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outgoing dmarc/tls reporting improvements

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- dmarc reports: add a cid to the log line about one run of sending reports, and log line for each report
- in smtpclient, also handle tls errors from the first read after a handshake. we appear to sometimes get tls alerts about bad certificates on the first read.
- for messages to dmarc/tls reporting addresses that we think should/can not be processed as reports, add an X-Mox- header explaining the reason.
- tls reports: send report messages with From address of postmaster at an actually configured domain for the mail host. and only send reports when dkim signing is configured for that domain. the domain is also the submitter domain. the rfc seems to require dkim-signing with an exact match with the message from and submitter.
- for incoming tls reports, in the smtp server, we do allow a dkim-signature domain that is higher-level (up to publicsuffix) of the message from domain. so we are stricter in what we send than what we receive.
This commit is contained in:
Mechiel Lukkien
2023-11-10 19:34:00 +01:00
parent b2af63b3ec
commit 61bae75228
7 changed files with 136 additions and 91 deletions
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33
smtpclient/client.go
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@ -11,6 +11,7 @@ import (
"fmt"
"io"
"net"
"reflect"
"strconv"
"strings"
"time"
@ -113,15 +114,16 @@ type Client struct {
recipientDomainResult *tlsrpt.Result // Either "sts" or "no-policy-found".
hostResult *tlsrpt.Result // Either "dane" or "no-policy-found".
r *bufio.Reader
w *bufio.Writer
tr *moxio.TraceReader // Kept for changing trace levels between cmd/auth/data.
tw *moxio.TraceWriter
log *mlog.Log
lastlog time.Time // For adding delta timestamps between log lines.
cmds []string // Last or active command, for generating errors and metrics.
cmdStart time.Time // Start of command.
tls bool // Whether connection is TLS protected.
r *bufio.Reader
w *bufio.Writer
tr *moxio.TraceReader // Kept for changing trace levels between cmd/auth/data.
tw *moxio.TraceWriter
log *mlog.Log
lastlog time.Time // For adding delta timestamps between log lines.
cmds []string // Last or active command, for generating errors and metrics.
cmdStart time.Time // Start of command.
tls bool // Whether connection is TLS protected.
firstReadAfterHandshake bool // To detect TLS alert error from remote just after handshake.
botched bool // If set, protocol is out of sync and no further commands can be sent.
needRset bool // If set, a new delivery requires an RSET command.
@ -274,6 +276,7 @@ func New(ctx context.Context, log *mlog.Log, conn net.Conn, tlsMode TLSMode, tls
c.tlsResultAdd(0, 1, err)
return nil, err
}
c.firstReadAfterHandshake = true
c.tlsResultAdd(1, 0, nil)
c.conn = tlsconn
tlsversion, ciphersuite := mox.TLSInfo(tlsconn)
@ -444,8 +447,19 @@ func (c *Client) readline() (string, error) {
line, err := bufs.Readline(c.r)
if err != nil {
// See if this is a TLS alert from remote, and one other than 0 (which notifies
// that the connection is being closed. If so, we register a TLS connection
// failure. This handles TLS alerts that happen just after a successful handshake.
var netErr *net.OpError
if c.firstReadAfterHandshake && errors.As(err, &netErr) && netErr.Op == "remote error" && netErr.Err != nil && reflect.ValueOf(netErr.Err).Kind() == reflect.Uint8 && reflect.ValueOf(netErr.Err).Uint() != 0 {
resultType, reasonCode := tlsrpt.TLSFailureDetails(err)
// We count -1 success to compensate for the assumed success right after the handshake.
c.tlsResultAddFailureDetails(-1, 1, c.tlsrptFailureDetails(resultType, reasonCode))
}
return line, c.botchf(0, "", "", "%s: %w", strings.Join(c.cmds, ","), err)
}
c.firstReadAfterHandshake = false
return line, nil
}
@ -749,6 +763,7 @@ func (c *Client) hello(ctx context.Context, tlsMode TLSMode, ehloHostname dns.Do
c.tlsResultAdd(0, 1, err)
c.xerrorf(false, 0, "", "", "%w: STARTTLS TLS handshake: %s", ErrTLS, err)
}
c.firstReadAfterHandshake = true
cancel()
c.tr = moxio.NewTraceReader(c.log, "RS: ", c.conn)
c.tw = moxio.NewTraceWriter(c.log, "LC: ", c.conn) // No need to wrap in timeoutWriter, it would just set the timeout on the underlying connection, which is still active.