mirror of
https://github.com/mjl-/mox.git
synced 2024-12-26 16:33:47 +03:00
480 lines
10 KiB
Go
480 lines
10 KiB
Go
package message
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import (
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"fmt"
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"strings"
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"github.com/mjl-/mox/dns"
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)
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// ../rfc/8601:577
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// Authentication-Results header, see RFC 8601.
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type AuthResults struct {
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Hostname string
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// Optional version of Authentication-Results header, assumed "1" when absent,
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// which is common.
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Version string
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Comment string // If not empty, header comment without "()", added after Hostname.
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Methods []AuthMethod // Can be empty, in case of "none".
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}
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// ../rfc/8601:598
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// AuthMethod is a result for one authentication method.
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//
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// Example encoding in the header: "spf=pass smtp.mailfrom=example.net".
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type AuthMethod struct {
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// E.g. "dkim", "spf", "iprev", "auth".
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Method string
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Version string // For optional method version. "1" is implied when missing, which is common.
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Result string // Each method has a set of known values, e.g. "pass", "temperror", etc.
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Comment string // Optional, message header comment.
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Reason string // Optional.
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Props []AuthProp
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}
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// ../rfc/8601:606
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// AuthProp describes properties for an authentication method.
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// Each method has a set of known properties.
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// Encoded in the header as "type.property=value", e.g. "smtp.mailfrom=example.net"
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// for spf.
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type AuthProp struct {
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// Valid values maintained at https://www.iana.org/assignments/email-auth/email-auth.xhtml
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Type string
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Property string
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Value string
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// Whether value is address-like (localpart@domain, or domain). Or another value,
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// which is subject to escaping.
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IsAddrLike bool
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Comment string // If not empty, header comment without "()", added after Value.
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}
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// MakeAuthProp is a convenient way to make an AuthProp.
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func MakeAuthProp(typ, property, value string, isAddrLike bool, Comment string) AuthProp {
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return AuthProp{typ, property, value, isAddrLike, Comment}
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}
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// todo future: we could store fields as dns.Domain, and when we encode as non-ascii also add the ascii version as a comment.
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// Header returns an Authentication-Results header, possibly spanning multiple
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// lines, always ending in crlf.
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func (h AuthResults) Header() string {
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// Escaping of values: ../rfc/8601:684 ../rfc/2045:661
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optComment := func(s string) string {
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if s != "" {
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return " (" + s + ")"
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}
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return s
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}
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w := &HeaderWriter{}
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w.Add("", "Authentication-Results:"+optComment(h.Comment)+" "+value(h.Hostname, false)+";")
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for i, m := range h.Methods {
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w.Newline()
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tokens := []string{}
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addf := func(format string, args ...any) {
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s := fmt.Sprintf(format, args...)
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tokens = append(tokens, s)
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}
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addf("%s=%s", m.Method, m.Result)
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if m.Comment != "" && (m.Reason != "" || len(m.Props) > 0) {
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addf("(%s)", m.Comment)
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}
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if m.Reason != "" {
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addf("reason=%s", value(m.Reason, false))
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}
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for _, p := range m.Props {
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v := value(p.Value, p.IsAddrLike)
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addf("%s.%s=%s%s", p.Type, p.Property, v, optComment(p.Comment))
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}
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for j, t := range tokens {
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var sep string
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if j > 0 {
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sep = " "
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}
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if j == len(tokens)-1 && i < len(h.Methods)-1 {
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t += ";"
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}
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w.Add(sep, t)
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}
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}
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return w.String()
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}
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func value(s string, isAddrLike bool) string {
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quote := s == ""
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for _, c := range s {
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// utf-8 does not have to be quoted. ../rfc/6532:242
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// Characters outside of tokens do. ../rfc/2045:661
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if c <= ' ' || c == 0x7f || (c == '@' && !isAddrLike) || strings.ContainsRune(`()<>,;:\\"/[]?= `, c) {
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quote = true
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break
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}
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}
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if !quote {
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return s
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}
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r := `"`
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for _, c := range s {
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if c == '"' || c == '\\' {
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r += "\\"
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}
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r += string(c)
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}
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r += `"`
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return r
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}
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// ParseAuthResults parses a Authentication-Results header value.
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//
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// Comments are not populated in the returned AuthResults.
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// Both crlf and lf line-endings are accepted. The input string must end with
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// either crlf or lf.
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func ParseAuthResults(s string) (ar AuthResults, err error) {
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// ../rfc/8601:577
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lower := make([]byte, len(s))
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for i, c := range []byte(s) {
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if c >= 'A' && c <= 'Z' {
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c += 'a' - 'A'
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}
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lower[i] = c
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}
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p := &parser{s: s, lower: string(lower)}
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defer p.recover(&err)
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p.cfws()
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ar.Hostname = p.xvalue()
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p.cfws()
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ar.Version = p.digits()
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p.cfws()
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for {
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p.xtake(";")
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p.cfws()
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// Yahoo has ";" at the end of the header value, incorrect.
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if !Pedantic && p.end() {
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break
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}
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method := p.xkeyword(false)
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p.cfws()
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if method == "none" {
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if len(ar.Methods) == 0 {
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p.xerrorf("missing results")
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}
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if !p.end() {
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p.xerrorf(`data after "none" result`)
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}
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return
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}
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ar.Methods = append(ar.Methods, p.xresinfo(method))
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p.cfws()
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if p.end() {
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break
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}
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}
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return
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}
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type parser struct {
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s string
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lower string // Like s, but with ascii characters lower-cased (utf-8 offsets preserved).
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o int
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}
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type parseError struct{ err error }
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func (p *parser) recover(err *error) {
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x := recover()
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if x == nil {
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return
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}
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perr, ok := x.(parseError)
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if ok {
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*err = perr.err
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return
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}
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panic(x)
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}
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func (p *parser) xerrorf(format string, args ...any) {
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panic(parseError{fmt.Errorf(format, args...)})
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}
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func (p *parser) end() bool {
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return p.s[p.o:] == "\r\n" || p.s[p.o:] == "\n"
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}
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// ../rfc/5322:599
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func (p *parser) cfws() {
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p.fws()
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for p.prefix("(") {
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p.xcomment()
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}
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p.fws()
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}
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func (p *parser) fws() {
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for p.take(" ") || p.take("\t") {
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}
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opts := []string{"\n ", "\n\t", "\r\n ", "\r\n\t"}
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for _, o := range opts {
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if p.take(o) {
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break
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}
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}
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for p.take(" ") || p.take("\t") {
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}
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}
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func (p *parser) xcomment() {
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p.xtake("(")
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p.fws()
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for !p.take(")") {
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if p.empty() {
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p.xerrorf("unexpected end in comment")
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}
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if p.prefix("(") {
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p.xcomment()
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p.fws()
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continue
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}
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p.take(`\`)
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if c := p.s[p.o]; c > ' ' && c < 0x7f {
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p.o++
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} else {
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p.xerrorf("bad character %c in comment", c)
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}
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p.fws()
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}
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}
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func (p *parser) prefix(s string) bool {
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return strings.HasPrefix(p.lower[p.o:], s)
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}
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func (p *parser) xvalue() string {
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if p.prefix(`"`) {
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return p.xquotedString()
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}
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return p.xtakefn1("value token", func(c rune, i int) bool {
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// ../rfc/2045:661
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// todo: token cannot contain utf-8? not updated in ../rfc/6532. however, we also use it for the localpart & domain parsing, so we'll allow it.
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return c > ' ' && !strings.ContainsRune(`()<>@,;:\\"/[]?= `, c)
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})
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}
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func (p *parser) xchar() rune {
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// We are careful to track invalid utf-8 properly.
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if p.empty() {
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p.xerrorf("need another character")
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}
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var r rune
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var o int
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for i, c := range p.s[p.o:] {
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if i > 0 {
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o = i
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break
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}
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r = c
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}
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if o == 0 {
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p.o = len(p.s)
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} else {
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p.o += o
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}
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return r
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}
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func (p *parser) xquotedString() string {
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p.xtake(`"`)
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var s string
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var esc bool
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for {
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c := p.xchar()
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if esc {
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if c >= ' ' && c < 0x7f {
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s += string(c)
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esc = false
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continue
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}
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p.xerrorf("bad escaped char %c in quoted string", c)
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}
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if c == '\\' {
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esc = true
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continue
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}
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if c == '"' {
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return s
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}
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if c >= ' ' && c != '\\' && c != '"' {
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s += string(c)
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continue
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}
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p.xerrorf("invalid quoted string, invalid character %c", c)
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}
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}
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func (p *parser) digits() string {
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o := p.o
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for o < len(p.s) && p.s[o] >= '0' && p.s[o] <= '9' {
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o++
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}
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p.o = o
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return p.s[o:p.o]
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}
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func (p *parser) xdigits() string {
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s := p.digits()
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if s == "" {
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p.xerrorf("expected digits, remaining %q", p.s[p.o:])
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}
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return s
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}
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func (p *parser) xtake(s string) {
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if !p.prefix(s) {
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p.xerrorf("expected %q, remaining %q", s, p.s[p.o:])
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}
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p.o += len(s)
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}
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func (p *parser) empty() bool {
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return p.o >= len(p.s)
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}
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func (p *parser) take(s string) bool {
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if p.prefix(s) {
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p.o += len(s)
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return true
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}
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return false
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}
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func (p *parser) xtakefn1(what string, fn func(c rune, i int) bool) string {
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if p.empty() {
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p.xerrorf("need at least one char for %s", what)
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}
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for i, c := range p.s[p.o:] {
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if !fn(c, i) {
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if i == 0 {
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p.xerrorf("expected at least one char for %s, remaining %q", what, p.s[p.o:])
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}
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s := p.s[p.o : p.o+i]
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p.o += i
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return s
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}
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}
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s := p.s[p.o:]
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p.o = len(p.s)
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return s
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}
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// ../rfc/5321:2287
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func (p *parser) xkeyword(isResult bool) string {
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s := strings.ToLower(p.xtakefn1("keyword", func(c rune, i int) bool {
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// Yahoo sends results like "dkim=perm_fail".
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return c >= 'a' && c <= 'z' || c >= '0' && c <= '9' || c == '-' || isResult && !Pedantic && c == '_'
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}))
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if s == "-" {
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p.xerrorf("missing keyword")
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} else if strings.HasSuffix(s, "-") {
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p.o--
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s = s[:len(s)-1]
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}
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return s
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}
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func (p *parser) xmethodspec(methodKeyword string) (string, string, string) {
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p.cfws()
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var methodDigits string
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if p.take("/") {
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methodDigits = p.xdigits()
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p.cfws()
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}
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p.xtake("=")
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p.cfws()
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result := p.xkeyword(true)
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return methodKeyword, methodDigits, result
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}
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func (p *parser) xpropspec() (ap AuthProp) {
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ap.Type = p.xkeyword(false)
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p.cfws()
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p.xtake(".")
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p.cfws()
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if p.take("mailfrom") {
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ap.Property = "mailfrom"
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} else if p.take("rcptto") {
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ap.Property = "rcptto"
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} else {
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ap.Property = p.xkeyword(false)
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}
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p.cfws()
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p.xtake("=")
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ap.IsAddrLike, ap.Value = p.xpvalue()
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return
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}
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// method keyword has been parsed, method-version not yet.
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func (p *parser) xresinfo(methodKeyword string) (am AuthMethod) {
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p.cfws()
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am.Method, am.Version, am.Result = p.xmethodspec(methodKeyword)
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p.cfws()
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if p.take("reason") {
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p.cfws()
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p.xtake("=")
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p.cfws()
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am.Reason = p.xvalue()
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}
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p.cfws()
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for !p.prefix(";") && !p.end() {
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am.Props = append(am.Props, p.xpropspec())
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p.cfws()
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}
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return
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}
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// todo: could keep track whether this is a localpart.
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func (p *parser) xpvalue() (bool, string) {
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p.cfws()
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if p.take("@") {
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// Bare domain.
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dom, _ := p.xdomain()
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return true, "@" + dom
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}
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s := p.xvalue()
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if p.take("@") {
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dom, _ := p.xdomain()
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s += "@" + dom
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return true, s
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}
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return false, s
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}
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// ../rfc/5321:2291
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func (p *parser) xdomain() (string, dns.Domain) {
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s := p.xsubdomain()
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for p.take(".") {
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s += "." + p.xsubdomain()
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}
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d, err := dns.ParseDomain(s)
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if err != nil {
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p.xerrorf("parsing domain name %q: %s", s, err)
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}
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if len(s) > 255 {
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// ../rfc/5321:3491
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p.xerrorf("domain longer than 255 octets")
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}
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return s, d
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}
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// ../rfc/5321:2303
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// ../rfc/5321:2303 ../rfc/6531:411
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func (p *parser) xsubdomain() string {
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return p.xtakefn1("subdomain", func(c rune, i int) bool {
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return c >= '0' && c <= '9' || c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || i > 0 && c == '-' || c > 0x7f
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})
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}
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