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appview: expand domain of acceptable email addresses
Use address resolution steps from RFC5321 section 5.1 when validating
email addresses.
ref: https://datatracker.ietf.org/doc/html/rfc5321#section-5.1
Signed-off-by: tjh <x@tjh.dev>
+27
-4
+27
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appview/email/email.go
+27
-4
appview/email/email.go
···
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parts := strings.Split(addr.Address, "@")
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domain := parts[1]
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mx, err := net.LookupMX(domain)
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if err != nil || len(mx) == 0 {
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return false
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canonical := coalesceToCanonicalName(domain)
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mx, err := net.LookupMX(canonical)
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+
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// Don't check err here; mx will only contain valid mx records, and we should
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// only fallback to an implicit mx if there are no mx records defined (whether
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// they are valid or not).
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if len(mx) != 0 {
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return true
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}
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if err != nil {
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// If the domain resolves to an address, assume it's an implicit mx.
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address, _ := net.LookupIP(canonical)
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if len(address) != 0 {
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return true
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}
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}
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return true
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return false
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}
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func coalesceToCanonicalName(domain string) string {
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canonical, err := net.LookupCNAME(domain)
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if err != nil {
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// net.LookupCNAME() returns an error if there is no cname record *and* no
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// a/aaaa records, but there may still be mx records.
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return domain
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}
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return canonical
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}