mirror of
https://github.com/mjl-/mox.git
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72ac1fde29
- prometheus is now behind an interface, they aren't dependencies for the reusable components anymore. - some dependencies have been inverted: instead of packages importing a main package to get configuration, the main package now sets configuration in these packages. that means fewer internals are pulled in. - some functions now have new parameters for values that were retrieved from package "mox-".
52 lines
1.7 KiB
Go
52 lines
1.7 KiB
Go
package message
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import (
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"errors"
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"fmt"
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"strings"
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"github.com/mjl-/mox/smtp"
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)
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var errBadMessageID = errors.New("not a message-id")
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// MessageIDCanonical parses the Message-ID, returning a canonical value that is
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// lower-cased, without <>, and no unneeded quoting. For matching in threading,
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// with References/In-Reply-To. If the message-id is invalid (e.g. no <>), an error
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// is returned. If the message-id could not be parsed as address (localpart "@"
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// domain), the raw value and the bool return parameter true is returned. It is
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// quite common that message-id's don't adhere to the localpart @ domain
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// syntax.
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func MessageIDCanonical(s string) (string, bool, error) {
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// ../rfc/5322:1383
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s = strings.TrimSpace(s)
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if !strings.HasPrefix(s, "<") {
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return "", false, fmt.Errorf("%w: missing <", errBadMessageID)
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}
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s = s[1:]
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// Seen in practice: Message-ID: <valid@valid.example> (added by postmaster@some.example)
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// Doesn't seem valid, but we allow it.
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s, rem, have := strings.Cut(s, ">")
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if !have || (rem != "" && (Pedantic || !strings.HasPrefix(rem, " "))) {
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return "", false, fmt.Errorf("%w: missing >", errBadMessageID)
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}
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// We canonicalize the Message-ID: lower-case, no unneeded quoting.
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s = strings.ToLower(s)
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if s == "" {
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return "", false, fmt.Errorf("%w: empty message-id", errBadMessageID)
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}
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addr, err := smtp.ParseAddress(s)
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if err != nil {
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// Common reasons for not being an address:
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// 1. underscore in hostname.
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// 2. ip literal instead of domain.
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// 3. two @'s, perhaps intended as time-separator
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// 4. no @'s, so no domain/host
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return s, true, nil
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}
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// We preserve the unicode-ness of domain.
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t := strings.Split(s, "@")
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s = addr.Localpart.String() + "@" + t[len(t)-1]
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return s, false, nil
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}
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