update scala version in scripts

Update scala3-library to 3.6.2

.git-blame-ignore-revs

@@ -0,0 +1,5 @@
+# Scala Steward: Reformat with sbt-java-formatter 0.8.0
+57ce691a00babb03e0cae03a26fe56d63fc609af
+
+# Scala Steward: Reformat with scalafmt 3.6.1
+f2b19baca828a4d88b46bc009aef6d7115e63924

.github/scala-steward.conf

@@ -0,0 +1,3 @@
+# If true, Scala Steward will sign off all commits (e.g. `git --signoff`).
+# Default: false
+signoffCommits = true

.github/workflows/ci.yml

@@ -16,6 +16,7 @@ jobs:
       uses: actions/setup-java@v1
       with:
         java-version: 1.11
+    - uses: sbt/setup-sbt@v1
     - name: Run tests
       run: sbt test assembly
     - name: Run linter

.github/workflows/docker-latest.yml

@@ -54,6 +54,10 @@ jobs:
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+          platforms: |
+            linux/amd64
+            linux/arm64
+            linux/arm/v7
 
       - name: Image digest
         run: echo ${{ steps.docker_build.outputs.digest }}

.scalafmt.conf

@@ -1,3 +1,3 @@
-version="3.4.3" 
+version="3.8.3" 
 maxColumn = 120
 runner.dialect = scala3

Dockerfile

@@ -1,12 +1,13 @@
-FROM adoptopenjdk/openjdk16:alpine AS base-builder
+FROM eclipse-temurin:17-jre-jammy AS base-builder
-ARG SBT_VERSION=1.3.13
+ARG SBT_VERSION=1.7.1
-RUN apk add --no-cache bash
 ENV JAVA_HOME="/usr/lib/jvm/default-jvm/"
 ENV PATH=$PATH:${JAVA_HOME}/bin
 RUN \
+        apt update && \
+        apt install -y wget && \
 	wget -O sbt-$SBT_VERSION.tgz https://github.com/sbt/sbt/releases/download/v$SBT_VERSION/sbt-$SBT_VERSION.tgz && \
-  	tar -xzvf sbt-$SBT_VERSION.tgz && \
+        tar -xzvf sbt-$SBT_VERSION.tgz && \
-  	rm sbt-$SBT_VERSION.tgz
+        rm sbt-$SBT_VERSION.tgz
 
 ENV PATH=$PATH:/sbt/bin/
 
@@ -22,15 +23,15 @@ FROM sbt-builder as builder
 COPY src/ src/
 RUN sbt assembly
 
-FROM adoptopenjdk/openjdk16:alpine-jre  AS base-core
+FROM eclipse-temurin:17-jre-jammy  AS base-core
 ENV JAVA_HOME="/usr/lib/jvm/default-jvm/"
-RUN apk add --update ttf-dejavu
+RUN apt update && apt install -y fonts-dejavu
 ENV PATH=$PATH:${JAVA_HOME}/bin
 
 
 FROM base-core
 WORKDIR /lc-core
-COPY --from=builder /build/target/scala-2.13/LibreCaptcha.jar .
+COPY --from=builder /build/target/scala-3.6.2/LibreCaptcha.jar .
 RUN mkdir data/
 
 EXPOSE 8888

README.md

@@ -2,12 +2,12 @@
 LibreCaptcha is a framework that allows developers to create their own [CAPTCHA](https://en.wikipedia.org/wiki/CAPTCHA)s.
 The framework defines the API for a CAPTCHA generator and takes care of mundane details
 such as:
-  * An HTTP interface for serving CAPTCHAs
+* An HTTP interface for serving CAPTCHAs
-  * Background workers to pre-compute CAPTCHAs and to store them in a database
+* Background workers to pre-compute CAPTCHAs and to store them in a database
-  * Managing secrets for the CAPTCHAs (tokens, expected answers, etc)
+* Managing secrets for the CAPTCHAs (tokens, expected answers, etc)
-  * Safe re-impressions of CAPTCHA images (by creating unique tokens for every impression)
+* Safe re-impressions of CAPTCHA images (by creating unique tokens for every impression)
-  * Garbage collection of stale CAPTCHAs
+* Garbage collection of stale CAPTCHAs
-  * Sandboxed plugin architecture (TBD)
+* Sandboxed plugin architecture (TBD)
 
 Some sample CAPTCHA generators are included in the distribution (see below). We will continue adding more samples to the list. For quick
 deployments the samples themselves might be sufficient. Projects with more resources might want create their own CAPTCHAs
@@ -47,18 +47,25 @@ docker-compose up
 Using `docker`:
 
 ```
-docker run -v lcdata:/lc-core/data librecaptcha/lc-core:1.1.0-stable
+docker run -p=8888:8888 -v ./lcdata:/lc-core/data librecaptcha/lc-core:2.0
 ```
 
 A default `config.json` is automatically created in the mounted volume.
 
+The above commands should work with `podman` as well, if docker.io registry is pre-configured. Otherwise,
+you can manually specify the repository like so:
+
+```
+podman run -p=8888:8888 -v ./lcdata:/lc-core/data docker.io/librecaptcha/lc-core:2.0
+```
+
 ## Quick test
 Open [localhost:8888/demo/index.html](http://localhost:8888/demo/index.html) in browser.
 
 Alternatively, on the command line, try:
 
 ```
-> $ curl -d '{"media":"image/png","level":"easy","input_type":"text"}' localhost:8888/v1/captcha
+> $ curl -d '{"media":"image/png","level":"easy","input_type":"text","size":"350x100"}' localhost:8888/v2/captcha
 {"id":"3bf928ce-a1e7-4616-b34f-8252d777855d"}
 
 > $ curl "localhost:8888/v1/media?id=3bf928ce-a1e7-4616-b34f-8252d777855d" -o sample.png
@@ -124,48 +131,48 @@ If a sufficient number of users agree on their answer to the unknown word, it is
 The service can be accessed using a simple HTTP API.
 
 ### - `/v1/captcha`: `POST`
-  - Parameters:
+- Parameters:
     - `level`: `String` -
       The difficulty level of a captcha
-       - easy
+        - easy
-       - medium
+        - medium
-       - hard
+        - hard
     - `input_type`: `String` -
       The type of input option for a captcha
-       - text
+        - text
-       - (More to come)
+        - (More to come)
     - `media`: `String` -
       The type of media of a captcha
-       - image/png
+        - image/png
-       - image/gif
+        - image/gif
-       - (More to come)
+        - (More to come)
-    - `size`: `Map` -
+    - `size`: String -
-      The dimensions of a captcha (Optional). It needs two more fields nested in this parameter
+      The dimensions of a captcha. It needs to be a string in the format `"widthxheight"` in pixels, and will be matched
-       - `height`: `Int`
+      with the `allowedSizes` config setting. Example: `size: "450x200"` which requests an image of width 450 and height
-       - `width`: `Int`
+      200 pixels.
 
-  - Returns:
+- Returns:
     - `id`: `String` - The uuid of the captcha generated
 
 
 ### - `/v1/media`: `GET`
-  - Parameters:
+- Parameters:
     - `id`: `String` - The uuid of the captcha
 
-  - Returns:
+- Returns:
     - `image`: `Array[Byte]` - The requested media as bytes
 
 
 ### - `/v1/answer`: `POST`
-  - Parameter:
+- Parameter:
     - `id`: `String` - The uuid of the captcha that needs to be solved
     - `answer`: `String` - The answer to the captcha that needs to be validated
 
-  - Returns:
+- Returns:
     - `result`: `String` - The result after validation/checking of the answer
-      - True - If the answer is correct
+        - True - If the answer is correct
-      - False - If the answer is incorrect
+        - False - If the answer is incorrect
-      - Expired - If the time limit to solve the captcha exceeds
+        - Expired - If the time limit to solve the captcha exceeds
 
 
 ## Example usage
@@ -173,9 +180,9 @@ The service can be accessed using a simple HTTP API.
 In javascript:
 
 ```js
-const resp = await fetch("/v1/captcha", {
+const resp = await fetch("/v2/captcha", {
-   method: 'POST',
+    method: 'POST',
-   body: JSON.stringify({level: "easy", media: "image/png", "input_type" : "text"})
+    body: JSON.stringify({level: "easy", media: "image/png", "input_type" : "text", size: "350x100"})
 })
 
 const respJson = await resp.json();
@@ -183,19 +190,19 @@ const respJson = await resp.json();
 let captchaId = null;
 
 if (resp.ok) {
-  // The CAPTCHA can be displayed using the data in respJson.
+    // The CAPTCHA can be displayed using the data in respJson.
-  console.log(respJson);
+    console.log(respJson);
-  // Store the id somewhere so that it can be used later for answer verification
+    // Store the id somewhere so that it can be used later for answer verification
-  captchaId = respJson.id;
+    captchaId = respJson.id;
 } else {
-  console.err(respJson);
+    console.err(respJson);
 }
 
 
 // When user submits an answer it can be sent to the server for verification thusly:
-const resp = await fetch("/v1/answer", {
+const resp = await fetch("/v2/answer", {
-   method: 'POST',
+    method: 'POST',
-   body: JSON.stringify({id: captchaId, answer: "user input"})
+    body: JSON.stringify({id: captchaId, answer: "user input"})
 });
 const respJson = await resp.json();
 console.log(respJson.result);

Runner.Dockerfile

@@ -1,12 +1,12 @@
-FROM adoptopenjdk/openjdk16:alpine-jre  AS base-core
+FROM eclipse-temurin:17-jre-jammy  AS base-core
 ENV JAVA_HOME="/usr/lib/jvm/default-jvm/"
-RUN apk add --update ttf-dejavu
+RUN apt update && apt install -y fonts-dejavu
 ENV PATH=$PATH:${JAVA_HOME}/bin
 
 
 FROM base-core
 RUN mkdir /lc-core
-COPY target/scala-3.1.1/LibreCaptcha.jar /lc-core
+COPY target/scala-3.6.2/LibreCaptcha.jar /lc-core
 WORKDIR /lc-core
 RUN mkdir data/
 

build.sbt

@@ -2,8 +2,8 @@ lazy val root = (project in file(".")).settings(
   inThisBuild(
     List(
       organization := "com.example",
-      scalaVersion := "3.1.1",
+      scalaVersion := "3.6.2",
-      version := "0.1.0-SNAPSHOT",
+      version := "0.2.1-snapshot",
       semanticdbEnabled := true,
       semanticdbVersion := scalafixSemanticdb.revision
 
@@ -12,9 +12,9 @@ lazy val root = (project in file(".")).settings(
     )
   ),
   name := "LibreCaptcha",
-  libraryDependencies += "com.sksamuel.scrimage" % "scrimage-core" % "4.0.30",
+  libraryDependencies += "com.sksamuel.scrimage" % "scrimage-core" % "4.3.0",
-  libraryDependencies += "com.sksamuel.scrimage" % "scrimage-filters" % "4.0.30",
+  libraryDependencies += "com.sksamuel.scrimage" % "scrimage-filters" % "4.3.0",
-  libraryDependencies += "org.json4s" %% "json4s-jackson" % "4.0.4"
+  libraryDependencies += "org.json4s" %% "json4s-jackson" % "4.0.7"
 )
 
 Compile / unmanagedResourceDirectories += { baseDirectory.value / "lib" }

docker-compose.yml

@@ -3,7 +3,9 @@ version: "3.6"
 services:
   lc-core:
     container_name: "libre-captcha"
-    image: librecaptcha/lc-core:1.0.0-stable
+    image: librecaptcha/lc-core:latest
+    # Comment "image" & uncomment "build" if you intend to build from source
+    #build: .
     volumes: 
       - "./docker-data:/lc-core/data"
     ports: 

project/build.properties

@@ -1 +1 @@
-sbt.version=1.6.2
+sbt.version=1.10.6

project/plugins.sbt

@@ -1,4 +1,4 @@
-addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.34")
+addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.13.0")
-addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.6")
+addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.5.2")
-addSbtPlugin("com.lightbend.sbt" % "sbt-java-formatter" % "0.7.0")
+addSbtPlugin("com.lightbend.sbt" % "sbt-java-formatter" % "0.8.0")
-addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "1.2.0")
+addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "2.3.0")

src/main/java/lc/captchas/FontFunCaptcha.java

@@ -5,12 +5,12 @@ import java.awt.image.BufferedImage;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FilenameFilter;
-import java.util.Map;
 import java.util.List;
+import java.util.Map;
 import lc.captchas.interfaces.Challenge;
 import lc.captchas.interfaces.ChallengeProvider;
-import lc.misc.PngImageWriter;
 import lc.misc.HelperFunctions;
+import lc.misc.PngImageWriter;
 
 public class FontFunCaptcha implements ChallengeProvider {
 
@@ -58,9 +58,10 @@ public class FontFunCaptcha implements ChallengeProvider {
     return null;
   }
 
-  private byte[] fontFun(String captchaText, String level, String path) {
+  private byte[] fontFun(
+      final int width, final int height, String captchaText, String level, String path) {
     String[] colors = {"#f68787", "#f8a978", "#f1eb9a", "#a4f6a5"};
-    BufferedImage img = new BufferedImage(350, 100, BufferedImage.TYPE_INT_RGB);
+    BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
     Graphics2D graphics2D = img.createGraphics();
     for (int i = 0; i < captchaText.length(); i++) {
       Font font = loadCustomFont(level, path);
@@ -81,10 +82,14 @@ public class FontFunCaptcha implements ChallengeProvider {
     return baos.toByteArray();
   }
 
-  public Challenge returnChallenge() {
+  public Challenge returnChallenge(String level, String size) {
     String secret = HelperFunctions.randomString(7);
+    final int[] size2D = HelperFunctions.parseSize2D(size);
+    final int width = size2D[0];
+    final int height = size2D[1];
     String path = "./lib/fonts/";
-    return new Challenge(fontFun(secret, "medium", path), "image/png", secret.toLowerCase());
+    return new Challenge(
+        fontFun(width, height, secret, "medium", path), "image/png", secret.toLowerCase());
   }
 
   public boolean checkAnswer(String secret, String answer) {

src/main/java/lc/captchas/PoppingCharactersCaptcha.java

@@ -1,51 +1,51 @@
 package lc.captchas;
 
-import java.awt.Font;
-import java.awt.RenderingHints;
 import java.awt.Color;
+import java.awt.Font;
 import java.awt.Graphics2D;
+import java.awt.RenderingHints;
 import java.awt.image.BufferedImage;
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.util.List;
 import java.util.Map;
 import java.util.function.Consumer;
 import java.util.stream.IntStream;
-import java.util.LinkedList;
-import java.util.List;
-
 import javax.imageio.stream.MemoryCacheImageOutputStream;
-import java.io.ByteArrayOutputStream;
 import lc.captchas.interfaces.Challenge;
 import lc.captchas.interfaces.ChallengeProvider;
-import lc.misc.HelperFunctions;
 import lc.misc.GifSequenceWriter;
+import lc.misc.HelperFunctions;
 
 public class PoppingCharactersCaptcha implements ChallengeProvider {
-  private final Font font = new Font("Arial", Font.ROMAN_BASELINE, 48);
-  private final int width = 250;
-  private final int height = 100;
 
-  private Integer[] computeOffsets(final String text) {
+  private int[] computeOffsets(
+      final Font font, final int width, final int height, final String text) {
     final var img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
     final var graphics2D = img.createGraphics();
     final var frc = graphics2D.getFontRenderContext();
-    final var advances = new LinkedList<Integer>();
+    final var advances = new int[text.length() + 1];
     final var spacing = font.getStringBounds(" ", frc).getWidth() / 3;
     var currX = 0;
     for (int i = 0; i < text.length(); i++) {
       final var c = text.charAt(i);
-      advances.add(currX);
+      advances[i] = currX;
       currX += font.getStringBounds(String.valueOf(c), frc).getWidth();
       currX += spacing;
-    };
+    }
+    ;
+    advances[text.length()] = currX;
     graphics2D.dispose();
-    return advances.toArray(new Integer[]{});
+    return advances;
   }
 
-  private BufferedImage makeImage(final Consumer<Graphics2D> f) {
+  private BufferedImage makeImage(
+      final Font font, final int width, final int height, final Consumer<Graphics2D> f) {
     final var img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
     final var graphics2D = img.createGraphics();
     graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
-    graphics2D.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+    graphics2D.setRenderingHint(
+        RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
     graphics2D.setFont(font);
     f.accept(graphics2D);
     graphics2D.dispose();
@@ -56,30 +56,49 @@ public class PoppingCharactersCaptcha implements ChallengeProvider {
     return HelperFunctions.randomNumber(-2, +2);
   }
 
-  private byte[] gifCaptcha(final String text) {
+  private byte[] gifCaptcha(final int width, final int height, final String text) {
     try {
+      final var fontHeight = (int) (height * 0.5);
+      final Font font = new Font("Arial", Font.ROMAN_BASELINE, fontHeight);
       final var byteArrayOutputStream = new ByteArrayOutputStream();
       final var output = new MemoryCacheImageOutputStream(byteArrayOutputStream);
       final var writer = new GifSequenceWriter(output, 1, 900, true);
-      final var advances = computeOffsets(text);
+      final var advances = computeOffsets(font, width, height, text);
+      final var expectedWidth = advances[advances.length - 1];
+      final var scale = width / (float) expectedWidth;
       final var prevColor = Color.getHSBColor(0f, 0f, 0.1f);
-      IntStream.range(0, text.length()).forEach(i -> {
+      IntStream.range(0, text.length())
-        final var color = Color.getHSBColor(HelperFunctions.randomNumber(0, 100)/100.0f, 0.6f, 1.0f);
+          .forEach(
-        final var nextImage = makeImage((g) -> {
+              i -> {
-          if (i > 0) {
+                final var color =
-            final var prevI = (i - 1) % text.length();
+                    Color.getHSBColor(HelperFunctions.randomNumber(0, 100) / 100.0f, 0.6f, 1.0f);
-            g.setColor(prevColor);
+                final var nextImage =
-            g.drawString(String.valueOf(text.charAt(prevI)), advances[prevI] + jitter(), 45 + jitter());
+                    makeImage(
-          }
+                        font,
-          g.setColor(color);
+                        width,
-          g.drawString(String.valueOf(text.charAt(i)), advances[i] + jitter(), 45 + jitter());
+                        height,
-        });
+                        (g) -> {
-        try {
+                          g.scale(scale, 1);
-          writer.writeToSequence(nextImage);
+                          if (i > 0) {
-        } catch (final IOException e) {
+                            final var prevI = (i - 1) % text.length();
-          e.printStackTrace();
+                            g.setColor(prevColor);
-        }
+                            g.drawString(
-      });
+                                String.valueOf(text.charAt(prevI)),
+                                advances[prevI] + jitter(),
+                                fontHeight * 1.1f + jitter());
+                          }
+                          g.setColor(color);
+                          g.drawString(
+                              String.valueOf(text.charAt(i)),
+                              advances[i] + jitter(),
+                              fontHeight * 1.1f + jitter());
+                        });
+                try {
+                  writer.writeToSequence(nextImage);
+                } catch (final IOException e) {
+                  e.printStackTrace();
+                }
+              });
       writer.close();
       output.close();
       return byteArrayOutputStream.toByteArray();
@@ -100,9 +119,12 @@ public class PoppingCharactersCaptcha implements ChallengeProvider {
         "supportedInputType", List.of("text"));
   }
 
-  public Challenge returnChallenge() {
+  public Challenge returnChallenge(String level, String size) {
     final var secret = HelperFunctions.randomString(6);
-    return new Challenge(gifCaptcha(secret), "image/gif", secret.toLowerCase());
+    final int[] size2D = HelperFunctions.parseSize2D(size);
+    final int width = size2D[0];
+    final int height = size2D[1];
+    return new Challenge(gifCaptcha(width, height, secret), "image/gif", secret.toLowerCase());
   }
 
   public boolean checkAnswer(String secret, String answer) {

src/main/java/lc/captchas/ShadowTextCaptcha.java

@@ -1,21 +1,18 @@
 package lc.captchas;
 
-import java.awt.Graphics2D;
-import java.awt.RenderingHints;
 import java.awt.Color;
 import java.awt.Font;
-import java.awt.font.TextLayout;
+import java.awt.Graphics2D;
 import java.awt.image.BufferedImage;
 import java.awt.image.ConvolveOp;
 import java.awt.image.Kernel;
 import java.io.ByteArrayOutputStream;
-import java.util.Map;
 import java.util.List;
-
+import java.util.Map;
-import lc.misc.HelperFunctions;
-import lc.misc.PngImageWriter;
 import lc.captchas.interfaces.Challenge;
 import lc.captchas.interfaces.ChallengeProvider;
+import lc.misc.HelperFunctions;
+import lc.misc.PngImageWriter;
 
 public class ShadowTextCaptcha implements ChallengeProvider {
 
@@ -38,32 +35,43 @@ public class ShadowTextCaptcha implements ChallengeProvider {
     return answer.toLowerCase().equals(secret);
   }
 
-  private byte[] shadowText(String text) {
+  private float[] makeKernel(int size) {
-    BufferedImage img = new BufferedImage(350, 100, BufferedImage.TYPE_INT_RGB);
+    final int N = size * size;
-    Font font = new Font("Arial", Font.ROMAN_BASELINE, 48);
+    final float weight = 1.0f / (N);
-    Graphics2D graphics2D = img.createGraphics();
+    final float[] kernel = new float[N];
-    graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+    java.util.Arrays.fill(kernel, weight);
-    graphics2D.setRenderingHint(
+    return kernel;
-        RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+  };
 
-    TextLayout textLayout = new TextLayout(text, font, graphics2D.getFontRenderContext());
+  private byte[] shadowText(final int width, final int height, String text) {
+    BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
+    final int fontHeight = (int) (height * 0.5f);
+    Font font = new Font("Arial", Font.PLAIN, fontHeight);
+    Graphics2D graphics2D = img.createGraphics();
     HelperFunctions.setRenderingHints(graphics2D);
     graphics2D.setPaint(Color.WHITE);
-    graphics2D.fillRect(0, 0, 350, 100);
+    graphics2D.fillRect(0, 0, width, height);
     graphics2D.setPaint(Color.BLACK);
-    textLayout.draw(graphics2D, 15, 50);
+    graphics2D.setFont(font);
+    final var stringWidth = graphics2D.getFontMetrics().stringWidth(text);
+    final var padding = (stringWidth > width) ? 0 : (width - stringWidth) / 2;
+    final var scaleX = (stringWidth > width) ? width / ((double) stringWidth) : 1d;
+    graphics2D.scale(scaleX, 1d);
+    graphics2D.drawString(text, padding, fontHeight * 1.1f);
     graphics2D.dispose();
-    float[] kernel = {
+    final int kernelSize = (int) Math.ceil((Math.min(width, height) / 50.0));
-      1f / 9f, 1f / 9f, 1f / 9f,
+    ConvolveOp op =
-      1f / 9f, 1f / 9f, 1f / 9f,
+        new ConvolveOp(
-      1f / 9f, 1f / 9f, 1f / 9f
+            new Kernel(kernelSize, kernelSize, makeKernel(kernelSize)),
-    };
+            ConvolveOp.EDGE_NO_OP,
-    ConvolveOp op = new ConvolveOp(new Kernel(3, 3, kernel), ConvolveOp.EDGE_NO_OP, null);
+            null);
     BufferedImage img2 = op.filter(img, null);
     Graphics2D g2d = img2.createGraphics();
     HelperFunctions.setRenderingHints(g2d);
     g2d.setPaint(Color.WHITE);
-    textLayout.draw(g2d, 13, 50);
+    g2d.scale(scaleX, 1d);
+    g2d.setFont(font);
+    g2d.drawString(text, padding - kernelSize, fontHeight * 1.1f);
     g2d.dispose();
     ByteArrayOutputStream baos = new ByteArrayOutputStream();
     try {
@@ -74,8 +82,11 @@ public class ShadowTextCaptcha implements ChallengeProvider {
     return baos.toByteArray();
   }
 
-  public Challenge returnChallenge() {
+  public Challenge returnChallenge(String level, String size) {
     String secret = HelperFunctions.randomString(6);
-    return new Challenge(shadowText(secret), "image/png", secret.toLowerCase());
+    final int[] size2D = HelperFunctions.parseSize2D(size);
+    final int width = size2D[0];
+    final int height = size2D[1];
+    return new Challenge(shadowText(width, height, secret), "image/png", secret.toLowerCase());
   }
 }

src/main/java/lc/captchas/interfaces/ChallengeProvider.java

@@ -1,12 +1,12 @@
 package lc.captchas.interfaces;
 
-import java.util.Map;
 import java.util.List;
+import java.util.Map;
 
 public interface ChallengeProvider {
   public String getId();
 
-  public Challenge returnChallenge();
+  public Challenge returnChallenge(String level, String size);
 
   public boolean checkAnswer(String secret, String answer);
 

src/main/java/lc/misc/GifSequenceWriter.java

@@ -3,12 +3,12 @@
 
 package lc.misc;
 
-import javax.imageio.*;
-import javax.imageio.metadata.*;
-import javax.imageio.stream.*;
 import java.awt.image.*;
 import java.io.*;
 import java.util.Iterator;
+import javax.imageio.*;
+import javax.imageio.metadata.*;
+import javax.imageio.stream.*;
 
 public class GifSequenceWriter {
   protected ImageWriter gifWriter;

src/main/java/lc/misc/HelperFunctions.java

@@ -11,7 +11,14 @@ public class HelperFunctions {
     random.setSeed(seed);
   }
 
+  public static int[] parseSize2D(final String size) {
+    final String[] fields = size.split("x");
+    final int[] result = {Integer.parseInt(fields[0]), Integer.parseInt(fields[1])};
+    return result;
+  }
+
   public static void setRenderingHints(Graphics2D g2d) {
+    g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
     g2d.setRenderingHint(
         RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
     g2d.setRenderingHint(
@@ -23,7 +30,8 @@ public class HelperFunctions {
   public static final String safeNumbers = "23456789";
   public static final String allNumbers = safeNumbers + "10";
   public static final String specialCharacters = "$#%@&?";
-  public static final String safeCharacters = safeAlphabets + safeNumbers + specialCharacters;
+  public static final String safeAlphaNum = safeAlphabets + safeNumbers;
+  public static final String safeCharacters = safeAlphaNum + specialCharacters;
 
   public static String randomString(final int n) {
     return randomString(n, safeCharacters);

src/main/java/lc/misc/PngImageWriter.java

@@ -1,9 +1,9 @@
 package lc.misc;
 
+import java.awt.image.BufferedImage;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.util.Iterator;
-
 import javax.imageio.IIOImage;
 import javax.imageio.ImageIO;
 import javax.imageio.ImageTypeSpecifier;
@@ -13,7 +13,6 @@ import javax.imageio.metadata.IIOInvalidTreeException;
 import javax.imageio.metadata.IIOMetadata;
 import javax.imageio.metadata.IIOMetadataNode;
 import javax.imageio.stream.ImageOutputStream;
-import java.awt.image.BufferedImage;
 
 public class PngImageWriter {
 
@@ -26,7 +25,8 @@ public class PngImageWriter {
         iw.hasNext(); ) {
       ImageWriter writer = iw.next();
       ImageWriteParam writeParam = writer.getDefaultWriteParam();
-      ImageTypeSpecifier typeSpecifier = ImageTypeSpecifier.createFromBufferedImageType(BufferedImage.TYPE_INT_RGB);
+      ImageTypeSpecifier typeSpecifier =
+          ImageTypeSpecifier.createFromBufferedImageType(BufferedImage.TYPE_INT_RGB);
       IIOMetadata metadata = writer.getDefaultImageMetadata(typeSpecifier, writeParam);
       if (metadata.isReadOnly() || !metadata.isStandardMetadataFormatSupported()) {
         continue;

src/main/java/org/limium/picoserve/Server.java

@@ -3,21 +3,21 @@
 
 package org.limium.picoserve;
 
-import java.net.InetSocketAddress;
+import com.sun.net.httpserver.HttpExchange;
+import com.sun.net.httpserver.HttpHandler;
+import com.sun.net.httpserver.HttpServer;
 import java.io.IOException;
-import java.util.List;
+import java.net.InetSocketAddress;
-import java.util.Map;
-import java.util.LinkedList;
-import java.util.concurrent.Executor;
-import java.util.regex.Pattern;
-import java.util.Arrays;
-import java.util.Optional;
-import java.util.stream.Collectors;
 import java.net.URLDecoder;
 import java.nio.charset.StandardCharsets;
-import com.sun.net.httpserver.HttpServer;
+import java.util.Arrays;
-import com.sun.net.httpserver.HttpHandler;
+import java.util.LinkedList;
-import com.sun.net.httpserver.HttpExchange;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.Executor;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 
 public final class Server {
   private final HttpServer server;

src/main/resources/index.html

@@ -20,9 +20,10 @@
     const levelInput = document.getElementById("levelInput").value
     const mediaInput = document.getElementById("mediaInput").value
     const typeInput = document.getElementById("typeInput").value
-    fetch("/v1/captcha", {
+    const sizeInput = document.getElementById("sizeInput").value
+    fetch("/v2/captcha", {
        method: 'POST',
-       body: JSON.stringify({level: levelInput, media: mediaInput, "input_type" : typeInput})
+       body: JSON.stringify({level: levelInput, media: mediaInput, "input_type" : typeInput, "size": sizeInput})
     }).then(async function(resp) {
       const respJson = await resp.json()
       if (resp.ok) {
@@ -30,7 +31,7 @@
         const resultDiv = document.getElementById("result")
         const result = `
           <p>Id: ${id}</p>
-          <p><img src="/v1/media?id=${id}" /> </p>
+          <p><img src="/v2/media?id=${id}" /> </p>
           <input type="text" id="answerInput" />
           <button onClick="submitAnswer('${id}')">Submit</button>
           <div id="answerResult" />
@@ -43,7 +44,7 @@
   }
   async function submitAnswer(id) {
     const ans = document.getElementById("answerInput").value;
-    const resp = await fetch("/v1/answer", {
+    const resp = await fetch("/v2/answer", {
        method: 'POST',
        body: JSON.stringify({id: id, answer: ans})
     })
@@ -70,6 +71,10 @@
       <span>Input Type</span>
       <input type="text" id="typeInput" value="text" />
     </div>
+    <div class="inputGroup">
+      <span>Input Size</span>
+      <input type="text" id="sizeInput" value="350x100" />
+    </div>
     <div class="inputGroup">
       <button onClick="loadCaptcha()">Get New CAPTCHA</button>
     </div>
@@ -79,4 +84,4 @@
   </div>
 </body>
 
-</html>
+</html>

src/main/scala/lc/Main.scala

@@ -25,6 +25,14 @@ object LCFramework {
       playgroundEnabled = config.playgroundEnabled,
       corsHeader = config.corsHeader
     )
+
+    Runtime.getRuntime.addShutdownHook(new Thread {
+      override def run(): Unit = {
+        println("Shutting down gracefully...")
+        backgroundTask.shutdown()
+      }
+    })
+
     server.start()
   }
 }

src/main/scala/lc/background/taskThread.scala

@@ -18,38 +18,73 @@ class BackgroundTask(config: Config, captchaManager: CaptchaManager) {
         val challengeGCPstmt = Statements.tlStmts.get.challengeGCPstmt
         challengeGCPstmt.executeUpdate()
 
-        val imageNumResult = Statements.tlStmts.get.getCountChallengeTable.executeQuery()
+        val allCombinations = allParameterCombinations()
-        val imageNum = if (imageNumResult.next()) {
+        val requiredCountPerCombination = Math.max(1, (config.bufferCount * 1.01) / allCombinations.size).toInt
-          imageNumResult.getInt("total")
-        } else {
-          0
-        }
 
-        val throttle = (config.throttle * 1.1).toInt - imageNum
+        for (param <- allCombinations) {
+          if (!shutdownInProgress) {
+            val countExisting = captchaManager.getCount(param).getOrElse(0)
+            val countRequired = requiredCountPerCombination - countExisting
+            if (countRequired > 0) {
+              val countCreate = Math.min(1.0 + requiredCountPerCombination / 10.0, countRequired).toInt
+              println(s"Creating $countCreate of $countRequired captchas for $param")
 
-        for (i <- 0 until throttle) {
+              for (i <- 0 until countCreate) {
-          captchaManager.generateChallenge(getRandomParam())
+                if (!shutdownInProgress) {
+                  captchaManager.generateChallenge(param)
+                }
+              }
+            }
+          }
         }
       } catch { case exception: Exception => println(exception) }
     }
   }
 
+  private def allParameterCombinations(): List[Parameters] = {
+    (config.captchaConfig).flatMap { captcha =>
+      (captcha.allowedLevels).flatMap { level =>
+        (captcha.allowedMedia).flatMap { media =>
+          (captcha.allowedInputType).flatMap { inputType =>
+            (captcha.allowedSizes).map { size =>
+              Parameters(level, media, inputType, size)
+            }
+          }
+        }
+      }
+    }
+  }
+
   private def getRandomParam(): Parameters = {
     val captcha = pickRandom(config.captchaConfig)
     val level = pickRandom(captcha.allowedLevels)
     val media = pickRandom(captcha.allowedMedia)
     val inputType = pickRandom(captcha.allowedInputType)
+    val size = pickRandom(captcha.allowedSizes)
 
-    Parameters(level, media, inputType, Some(Size(0, 0)))
+    Parameters(level, media, inputType, size)
   }
 
   private def pickRandom[T](list: List[T]): T = {
     list(HelperFunctions.randomNumber(list.size))
   }
 
+  private val ex = new ScheduledThreadPoolExecutor(1)
+
   def beginThread(delay: Int): Unit = {
-    val ex = new ScheduledThreadPoolExecutor(1)
     ex.scheduleWithFixedDelay(task, 1, delay, TimeUnit.SECONDS)
   }
 
+  @volatile var shutdownInProgress = false
+
+  def shutdown(): Unit = {
+    println("  Shutting down background task...")
+    shutdownInProgress = true
+    ex.shutdown()
+    println("    Finished Shutting background task")
+    println("  Shutting down DB...")
+    Statements.tlStmts.get.shutdown.execute()
+    println("    Finished shutting down db")
+  }
+
 }

src/main/scala/lc/captchas/DebugCaptcha.scala

@@ -45,14 +45,14 @@ class DebugCaptcha extends ChallengeProvider {
     matches
   }
 
-  private def simpleText(text: String): Array[Byte] = {
+  private def simpleText(width: Int, height: Int, text: String): Array[Byte] = {
-    val img = new BufferedImage(350, 100, BufferedImage.TYPE_INT_RGB)
+    val img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB)
     val font = new Font("Arial", Font.ROMAN_BASELINE, 56)
     val graphics2D = img.createGraphics()
     val textLayout = new TextLayout(text, font, graphics2D.getFontRenderContext())
     HelperFunctions.setRenderingHints(graphics2D)
     graphics2D.setPaint(Color.WHITE)
-    graphics2D.fillRect(0, 0, 350, 100)
+    graphics2D.fillRect(0, 0, width, height)
     graphics2D.setPaint(Color.BLACK)
     textLayout.draw(graphics2D, 15, 50)
     graphics2D.dispose()
@@ -66,8 +66,11 @@ class DebugCaptcha extends ChallengeProvider {
     baos.toByteArray()
   }
 
-  def returnChallenge(): Challenge = {
+  def returnChallenge(level: String, size: String): Challenge = {
     val secret = HelperFunctions.randomString(6, HelperFunctions.safeAlphabets)
-    new Challenge(simpleText(secret), "image/png", secret.toLowerCase())
+    val size2D = HelperFunctions.parseSize2D(size)
+    val width = size2D(0)
+    val height = size2D(1)
+    new Challenge(simpleText(width, height, secret), "image/png", secret.toLowerCase())
   }
 }

src/main/scala/lc/captchas/FilterChallenge.scala

@@ -10,6 +10,7 @@ import lc.captchas.interfaces.Challenge
 import java.util.{List => JavaList, Map => JavaMap}
 import java.io.ByteArrayOutputStream
 import lc.misc.PngImageWriter
+import lc.misc.HelperFunctions
 
 class FilterChallenge extends ChallengeProvider {
   def getId = "FilterChallenge"
@@ -29,31 +30,38 @@ class FilterChallenge extends ChallengeProvider {
     )
   }
 
-  def returnChallenge(): Challenge = {
+  private val filterTypes = List(new FilterType1, new FilterType2)
-    val filterTypes = List(new FilterType1, new FilterType2)
+
+  def returnChallenge(level: String, size: String): Challenge = {
+    val mediumLevel = level == "medium"
     val r = new scala.util.Random
-    val alphabet = "abcdefghijklmnopqrstuvwxyz"
+    val characters = if (mediumLevel) HelperFunctions.safeAlphaNum else HelperFunctions.safeCharacters
-    val n = 8
+    val n = if (mediumLevel) 5 else 7
-    val secret = LazyList.continually(r.nextInt(alphabet.size)).map(alphabet).take(n).mkString
+    val secret = LazyList.continually(r.nextInt(characters.size)).map(characters).take(n).mkString
-    val canvas = new BufferedImage(225, 50, BufferedImage.TYPE_INT_RGB)
+    val size2D = HelperFunctions.parseSize2D(size)
+    val width = size2D(0)
+    val height = size2D(1)
+    val canvas = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB)
     val g = canvas.createGraphics()
+    val fontHeight = (height * 0.6).toInt
     g.setColor(Color.WHITE)
     g.fillRect(0, 0, canvas.getWidth, canvas.getHeight)
     g.setColor(Color.BLACK)
-    g.setFont(new Font("Serif", Font.PLAIN, 30))
+    val font = new Font("Serif", Font.BOLD, fontHeight)
-    g.drawString(secret, 5, 30)
+    g.setFont(font)
+    val stringWidth = g.getFontMetrics().stringWidth(secret)
+    val scaleX = if (stringWidth > width) width / (stringWidth.toDouble) else 1d
+    val margin = if (stringWidth > width) 0 else (width - stringWidth)
+    val xOffset = (margin * r.nextDouble).toInt
+    g.scale(scaleX, 1d)
+    g.drawString(secret, xOffset, fontHeight)
     g.dispose()
     var image = ImmutableImage.fromAwt(canvas)
-    val s = scala.util.Random.nextInt(2)
+    val s = r.nextInt(2)
-    image = filterTypes(s).applyFilter(image)
+    image = filterTypes(s).applyFilter(image, !mediumLevel)
     val img = image.awt()
     val baos = new ByteArrayOutputStream()
-    try {
+    PngImageWriter.write(baos, img);
-      PngImageWriter.write(baos, img);
-    } catch {
-      case e: Exception =>
-        e.printStackTrace()
-    }
     new Challenge(baos.toByteArray, "image/png", secret)
   }
   def checkAnswer(secret: String, answer: String): Boolean = {
@@ -62,14 +70,15 @@ class FilterChallenge extends ChallengeProvider {
 }
 
 trait FilterType {
-  def applyFilter(image: ImmutableImage): ImmutableImage
+  def applyFilter(image: ImmutableImage, hardLevel: Boolean): ImmutableImage
 }
 
 class FilterType1 extends FilterType {
-  override def applyFilter(image: ImmutableImage): ImmutableImage = {
+  override def applyFilter(image: ImmutableImage, hardLevel: Boolean): ImmutableImage = {
-    val blur = new GaussianBlurFilter(2)
+    val radius = if (hardLevel) 3 else 2
+    val blur = new GaussianBlurFilter(radius)
     val smear = new SmearFilter(com.sksamuel.scrimage.filter.SmearType.Circles, 10, 10, 10, 0, 1)
-    val diffuse = new DiffuseFilter(2)
+    val diffuse = new DiffuseFilter(radius.toFloat)
     blur.apply(image)
     diffuse.apply(image)
     smear.apply(image)
@@ -78,9 +87,10 @@ class FilterType1 extends FilterType {
 }
 
 class FilterType2 extends FilterType {
-  override def applyFilter(image: ImmutableImage): ImmutableImage = {
+  override def applyFilter(image: ImmutableImage, hardLevel: Boolean): ImmutableImage = {
+    val radius = if (hardLevel) 2f else 1f
     val smear = new SmearFilter(com.sksamuel.scrimage.filter.SmearType.Circles, 10, 10, 10, 0, 1)
-    val diffuse = new DiffuseFilter(1)
+    val diffuse = new DiffuseFilter(radius)
     val ripple = new RippleFilter(com.sksamuel.scrimage.filter.RippleType.Noise, 1, 1, 0.005.toFloat, 0.005.toFloat)
     diffuse.apply(image)
     ripple.apply(image)

src/main/scala/lc/captchas/LabelCaptcha.scala

@@ -40,7 +40,7 @@ class LabelCaptcha extends ChallengeProvider {
     )
   }
 
-  def returnChallenge(): Challenge =
+  def returnChallenge(level: String, size: String): Challenge =
     synchronized {
       val r = scala.util.Random.nextInt(knownFiles.length)
       val s = scala.util.Random.nextInt(unknownFiles.length)

src/main/scala/lc/captchas/RainDropsCaptcha.scala

@@ -11,6 +11,7 @@ import lc.captchas.interfaces.ChallengeProvider
 import lc.captchas.interfaces.Challenge
 import lc.misc.GifSequenceWriter
 import java.util.{List => JavaList, Map => JavaMap}
+import lc.misc.HelperFunctions
 
 class Drop {
   var x = 0
@@ -24,8 +25,6 @@ class Drop {
 }
 
 class RainDropsCP extends ChallengeProvider {
-  private val alphabet = "abcdefghijklmnopqrstuvwxyz"
-  private val n = 6
   private val bgColor = new Color(200, 200, 200)
   private val textColor = new Color(208, 208, 218)
   private val textHighlightColor = new Color(100, 100, 125)
@@ -56,11 +55,13 @@ class RainDropsCP extends ChallengeProvider {
     })
   }
 
-  def returnChallenge(): Challenge = {
+  def returnChallenge(level: String, size: String): Challenge = {
     val r = new scala.util.Random
-    val secret = LazyList.continually(r.nextInt(alphabet.size)).map(alphabet).take(n).mkString
+    val n = if (level == "easy") 4 else 6
-    val width = 450
+    val secret = HelperFunctions.randomString(n, HelperFunctions.safeAlphaNum)
-    val height = 100
+    val size2D = HelperFunctions.parseSize2D(size)
+    val width = size2D(0)
+    val height = size2D(1)
     val imgType = BufferedImage.TYPE_INT_RGB
     val xOffset = 2 + r.nextInt(3)
     val xBias = (height / 10) - 2
@@ -80,7 +81,8 @@ class RainDropsCP extends ChallengeProvider {
       xOffset
     )
 
-    val baseFont = new Font(Font.MONOSPACED, Font.BOLD, 80)
+    val fontHeight = (height * 0.5f).toInt
+    val baseFont = new Font(Font.MONOSPACED, Font.BOLD, fontHeight)
     val attributes = new java.util.HashMap[TextAttribute, Object]()
     attributes.put(TextAttribute.TRACKING, Double.box(0.2))
     attributes.put(TextAttribute.WEIGHT, TextAttribute.WEIGHT_EXTRABOLD)
@@ -117,17 +119,22 @@ class RainDropsCP extends ChallengeProvider {
         }
       }
 
-      // center the text
       g.setFont(spacedFont)
-      val textWidth = g.getFontMetrics().charsWidth(secret.toCharArray, 0, secret.toCharArray.length)
+      val textWidth = g.getFontMetrics().stringWidth(secret)
-      val textX = (width - textWidth) / 2
+      val scaleX = if (textWidth > width) width / textWidth.toDouble else 1.0d
+      g.scale(scaleX, 1)
 
-      // paint the top outline
+      // center the text
+      val textX = if (textWidth > width) 0 else ((width - textWidth) / 2)
+
+      // this will be overlapped by the following text to show the top outline because of the offset
+      val yOffset = (fontHeight * 0.01).ceil.toInt
       g.setColor(textHighlightColor)
-      g.drawString(secret, textX, 69)
+      g.drawString(secret, textX, (fontHeight * 1.1).toInt - yOffset)
+
       // paint the text
       g.setColor(textColor)
-      g.drawString(secret, textX, 70)
+      g.drawString(secret, textX, (fontHeight * 1.1).toInt)
 
       g.dispose()
       writer.writeToSequence(canvas)

src/main/scala/lc/core/captchaFields.scala

@@ -10,7 +10,7 @@ object ParametersEnum extends Enumeration {
   val ALLOWEDLEVELS: Value = Value("allowedLevels")
   val ALLOWEDMEDIA: Value = Value("allowedMedia")
   val ALLOWEDINPUTTYPE: Value = Value("allowedInputType")
-
+  val ALLOWEDSIZES: Value = Value("allowedSizes")
 }
 
 object AttributesEnum extends Enumeration {
@@ -21,12 +21,12 @@ object AttributesEnum extends Enumeration {
   val PORT: Value = Value("port")
   val ADDRESS: Value = Value("address")
   val CAPTCHA_EXPIRY_TIME_LIMIT: Value = Value("captchaExpiryTimeLimit")
-  val THROTTLE: Value = Value("throttle")
+  val BUFFER_COUNT: Value = Value("bufferCount")
   val THREAD_DELAY: Value = Value("threadDelay")
   val PLAYGROUND_ENABLED: Value = Value("playgroundEnabled")
   val CORS_HEADER: Value = Value("corsHeader")
   val CONFIG: Value = Value("config")
-  val MAX_ATTEMPTS: Value = Value("maxAttempts")
+  val MAX_ATTEMPTS_RATIO: Value = Value("maxAttemptsRatio")
 }
 
 object ResultEnum extends Enumeration {

src/main/scala/lc/core/captchaManager.scala

@@ -34,17 +34,19 @@ class CaptchaManager(config: Config, captchaProviders: CaptchaProviders) {
   }
 
   def generateChallenge(param: Parameters): Option[Int] = {
-    val provider = captchaProviders.getProvider(param)
+    try {
-    provider match {
+      captchaProviders.getProvider(param).flatMap { provider =>
-      case Some(value) => {
+        val providerId = provider.getId()
-        val providerId = value.getId()
+        val challenge = provider.returnChallenge(param.level, param.size)
-        val challenge = value.returnChallenge()
         val blob = new ByteArrayInputStream(challenge.content)
-        val token = insertCaptcha(value, challenge, providerId, param, blob)
+        val token = insertCaptcha(provider, challenge, providerId, param, blob)
         // println("Added new challenge: " + token.toString)
         token.map(_.toInt)
       }
-      case None => None
+    } catch {
+      case e: Exception =>
+        e.printStackTrace()
+        None
     }
   }
 
@@ -62,7 +64,8 @@ class CaptchaManager(config: Config, captchaProviders: CaptchaProviders) {
     insertPstmt.setString(4, challenge.contentType)
     insertPstmt.setString(5, param.level)
     insertPstmt.setString(6, param.input_type)
-    insertPstmt.setBlob(7, blob)
+    insertPstmt.setString(7, param.size)
+    insertPstmt.setBlob(8, blob)
     insertPstmt.executeUpdate()
     val rs: ResultSet = insertPstmt.getGeneratedKeys()
     if (rs.next()) {
@@ -105,19 +108,40 @@ class CaptchaManager(config: Config, captchaProviders: CaptchaProviders) {
     }
   }
 
-  private def getToken(param: Parameters): Option[Int] = {
+  def getCount(param: Parameters): Option[Int] = {
-    val tokenPstmt = Statements.tlStmts.get.tokenPstmt
+    val countPstmt = Statements.tlStmts.get.countForParameterPstmt
-    tokenPstmt.setString(1, param.level)
+    countPstmt.setString(1, param.level)
-    tokenPstmt.setString(2, param.media)
+    countPstmt.setString(2, param.media)
-    tokenPstmt.setString(3, param.input_type)
+    countPstmt.setString(3, param.input_type)
-    val rs = tokenPstmt.executeQuery()
+    countPstmt.setString(4, param.size.toString())
+    val rs = countPstmt.executeQuery()
     if (rs.next()) {
-      Some(rs.getInt("token"))
+      Some(rs.getInt("count"))
     } else {
       None
     }
   }
 
+  private def getToken(param: Parameters): Option[Int] = {
+    val count = getCount(param).getOrElse(0)
+    if (count == 0) {
+      None
+    } else {
+      val tokenPstmt = Statements.tlStmts.get.tokenPstmt
+      tokenPstmt.setString(1, param.level)
+      tokenPstmt.setString(2, param.media)
+      tokenPstmt.setString(3, param.input_type)
+      tokenPstmt.setString(4, param.size)
+      tokenPstmt.setInt(5, count)
+      val rs = tokenPstmt.executeQuery()
+      if (rs.next()) {
+        Some(rs.getInt("token"))
+      } else {
+        None
+      }
+    }
+  }
+
   private def updateAttempted(token: Int): Unit = {
     val updateAttemptedPstmt = Statements.tlStmts.get.updateAttemptedPstmt
     updateAttemptedPstmt.setInt(1, token)

src/main/scala/lc/core/captchaProviders.scala

@@ -19,7 +19,7 @@ class CaptchaProviders(config: Config) {
 
   def generateChallengeSamples(): Map[String, Challenge] = {
     providers.map { case (key, provider) =>
-      (key, provider.returnChallenge())
+      (key, provider.returnChallenge("easy", "350x100"))
     }
   }
 
@@ -35,6 +35,7 @@ class CaptchaProviders(config: Config) {
       if configValue.allowedLevels.contains(param.level)
       if configValue.allowedMedia.contains(param.media)
       if configValue.allowedInputType.contains(param.input_type)
+      if configValue.allowedSizes.contains(param.size)
     } yield (configValue.name, configValue.config)
 
     val providerFilter = for {

src/main/scala/lc/core/config.scala

@@ -45,13 +45,13 @@ class Config(configFilePath: String) {
 
   val port: Int = configFields.portInt.getOrElse(8888)
   val address: String = configFields.address.getOrElse("0.0.0.0")
-  val throttle: Int = configFields.throttleInt.getOrElse(1000)
+  val bufferCount: Int = configFields.bufferCountInt.getOrElse(1000)
   val seed: Int = configFields.seedInt.getOrElse(375264328)
   val captchaExpiryTimeLimit: Int = configFields.captchaExpiryTimeLimitInt.getOrElse(5)
   val threadDelay: Int = configFields.threadDelayInt.getOrElse(2)
   val playgroundEnabled: Boolean = configFields.playgroundEnabledBool.getOrElse(true)
   val corsHeader: String = configFields.corsHeader.getOrElse("")
-  val maxAttempts: Int = configFields.maxAttemptsInt.getOrElse(10)
+  val maxAttempts: Int = Math.max(1, (configFields.maxAttemptsRatioFloat.getOrElse(0.01f) * bufferCount).toInt)
 
   private val captchaConfigJson = (configJson \ "captchas")
   val captchaConfigTransform: JValue = captchaConfigJson transformField { case JField("config", JObject(config)) =>
@@ -70,17 +70,18 @@ class Config(configFilePath: String) {
         (AttributesEnum.PORT.toString -> 8888) ~
         (AttributesEnum.ADDRESS.toString -> "0.0.0.0") ~
         (AttributesEnum.CAPTCHA_EXPIRY_TIME_LIMIT.toString -> 5) ~
-        (AttributesEnum.THROTTLE.toString -> 1000) ~
+        (AttributesEnum.BUFFER_COUNT.toString -> 1000) ~
         (AttributesEnum.THREAD_DELAY.toString -> 2) ~
         (AttributesEnum.PLAYGROUND_ENABLED.toString -> true) ~
         (AttributesEnum.CORS_HEADER.toString -> "") ~
-        (AttributesEnum.MAX_ATTEMPTS.toString -> 10) ~
+        (AttributesEnum.MAX_ATTEMPTS_RATIO.toString -> 0.01f) ~
         ("captchas" -> List(
           (
             (AttributesEnum.NAME.toString -> "FilterChallenge") ~
               (ParametersEnum.ALLOWEDLEVELS.toString -> List("medium", "hard")) ~
               (ParametersEnum.ALLOWEDMEDIA.toString -> List("image/png")) ~
               (ParametersEnum.ALLOWEDINPUTTYPE.toString -> List("text")) ~
+              (ParametersEnum.ALLOWEDSIZES.toString -> List("350x100")) ~
               (AttributesEnum.CONFIG.toString -> JObject())
           ),
           (
@@ -88,6 +89,7 @@ class Config(configFilePath: String) {
               (ParametersEnum.ALLOWEDLEVELS.toString -> List("hard")) ~
               (ParametersEnum.ALLOWEDMEDIA.toString -> List("image/gif")) ~
               (ParametersEnum.ALLOWEDINPUTTYPE.toString -> List("text")) ~
+              (ParametersEnum.ALLOWEDSIZES.toString -> List("350x100")) ~
               (AttributesEnum.CONFIG.toString -> JObject())
           ),
           (
@@ -95,6 +97,7 @@ class Config(configFilePath: String) {
               (ParametersEnum.ALLOWEDLEVELS.toString -> List("easy")) ~
               (ParametersEnum.ALLOWEDMEDIA.toString -> List("image/png")) ~
               (ParametersEnum.ALLOWEDINPUTTYPE.toString -> List("text")) ~
+              (ParametersEnum.ALLOWEDSIZES.toString -> List("350x100")) ~
               (AttributesEnum.CONFIG.toString -> JObject())
           ),
           (
@@ -102,6 +105,7 @@ class Config(configFilePath: String) {
               (ParametersEnum.ALLOWEDLEVELS.toString -> List("easy", "medium")) ~
               (ParametersEnum.ALLOWEDMEDIA.toString -> List("image/gif")) ~
               (ParametersEnum.ALLOWEDINPUTTYPE.toString -> List("text")) ~
+              (ParametersEnum.ALLOWEDSIZES.toString -> List("350x100")) ~
               (AttributesEnum.CONFIG.toString -> JObject())
           )
         ))

src/main/scala/lc/core/models.scala

@@ -5,7 +5,7 @@ import lc.core.Config.formats
 
 trait ByteConvert { def toBytes(): Array[Byte] }
 case class Size(height: Int, width: Int)
-case class Parameters(level: String, media: String, input_type: String, size: Option[Size])
+case class Parameters(level: String, media: String, input_type: String, size: String)
 case class Id(id: String) extends ByteConvert { def toBytes(): Array[Byte] = { write(this).getBytes } }
 case class Image(image: Array[Byte]) extends ByteConvert { def toBytes(): Array[Byte] = { image } }
 case class Answer(answer: String, id: String)
@@ -16,28 +16,32 @@ case class CaptchaConfig(
     allowedLevels: List[String],
     allowedMedia: List[String],
     allowedInputType: List[String],
+    allowedSizes: List[String],
     config: String
 )
 case class ConfigField(
     port: Option[Integer],
     address: Option[String],
-    throttle: Option[Integer],
+    bufferCount: Option[Integer],
     seed: Option[Integer],
     captchaExpiryTimeLimit: Option[Integer],
     threadDelay: Option[Integer],
     playgroundEnabled: Option[java.lang.Boolean],
     corsHeader: Option[String],
-    maxAttempts: Option[Integer]
+    maxAttemptsRatio: Option[java.lang.Float]
 ) {
   lazy val portInt: Option[Int] = mapInt(port)
-  lazy val throttleInt: Option[Int] = mapInt(throttle)
+  lazy val bufferCountInt: Option[Int] = mapInt(bufferCount)
   lazy val seedInt: Option[Int] = mapInt(seed)
   lazy val captchaExpiryTimeLimitInt: Option[Int] = mapInt(captchaExpiryTimeLimit)
   lazy val threadDelayInt: Option[Int] = mapInt(threadDelay)
-  lazy val maxAttemptsInt: Option[Int] = mapInt(maxAttempts)
+  lazy val maxAttemptsRatioFloat: Option[Float] = mapFloat(maxAttemptsRatio)
-  lazy val playgroundEnabledBool: Option[Boolean] = playgroundEnabled.map(_ || true)
+  lazy val playgroundEnabledBool: Option[Boolean] = playgroundEnabled.map(_ || false)
 
   private def mapInt(x: Option[Integer]): Option[Int] = {
     x.map(_ + 0)
   }
+  private def mapFloat(x: Option[java.lang.Float]): Option[Float] = {
+    x.map(_ + 0.0f)
+  }
 }

src/main/scala/lc/database/DB.scala

@@ -3,7 +3,8 @@ package lc.database
 import java.sql.{Connection, DriverManager, Statement}
 
 class DBConn() {
-  val con: Connection = DriverManager.getConnection("jdbc:h2:./data/H2/captcha2", "sa", "")
+  val con: Connection =
+    DriverManager.getConnection("jdbc:h2:./data/H2/captcha3;MAX_COMPACT_TIME=8000;DB_CLOSE_ON_EXIT=FALSE", "sa", "")
 
   def getStatement(): Statement = {
     con.createStatement()

src/main/scala/lc/database/statements.scala

@@ -17,6 +17,7 @@ class Statements(dbConn: DBConn, maxAttempts: Int) {
       "contentType varchar, " +
       "contentLevel varchar, " +
       "contentInput varchar, " +
+      "size varchar, " +
       "image blob, " +
       "attempted int default 0, " +
       "PRIMARY KEY(token));" +
@@ -37,8 +38,8 @@ class Statements(dbConn: DBConn, maxAttempts: Int) {
 
   val insertPstmt: PreparedStatement = dbConn.con.prepareStatement(
     "INSERT INTO " +
-      "challenge(id, secret, provider, contentType, contentLevel, contentInput, image) " +
+      "challenge(id, secret, provider, contentType, contentLevel, contentInput, size, image) " +
-      "VALUES (?, ?, ?, ?, ?, ?, ?)",
+      "VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
     Statement.RETURN_GENERATED_KEYS
   )
 
@@ -70,6 +71,18 @@ class Statements(dbConn: DBConn, maxAttempts: Int) {
       "WHERE token = ?;"
   )
 
+  val countForParameterPstmt: PreparedStatement = dbConn.con.prepareStatement(
+    s"""
+      SELECT count(*) as count
+        FROM challenge
+        WHERE attempted < $maxAttempts AND
+        contentLevel = ? AND
+        contentType = ? AND
+        contentInput = ? AND
+        size = ?
+        """
+  )
+
   val tokenPstmt: PreparedStatement = dbConn.con.prepareStatement(
     s"""
       SELECT token, attempted
@@ -77,8 +90,11 @@ class Statements(dbConn: DBConn, maxAttempts: Int) {
         WHERE attempted < $maxAttempts AND
         contentLevel = ? AND
         contentType = ? AND
-        contentInput = ?
+        contentInput = ? AND
-        ORDER BY attempted ASC LIMIT 1"""
+        size = ?
+        LIMIT 1
+        OFFSET FLOOR(RAND()*?)
+         """
   )
 
   val deleteAnswerPstmt: PreparedStatement = dbConn.con.prepareStatement(
@@ -107,6 +123,14 @@ class Statements(dbConn: DBConn, maxAttempts: Int) {
     "SELECT * FROM mapId"
   )
 
+  val shutdown: PreparedStatement = dbConn.con.prepareStatement(
+    "SHUTDOWN"
+  )
+
+  val shutdownCompact: PreparedStatement = dbConn.con.prepareStatement(
+    "SHUTDOWN COMPACT"
+  )
+
 }
 
 object Statements {

src/main/scala/lc/server/Server.scala

@@ -13,7 +13,13 @@ import java.net.InetSocketAddress
 import java.util
 import scala.jdk.CollectionConverters._
 
-class Server(address: String, port: Int, captchaManager: CaptchaManager, playgroundEnabled: Boolean, corsHeader: String) {
+class Server(
+    address: String,
+    port: Int,
+    captchaManager: CaptchaManager,
+    playgroundEnabled: Boolean,
+    corsHeader: String
+) {
   var headerMap: util.Map[String, util.List[String]] = _
   if (corsHeader.nonEmpty) {
     headerMap = Map("Access-Control-Allow-Origin" -> List(corsHeader).asJava).asJava
@@ -23,7 +29,7 @@ class Server(address: String, port: Int, captchaManager: CaptchaManager, playgro
     .address(new InetSocketAddress(address, port))
     .backlog(32)
     .POST(
-      "/v1/captcha",
+      "/v2/captcha",
       (request) => {
         val json = parse(request.getBodyString())
         val param = json.extract[Parameters]
@@ -32,7 +38,7 @@ class Server(address: String, port: Int, captchaManager: CaptchaManager, playgro
       }
     )
     .GET(
-      "/v1/media",
+      "/v2/media",
       (request) => {
         val params = request.getQueryParams()
         val result = if (params.containsKey("id")) {
@@ -46,7 +52,7 @@ class Server(address: String, port: Int, captchaManager: CaptchaManager, playgro
       }
     )
     .POST(
-      "/v1/answer",
+      "/v2/answer",
       (request) => {
         val json = parse(request.getBodyString())
         val answer = json.extract[Answer]
@@ -63,6 +69,20 @@ class Server(address: String, port: Int, captchaManager: CaptchaManager, playgro
         new StringResponse(200, str)
       }
     )
+    serverBuilder.GET(
+      "/",
+      (_) => {
+        val str = """
+        <html>
+          <h2>Welcome to LibreCaptcha server</h2>
+          <h3><a href="/demo/index.html">Link to Demo</a></h3>
+          <h3>API is served at <b>/v2/</b></h3>
+        </html>
+        """
+        new StringResponse(200, str)
+      }
+    )
+    println("Playground enabled on /demo/index.html")
   }
 
   val server: picoserve.Server = serverBuilder.build()

tests/debug-config.json

@@ -3,16 +3,17 @@
   "port" : 8888,
   "address" : "0.0.0.0",
   "captchaExpiryTimeLimit" : 5,
-  "throttle" : 10,
+  "bufferCount" : 10,
   "threadDelay" : 2,
   "playgroundEnabled" : false,
   "corsHeader" : "*",
-  "maxAttempts" : 20,
+  "maxAttemptsRatio" : 0.01,
   "captchas" : [ {
     "name" : "DebugCaptcha",
     "allowedLevels" : [ "debug" ],
     "allowedMedia" : [ "image/png" ],
     "allowedInputType" : [ "text" ],
+    "allowedSizes" : [ "350x100" ],
     "config" : { }
   }]
 }

tests/locustfile-functional.py

@@ -22,9 +22,9 @@ class QuickStartUser(SequentialTaskSet):
 
     @task
     def captcha(self):
-        captcha_params = {"level":"debug","media":"image/png","input_type":"text"}
+        captcha_params = {"level":"debug","media":"image/png","input_type":"text", "size":"350x100"}
 
-        with self.client.post(path="/v1/captcha", json=captcha_params, name="/captcha", catch_response = True) as resp:
+        with self.client.post(path="/v2/captcha", json=captcha_params, name="/captcha", catch_response = True) as resp:
           if resp.status_code != 200:
             resp.failure("Status was not 200: " + resp.text)
           captchaJson = resp.json()
@@ -32,7 +32,7 @@ class QuickStartUser(SequentialTaskSet):
           if not uuid:
             resp.failure("uuid not returned on /captcha endpoint: " + resp.text)
 
-        with self.client.get(path="/v1/media?id=%s" % uuid, name="/media", stream=True, catch_response = True) as resp:
+        with self.client.get(path="/v2/media?id=%s" % uuid, name="/media", stream=True, catch_response = True) as resp:
           if resp.status_code != 200:
             resp.failure("Status was not 200: " + resp.text)
 
@@ -41,7 +41,7 @@ class QuickStartUser(SequentialTaskSet):
         ocrAnswer = self.solve(uuid, media)
 
         answerBody = {"answer": ocrAnswer,"id": uuid}
-        with self.client.post(path='/v1/answer', json=answerBody, name="/answer", catch_response=True) as resp:
+        with self.client.post(path='/v2/answer', json=answerBody, name="/answer", catch_response=True) as resp:
           if resp.status_code != 200:
               resp.failure("Status was not 200: " + resp.text)
           else:

tests/locustfile.py

@@ -24,9 +24,9 @@ class QuickStartUser(SequentialTaskSet):
     @task
     def captcha(self):
         # TODO: Iterate over parameters for a more comprehensive test
-        captcha_params = {"level":"easy","media":"image/png","input_type":"text"}
+        captcha_params = {"level":"easy","media":"image/png","input_type":"text", "size":"350x100"}
 
-        resp = self.client.post(path="/v1/captcha", json=captcha_params, name="/captcha")
+        resp = self.client.post(path="/v2/captcha", json=captcha_params, name="/captcha")
         if resp.status_code != 200:
             print("\nError on /captcha endpoint: ")
             print(resp)
@@ -36,14 +36,14 @@ class QuickStartUser(SequentialTaskSet):
         uuid = json.loads(resp.text).get("id")
         answerBody = {"answer": "qwer123","id": uuid}
 
-        resp = self.client.get(path="/v1/media?id=%s" % uuid, name="/media")
+        resp = self.client.get(path="/v2/media?id=%s" % uuid, name="/media")
         if resp.status_code != 200:
             print("\nError on /media endpoint: ")
             print(resp)
             print(resp.text)
             print("----------------END.MEDIA-------------------\n\n")
 
-        resp = self.client.post(path='/v1/answer', json=answerBody, name="/answer")
+        resp = self.client.post(path='/v2/answer', json=answerBody, name="/answer")
         if resp.status_code != 200:
             print("\nError on /answer endpoint: ")
             print(resp)

tests/run.sh

@@ -4,7 +4,7 @@ python3 -m venv testEnv
 source ./testEnv/bin/activate
 pip install locust
 mkdir -p data/
-java -jar target/scala-3.1.1/LibreCaptcha.jar &
+java -jar target/scala-3.6.2/LibreCaptcha.jar &
 JAVA_PID=$!
 sleep 4
 
@@ -22,7 +22,7 @@ echo Run functional test
 cp data/config.json data/config.json.bak
 cp tests/debug-config.json data/config.json
 
-java -jar target/scala-3.1.1/LibreCaptcha.jar &
+java -jar target/scala-3.6.2/LibreCaptcha.jar &
 JAVA_PID=$!
 sleep 4