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2ff87a0f9c
both cases are quite typical for spammers, and not for legitimate senders. this doesn't apply to known senders. and it only requires that the content look more like ham instead of spam. so legitimate mail can still get through with these properties.
44 lines
1.4 KiB
Go
44 lines
1.4 KiB
Go
package message
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import (
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"fmt"
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"io"
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"net/textproto"
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"github.com/mjl-/mox/dns"
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"github.com/mjl-/mox/mlog"
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"github.com/mjl-/mox/smtp"
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)
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// From extracts the address in the From-header.
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//
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// An RFC5322 message must have a From header.
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// In theory, multiple addresses may be present. In practice zero or multiple
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// From headers may be present. From returns an error if there is not exactly
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// one address. This address can be used for evaluating a DMARC policy against
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// SPF and DKIM results.
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func From(log *mlog.Log, strict bool, r io.ReaderAt) (raddr smtp.Address, envelope *Envelope, header textproto.MIMEHeader, rerr error) {
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// ../rfc/7489:1243
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// todo: only allow utf8 if enabled in session/message?
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p, err := Parse(log, strict, r)
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if err != nil {
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// todo: should we continue with p, perhaps headers can be parsed?
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return raddr, nil, nil, fmt.Errorf("parsing message: %v", err)
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}
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header, err = p.Header()
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if err != nil {
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return raddr, nil, nil, fmt.Errorf("parsing message header: %v", err)
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}
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from := p.Envelope.From
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if len(from) != 1 {
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return raddr, nil, nil, fmt.Errorf("from header has %d addresses, need exactly 1 address", len(from))
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}
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d, err := dns.ParseDomain(from[0].Host)
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if err != nil {
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return raddr, nil, nil, fmt.Errorf("bad domain in from address: %v", err)
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}
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addr := smtp.Address{Localpart: smtp.Localpart(from[0].User), Domain: d}
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return addr, p.Envelope, textproto.MIMEHeader(header), nil
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}
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