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dns-stream: only read DNS packet data if we identified the peer properly

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If we use TCP fastopen to connect to a DNS server via TCP, and it
responds really quickly between our connection attempt and our immediate
check back, then we have not identified the peer yet, and will not be
able to use the peer metadata to fill in our packet info.

Let's fix that, and simply not read from the socket until identification
is complete.

Fixes: #34956
(cherry picked from commit facc9439a76b4c3a5c273c71bd7a676e4c74778c)
(cherry picked from commit 11da52785c978369e4cd92e67e5017a436404340)
This commit is contained in:
Lennart Poettering 2025-03-04 00:17:21 +01:00 committed by Luca Boccassi
parent 6cb60bbe83
commit 9bf15a285e
1 changed files with 2 additions and 1 deletions
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3
src/resolve/resolved-dns-stream.c
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@ -359,7 +359,8 @@ static int on_stream_io(sd_event_source *es, int fd, uint32_t revents, void *use
}
}
while ((revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) &&
while (s->identified && /* Only read data once we identified the peer, because we cannot fill in the DNS packet meta info otherwise */
(revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) &&
(!s->read_packet ||
s->n_read < sizeof(s->read_size) + s->read_packet->size)) {