Merge pull request #64 from stalomeow/zfw-captcha

feat: zfw captcha

Author: BenderBlog

.flutter

@@ -4,33 +4,149 @@
 // A captcha input dialog.
 
 import 'dart:typed_data';
+import 'dart:math';
 
 import 'package:flutter/material.dart';
 import 'package:flutter_i18n/flutter_i18n.dart';
 import 'package:watermeter/page/public_widget/toast.dart';
 import 'package:image/image.dart' as img;
 import 'package:tflite_flutter/tflite_flutter.dart';
 
+enum DigitCaptchaType { payment, zfw }
+
 class DigitCaptchaClientProvider {
-  static const String _interpreterAssetName = 'assets/captcha-solver.tflite';
+  // Ref: https://github.com/stalomeow/captcha-solver
+
+  static String _getInterpreterAssetName(DigitCaptchaType type) {
+    return 'assets/captcha-solver-${type.name.toLowerCase()}.tflite';
+  }
+
+  static double _lerp(double a, double b, double t) {
+    return a + (b - a) * t;
+  }
+
+  static num _sampleMin(img.Image image, List<int> bb, double u, double v) {
+    int x = _lerp(bb[0] * 1.0, bb[2] - 1.0, u).floor();
+    int y = _lerp(bb[1] * 1.0, bb[3] - 1.0, v).floor();
+    num px = min(image.getPixelClamped(x, y + 0).r,
+        image.getPixelClamped(x + 1, y + 0).r);
+    num py = min(image.getPixelClamped(x, y + 1).r,
+        image.getPixelClamped(x + 1, y + 1).r);
+    return min(px, py);
+  }
+
+  static List<int> _getbbox(img.Image image) {
+    int left = image.width;
+    int upper = image.height;
+    int right = 0; // Exclusive
+    int lower = 0; // Exclusive
 
-  static Future<String> infer(List<int> imageData) async {
-    // Ref: https://github.com/stalomeow/captcha-solver
+    for (int x = 0; x < image.width; x++) {
+      for (int y = 0; y < image.height; y++) {
+        num p = image.getPixel(x, y).r;
 
+        // Binarization
+        if (p < 0.98) {
+          continue;
+        }
+
+        left = min(left, x);
+        upper = min(upper, y);
+        right = max(right, x + 1);
+        lower = max(lower, y + 1);
+      }
+    }
+
+    // Expand the bounding box by 1 pixel
+    left = max(0, left - 1);
+    upper = max(0, upper - 1);
+    right = min(image.width, right + 1);
+    lower = min(image.height, lower + 1);
+
+    return [left, upper, right, lower];
+  }
+
+  static img.Image? _getImage(DigitCaptchaType type, List<int> imageData) {
     img.Image image = img.decodeImage(Uint8List.fromList(imageData))!;
     image = img.grayscale(image);
     image = image.convert(
         format: img.Format.float32, numChannels: 1); // 0-256 to 0-1
 
+    if (type == DigitCaptchaType.zfw) {
+      // Invert the image
+      for (int x = 0; x < image.width; x++) {
+        for (int y = 0; y < image.height; y++) {
+          image.setPixelR(x, y, 1.0 - image.getPixel(x, y).r);
+        }
+      }
+
+      List<int> bb = _getbbox(image);
+
+      // The numbers are too close
+      if (bb[2] - bb[0] < 44) {
+        return null;
+      }
+
+      // Align with the size of payment captcha
+      img.Image result = new img.Image(
+          width: 200, height: 80, format: img.Format.float32, numChannels: 1);
+      for (int x = 0; x < result.width; x++) {
+        for (int y = 0; y < result.height; y++) {
+          double u = x * 1.0 / result.width;
+          double v = y * 1.0 / result.height;
+          num r = _sampleMin(image, bb, u, v);
+          result.setPixelR(x, y, r);
+        }
+      }
+      image = result;
+    }
+
+    return image;
+  }
+
+  static int _argmax(List<double> list) {
+    int result = 0;
+    for (int i = 1; i < list.length; i++) {
+      if (list[i] > list[result]) {
+        result = i;
+      }
+    }
+    return result;
+  }
+
+  static int _getClassCount(DigitCaptchaType type) {
+    if (type == DigitCaptchaType.payment) {
+      return 9; // The payment captcha only contains number 1-9
+    }
+    return 10;
+  }
+
+  static int _getClassLabel(DigitCaptchaType type, int klass) {
+    if (type == DigitCaptchaType.payment) {
+      return klass + 1; // The payment captcha only contains number 1-9
+    }
+    return klass;
+  }
+
+  static Future<String?> infer(
+      DigitCaptchaType type, List<int> imageData) async {
+    img.Image? image = _getImage(type, imageData);
+
+    if (image == null) {
+      return null;
+    }
+
     int dim2 = image.height;
     int dim3 = image.width ~/ 4;
+    int classCount = _getClassCount(type);
 
     var input = List.filled(dim2 * dim3, 0.0)
         .reshape<double>([1, dim2, dim3, 1]) as List<List<List<List<double>>>>;
-    var output =
-        List.filled(9, 0.0).reshape<double>([1, 9]) as List<List<double>>;
+    var output = List.filled(classCount, 0.0).reshape<double>([1, classCount])
+        as List<List<double>>;
 
-    final interpreter = await Interpreter.fromAsset(_interpreterAssetName);
+    final interpreter =
+        await Interpreter.fromAsset(_getInterpreterAssetName(type));
     List<int> nums = [];
 
     // Four numbers
@@ -42,21 +158,11 @@ class DigitCaptchaClientProvider {
       }
 
       interpreter.run(input, output);
-      nums.add(_argmax(output[0]) + 1);
+      nums.add(_getClassLabel(type, _argmax(output[0])));
     }
 
     return nums.join('');
   }
-
-  static int _argmax(List<double> list) {
-    int result = 0;
-    for (int i = 1; i < list.length; i++) {
-      if (list[i] > list[result]) {
-        result = i;
-      }
-    }
-    return result;
-  }
 }
 
 class CaptchaInputDialog extends StatelessWidget {

assets/captcha-solver-payment.tflite

@@ -97,21 +97,36 @@ class SchoolnetSession extends NetworkSession {
     if (csrf.isEmpty || key.isEmpty) throw NotInitalizedException;
 
     String lastErrorMessage = "";
-    for (int retry = 5; retry > 0; retry--) {
+    for (int retry = 10; retry > 0; retry--) {
+      // Refresh captcha
+      await _dio
+          .get('https://zfw.xidian.edu.cn/site/captcha', queryParameters: {
+        'refresh': 1,
+        '_': DateTime.now().millisecondsSinceEpoch,
+      });
       // Get verifycode
-      String imgPath = parse(page.data.toString())
-              .getElementById("loginform-verifycode-image")
-              ?.attributes["src"] ??
-          "";
       var picture = await _dio
-          .get(imgPath, options: Options(responseType: ResponseType.bytes))
+          .get(
+            "https://zfw.xidian.edu.cn/site/captcha",
+            options: Options(responseType: ResponseType.bytes),
+          )
           .then((data) => data.data);
 
-      String verifycode = retry == 1
+      String? verifycode = retry == 1
           ? captchaFunction != null
               ? await captchaFunction(picture)
               : throw CaptchaFailedException() // The last try
-          : await DigitCaptchaClientProvider.infer(picture);
+          : await DigitCaptchaClientProvider.infer(
+              DigitCaptchaType.zfw, picture);
+
+      if (verifycode == null) {
+        log.info(
+            '[SchoolnetSession] Captcha is impossible to be inferred.');
+        retry++; // Do not count this try
+        continue;
+      }
+
+      log.info("[SchoolnetSession] verifycode is $verifycode");
 
       // Encrypt the password
       var rsaKey = RSAKeyParser().parse(key);
@@ -140,9 +155,16 @@ class SchoolnetSession extends NetworkSession {
       if (!jsonDecode(page.data)["success"]) {
         lastErrorMessage = jsonDecode(page.data)["message"] ?? "未知错误";
         log.info(
-          "[SchoolNetSession] Attempt ${5 - retry} "
+          "[SchoolNetSession] Attempt ${11 - retry} "
           "failed: $lastErrorMessage",
         );
+
+        // No need to retry if the error is about username or password
+        if (lastErrorMessage.contains("用户名") ||
+            lastErrorMessage.contains("密码")) {
+          break;
+        }
+
         continue;
       }
       // Login post

assets/captcha-solver-zfw.tflite

@@ -369,11 +369,19 @@ xh5zeF9usFgtdabgACU/cQIDAQAB
           )
           .then((data) => data.data);
 
-      String checkCode = retry == 1
+      String? checkCode = retry == 1
           ? captchaFunction != null
               ? await captchaFunction(picture)
               : throw CaptchaFailedException() // The last try
-          : await DigitCaptchaClientProvider.infer(picture);
+          : await DigitCaptchaClientProvider.infer(
+              DigitCaptchaType.payment, picture);
+
+      if (checkCode == null) {
+        log.info(
+            '[PaymentSession][getOwe] Captcha is impossible to be inferred.');
+        retry++; // Do not count this try
+        continue;
+      }
 
       log.info("[PaymentSession][getOwe] checkcode is $checkCode");