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libpq: Handle NegotiateProtocolVersion message

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Before, receiving a NegotiateProtocolVersion message would result in a
confusing error message like

    expected authentication request from server, but received v

This adds proper handling of this protocol message and produces an
on-topic error message from it.

Reviewed-by: Jacob Champion <jchampion@timescale.com>
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/f9c7862f-b864-8ef7-a861-c4638c83e209%40enterprisedb.com
This commit is contained in:
Peter Eisentraut
2022-11-17 15:14:44 +01:00
parent dce92e59b1
commit bbf9c282ce
3 changed files with 73 additions and 5 deletions
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22
src/interfaces/libpq/fe-connect.c
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@@ -3194,10 +3194,11 @@ keep_going: /* We will come back to here until there is
/*
* Validate message type: we expect only an authentication
* request or an error here. Anything else probably means
* it's not Postgres on the other end at all.
* request, NegotiateProtocolVersion, or an error here.
* Anything else probably means it's not Postgres on the other
* end at all.
*/
if (!(beresp == 'R' || beresp == 'E'))
if (!(beresp == 'R' || beresp == 'v' || beresp == 'E'))
{
libpq_append_conn_error(conn, "expected authentication request from server, but received %c",
beresp);
@@ -3214,14 +3215,15 @@ keep_going: /* We will come back to here until there is
/*
* Try to validate message length before using it.
* Authentication requests can't be very large, although GSS
* auth requests may not be that small. Errors can be a
* auth requests may not be that small. Same for
* NegotiateProtocolVersion. Errors can be a
* little larger, but not huge. If we see a large apparent
* length in an error, it means we're really talking to a
* pre-3.0-protocol server; cope. (Before version 14, the
* server also used the old protocol for errors that happened
* before processing the startup packet.)
*/
if (beresp == 'R' && (msgLength < 8 || msgLength > 2000))
if ((beresp == 'R' || beresp == 'v') && (msgLength < 8 || msgLength > 2000))
{
libpq_append_conn_error(conn, "expected authentication request from server, but received %c",
beresp);
@@ -3351,6 +3353,16 @@ keep_going: /* We will come back to here until there is
goto error_return;
}
else if (beresp == 'v')
{
if (pqGetNegotiateProtocolVersion3(conn))
{
goto error_return;
}
/* OK, we read the message; mark data consumed */
conn->inStart = conn->inCursor;
goto error_return;
}
/* It is an authentication request. */
conn->auth_req_received = true;