ContentsViewer · ContentsViewer · Sep 2, 2026 · Sep 2, 2026 · Sep 4, 2026 · Sep 4, 2026
diff --git a/Client/AccessGate/access-gate.js b/Client/AccessGate/access-gate.js
@@ -0,0 +1,97 @@
+;(function () {
+    "use strict"
+
+    /**
+     * AccessGate client: solves the proof-of-work challenge issued by
+     * Service/access-gate-seed-service.php and stores the resulting token
+     * in the `cv_gate` cookie (see Module/AccessGate.php for the protocol).
+     *
+     * Used by Client/AccessGate/challenge.html (full-page challenge) and by
+     * XHR/fetch callers (e.g. ContentsViewer feedback) via ensureToken().
+     */
+    var AG = {}
+
+    AG.COOKIE_NAME = "cv_gate"
+
+    AG.isSupported = function () {
+        return !!(window.crypto && window.crypto.subtle && window.TextEncoder)
+    }
+
+    AG.hasToken = function () {
+        return document.cookie.indexOf(AG.COOKIE_NAME + "=") !== -1
+    }
+
+    /**
+     * Finds a nonce such that sha256(seed + "." + nonce) has `bits` leading
+     * zero bits. Resolves with the nonce (number). onProgress(attempts) is
+     * called periodically.
+     */
+    AG.solve = async function (seed, bits, onProgress) {
+        var encoder = new TextEncoder()
+        var fullBytes = bits >> 3
+        var restBits = bits & 7
+        for (var nonce = 0; ; nonce++) {
+            var data = encoder.encode(seed + "." + nonce)
+            var digest = new Uint8Array(await crypto.subtle.digest("SHA-256", data))
+            var ok = true
+            for (var i = 0; i < fullBytes; i++) {
+                if (digest[i] !== 0) { ok = false; break }
+            }
+            if (ok && restBits > 0 && (digest[fullBytes] >> (8 - restBits)) !== 0) {
+                ok = false
+            }
+            if (ok) return nonce
+            if (onProgress && (nonce & 255) === 0) onProgress(nonce)
+        }
+    }
+
+    AG.setCookie = function (token) {
+        // seed = v1.{expiry}.{bits}.{mac}; cookie lifetime follows the token expiry.
+        var expiry = parseInt(token.split(".")[1], 10)
+        var maxAge = Math.max(60, expiry - Math.floor(Date.now() / 1000))
+        document.cookie = AG.COOKIE_NAME + "=" + token +
+            "; path=/; max-age=" + maxAge + "; SameSite=Lax" +
+            (location.protocol === "https:" ? "; Secure" : "")
+        return AG.hasToken()
+    }
+
+    /**
+     * Fetches a seed from `serviceUri` (e.g. CV.vars.serviceUri), solves the
+     * proof-of-work and stores the cookie.
+     * Resolves with {ok: true} or {ok: false, reason: string}.
+     */
+    AG.acquireToken = async function (serviceUri, onProgress) {
+        if (!AG.isSupported()) return { ok: false, reason: "unsupported" }
+        if (!navigator.cookieEnabled) return { ok: false, reason: "cookie-disabled" }
+        var response
+        try {
+            response = await fetch(serviceUri + "/access-gate-seed-service.php", {
+                method: "POST",
+                cache: "no-store",
+            })
+        } catch (error) {
+            return { ok: false, reason: "network" }
+        }
+        if (!response.ok) return { ok: false, reason: "seed-failed" }
+        var body
+        try {
+            body = await response.json()
+        } catch (error) {
+            return { ok: false, reason: "seed-failed" }
+        }
+        if (!body || typeof body.seed !== "string") return { ok: false, reason: "seed-failed" }
+        var nonce = await AG.solve(body.seed, body.bits, onProgress)
+        if (!AG.setCookie(body.seed + "." + nonce)) {
+            return { ok: false, reason: "cookie-disabled" }
+        }
+        return { ok: true }
+    }
+
+    /** acquireToken() unless a token cookie is already present. */
+    AG.ensureToken = async function (serviceUri, onProgress) {
+        if (AG.hasToken()) return { ok: true }
+        return AG.acquireToken(serviceUri, onProgress)
+    }
+
+    window.AccessGate = AG
+})()
diff --git a/Client/AccessGate/challenge.html b/Client/AccessGate/challenge.html
@@ -0,0 +1,121 @@
+<!doctype html>
+<html lang="ja">
+<head>
+<meta charset="utf-8">
+<meta name="robots" content="noindex">
+<meta name="viewport" content="width=device-width,initial-scale=1">
+<title>Checking your browser…</title>
+<style>
+  html { color-scheme: light dark; }
+  body {
+    font-family: system-ui, sans-serif;
+    display: flex; flex-direction: column; align-items: center;
+    justify-content: center; min-height: 80vh; margin: 0; padding: 1em;
+    text-align: center;
+  }
+  .spinner {
+    width: 2em; height: 2em; margin-bottom: 1em;
+    border: 3px solid rgba(128, 128, 128, .3); border-top-color: currentColor;
+    border-radius: 50%; animation: ag-spin 1s linear infinite;
+  }
+  @keyframes ag-spin { to { transform: rotate(360deg); } }
+  #progress { opacity: .6; font-size: .85em; min-height: 1.2em; }
+</style>
+</head>
+<body>
+<div class="spinner" aria-hidden="true"></div>
+<p id="msg">ページを確認しています… / Verifying your browser…</p>
+<p id="progress"></p>
+<noscript><p>JavaScriptとCookieを有効にして再読み込みしてください。<br>Please enable JavaScript and cookies, then reload.</p></noscript>
+<script>
+;(function () {
+    "use strict"
+
+    // This page is served statically (rewritten under the protected URL by
+    // .htaccess, or inlined by AccessGate with status 428), so the app root
+    // is unknown here. Probe candidate roots, shortest first: non-roots
+    // answer with a cheap static 404, the real root answers the seed.
+
+    var msg = document.getElementById("msg")
+    var progress = document.getElementById("progress")
+
+    function fail(text) {
+        msg.textContent = text
+        progress.textContent = ""
+        var spinner = document.querySelector(".spinner")
+        if (spinner) spinner.style.display = "none"
+    }
+
+    function rootCandidates() {
+        var segments = location.pathname.split("/").filter(function (s) { return s !== "" })
+        var candidates = [""]
+        var prefix = ""
+        for (var i = 0; i < segments.length - 1 && i < 4; i++) {
+            prefix += "/" + segments[i]
+            candidates.push(prefix)
+        }
+        return candidates
+    }
+
+    async function findSeedRoot() {
+        var candidates = rootCandidates()
+        for (var i = 0; i < candidates.length; i++) {
+            try {
+                var response = await fetch(candidates[i] + "/Service/access-gate-seed-service.php", {
+                    method: "POST",
+                    cache: "no-store",
+                })
+                if (response.ok) return candidates[i]
+            } catch (error) { /* try next candidate */ }
+        }
+        return null
+    }
+
+    function loadSolver(root) {
+        return new Promise(function (resolve, reject) {
+            if (window.AccessGate) { resolve(); return }
+            var script = document.createElement("script")
+            script.src = root + "/Client/AccessGate/access-gate.js"
+            script.onload = resolve
+            script.onerror = reject
+            document.head.appendChild(script)
+        })
+    }
+
+    async function run() {
+        if (!(window.crypto && window.crypto.subtle && window.TextEncoder)) {
+            fail("このブラウザは対応していません。 / This browser is not supported.")
+            return
+        }
+        if (!navigator.cookieEnabled) {
+            fail("Cookieを有効にして再読み込みしてください。 / Please enable cookies and reload.")
+            return
+        }
+        var root = await findSeedRoot()
+        if (root === null) {
+            fail("確認サービスに接続できませんでした。しばらくして再読み込みしてください。 / Could not reach the verification service. Please reload later.")
+            return
+        }
+        try {
+            await loadSolver(root)
+        } catch (error) {
+            fail("読み込みに失敗しました。再読み込みしてください。 / Failed to load. Please reload.")
+            return
+        }
+        var result = await window.AccessGate.acquireToken(root + "/Service", function (attempts) {
+            progress.textContent = attempts + " …"
+        })
+        if (result.ok) {
+            location.reload()
+        } else if (result.reason === "cookie-disabled") {
+            fail("Cookieを有効にして再読み込みしてください。 / Please enable cookies and reload.")
+        } else {
+            fail("確認に失敗しました。再読み込みしてください。 / Verification failed. Please reload.")
+        }
+    }
+
+    run()
+})()
+</script>
+</body>
+</html>
diff --git a/Client/ContentsViewer/ContentsViewer.js b/Client/ContentsViewer/ContentsViewer.js
@@ -710,30 +710,50 @@
     CV.elements.searchResults.appendChild(div)
   }
 
+  // Sends a FormData to feedback-service with an AccessGate token
+  // (see Client/AccessGate/access-gate.js), acquiring one first when
+  // missing (proof-of-work, about a second) and retrying once on 428.
+  CV.sendFeedbackForm = function (form) {
+    var send = function (isRetry) {
+      var xhr = new XMLHttpRequest()
+      xhr.open("POST", CV.vars.serviceUri + "/feedback-service.php", true)
+      xhr.onload = function (e) {
+        if (this.status == 428 && !isRetry && window.AccessGate) {
+          AccessGate.acquireToken(CV.vars.serviceUri).then(function (result) {
+            if (result.ok) send(true)
+            else console.error("AccessGate: " + result.reason)
+          })
+          return
+        }
+        try {
+          if (!CV.validateResponse(this)) {
+            throw "Sorry... Internal Error occured."
+          }
+
+          if (this.parsedResponse.error) {
+            throw this.parsedResponse.error
+          }
+        } catch (err) {
+          console.error(err)
+          return
+        }
+      }
+      xhr.send(form)
+    }
+
+    if (window.AccessGate) {
+      AccessGate.ensureToken(CV.vars.serviceUri).then(function () { send(false) })
+    } else {
+      send(false)
+    }
+  }
+
   CV.sendRating = function (button) {
     var rating = button.getAttribute("data-value")
     var form = new FormData()
     form.append("cmd", "rate")
     form.append("contentPath", CV.vars.contentPath)
     form.append("rating", rating)
-    form.append("otp", CV.vars.otp)
-
-    var xhr = new XMLHttpRequest()
-    xhr.open("POST", CV.vars.serviceUri + "/feedback-service.php", true)
-    xhr.onload = function (e) {
-      try {
-        if (!CV.validateResponse(this)) {
-          throw "Sorry... Internal Error occured."
-        }
-
-        if (this.parsedResponse.error) {
-          throw this.parsedResponse.error
-        }
-      } catch (err) {
-        console.error(err)
-        return
-      }
-    }
 
     var survey = document.getElementById("content-survey")
     document.querySelector("#content-survey .button-group").style.display = "none"
@@ -759,7 +779,7 @@
     }
     button.classList.add("submit-button")
     survey.appendChild(button)
-    xhr.send(form)
+    CV.sendFeedbackForm(form)
   }
 
   CV.sendMessage = function () {
@@ -768,31 +788,13 @@
     form.append("cmd", "message")
     form.append("contentPath", CV.vars.contentPath)
     form.append("message", message)
-    form.append("otp", CV.vars.otp)
-
-    var xhr = new XMLHttpRequest()
-    xhr.open("POST", CV.vars.serviceUri + "/feedback-service.php", true)
-    xhr.onload = function (e) {
-      try {
-        if (!CV.validateResponse(this)) {
-          throw "Sorry... Internal Error occured."
-        }
-
-        if (this.parsedResponse.error) {
-          throw this.parsedResponse.error
-        }
-      } catch (err) {
-        console.error(err)
-        return
-      }
-    }
 
     var survey = document.getElementById("content-survey")
     survey.classList.add("submitted")
     document.querySelector("#content-survey .how-improve").style.display = "none"
     document.querySelector("#content-survey .any-feedback").style.display = "none"
 
-    xhr.send(form)
+    CV.sendFeedbackForm(form)
   }
 
   CV.onClickLayerSelector = function (element, event) {
@@ -854,7 +856,6 @@
     CV.vars.token = (item = document.getElementsByName("token").item(0)) ? item.content : undefined
     CV.vars.contentPath = (item = document.getElementsByName("content-path").item(0)) ? item.content : undefined
     CV.vars.serviceUri = (item = document.getElementsByName("service-uri").item(0)) ? item.content : undefined
-    CV.vars.otp = (item = document.getElementsByName("otp").item(0)) ? item.content : undefined
 
     CV.elements = {}
     CV.elements.header = document.querySelector("#header")