Give nicer error message when connecting to a v10 server requiring SCRAM.

This is just to give the user a hint that they need to upgrade, if they try
to connect to a v10 server that uses SCRAM authentication, with an older
client.

Commit to all stable branches, but not master.

Discussion: https://www.postgresql.org/message-id/bbf45d92-3896-eeb7-7399-2111d517261b@pivotal.io

diff --git a/src/include/libpq/pqcomm.h b/src/include/libpq/pqcomm.h
index c6bbfc237725298c7c8123916a0d39c774b592a2..1d063d12489b60e933825680e46299aeee733486 100644 (file)
--- a/src/include/libpq/pqcomm.h
+++ b/src/include/libpq/pqcomm.h
@@ -172,6 +172,8 @@ extern bool Db_user_namespace;
 #define AUTH_REQ_GSS           7       /* GSSAPI without wrap() */
 #define AUTH_REQ_GSS_CONT      8       /* Continue GSS exchanges */
 #define AUTH_REQ_SSPI          9       /* SSPI negotiate without wrap() */
+#define AUTH_REQ_SASL     10   /* SASL authentication. Not supported before
+                                                                * libpq version 10. */
 
 typedef uint32 AuthRequest;
 

diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c
index 9bf6e52d631258909318895cb6a50516a4f5d65d..493ef82d4a7cefcc29f5437a26f3a63449f1b60c 100644 (file)
--- a/src/interfaces/libpq/fe-auth.c
+++ b/src/interfaces/libpq/fe-auth.c
@@ -703,6 +703,19 @@ pg_fe_sendauth(AuthRequest areq, PGconn *conn)
                                return STATUS_ERROR;
                        break;
 
+                       /*
+                        * SASL authentication was introduced in version 10. Older
+                        * versions recognize the request only to give a nicer error
+                        * message. We call it "SCRAM authentication" in the error, rather
+                        * than SASL, because SCRAM is more familiar to users, and it's
+                        * the only SASL authentication mechanism that has been
+                        * implemented as of this writing, anyway.
+                        */
+               case AUTH_REQ_SASL:
+                       printfPQExpBuffer(&conn->errorMessage,
+                                                         libpq_gettext("SCRAM authentication requires libpq version 10 or above\n"));
+                       return STATUS_ERROR;
+
                default:
                        printfPQExpBuffer(&conn->errorMessage,
                        libpq_gettext("authentication method %u not supported\n"), areq);