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crypto/tls: return a typed error on invalid record headers

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The user can inspect the record data to detect that the other side is
not using the TLS protocol.

This will be used by the net/http client (in a follow-on CL) to detect
when an HTTPS client is speaking to an HTTP server.

Updates #11111.

Change-Id: I872f78717aa8e8e98cebd8075436209a52039a73
Reviewed-on: https://go-review.googlesource.com/16078
Reviewed-by: Adam Langley <agl@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Caleb Spare 2015-10-20 00:23:11 -07:00 committed by Adam Langley
parent e90a6f8498
commit 4d57d90e8e
1 changed files with 23 additions and 4 deletions
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27
conn.go
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@ -506,6 +506,23 @@ func (hc *halfConn) splitBlock(b *block, n int) (*block, *block) {
return b, bb
}
// RecordHeaderError results when a TLS record header is invalid.
type RecordHeaderError struct {
// Msg contains a human readable string that describes the error.
Msg string
// RecordHeader contains the five bytes of TLS record header that
// triggered the error.
RecordHeader [5]byte
}
func (e RecordHeaderError) Error() string { return "tls: " + e.Msg }
func (c *Conn) newRecordHeaderError(msg string) (err RecordHeaderError) {
err.Msg = msg
copy(err.RecordHeader[:], c.rawInput.data)
return err
}
// readRecord reads the next TLS record from the connection
// and updates the record layer state.
// c.in.Mutex <= L; c.input == nil.
@ -556,18 +573,20 @@ Again:
// an SSLv2 client.
if want == recordTypeHandshake && typ == 0x80 {
c.sendAlert(alertProtocolVersion)
return c.in.setErrorLocked(errors.New("tls: unsupported SSLv2 handshake received"))
return c.in.setErrorLocked(c.newRecordHeaderError("unsupported SSLv2 handshake received"))
}
vers := uint16(b.data[1])<<8 | uint16(b.data[2])
n := int(b.data[3])<<8 | int(b.data[4])
if c.haveVers && vers != c.vers {
c.sendAlert(alertProtocolVersion)
return c.in.setErrorLocked(fmt.Errorf("tls: received record with version %x when expecting version %x", vers, c.vers))
msg := fmt.Sprintf("received record with version %x when expecting version %x", vers, c.vers)
return c.in.setErrorLocked(c.newRecordHeaderError(msg))
}
if n > maxCiphertext {
c.sendAlert(alertRecordOverflow)
return c.in.setErrorLocked(fmt.Errorf("tls: oversized record received with length %d", n))
msg := fmt.Sprintf("oversized record received with length %d", n)
return c.in.setErrorLocked(c.newRecordHeaderError(msg))
}
if !c.haveVers {
// First message, be extra suspicious: this might not be a TLS
@ -576,7 +595,7 @@ Again:
// it's probably not real.
if (typ != recordTypeAlert && typ != want) || vers >= 0x1000 {
c.sendAlert(alertUnexpectedMessage)
return c.in.setErrorLocked(fmt.Errorf("tls: first record does not look like a TLS handshake"))
return c.in.setErrorLocked(c.newRecordHeaderError("first record does not look like a TLS handshake"))
}
}
if err := b.readFromUntil(c.conn, recordHeaderLen+n); err != nil {