emersion
commented
3 months ago Good catch!
It seems like ESEARCH UID\r\n is also valid per the ABNF from the RFC (and that doesn't seem handled here):
esearch-response = "ESEARCH" [search-correlator] [SP "UID"]
*(SP search-return-data)
; ESEARCH response replaces SEARCH response
; from IMAP4rev1.Same for a search-correlator followed by CRLF.
Suggestion to handle that case and simplify the code:
func readESearchResponse(dec *imapwire.Decoder) (tag string, data *imap.SearchData, err error) {
data = &imap.SearchData{}
if dec.Special('(') { // search-correlator
var correlator string
if !dec.ExpectAtom(&correlator) || !dec.ExpectSP() || !dec.ExpectAString(&tag) || !dec.ExpectSpecial(')') {
return "", nil, dec.Err()
}
if correlator != "TAG" {
return "", nil, fmt.Errorf("in search-correlator: name must be TAG, but got %q", correlator)
}
}
var name string
if !dec.SP() {
return tag, data, nil
} else if !dec.ExpectAtom(&name) {
return "", nil, dec.Err()
}
data.UID = name == "UID"
if data.UID {
if !dec.SP() {
return tag, data, nil
} else if !dec.ExpectAtom(&name) {
return "", nil, dec.Err()
}
}
for {
switch strings.ToUpper(name) {
// ...
}
if !dec.SP() {
break
} else if !dec.ExpectAtom(&name) {
return "", nil, dec.Err()
}
}
return tag, data, nil
}
Shugyousha
When searching for unseen mails we can get the following error if there are none.
The reason is that the IMAP server is sending a response like this in case there are no search hits.
T7 UID SEARCH RETURN (ALL) (UNSEEN)
The wire protocol parser is expecting a search option (like "ALL") to be present in any search result. As we can see above, this is not the case if there are no results, which results in the parser hitting a CRLF when it expected a space.
To account for this we peek into the reply of the server to see whether there is a CRLF after the "UID" atom. If there is, we assume there were no results and return an empty result.