QUIC: quic retry log error when ngx_exiting

[Vladimir Homutov]

Hi Gao Yan,

> On Wed, Mar 03, 2021 at 11:53:57AM +0000, Gao,Yan(ACG VCP) wrote:
> 2021/03/03 19:34:49 [debug] 176572#0: *19974 recvmsg: 111.206.214.32:59242 fd:12 n:1350
> 2021/03/03 19:34:49 [debug] 176572#0: *19974 quic run
> 2021/03/03 19:34:49 [debug] 176572#0: *19974 quic packet rx long flags:c8 version:ff00001d
> 2021/03/03 19:34:49 [debug] 176572#0: *19974 quic packet rx init len:1332
> 2021/03/03 19:34:49 [debug] 176572#0: *19974 quic packet rx dcid len:8 92545cbefeb0567c
> 2021/03/03 19:34:49 [debug] 176572#0: *19974 quic packet rx scid len:0
                                                                   ^^
What we see here is the quic packet with zero length source id arrived
(note this is possible in quic protocol)

> 2021/03/03 19:34:49 [debug] 176572#0: *19974 quic address validation token len:0
> 2021/03/03 19:34:49 [debug] 176572#0: *19974 sendmsg: 107 of 107
> 2021/03/03 19:34:49 [debug] 176572#0: *19974 quic retry packet sent to

Here we send the retry packet in reply; since source id is zero length, nothing
is printed here in debug for destination