75 lines
2.0 KiB
Go
75 lines
2.0 KiB
Go
// Package policy holds pure enforcement functions: address matching,
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// inbound filtering, and (in a later phase) outbound checks.
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package policy
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import (
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"errors"
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"fmt"
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"net/mail"
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"strings"
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)
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// NormalizeAddr lower-cases an address and strips any display name/brackets.
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func NormalizeAddr(addr string) string {
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addr = strings.TrimSpace(addr)
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if a, err := mail.ParseAddress(addr); err == nil {
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return strings.ToLower(a.Address)
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}
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return strings.ToLower(strings.Trim(addr, "<> "))
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}
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// MatchAddress reports whether addr matches any whitelist entry.
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// Entries beginning with '@' match a whole domain; others match exactly.
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func MatchAddress(entries []string, addr string) bool {
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norm := NormalizeAddr(addr)
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if norm == "" {
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return false
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}
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at := strings.LastIndex(norm, "@")
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domain := ""
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if at >= 0 {
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domain = norm[at:] // includes '@'
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}
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for _, e := range entries {
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e = strings.ToLower(strings.TrimSpace(e))
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if strings.HasPrefix(e, "@") {
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if e == domain {
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return true
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}
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continue
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}
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if e == norm {
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return true
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}
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}
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return false
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}
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// ValidWhitelistAddress reports an error if s is not a usable whitelist entry.
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// Accepted forms: a bare address "local@domain", or a domain wildcard "@domain".
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// The domain must contain at least one dot. Display-name forms ("Bob <b@x>")
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// are rejected because the store keeps the raw string, which would never match.
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func ValidWhitelistAddress(s string) error {
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s = strings.TrimSpace(s)
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if s == "" {
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return errors.New("address must not be empty")
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}
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bad := fmt.Errorf("invalid address %q: expected local@domain or @domain", s)
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if strings.HasPrefix(s, "@") {
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domain := s[1:]
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if domain == "" || strings.Contains(domain, "@") || !strings.Contains(domain, ".") {
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return bad
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}
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return nil
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}
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addr, err := mail.ParseAddress(s)
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if err != nil || !strings.EqualFold(addr.Address, s) {
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return bad // parse failure or a display-name/extra-token form
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}
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at := strings.LastIndex(addr.Address, "@")
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if at < 1 || !strings.Contains(addr.Address[at+1:], ".") {
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return bad
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}
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return nil
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}
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