3948f47354
A single dnsExchangeTimeout around CheckCAA let slow empty answers at child names consume the budget before parent policy was queried. Give each label its own exchange timeout inside the climb instead. Signed-off-by: Cursor Agent <cursoragent@cursor.com> Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>
116 lines
3.3 KiB
Go
116 lines
3.3 KiB
Go
// Copyright (c) 2026 Probo Inc <hello@probo.com>.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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package dnsclient
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import (
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"context"
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"fmt"
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"time"
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"codeberg.org/miekg/dns"
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)
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const (
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// DefaultExchangeTimeout is the per-lookup budget for a single DNS
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// exchange (UDP, with optional TCP retry on truncation).
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DefaultExchangeTimeout = 10 * time.Second
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)
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type (
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// Client performs DNS lookups used to verify domain ownership and
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// certificate prerequisites.
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Client struct {
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ResolverAddr string
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ExchangeTimeout time.Duration
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exchange exchangeFunc
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}
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exchangeFunc func(ctx context.Context, msg *dns.Msg, network string) (*dns.Msg, error)
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)
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// NewClient returns a client that resolves names through resolverAddr.
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func NewClient(resolverAddr string) *Client {
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return &Client{
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ResolverAddr: resolverAddr,
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ExchangeTimeout: DefaultExchangeTimeout,
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}
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}
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// withExchangeTimeout returns a child context limited to ExchangeTimeout for a
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// single DNS lookup. A zero or negative timeout leaves ctx unchanged.
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func (c *Client) withExchangeTimeout(ctx context.Context) (context.Context, context.CancelFunc) {
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if c.ExchangeTimeout <= 0 {
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return ctx, func() {}
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}
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return context.WithTimeout(ctx, c.ExchangeTimeout)
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}
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func (c *Client) exchangeUDP(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
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if c.exchange != nil {
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return c.exchange(ctx, msg, "udp")
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}
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client := dns.NewClient()
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resp, _, err := client.Exchange(ctx, msg, "udp", c.ResolverAddr)
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if err != nil {
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return nil, err
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}
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return resp, nil
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}
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func (c *Client) exchangeTCP(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
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if c.exchange != nil {
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return c.exchange(ctx, msg, "tcp")
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}
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client := dns.NewClient()
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resp, _, err := client.Exchange(ctx, msg, "tcp", c.ResolverAddr)
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if err != nil {
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return nil, err
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}
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return resp, nil
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}
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func (c *Client) query(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
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resp, err := c.exchangeUDP(ctx, msg)
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if err != nil {
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return nil, fmt.Errorf("cannot exchange dns message: %w", err)
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}
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if resp.Truncated {
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resp, err = c.exchangeTCP(ctx, msg)
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if err != nil {
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return nil, fmt.Errorf("cannot exchange dns message over TCP: %w", err)
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}
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}
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if resp.Truncated {
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return nil, fmt.Errorf("cannot exchange dns message: truncated response")
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}
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return resp, nil
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}
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