha) Expiry() time.Time {
-	return c.expireIn
+	return c.expiry
 }
 
 // ExpiryDate returns a date when CAPTCHA expires. It adds a passed

pkg/captcha/db.go

@@ -1,147 +1,45 @@
 package captcha
 
 import (
+	"crypto/rand"
 	"crypto/sha256"
 	"encoding/base64"
 	"errors"
 	"image"
 	"strconv"
-	"sync"
 	"time"
 )
 
-var errorNotFound = errors.New("captcha not found")
+var ErrorNotFound = errors.New("captcha not found")
 
-var defaultExpiredScanInterval = 60 * time.Second
+const DefaultExpiredScanInterval = 60 * time.Second
 
+// ID is a CAPTCHA identifier.
 type ID string
 
-// NewID generates an ID as a sha256 hash of additionalData, current time
-// and answer encoded with base64 in raw URL variant.
+// NewID generates an ID as a sha256 hash of additionalData (usually IP-address),
+// current time, answer and more, it adds a set of random bytes and encodes all
+// of it with base64 in raw URL variant.
 func NewID(additionalData string, answer Answer) ID {
 	idHash := sha256.New()
 
 	idHash.Write([]byte(additionalData))
 	idHash.Write([]byte(strconv.FormatInt(time.Now().UnixMicro(), 16)))
 	idHash.Write([]byte(answer))
+	randData := make([]byte, 32)
+	rand.Read(randData)
+	idHash.Write(randData)
 
 	return ID(base64.RawURLEncoding.EncodeToString(idHash.Sum(nil)))
 }
 
+// CaptchaDB interface with all necessary methods.
 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
-	cleanExpired()
-}
-
-type InMemoryCaptchaDB struct {
-	sync.Mutex
-
-	db                 map[ID]Captcha
-	expireIn           time.Duration
-	expireScanInterval time.Duration
-}
-
-func NewInMemoryCaptchaDB(expire time.Duration) *InMemoryCaptchaDB {
-	db := &InMemoryCaptchaDB{
-		db:       make(map[ID]Captcha),
-		expireIn: expire}
-
-	if expire < defaultExpiredScanInterval {
-		db.expireScanInterval = expire
-	} else {
-		db.expireScanInterval = defaultExpiredScanInterval
-	}
-
-	db.cleanExpired()
-
-	return db
-}
-
-// New accepts an Captcha instance, generates an ID and store it in a database.
-// `data` string is an additional random data used to generate an ID,
-// e.g. IP-address.
-func (cdb *InMemoryCaptchaDB) New(data string, captcha Captcha) (Captcha, ID) {
-	id := NewID(data, captcha.Answer())
-
-	cdb.Lock()
-	cdb.db[id] = captcha
-	cdb.Unlock()
-
-	return captcha, id
-}
-
-// cleanExpired starts a goroutine that deletes expired CAPTCHAs.
-func (cdb *InMemoryCaptchaDB) cleanExpired() {
-	go func() {
-		for {
-			sleepFor := cdb.expireScanInterval - (time.Duration(time.Now().Second()) % cdb.expireScanInterval)
-			time.Sleep(sleepFor)
-
-			cdb.Lock()
-			for id, captcha := range cdb.db {
-				if time.Since(captcha.Expiry()) >= cdb.expireIn {
-					delete(cdb.db, id)
-				}
-			}
-			cdb.Unlock()
-		}
-	}()
-}
-
-// GetExpiry returns time for how long CAPTCHA will last.
-func (cdb *InMemoryCaptchaDB) GetExpiry() time.Duration {
-	return cdb.expireIn
-}
-
-// Image returns image for a CAPTCHA.
-func (cdb *InMemoryCaptchaDB) Image(id ID, style string) (*image.Image, error) {
-	cdb.Lock()
-	defer cdb.Unlock()
-	if c, ok := cdb.db[id]; ok {
-		return c.Image(style), nil
-	}
-	return nil, errorNotFound
-}
-
-// Solve compares given answer with a stored one and if failed
-// deletes a CAPTCHA from database.
-func (cdb *InMemoryCaptchaDB) Solve(id ID, answer Answer) (bool, error) {
-	cdb.Lock()
-	defer cdb.Unlock()
-	if c, ok := cdb.db[id]; ok {
-		ok = c.Solve(answer)
-		if !ok {
-			delete(cdb.db, id)
-		}
-		return ok, nil
-	}
-	return false, errorNotFound
-}
-
-// IsSolved checks if CAPTCHA was solved and removes it
-// from a database.
-func (cdb *InMemoryCaptchaDB) IsSolved(id ID) (bool, error) {
-	cdb.Lock()
-	defer cdb.Unlock()
-	if c, ok := cdb.db[id]; ok {
-		delete(cdb.db, id)
-		return c.IsSolved(), nil
-	}
-	return false, errorNotFound
-}
-
-// Remove a CAPTCHA from a database.
-func (cdb *InMemoryCaptchaDB) Remove(id ID) error {
-	cdb.Lock()
-	defer cdb.Unlock()
-	if _, ok := cdb.db[id]; ok {
-		delete(cdb.db, id)
-		return nil
-	}
-	return errorNotFound
 }

pkg/captcha/inmemdb/inmemdb.go

@@ -0,0 +1,157 @@
+package inmemdb
+
+import (
+	"image"
+	"justcaptcha/pkg/captcha"
+	"sync"
+	"time"
+)
+
+type InMemoryCaptchaDB struct {
+	sync.Mutex
+
+	db                 map[captcha.ID]captcha.Captcha
+	expiry             time.Duration
+	expiryScanInterval time.Duration
+}
+
+// NewInMemoryCaptchaDB returns an initialised instance of an InMemoryCaptchaDB.
+// An expiry duration is a time for how long CAPTCHA will be valid.
+func NewInMemoryCaptchaDB(expiry time.Duration) *InMemoryCaptchaDB {
+	db := &InMemoryCaptchaDB{
+		db:     make(map[captcha.ID]captcha.Captcha),
+		expiry: expiry}
+
+	if expiry < captcha.DefaultExpiredScanInterval {
+		db.expiryScanInterval = expiry
+	} else {
+		db.expiryScanInterval = captcha.DefaultExpiredScanInterval
+	}
+
+	go db.cleanExpired()
+
+	return db
+}
+
+// New accepts a CAPTHA instance, generates an ID and store it in a database.
+// A data string is an additional random data used to generate an ID,
+// e.g. an IP-address.
+func (imcdb *InMemoryCaptchaDB) New(data string, cptcha captcha.Captcha) (captcha.Captcha, captcha.ID) {
+	id := captcha.NewID(data, cptcha.Answer())
+
+	imcdb.Lock()
+	imcdb.db[id] = cptcha
+	imcdb.Unlock()
+
+	return cptcha, id
+}
+
+// GetExpiry returns time for how long CAPTCHA will last.
+func (imcdb *InMemoryCaptchaDB) GetExpiry() time.Duration {
+	return imcdb.expiry
+}
+
+// SetExpiry changes an expiry duration to a new one.
+func (imcdb *InMemoryCaptchaDB) SetExpiry(expiry time.Duration) {
+	if expiry < captcha.DefaultExpiredScanInterval {
+		imcdb.expiryScanInterval = expiry
+	} else {
+		imcdb.expiryScanInterval = captcha.DefaultExpiredScanInterval
+	}
+}
+
+// Image returns a freshly generated image for a CAPTCHA.
+func (imcdb *InMemoryCaptchaDB) Image(id captcha.ID, style string) (*image.Image, error) {
+	imcdb.Lock()
+	defer imcdb.Unlock()
+	if c, ok := imcdb.db[id]; ok {
+		return c.Image(style), nil
+	}
+	return nil, captcha.ErrorNotFound
+}
+
+// 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) {
+	imcdb.Lock()
+	defer imcdb.Unlock()
+	if c, ok := imcdb.db[id]; ok {
+		ok = c.Solve(answer)
+		if !ok {
+			delete(imcdb.db, id)
+		}
+		return ok, nil
+	}
+	return false, captcha.ErrorNotFound
+}
+
+// IsSolved checks if CAPTCHA was solved and removes it
+// from a database.
+func (imcdb *InMemoryCaptchaDB) IsSolved(id captcha.ID) (bool, error) {
+	imcdb.Lock()
+	defer imcdb.Unlock()
+	if c, ok := imcdb.db[id]; ok {
+		delete(imcdb.db, id)
+		return c.IsSolved(), nil
+	}
+	return false, captcha.ErrorNotFound
+}
+
+// Remove a CAPTCHA from a database.
+func (imcdb *InMemoryCaptchaDB) Remove(id captcha.ID) error {
+	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.
+func (imcdb *InMemoryCaptchaDB) cleanExpired() {
+	for {
+		sleepFor := imcdb.expiryScanInterval - (time.Duration(time.Now().Second()) % imcdb.expiryScanInterval)
+		time.Sleep(sleepFor)
+
+		imcdb.Lock()
+		for id, captcha := range imcdb.db {
+			if time.Since(captcha.Expiry()) >= imcdb.expiry {
+				delete(imcdb.db, id)
+			}
+		}
+		imcdb.Unlock()
+	}
+}
+
+// An instance of InMemoryCaptchaDB
+
+var imcdb = NewInMemoryCaptchaDB(captcha.DefaultExpiredScanInterval)
+
+func GetExpiry() time.Duration {
+	return imcdb.GetExpiry()
+}
+
+func SetExpiry(expiry time.Duration) {
+	imcdb.SetExpiry(expiry)
+}
+
+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) {
+	return imcdb.Image(id, style)
+}
+
+func Solve(id captcha.ID, answer captcha.Answer) (bool, error) {
+	return imcdb.Solve(id, answer)
+}
+
+func IsSolved(id captcha.ID) (bool, error) {
+	return imcdb.IsSolved(id)
+}
+
+func Remove(id captcha.ID) error {
+	return imcdb.Remove(id)
+}