From a49fbaaf8d461ff91912c30b3563d54649474c80 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 27 Aug 2011 16:36:57 -0400 Subject: [PATCH] Don't assume that "E" response to NEGOTIATE_SSL_CODE means pre-7.0 server. These days, such a response is far more likely to signify a server-side problem, such as fork failure. Reporting "server does not support SSL" (in sslmode=require) could be quite misleading. But the results could be even worse in sslmode=prefer: if the problem was transient and the next connection attempt succeeds, we'll have silently fallen back to protocol version 2.0, possibly disabling features the user needs. Hence, it seems best to just eliminate the assumption that backing off to non-SSL/2.0 protocol is the way to recover from an "E" response, and instead treat the server error the same as we would in non-SSL cases. I tested this change against a pre-7.0 server, and found that there was a second logic bug in the "prefer" path: the test to decide whether to make a fallback connection attempt assumed that we must have opened conn->ssl, which in fact does not happen given an "E" response. After fixing that, the code does indeed connect successfully to pre-7.0, as long as you didn't set sslmode=require. (If you did, you get "Unsupported frontend protocol", which isn't completely off base given the server certainly doesn't support SSL.) Since there seems no reason to believe that pre-7.0 servers exist anymore in the wild, back-patch to all supported branches. --- src/interfaces/libpq/fe-connect.c | 44 ++++++++++++------------------- 1 file changed, 17 insertions(+), 27 deletions(-) diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c index bf6aaae761..6803649075 100644 --- a/src/interfaces/libpq/fe-connect.c +++ b/src/interfaces/libpq/fe-connect.c @@ -2022,16 +2022,19 @@ keep_going: /* We will come back to here until there is /* should not happen really */ return PGRES_POLLING_READING; } - /* mark byte consumed */ - conn->inStart = conn->inCursor; if (SSLok == 'S') { + /* mark byte consumed */ + conn->inStart = conn->inCursor; /* Set up global SSL state if required */ if (pqsecure_initialize(conn) != 0) goto error_return; } else if (SSLok == 'N') { + /* mark byte consumed */ + conn->inStart = conn->inCursor; + /* OK to do without SSL? */ if (conn->sslmode[0] == 'r' || /* "require" */ conn->sslmode[0] == 'v') /* "verify-ca" or * "verify-full" */ @@ -2048,29 +2051,17 @@ keep_going: /* We will come back to here until there is } else if (SSLok == 'E') { - /* Received error - probably protocol mismatch */ - if (conn->Pfdebug) - fprintf(conn->Pfdebug, "received error from server, attempting fallback to pre-7.0\n"); - if (conn->sslmode[0] == 'r' || /* "require" */ - conn->sslmode[0] == 'v') /* "verify-ca" or - * "verify-full" */ - { - /* Require SSL, but server is too old */ - appendPQExpBuffer(&conn->errorMessage, - libpq_gettext("server does not support SSL, but SSL was required\n")); - goto error_return; - } - /* Otherwise, try again without SSL */ - conn->allow_ssl_try = false; - /* Assume it ain't gonna handle protocol 3, either */ - conn->pversion = PG_PROTOCOL(2, 0); - /* Must drop the old connection */ - closesocket(conn->sock); - conn->sock = -1; - conn->status = CONNECTION_NEEDED; - /* Discard any unread/unsent data */ - conn->inStart = conn->inCursor = conn->inEnd = 0; - conn->outCount = 0; + /* + * Server failure of some sort, such as failure to + * fork a backend process. We need to process and + * report the error message, which might be formatted + * according to either protocol 2 or protocol 3. + * Rather than duplicate the code for that, we flip + * into AWAITING_RESPONSE state and let the code there + * deal with it. Note we have *not* consumed the "E" + * byte here. + */ + conn->status = CONNECTION_AWAITING_RESPONSE; goto keep_going; } else @@ -2305,8 +2296,7 @@ keep_going: /* We will come back to here until there is * then do a non-SSL retry */ if (conn->sslmode[0] == 'p' /* "prefer" */ - && conn->ssl - && conn->allow_ssl_try /* redundant? */ + && conn->allow_ssl_try && !conn->wait_ssl_try) /* redundant? */ { /* only retry once */