fix body hash issue in relaxe mode #38

[mschneider82]

I have added a test which failed before. With this fix i can sucessfully verify my testmail which was valid but the libray said body hash missmatch.

verify issue described in #38

[emersion]

So, it seems like you're doing essentially this:

b = bytes.TrimRight(b, "\r")

ie. removing trailing \r if any. Is this correct?

This should likely be part of the relaxedBodyCanonicalizer.Write loop, because it's specific to the relaxed mode.

---

This seems to be yet another quirk for relaxed mode. The RFC doesn't seem to mention it. Or maybe it's part of "Ignore all whitespace at the end of lines"? Or maybe "Ignore all empty lines at the end of the message body"?

[mschneider82]

@emersion yes its basicly bytes.TrimRight, but i just remove exact one \r at the end. not more (TrimRight could trim more than one).

[mschneider82]

are you thinking about?

b = fixCRLF(b)
b = bytes.TrimRight(b, "\r")

this seems like fixCRLF doesnt fix correct, thats why i included it into fixCRLF()

[emersion]

Hmm, wait. Your bug only happens when a slice passed to Write ends with a \r. That likely happens because a CRLF sequence is split between two Write calls:

Write([]byte("line1\r"))
Write([]byte("\nline2"))

I've written a failing test:

func TestRelaxedCanonicalizer_CanonicalBody_splitCRLF(t *testing.T) {
    want := "line 1\r\nline 2\r\n"
    writes := [][]byte{
        []byte("line 1\r"),
        []byte("\nline 2"),
    }

    var b bytes.Buffer
    wc := new(relaxedCanonicalizer).CanonicalizeBody(&b)
    for _, b := range writes {
        if _, err := wc.Write(b); err != nil {
            t.Errorf("Expected no error while writing to relaxed body canonicalizer, got: %v", err)
        }
    }
    if err := wc.Close(); err != nil {
        t.Errorf("Expected no error while closing relaxed body canonicalizer, got: %v", err)
    } else if s := b.String(); s != want {
        t.Errorf("Expected canonical body to be %q, but got %q", want, s)
    }
}

[emersion]

Superseded by https://github.com/emersion/go-msgauth/pull/39