feat: dnssec-validation toggle in upstream DNS form

Web 端 '上游 DNS 转发' 卡片新增第三个字段：DNSSEC 验证（auto/yes/no），
解决 SERVFAIL 经典坑：内网 DNS 用 auto 时会被根服务器坏 DS 记录卡住，
返回 SERVFAIL 而非答案。

实现：
- _parse_options_dnssec() 抽出当前 dnssec-validation 值
- _replace_or_append_option() 扩展支持 value-terminated directives
  （'dnssec-validation auto;' 而非 '{...}'），用负向断言避免误匹配
  'listen-on' 时把 'listen-on-v6' 也吃掉
- config_view 多传 dnssec_value/dnssec_values 给模板
- config_upstream_save 多处理 dnssec 表单字段
- 模板加 <select> 下拉，默认选中当前文件里的值

测试覆盖：brace-delimited 替换、value-terminated 替换、hyphen
lookbehind、append-when-missing、parse 各种值、完整 round-trip。

app.py

@@ -1045,23 +1045,54 @@ def _parse_options_lists(content):
     return forwarders, recursion
 
 
-def _replace_or_append_option(content, directive, new_block):
+_VALIDATION_VALUES = ("auto", "yes", "no")
-    """Replace an existing 'directive { ... };' in an options block with new_block,
-    or append it after the opening 'options {' if not present.
 
-    `new_block` is the full 'directive { ... };' text (without leading/trailing newline).
 
-    Handles nested braces in directives by counting brace depth (so multi-line
+def _parse_options_dnssec(content):
-    directives like `forwarders { 1.1.1.1; }` work; nested ones like `key ...`
+    """Return current dnssec-validation value as one of 'auto'/'yes'/'no'.
-    are not expected in options block).
+    Returns 'auto' if the directive is absent (BIND default).
+    """
+    m = re.search(r'dnssec-validation\s+(\w+)\s*;', content)
+    if not m:
+        return "auto"
+    val = m.group(1).lower()
+    if val in _VALIDATION_VALUES:
+        return val
+    return "auto"
+
+
+def _listen_on_v4_set(content):
+    """True if the options block contains any IPv4 'listen-on' directive."""
+    # Match listen-on (port N)? { ... } but NOT listen-on-v6
+    return bool(re.search(r'(?<!-)listen-on\b', content))
+
+
+def _replace_or_append_option(content, directive, new_block):
+    """Replace an existing 'directive { ... };' or 'directive <value>;' in an
+    options block with new_block, or append it after the opening 'options {' if
+    not present.
+
+    `new_block` is the full directive text (without leading/trailing newline).
+    Handles:
+      - brace-delimited:  'forwarders { ... };'  /  'allow-recursion { ... };'
+      - value-terminated: 'dnssec-validation auto;'  /  'recursion yes;'
+    Nested braces are matched by counting depth.
     """
-    # Try to find an existing directive with balanced-brace body
     pattern = re.compile(
-        r'(' + re.escape(directive) + r')\s*\{',
+        r'(' + re.escape(directive) + r')\b(?!\-)',
         re.MULTILINE,
     )
-    m = pattern.search(content)
+
-    if m:
+    for m in pattern.finditer(content):
+        # Skip lines where the directive is part of a longer hyphenated name,
+        # e.g. don't match 'listen-on' when looking for 'listen-on-v6'.
+        # The negative lookbehind `(?<!\-)` in the regex above handles most
+        # cases; also check that the next char isn't '-' (handles 'foo-bar'
+        # matching 'foo').
+        end_kw = m.end()
+        if end_kw < len(content) and content[end_kw] == '-':
+            continue
+
         start = m.start()
         # Detect indentation by looking at whitespace before the directive
         line_start = content.rfind('\n', 0, start) + 1
@@ -1071,39 +1102,57 @@ def _replace_or_append_option(content, directive, new_block):
                 indent += ch
             else:
                 break
-        # Walk forward from `{` to find the matching `};`
+
-        depth = 0
+        # Look ahead: is this a brace-delimited directive or value-terminated?
-        i = m.end() - 1  # points at `{`
+        i = end_kw
-        for j in range(i, len(content)):
+        # Skip whitespace
-            c = content[j]
+        while i < len(content) and content[i] in ' \t':
-            if c == '{':
+            i += 1
-                depth += 1
+        if i >= len(content):
-            elif c == '}':
+            continue
-                depth -= 1
+
-                if depth == 0:
+        if content[i] == '{':
-                    # Expect `;` shortly after; consume any whitespace
+            # Brace-delimited: walk forward to matching `};`
-                    end = j + 1
+            depth = 0
-                    while end < len(content) and content[end] in ' \t\n':
+            for j in range(i, len(content)):
-                        end += 1
+                c = content[j]
-                    if end < len(content) and content[end] == ';':
+                if c == '{':
-                        end += 1
+                    depth += 1
-                    # Indent new_block to match the directive's indentation
+                elif c == '}':
-                    indented = '\n'.join(
+                    depth -= 1
-                        (indent + line) if line else line
+                    if depth == 0:
-                        for line in new_block.split('\n')
+                        end = j + 1
-                    )
+                        while end < len(content) and content[end] in ' \t\n':
-                    return content[:start] + indented + content[end:]
+                            end += 1
-        return content  # malformed, give up
+                        if end < len(content) and content[end] == ';':
+                            end += 1
+                        indented = '\n'.join(
+                            (indent + line) if line else line
+                            for line in new_block.split('\n')
+                        )
+                        return content[:start] + indented + content[end:]
+            continue  # malformed, try next match
+        else:
+            # Value-terminated: read tokens up to `;`
+            end = i
+            while end < len(content) and content[end] != ';':
+                end += 1
+            if end < len(content):
+                end += 1  # consume the `;`
+            indented = '\n'.join(
+                (indent + line) if line else line
+                for line in new_block.split('\n')
+            )
+            return content[:start] + indented + content[end:]
+        # else: malformed, try next match
 
     # Not found — append after the opening "options {" line
     opt_match = re.search(r'options\s*\{', content)
     if opt_match:
         insert_at = opt_match.end()
-        # Insert after the newline that follows
         nl = content.find('\n', insert_at)
         if nl >= 0:
             insert_at = nl + 1
-        # Indent new_block 4 spaces (typical options-body indent)
         indented = '\n'.join('    ' + line if line else line for line in new_block.split('\n'))
         indented = '\n' + indented + '\n'
         return content[:insert_at] + indented + content[insert_at:]
@@ -1176,6 +1225,7 @@ def config_view():
 
     # Parse structured fields for the upstream-DNS form
     forwarders, recursion = _parse_options_lists(options_content)
+    dnssec_value = _parse_options_dnssec(options_content)
 
     return render_template("config.html",
                            options_content=options_content,
@@ -1184,7 +1234,9 @@ def config_view():
                            config_ok=config_ok,
                            config_msg=config_msg,
                            forwarders=forwarders,
-                           recursion=recursion)
+                           recursion=recursion,
+                           dnssec_value=dnssec_value,
+                           dnssec_values=_VALIDATION_VALUES)
 
 
 @app.route("/config/options", methods=["POST"])
@@ -1267,6 +1319,9 @@ def config_upstream_save():
 
     raw_fwd = request.form.get("forwarders", "")
     raw_rc  = request.form.get("recursion", "")
+    dnssec_in = (request.form.get("dnssec") or "auto").strip().lower()
+    if dnssec_in not in _VALIDATION_VALUES:
+        dnssec_in = "auto"
     new_fwd = _parse_list(raw_fwd)
     new_rc  = _parse_list(raw_rc)
 
@@ -1287,6 +1342,10 @@ def config_upstream_save():
         new_content, "allow-recursion",
         _format_list_block("allow-recursion", new_rc),
     )
+    new_content = _replace_or_append_option(
+        new_content, "dnssec-validation",
+        f"dnssec-validation {dnssec_in};",
+    )
 
     # Validate BEFORE writing to the live file
     tmp = "/tmp/named_check.tmp"
@@ -1309,8 +1368,8 @@ def config_upstream_save():
 
     u = current_user()
     AuditLog.log(u.username, "修改上游DNS转发配置",
-                 f"forwarders={new_fwd}; allow-recursion={new_rc}")
+                 f"forwarders={new_fwd}; allow-recursion={new_rc}; dnssec={dnssec_in}")
-    flash(f"已保存：forwarders {len(new_fwd)} 条，allow-recursion {len(new_rc)} 条", "success")
+    flash(f"已保存：forwarders {len(new_fwd)} 条，allow-recursion {len(new_rc)} 条，dnssec-validation {dnssec_in}", "success")
     return redirect(url_for("config_view"))
 
 

templates/config.html

@@ -48,10 +48,21 @@
                           placeholder="127.0.0.0/8
10.0.0.0/8
172.16.0.0/12
192.168.0.0/16">{% for net in recursion %}{{ net }}
 {% endfor %}</textarea>
             </div>
+            <div class="form-group">
+                <label for="dnssec">
+                    <strong>DNSSEC 验证</strong>
+                    <span class="text-muted text-sm">内网 DNS 通常选 <code>no</code>，避免根服务器坏 DS 记录导致 SERVFAIL。</span>
+                </label>
+                <select name="dnssec" id="dnssec" class="form-control">
+                    {% for v in dnssec_values %}
+                    <option value="{{ v }}" {% if v == dnssec_value %}selected{% endif %}>{{ v }}{% if v == 'auto' %}（默认，验证根 key）{% elif v == 'yes' %}（强制验证）{% elif v == 'no' %}（关闭验证）{% endif %}</option>
+                    {% endfor %}
+                </select>
+            </div>
             <div class="form-actions">
                 <button type="submit" class="btn btn-primary">💾 保存并重载</button>
                 <span class="text-muted text-sm" style="margin-left: 12px;">
-                    此处只改 forwarders 和 allow-recursion；其它 options 字段请用下方文本编辑器。
+                    此处只改 forwarders / allow-recursion / dnssec-validation；其它 options 字段请用下方文本编辑器。
                 </span>
             </div>
         </form>