64ef051d18
Extract shared DNS checks into dnsclient and fail closed on truncated or non-success CAA responses. Climb past eTLD+1, validate RFC 8659 issue-value syntax, and map NXDOMAIN TXT lookups to the pending-verification path. Signed-off-by: Cursor Agent <cursoragent@cursor.com> Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>
77 lines
2.5 KiB
Go
77 lines
2.5 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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"strings"
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"codeberg.org/miekg/dns"
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)
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// CheckCNAME verifies that hostname has a single CNAME record owned by that
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// name and pointing at expectedTarget.
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func (c *Client) CheckCNAME(ctx context.Context, hostname, expectedTarget string) error {
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owner := ToFQDN(hostname)
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target := ToFQDN(expectedTarget)
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msg := &dns.Msg{MsgHeader: dns.MsgHeader{ID: dns.ID(), RecursionDesired: true}}
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msg.Question = []dns.RR{&dns.CNAME{Hdr: dns.Header{Name: owner, Class: dns.ClassINET}}}
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resp, err := c.query(ctx, msg)
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if err != nil {
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return err
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}
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if len(resp.Answer) == 0 {
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return fmt.Errorf("no cname records found for domain %q", hostname)
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}
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if len(resp.Answer) > 1 {
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return fmt.Errorf("multiple cname records found for domain %q", hostname)
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}
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resolvedRecord, ok := resp.Answer[0].(*dns.CNAME)
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if !ok {
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return fmt.Errorf("first answer is not a cname record for domain %q", hostname)
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}
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if !EqualNames(resolvedRecord.Hdr.Name, owner) {
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return fmt.Errorf(
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"cname owner mismatch: domain %q has record owned by %q",
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hostname,
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strings.TrimSuffix(resolvedRecord.Hdr.Name, "."),
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)
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}
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if !EqualNames(resolvedRecord.Target, target) {
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return fmt.Errorf(
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"cname target mismatch: domain %q resolves to %q, expected %q",
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hostname,
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strings.TrimSuffix(resolvedRecord.Target, "."),
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strings.TrimSuffix(expectedTarget, "."),
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)
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}
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return nil
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}
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