Rearrange the code in auth.c so that all functions for a single authentication
authorMagnus Hagander
Fri, 1 Aug 2008 11:41:12 +0000 (11:41 +0000)
committerMagnus Hagander
Fri, 1 Aug 2008 11:41:12 +0000 (11:41 +0000)
method is grouped together in a reasonably similar way, keeping the "global
shared functions" together in their own section as well. Makes it a lot easier
to find your way around the code.

src/backend/libpq/auth.c

index 3470417f241b7ad0da5268f4a37ff19372e8e701..1c50b8e588273259a571be936fa6affdbf2160ad 100644 (file)
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/libpq/auth.c,v 1.166 2008/08/01 09:09:49 mha Exp $
+ *   $PostgreSQL: pgsql/src/backend/libpq/auth.c,v 1.167 2008/08/01 11:41:12 mha Exp $
  *
  *-------------------------------------------------------------------------
  */
 #include "libpq/pqformat.h"
 #include "storage/ipc.h"
 
-
+/*----------------------------------------------------------------
+ * Global authentication functions 
+ *----------------------------------------------------------------
+ */
 static void sendAuthRequest(Port *port, AuthRequest areq);
 static void auth_failed(Port *port, int status);
 static char *recv_password_packet(Port *port);
 static int recv_and_check_password_packet(Port *port);
-static int  authident(hbaPort *port);
 
-char      *pg_krb_server_keyfile;
-char      *pg_krb_srvnam;
-bool       pg_krb_caseins_users;
-char      *pg_krb_server_hostname = NULL;
-char      *pg_krb_realm = NULL;
 
+/*----------------------------------------------------------------
+ * Ident authentication
+ *----------------------------------------------------------------
+ */
 /* Max size of username ident server can return */
 #define IDENT_USERNAME_MAX 512
 
 /* Standard TCP port number for Ident service. Assigned by IANA */
 #define IDENT_PORT 113
 
+static int  authident(hbaPort *port);
+
+
+/*----------------------------------------------------------------
+ * PAM authentication
+ *----------------------------------------------------------------
+ */
 #ifdef USE_PAM
 #ifdef HAVE_PAM_PAM_APPL_H
 #include 
@@ -75,6 +83,11 @@ static Port *pam_port_cludge;    /* Workaround for passing "Port *port" into
                                 * pam_passwd_conv_proc */
 #endif   /* USE_PAM */
 
+
+/*----------------------------------------------------------------
+ * LDAP authentication
+ *----------------------------------------------------------------
+ */
 #ifdef USE_LDAP
 #ifndef WIN32
 /* We use a deprecated function to keep the codepath the same as win32. */
@@ -95,21 +108,33 @@ ULONG(*__ldap_start_tls_sA) (
 #endif
 
 static int CheckLDAPAuth(Port *port);
-#endif
+#endif /* USE_LDAP */
+
+
+/*----------------------------------------------------------------
+ * Kerberos and GSSAPI GUCs
+ *----------------------------------------------------------------
+ */
+char      *pg_krb_server_keyfile;
+char      *pg_krb_srvnam;
+bool       pg_krb_caseins_users;
+char      *pg_krb_server_hostname = NULL;
+char      *pg_krb_realm = NULL;
 
 
-#ifdef KRB5
 /*----------------------------------------------------------------
  * MIT Kerberos authentication system - protocol version 5
  *----------------------------------------------------------------
  */
+static int pg_krb5_recvauth(Port *port);
+
+#ifdef KRB5
 
 #include 
 /* Some old versions of Kerberos do not include  in  */
 #if !defined(__COM_ERR_H) && !defined(__COM_ERR_H__)
 #include 
 #endif
-
 /*
  * Various krb5 state which is not connection specfic, and a flag to
  * indicate whether we have initialised it yet.
@@ -118,458 +143,549 @@ static int  pg_krb5_initialised;
 static krb5_context pg_krb5_context;
 static krb5_keytab pg_krb5_keytab;
 static krb5_principal pg_krb5_server;
+#endif /* KRB5 */
 
 
-static int
-pg_krb5_init(void)
-{
-   krb5_error_code retval;
-   char       *khostname;
+/*----------------------------------------------------------------
+ * GSSAPI Authentication
+ *----------------------------------------------------------------
+ */
+static int pg_GSS_recvauth(Port *port);
 
-   if (pg_krb5_initialised)
-       return STATUS_OK;
+#ifdef ENABLE_GSS
+#if defined(HAVE_GSSAPI_H)
+#include 
+#else
+#include 
+#endif
+#endif /* ENABLE_GSS */
 
-   retval = krb5_init_context(&pg_krb5_context);
-   if (retval)
-   {
-       ereport(LOG,
-               (errmsg("Kerberos initialization returned error %d",
-                       retval)));
-       com_err("postgres", retval, "while initializing krb5");
-       return STATUS_ERROR;
-   }
 
-   retval = krb5_kt_resolve(pg_krb5_context, pg_krb_server_keyfile, &pg_krb5_keytab);
-   if (retval)
-   {
-       ereport(LOG,
-               (errmsg("Kerberos keytab resolving returned error %d",
-                       retval)));
-       com_err("postgres", retval, "while resolving keytab file \"%s\"",
-               pg_krb_server_keyfile);
-       krb5_free_context(pg_krb5_context);
-       return STATUS_ERROR;
-   }
+/*----------------------------------------------------------------
+ * SSPI Authentication
+ *----------------------------------------------------------------
+ */
+static int pg_SSPI_recvauth(Port *port);
 
-   /*
-    * If no hostname was specified, pg_krb_server_hostname is already NULL.
-    * If it's set to blank, force it to NULL.
-    */
-   khostname = pg_krb_server_hostname;
-   if (khostname && khostname[0] == '\0')
-       khostname = NULL;
+#ifdef ENABLE_SSPI
+typedef        SECURITY_STATUS
+           (WINAPI * QUERY_SECURITY_CONTEXT_TOKEN_FN) (
+                                                      PCtxtHandle, void **);
+#endif
 
-   retval = krb5_sname_to_principal(pg_krb5_context,
-                                    khostname,
-                                    pg_krb_srvnam,
-                                    KRB5_NT_SRV_HST,
-                                    &pg_krb5_server);
-   if (retval)
-   {
-       ereport(LOG,
-               (errmsg("Kerberos sname_to_principal(\"%s\", \"%s\") returned error %d",
-        khostname ? khostname : "server hostname", pg_krb_srvnam, retval)));
-       com_err("postgres", retval,
-       "while getting server principal for server \"%s\" for service \"%s\"",
-               khostname ? khostname : "server hostname", pg_krb_srvnam);
-       krb5_kt_close(pg_krb5_context, pg_krb5_keytab);
-       krb5_free_context(pg_krb5_context);
-       return STATUS_ERROR;
-   }
 
-   pg_krb5_initialised = 1;
-   return STATUS_OK;
-}
+
+/*----------------------------------------------------------------
+ * Global authentication functions
+ *----------------------------------------------------------------
+ */
 
 
 /*
- * pg_krb5_recvauth -- server routine to receive authentication information
- *                    from the client
- *
- * We still need to compare the username obtained from the client's setup
- * packet to the authenticated name.
+ * Tell the user the authentication failed, but not (much about) why.
  *
- * We have our own keytab file because postgres is unlikely to run as root,
- * and so cannot read the default keytab.
+ * There is a tradeoff here between security concerns and making life
+ * unnecessarily difficult for legitimate users.  We would not, for example,
+ * want to report the password we were expecting to receive...
+ * But it seems useful to report the username and authorization method
+ * in use, and these are items that must be presumed known to an attacker
+ * anyway.
+ * Note that many sorts of failure report additional information in the
+ * postmaster log, which we hope is only readable by good guys.
  */
-static int
-pg_krb5_recvauth(Port *port)
+static void
+auth_failed(Port *port, int status)
 {
-   krb5_error_code retval;
-   int         ret;
-   krb5_auth_context auth_context = NULL;
-   krb5_ticket *ticket;
-   char       *kusername;
-   char       *cp;
-
-   if (get_role_line(port->user_name) == NULL)
-       return STATUS_ERROR;
+   const char *errstr;
 
-   ret = pg_krb5_init();
-   if (ret != STATUS_OK)
-       return ret;
+   /*
+    * If we failed due to EOF from client, just quit; there's no point in
+    * trying to send a message to the client, and not much point in logging
+    * the failure in the postmaster log.  (Logging the failure might be
+    * desirable, were it not for the fact that libpq closes the connection
+    * unceremoniously if challenged for a password when it hasn't got one to
+    * send.  We'll get a useless log entry for every psql connection under
+    * password auth, even if it's perfectly successful, if we log STATUS_EOF
+    * events.)
+    */
+   if (status == STATUS_EOF)
+       proc_exit(0);
 
-   retval = krb5_recvauth(pg_krb5_context, &auth_context,
-                          (krb5_pointer) & port->sock, pg_krb_srvnam,
-                          pg_krb5_server, 0, pg_krb5_keytab, &ticket);
-   if (retval)
+   switch (port->auth_method)
    {
-       ereport(LOG,
-               (errmsg("Kerberos recvauth returned error %d",
-                       retval)));
-       com_err("postgres", retval, "from krb5_recvauth");
-       return STATUS_ERROR;
+       case uaReject:
+           errstr = gettext_noop("authentication failed for user \"%s\": host rejected");
+           break;
+       case uaKrb5:
+           errstr = gettext_noop("Kerberos 5 authentication failed for user \"%s\"");
+           break;
+       case uaGSS:
+           errstr = gettext_noop("GSSAPI authentication failed for user \"%s\"");
+           break;
+       case uaSSPI:
+           errstr = gettext_noop("SSPI authentication failed for user \"%s\"");
+           break;
+       case uaTrust:
+           errstr = gettext_noop("\"trust\" authentication failed for user \"%s\"");
+           break;
+       case uaIdent:
+           errstr = gettext_noop("Ident authentication failed for user \"%s\"");
+           break;
+       case uaMD5:
+       case uaCrypt:
+       case uaPassword:
+           errstr = gettext_noop("password authentication failed for user \"%s\"");
+           break;
+#ifdef USE_PAM
+       case uaPAM:
+           errstr = gettext_noop("PAM authentication failed for user \"%s\"");
+           break;
+#endif   /* USE_PAM */
+#ifdef USE_LDAP
+       case uaLDAP:
+           errstr = gettext_noop("LDAP authentication failed for user \"%s\"");
+           break;
+#endif   /* USE_LDAP */
+       default:
+           errstr = gettext_noop("authentication failed for user \"%s\": invalid authentication method");
+           break;
    }
 
+   ereport(FATAL,
+           (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
+            errmsg(errstr, port->user_name)));
+   /* doesn't return */
+}
+
+
+/*
+ * Client authentication starts here.  If there is an error, this
+ * function does not return and the backend process is terminated.
+ */
+void
+ClientAuthentication(Port *port)
+{
+   int         status = STATUS_ERROR;
+
    /*
-    * The "client" structure comes out of the ticket and is therefore
-    * authenticated.  Use it to check the username obtained from the
-    * postmaster startup packet.
+    * Get the authentication method to use for this frontend/database
+    * combination.  Note: a failure return indicates a problem with the hba
+    * config file, not with the request.  hba.c should have dropped an error
+    * message into the postmaster logfile if it failed.
     */
-#if defined(HAVE_KRB5_TICKET_ENC_PART2)
-   retval = krb5_unparse_name(pg_krb5_context,
-                              ticket->enc_part2->client, &kusername);
-#elif defined(HAVE_KRB5_TICKET_CLIENT)
-   retval = krb5_unparse_name(pg_krb5_context,
-                              ticket->client, &kusername);
-#else
-#error "bogus configuration"
-#endif
-   if (retval)
-   {
-       ereport(LOG,
-               (errmsg("Kerberos unparse_name returned error %d",
-                       retval)));
-       com_err("postgres", retval, "while unparsing client name");
-       krb5_free_ticket(pg_krb5_context, ticket);
-       krb5_auth_con_free(pg_krb5_context, auth_context);
-       return STATUS_ERROR;
-   }
+   if (hba_getauthmethod(port) != STATUS_OK)
+       ereport(FATAL,
+               (errcode(ERRCODE_CONFIG_FILE_ERROR),
+                errmsg("missing or erroneous pg_hba.conf file"),
+                errhint("See server log for details.")));
 
-   cp = strchr(kusername, '@');
-   if (cp)
+   switch (port->auth_method)
    {
-       *cp = '\0';
-       cp++;
-
-       if (pg_krb_realm != NULL && strlen(pg_krb_realm))
-       {
-           /* Match realm against configured */
-           if (pg_krb_caseins_users)
-               ret = pg_strcasecmp(pg_krb_realm, cp);
-           else
-               ret = strcmp(pg_krb_realm, cp);
+       case uaReject:
 
-           if (ret)
+           /*
+            * This could have come from an explicit "reject" entry in
+            * pg_hba.conf, but more likely it means there was no matching
+            * entry.  Take pity on the poor user and issue a helpful error
+            * message.  NOTE: this is not a security breach, because all the
+            * info reported here is known at the frontend and must be assumed
+            * known to bad guys. We're merely helping out the less clueful
+            * good guys.
+            */
            {
-               elog(DEBUG2,
-                    "krb5 realm (%s) and configured realm (%s) don't match",
-                    cp, pg_krb_realm);
+               char        hostinfo[NI_MAXHOST];
 
-               krb5_free_ticket(pg_krb5_context, ticket);
-               krb5_auth_con_free(pg_krb5_context, auth_context);
-               return STATUS_ERROR;
+               pg_getnameinfo_all(&port->raddr.addr, port->raddr.salen,
+                                  hostinfo, sizeof(hostinfo),
+                                  NULL, 0,
+                                  NI_NUMERICHOST);
+
+#ifdef USE_SSL
+               ereport(FATAL,
+                       (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
+                        errmsg("no pg_hba.conf entry for host \"%s\", user \"%s\", database \"%s\", %s",
+                             hostinfo, port->user_name, port->database_name,
+                               port->ssl ? _("SSL on") : _("SSL off"))));
+#else
+               ereport(FATAL,
+                       (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
+                        errmsg("no pg_hba.conf entry for host \"%s\", user \"%s\", database \"%s\"",
+                          hostinfo, port->user_name, port->database_name)));
+#endif
+               break;
            }
-       }
-   }
-   else if (pg_krb_realm && strlen(pg_krb_realm))
-   {
-       elog(DEBUG2,
-            "krb5 did not return realm but realm matching was requested");
 
-       krb5_free_ticket(pg_krb5_context, ticket);
-       krb5_auth_con_free(pg_krb5_context, auth_context);
-       return STATUS_ERROR;
-   }
+       case uaKrb5:
+           sendAuthRequest(port, AUTH_REQ_KRB5);
+           status = pg_krb5_recvauth(port);
+           break;
 
-   if (pg_krb_caseins_users)
-       ret = pg_strncasecmp(port->user_name, kusername, SM_DATABASE_USER);
-   else
-       ret = strncmp(port->user_name, kusername, SM_DATABASE_USER);
-   if (ret)
-   {
-       ereport(LOG,
-               (errmsg("unexpected Kerberos user name received from client (received \"%s\", expected \"%s\")",
-                       port->user_name, kusername)));
-       ret = STATUS_ERROR;
-   }
-   else
-       ret = STATUS_OK;
+       case uaGSS:
+           sendAuthRequest(port, AUTH_REQ_GSS);
+           status = pg_GSS_recvauth(port);
+           break;
 
-   krb5_free_ticket(pg_krb5_context, ticket);
-   krb5_auth_con_free(pg_krb5_context, auth_context);
-   free(kusername);
+       case uaSSPI:
+           sendAuthRequest(port, AUTH_REQ_SSPI);
+           status = pg_SSPI_recvauth(port);
+           break;
 
-   return ret;
-}
-#else
+       case uaIdent:
 
-static int
-pg_krb5_recvauth(Port *port)
-{
-   ereport(LOG,
-           (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-            errmsg("Kerberos 5 not implemented on this server")));
-   return STATUS_ERROR;
-}
-#endif   /* KRB5 */
+           /*
+            * If we are doing ident on unix-domain sockets, use SCM_CREDS
+            * only if it is defined and SO_PEERCRED isn't.
+            */
+#if !defined(HAVE_GETPEEREID) && !defined(SO_PEERCRED) && \
+   (defined(HAVE_STRUCT_CMSGCRED) || defined(HAVE_STRUCT_FCRED) || \
+    (defined(HAVE_STRUCT_SOCKCRED) && defined(LOCAL_CREDS)))
+           if (port->raddr.addr.ss_family == AF_UNIX)
+           {
+#if defined(HAVE_STRUCT_FCRED) || defined(HAVE_STRUCT_SOCKCRED)
 
-/*----------------------------------------------------------------
- * GSSAPI authentication system
- *----------------------------------------------------------------
- */
+               /*
+                * Receive credentials on next message receipt, BSD/OS,
+                * NetBSD. We need to set this before the client sends the
+                * next packet.
+                */
+               int         on = 1;
 
-#ifdef ENABLE_GSS
+               if (setsockopt(port->sock, 0, LOCAL_CREDS, &on, sizeof(on)) < 0)
+                   ereport(FATAL,
+                           (errcode_for_socket_access(),
+                      errmsg("could not enable credential reception: %m")));
+#endif
 
-#if defined(HAVE_GSSAPI_H)
-#include 
-#else
-#include 
+               sendAuthRequest(port, AUTH_REQ_SCM_CREDS);
+           }
 #endif
+           status = authident(port);
+           break;
 
-#if defined(WIN32) && !defined(WIN32_ONLY_COMPILER)
-/*
- * MIT Kerberos GSSAPI DLL doesn't properly export the symbols for MingW
- * that contain the OIDs required. Redefine here, values copied
- * from src/athena/auth/krb5/src/lib/gssapi/generic/gssapi_generic.c
- */
-static const gss_OID_desc GSS_C_NT_USER_NAME_desc =
-{10, (void *) "\x2a\x86\x48\x86\xf7\x12\x01\x02\x01\x02"};
-static GSS_DLLIMP gss_OID GSS_C_NT_USER_NAME = &GSS_C_NT_USER_NAME_desc;
+       case uaMD5:
+           sendAuthRequest(port, AUTH_REQ_MD5);
+           status = recv_and_check_password_packet(port);
+           break;
+
+       case uaCrypt:
+           sendAuthRequest(port, AUTH_REQ_CRYPT);
+           status = recv_and_check_password_packet(port);
+           break;
+
+       case uaPassword:
+           sendAuthRequest(port, AUTH_REQ_PASSWORD);
+           status = recv_and_check_password_packet(port);
+           break;
+
+#ifdef USE_PAM
+       case uaPAM:
+           pam_port_cludge = port;
+           status = CheckPAMAuth(port, port->user_name, "");
+           break;
+#endif   /* USE_PAM */
+
+#ifdef USE_LDAP
+       case uaLDAP:
+           status = CheckLDAPAuth(port);
+           break;
 #endif
 
+       case uaTrust:
+           status = STATUS_OK;
+           break;
+   }
+
+   if (status == STATUS_OK)
+       sendAuthRequest(port, AUTH_REQ_OK);
+   else
+       auth_failed(port, status);
+}
+
 
+/*
+ * Send an authentication request packet to the frontend.
+ */
 static void
-pg_GSS_error(int severity, char *errmsg, OM_uint32 maj_stat, OM_uint32 min_stat)
+sendAuthRequest(Port *port, AuthRequest areq)
 {
-   gss_buffer_desc gmsg;
-   OM_uint32   lmaj_s,
-               lmin_s,
-               msg_ctx;
-   char        msg_major[128],
-               msg_minor[128];
+   StringInfoData buf;
 
-   /* Fetch major status message */
-   msg_ctx = 0;
-   lmaj_s = gss_display_status(&lmin_s, maj_stat, GSS_C_GSS_CODE,
-                               GSS_C_NO_OID, &msg_ctx, &gmsg);
-   strlcpy(msg_major, gmsg.value, sizeof(msg_major));
-   gss_release_buffer(&lmin_s, &gmsg);
+   pq_beginmessage(&buf, 'R');
+   pq_sendint(&buf, (int32) areq, sizeof(int32));
 
-   if (msg_ctx)
+   /* Add the salt for encrypted passwords. */
+   if (areq == AUTH_REQ_MD5)
+       pq_sendbytes(&buf, port->md5Salt, 4);
+   else if (areq == AUTH_REQ_CRYPT)
+       pq_sendbytes(&buf, port->cryptSalt, 2);
 
-       /*
-        * More than one message available. XXX: Should we loop and read all
-        * messages? (same below)
-        */
-       ereport(WARNING,
-               (errmsg_internal("incomplete GSS error report")));
+#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
 
-   /* Fetch mechanism minor status message */
-   msg_ctx = 0;
-   lmaj_s = gss_display_status(&lmin_s, min_stat, GSS_C_MECH_CODE,
-                               GSS_C_NO_OID, &msg_ctx, &gmsg);
-   strlcpy(msg_minor, gmsg.value, sizeof(msg_minor));
-   gss_release_buffer(&lmin_s, &gmsg);
+   /*
+    * Add the authentication data for the next step of the GSSAPI or SSPI
+    * negotiation.
+    */
+   else if (areq == AUTH_REQ_GSS_CONT)
+   {
+       if (port->gss->outbuf.length > 0)
+       {
+           elog(DEBUG4, "sending GSS token of length %u",
+                (unsigned int) port->gss->outbuf.length);
 
-   if (msg_ctx)
-       ereport(WARNING,
-               (errmsg_internal("incomplete GSS minor error report")));
+           pq_sendbytes(&buf, port->gss->outbuf.value, port->gss->outbuf.length);
+       }
+   }
+#endif
+
+   pq_endmessage(&buf);
 
    /*
-    * errmsg_internal, since translation of the first part must be done
-    * before calling this function anyway.
+    * Flush message so client will see it, except for AUTH_REQ_OK, which need
+    * not be sent until we are ready for queries.
     */
-   ereport(severity,
-           (errmsg_internal("%s", errmsg),
-            errdetail("%s: %s", msg_major, msg_minor)));
+   if (areq != AUTH_REQ_OK)
+       pq_flush();
 }
 
-static int
-pg_GSS_recvauth(Port *port)
+/*
+ * Collect password response packet from frontend.
+ *
+ * Returns NULL if couldn't get password, else palloc'd string.
+ */
+static char *
+recv_password_packet(Port *port)
 {
-   OM_uint32   maj_stat,
-               min_stat,
-               lmin_s,
-               gflags;
-   int         mtype;
-   int         ret;
    StringInfoData buf;
-   gss_buffer_desc gbuf;
-
-   /*
-    * GSS auth is not supported for protocol versions before 3, because it
-    * relies on the overall message length word to determine the GSS payload
-    * size in AuthenticationGSSContinue and PasswordMessage messages.
-    * (This is, in fact, a design error in our GSS support, because protocol
-    * messages are supposed to be parsable without relying on the length
-    * word; but it's not worth changing it now.)
-    */
-   if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
-       ereport(FATAL,
-               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-                errmsg("GSSAPI is not supported in protocol version 2")));
 
-   if (pg_krb_server_keyfile && strlen(pg_krb_server_keyfile) > 0)
+   if (PG_PROTOCOL_MAJOR(port->proto) >= 3)
    {
-       /*
-        * Set default Kerberos keytab file for the Krb5 mechanism.
-        *
-        * setenv("KRB5_KTNAME", pg_krb_server_keyfile, 0); except setenv()
-        * not always available.
-        */
-       if (getenv("KRB5_KTNAME") == NULL)
-       {
-           size_t  kt_len = strlen(pg_krb_server_keyfile) + 14;
-           char   *kt_path = malloc(kt_len);
+       /* Expect 'p' message type */
+       int         mtype;
 
-           if (!kt_path)
-           {
-               ereport(LOG,
-                       (errcode(ERRCODE_OUT_OF_MEMORY),
-                        errmsg("out of memory")));
-               return STATUS_ERROR;
-           }
-           snprintf(kt_path, kt_len, "KRB5_KTNAME=%s", pg_krb_server_keyfile);
-           putenv(kt_path);
+       mtype = pq_getbyte();
+       if (mtype != 'p')
+       {
+           /*
+            * If the client just disconnects without offering a password,
+            * don't make a log entry.  This is legal per protocol spec and in
+            * fact commonly done by psql, so complaining just clutters the
+            * log.
+            */
+           if (mtype != EOF)
+               ereport(COMMERROR,
+                       (errcode(ERRCODE_PROTOCOL_VIOLATION),
+                   errmsg("expected password response, got message type %d",
+                          mtype)));
+           return NULL;        /* EOF or bad message type */
        }
    }
+   else
+   {
+       /* For pre-3.0 clients, avoid log entry if they just disconnect */
+       if (pq_peekbyte() == EOF)
+           return NULL;        /* EOF */
+   }
 
-   /*
-    * We accept any service principal that's present in our keytab. This
-    * increases interoperability between kerberos implementations that see
-    * for example case sensitivity differently, while not really opening up
-    * any vector of attack.
-    */
-   port->gss->cred = GSS_C_NO_CREDENTIAL;
+   initStringInfo(&buf);
+   if (pq_getmessage(&buf, 1000))      /* receive password */
+   {
+       /* EOF - pq_getmessage already logged a suitable message */
+       pfree(buf.data);
+       return NULL;
+   }
 
    /*
-    * Initialize sequence with an empty context
+    * Apply sanity check: password packet length should agree with length of
+    * contained string.  Note it is safe to use strlen here because
+    * StringInfo is guaranteed to have an appended '\0'.
     */
-   port->gss->ctx = GSS_C_NO_CONTEXT;
+   if (strlen(buf.data) + 1 != buf.len)
+       ereport(COMMERROR,
+               (errcode(ERRCODE_PROTOCOL_VIOLATION),
+                errmsg("invalid password packet size")));
+
+   /* Do not echo password to logs, for security. */
+   ereport(DEBUG5,
+           (errmsg("received password packet")));
 
    /*
-    * Loop through GSSAPI message exchange. This exchange can consist of
-    * multiple messags sent in both directions. First message is always from
-    * the client. All messages from client to server are password packets
-    * (type 'p').
+    * Return the received string.  Note we do not attempt to do any
+    * character-set conversion on it; since we don't yet know the client's
+    * encoding, there wouldn't be much point.
     */
-   do
-   {
-       mtype = pq_getbyte();
-       if (mtype != 'p')
-       {
-           /* Only log error if client didn't disconnect. */
-           if (mtype != EOF)
-               ereport(COMMERROR,
-                       (errcode(ERRCODE_PROTOCOL_VIOLATION),
-                        errmsg("expected GSS response, got message type %d",
-                               mtype)));
-           return STATUS_ERROR;
-       }
-
-       /* Get the actual GSS token */
-       initStringInfo(&buf);
-       if (pq_getmessage(&buf, 2000))
-       {
-           /* EOF - pq_getmessage already logged error */
-           pfree(buf.data);
-           return STATUS_ERROR;
-       }
+   return buf.data;
+}
 
-       /* Map to GSSAPI style buffer */
-       gbuf.length = buf.len;
-       gbuf.value = buf.data;
 
-       elog(DEBUG4, "Processing received GSS token of length %u",
-            (unsigned int) gbuf.length);
+/*----------------------------------------------------------------
+ * MD5 and crypt authentication
+ *----------------------------------------------------------------
+ */
 
-       maj_stat = gss_accept_sec_context(
-                                         &min_stat,
-                                         &port->gss->ctx,
-                                         port->gss->cred,
-                                         &gbuf,
-                                         GSS_C_NO_CHANNEL_BINDINGS,
-                                         &port->gss->name,
-                                         NULL,
-                                         &port->gss->outbuf,
-                                         &gflags,
-                                         NULL,
-                                         NULL);
+/*
+ * Called when we have sent an authorization request for a password.
+ * Get the response and check it.
+ */
+static int
+recv_and_check_password_packet(Port *port)
+{
+   char       *passwd;
+   int         result;
 
-       /* gbuf no longer used */
-       pfree(buf.data);
+   passwd = recv_password_packet(port);
 
-       elog(DEBUG5, "gss_accept_sec_context major: %d, "
-            "minor: %d, outlen: %u, outflags: %x",
-            maj_stat, min_stat,
-            (unsigned int) port->gss->outbuf.length, gflags);
+   if (passwd == NULL)
+       return STATUS_EOF;      /* client wouldn't send password */
 
-       if (port->gss->outbuf.length != 0)
-       {
-           /*
-            * Negotiation generated data to be sent to the client.
-            */
-           OM_uint32   lmin_s;
+   result = md5_crypt_verify(port, port->user_name, passwd);
 
-           elog(DEBUG4, "sending GSS response token of length %u",
-                (unsigned int) port->gss->outbuf.length);
+   pfree(passwd);
 
-           sendAuthRequest(port, AUTH_REQ_GSS_CONT);
+   return result;
+}
 
-           gss_release_buffer(&lmin_s, &port->gss->outbuf);
-       }
 
-       if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED)
-       {
-           OM_uint32   lmin_s;
+/*----------------------------------------------------------------
+ * MIT Kerberos authentication system - protocol version 5
+ *----------------------------------------------------------------
+ */
+#ifdef KRB5
 
-           gss_delete_sec_context(&lmin_s, &port->gss->ctx, GSS_C_NO_BUFFER);
-           pg_GSS_error(ERROR,
-                      gettext_noop("accepting GSS security context failed"),
-                        maj_stat, min_stat);
-       }
+static int
+pg_krb5_init(void)
+{
+   krb5_error_code retval;
+   char       *khostname;
 
-       if (maj_stat == GSS_S_CONTINUE_NEEDED)
-           elog(DEBUG4, "GSS continue needed");
+   if (pg_krb5_initialised)
+       return STATUS_OK;
 
-   } while (maj_stat == GSS_S_CONTINUE_NEEDED);
+   retval = krb5_init_context(&pg_krb5_context);
+   if (retval)
+   {
+       ereport(LOG,
+               (errmsg("Kerberos initialization returned error %d",
+                       retval)));
+       com_err("postgres", retval, "while initializing krb5");
+       return STATUS_ERROR;
+   }
 
-   if (port->gss->cred != GSS_C_NO_CREDENTIAL)
+   retval = krb5_kt_resolve(pg_krb5_context, pg_krb_server_keyfile, &pg_krb5_keytab);
+   if (retval)
    {
-       /*
-        * Release service principal credentials
-        */
-       gss_release_cred(&min_stat, &port->gss->cred);
+       ereport(LOG,
+               (errmsg("Kerberos keytab resolving returned error %d",
+                       retval)));
+       com_err("postgres", retval, "while resolving keytab file \"%s\"",
+               pg_krb_server_keyfile);
+       krb5_free_context(pg_krb5_context);
+       return STATUS_ERROR;
    }
 
    /*
-    * GSS_S_COMPLETE indicates that authentication is now complete.
-    *
-    * Get the name of the user that authenticated, and compare it to the pg
-    * username that was specified for the connection.
+    * If no hostname was specified, pg_krb_server_hostname is already NULL.
+    * If it's set to blank, force it to NULL.
     */
-   maj_stat = gss_display_name(&min_stat, port->gss->name, &gbuf, NULL);
-   if (maj_stat != GSS_S_COMPLETE)
-       pg_GSS_error(ERROR,
-                    gettext_noop("retrieving GSS user name failed"),
-                    maj_stat, min_stat);
+   khostname = pg_krb_server_hostname;
+   if (khostname && khostname[0] == '\0')
+       khostname = NULL;
 
-   /*
-    * Split the username at the realm separator
-    */
-   if (strchr(gbuf.value, '@'))
+   retval = krb5_sname_to_principal(pg_krb5_context,
+                                    khostname,
+                                    pg_krb_srvnam,
+                                    KRB5_NT_SRV_HST,
+                                    &pg_krb5_server);
+   if (retval)
    {
-       char       *cp = strchr(gbuf.value, '@');
+       ereport(LOG,
+               (errmsg("Kerberos sname_to_principal(\"%s\", \"%s\") returned error %d",
+        khostname ? khostname : "server hostname", pg_krb_srvnam, retval)));
+       com_err("postgres", retval,
+       "while getting server principal for server \"%s\" for service \"%s\"",
+               khostname ? khostname : "server hostname", pg_krb_srvnam);
+       krb5_kt_close(pg_krb5_context, pg_krb5_keytab);
+       krb5_free_context(pg_krb5_context);
+       return STATUS_ERROR;
+   }
 
-       *cp = '\0';
-       cp++;
+   pg_krb5_initialised = 1;
+   return STATUS_OK;
+}
+
+
+/*
+ * pg_krb5_recvauth -- server routine to receive authentication information
+ *                    from the client
+ *
+ * We still need to compare the username obtained from the client's setup
+ * packet to the authenticated name.
+ *
+ * We have our own keytab file because postgres is unlikely to run as root,
+ * and so cannot read the default keytab.
+ */
+static int
+pg_krb5_recvauth(Port *port)
+{
+   krb5_error_code retval;
+   int         ret;
+   krb5_auth_context auth_context = NULL;
+   krb5_ticket *ticket;
+   char       *kusername;
+   char       *cp;
+
+   if (get_role_line(port->user_name) == NULL)
+       return STATUS_ERROR;
+
+   ret = pg_krb5_init();
+   if (ret != STATUS_OK)
+       return ret;
+
+   retval = krb5_recvauth(pg_krb5_context, &auth_context,
+                          (krb5_pointer) & port->sock, pg_krb_srvnam,
+                          pg_krb5_server, 0, pg_krb5_keytab, &ticket);
+   if (retval)
+   {
+       ereport(LOG,
+               (errmsg("Kerberos recvauth returned error %d",
+                       retval)));
+       com_err("postgres", retval, "from krb5_recvauth");
+       return STATUS_ERROR;
+   }
+
+   /*
+    * The "client" structure comes out of the ticket and is therefore
+    * authenticated.  Use it to check the username obtained from the
+    * postmaster startup packet.
+    */
+#if defined(HAVE_KRB5_TICKET_ENC_PART2)
+   retval = krb5_unparse_name(pg_krb5_context,
+                              ticket->enc_part2->client, &kusername);
+#elif defined(HAVE_KRB5_TICKET_CLIENT)
+   retval = krb5_unparse_name(pg_krb5_context,
+                              ticket->client, &kusername);
+#else
+#error "bogus configuration"
+#endif
+   if (retval)
+   {
+       ereport(LOG,
+               (errmsg("Kerberos unparse_name returned error %d",
+                       retval)));
+       com_err("postgres", retval, "while unparsing client name");
+       krb5_free_ticket(pg_krb5_context, ticket);
+       krb5_auth_con_free(pg_krb5_context, auth_context);
+       return STATUS_ERROR;
+   }
+
+   cp = strchr(kusername, '@');
+   if (cp)
+   {
+       *cp = '\0';
+       cp++;
 
        if (pg_krb_realm != NULL && strlen(pg_krb_realm))
        {
-           /*
-            * Match the realm part of the name first
-            */
+           /* Match realm against configured */
            if (pg_krb_caseins_users)
                ret = pg_strcasecmp(pg_krb_realm, cp);
            else
@@ -577,11 +693,12 @@ pg_GSS_recvauth(Port *port)
 
            if (ret)
            {
-               /* GSS realm does not match */
                elog(DEBUG2,
-                  "GSSAPI realm (%s) and configured realm (%s) don't match",
+                    "krb5 realm (%s) and configured realm (%s) don't match",
                     cp, pg_krb_realm);
-               gss_release_buffer(&lmin_s, &gbuf);
+
+               krb5_free_ticket(pg_krb5_context, ticket);
+               krb5_auth_con_free(pg_krb5_context, auth_context);
                return STATUS_ERROR;
            }
        }
@@ -589,116 +706,419 @@ pg_GSS_recvauth(Port *port)
    else if (pg_krb_realm && strlen(pg_krb_realm))
    {
        elog(DEBUG2,
-            "GSSAPI did not return realm but realm matching was requested");
+            "krb5 did not return realm but realm matching was requested");
 
-       gss_release_buffer(&lmin_s, &gbuf);
+       krb5_free_ticket(pg_krb5_context, ticket);
+       krb5_auth_con_free(pg_krb5_context, auth_context);
        return STATUS_ERROR;
    }
 
    if (pg_krb_caseins_users)
-       ret = pg_strcasecmp(port->user_name, gbuf.value);
+       ret = pg_strncasecmp(port->user_name, kusername, SM_DATABASE_USER);
    else
-       ret = strcmp(port->user_name, gbuf.value);
-
+       ret = strncmp(port->user_name, kusername, SM_DATABASE_USER);
    if (ret)
    {
-       /* GSS name and PGUSER are not equivalent */
-       elog(DEBUG2,
-            "provided username (%s) and GSSAPI username (%s) don't match",
-            port->user_name, (char *) gbuf.value);
-
-       gss_release_buffer(&lmin_s, &gbuf);
-       return STATUS_ERROR;
+       ereport(LOG,
+               (errmsg("unexpected Kerberos user name received from client (received \"%s\", expected \"%s\")",
+                       port->user_name, kusername)));
+       ret = STATUS_ERROR;
    }
+   else
+       ret = STATUS_OK;
 
-   gss_release_buffer(&lmin_s, &gbuf);
+   krb5_free_ticket(pg_krb5_context, ticket);
+   krb5_auth_con_free(pg_krb5_context, auth_context);
+   free(kusername);
 
-   return STATUS_OK;
+   return ret;
 }
-
-#else                          /* no ENABLE_GSS */
+#else
 
 static int
-pg_GSS_recvauth(Port *port)
+pg_krb5_recvauth(Port *port)
 {
    ereport(LOG,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-            errmsg("GSSAPI not implemented on this server")));
+            errmsg("Kerberos 5 not implemented on this server")));
    return STATUS_ERROR;
 }
+#endif   /* KRB5 */
 
-#endif   /* ENABLE_GSS */
 
 /*----------------------------------------------------------------
- * SSPI authentication system
+ * GSSAPI authentication system
  *----------------------------------------------------------------
  */
+#ifdef ENABLE_GSS
 
-#ifdef ENABLE_SSPI
+#if defined(WIN32) && !defined(WIN32_ONLY_COMPILER)
+/*
+ * MIT Kerberos GSSAPI DLL doesn't properly export the symbols for MingW
+ * that contain the OIDs required. Redefine here, values copied
+ * from src/athena/auth/krb5/src/lib/gssapi/generic/gssapi_generic.c
+ */
+static const gss_OID_desc GSS_C_NT_USER_NAME_desc =
+{10, (void *) "\x2a\x86\x48\x86\xf7\x12\x01\x02\x01\x02"};
+static GSS_DLLIMP gss_OID GSS_C_NT_USER_NAME = &GSS_C_NT_USER_NAME_desc;
+#endif
 
-typedef        SECURITY_STATUS
-           (WINAPI * QUERY_SECURITY_CONTEXT_TOKEN_FN) (
-                                                      PCtxtHandle, void **);
 
 static void
-pg_SSPI_error(int severity, char *errmsg, SECURITY_STATUS r)
+pg_GSS_error(int severity, char *errmsg, OM_uint32 maj_stat, OM_uint32 min_stat)
 {
-   char        sysmsg[256];
+   gss_buffer_desc gmsg;
+   OM_uint32   lmaj_s,
+               lmin_s,
+               msg_ctx;
+   char        msg_major[128],
+               msg_minor[128];
 
-   if (FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, r, 0, sysmsg, sizeof(sysmsg), NULL) == 0)
-       ereport(severity,
-               (errmsg_internal("%s", errmsg),
-                errdetail("SSPI error %x", (unsigned int) r)));
-   else
-       ereport(severity,
-               (errmsg_internal("%s", errmsg),
-                errdetail("%s (%x)", sysmsg, (unsigned int) r)));
+   /* Fetch major status message */
+   msg_ctx = 0;
+   lmaj_s = gss_display_status(&lmin_s, maj_stat, GSS_C_GSS_CODE,
+                               GSS_C_NO_OID, &msg_ctx, &gmsg);
+   strlcpy(msg_major, gmsg.value, sizeof(msg_major));
+   gss_release_buffer(&lmin_s, &gmsg);
+
+   if (msg_ctx)
+
+       /*
+        * More than one message available. XXX: Should we loop and read all
+        * messages? (same below)
+        */
+       ereport(WARNING,
+               (errmsg_internal("incomplete GSS error report")));
+
+   /* Fetch mechanism minor status message */
+   msg_ctx = 0;
+   lmaj_s = gss_display_status(&lmin_s, min_stat, GSS_C_MECH_CODE,
+                               GSS_C_NO_OID, &msg_ctx, &gmsg);
+   strlcpy(msg_minor, gmsg.value, sizeof(msg_minor));
+   gss_release_buffer(&lmin_s, &gmsg);
+
+   if (msg_ctx)
+       ereport(WARNING,
+               (errmsg_internal("incomplete GSS minor error report")));
+
+   /*
+    * errmsg_internal, since translation of the first part must be done
+    * before calling this function anyway.
+    */
+   ereport(severity,
+           (errmsg_internal("%s", errmsg),
+            errdetail("%s: %s", msg_major, msg_minor)));
 }
 
 static int
-pg_SSPI_recvauth(Port *port)
+pg_GSS_recvauth(Port *port)
 {
+   OM_uint32   maj_stat,
+               min_stat,
+               lmin_s,
+               gflags;
    int         mtype;
+   int         ret;
    StringInfoData buf;
-   SECURITY_STATUS r;
-   CredHandle  sspicred;
-   CtxtHandle *sspictx = NULL,
-               newctx;
-   TimeStamp   expiry;
-   ULONG       contextattr;
-   SecBufferDesc inbuf;
-   SecBufferDesc outbuf;
-   SecBuffer   OutBuffers[1];
-   SecBuffer   InBuffers[1];
-   HANDLE      token;
-   TOKEN_USER *tokenuser;
-   DWORD       retlen;
-   char        accountname[MAXPGPATH];
-   char        domainname[MAXPGPATH];
-   DWORD       accountnamesize = sizeof(accountname);
-   DWORD       domainnamesize = sizeof(domainname);
-   SID_NAME_USE accountnameuse;
-   HMODULE     secur32;
-   QUERY_SECURITY_CONTEXT_TOKEN_FN _QuerySecurityContextToken;
+   gss_buffer_desc gbuf;
 
    /*
-    * SSPI auth is not supported for protocol versions before 3, because it
-    * relies on the overall message length word to determine the SSPI payload
+    * GSS auth is not supported for protocol versions before 3, because it
+    * relies on the overall message length word to determine the GSS payload
     * size in AuthenticationGSSContinue and PasswordMessage messages.
-    * (This is, in fact, a design error in our SSPI support, because protocol
+    * (This is, in fact, a design error in our GSS support, because protocol
     * messages are supposed to be parsable without relying on the length
     * word; but it's not worth changing it now.)
     */
    if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
        ereport(FATAL,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-                errmsg("SSPI is not supported in protocol version 2")));
+                errmsg("GSSAPI is not supported in protocol version 2")));
+
+   if (pg_krb_server_keyfile && strlen(pg_krb_server_keyfile) > 0)
+   {
+       /*
+        * Set default Kerberos keytab file for the Krb5 mechanism.
+        *
+        * setenv("KRB5_KTNAME", pg_krb_server_keyfile, 0); except setenv()
+        * not always available.
+        */
+       if (getenv("KRB5_KTNAME") == NULL)
+       {
+           size_t  kt_len = strlen(pg_krb_server_keyfile) + 14;
+           char   *kt_path = malloc(kt_len);
+
+           if (!kt_path)
+           {
+               ereport(LOG,
+                       (errcode(ERRCODE_OUT_OF_MEMORY),
+                        errmsg("out of memory")));
+               return STATUS_ERROR;
+           }
+           snprintf(kt_path, kt_len, "KRB5_KTNAME=%s", pg_krb_server_keyfile);
+           putenv(kt_path);
+       }
+   }
 
    /*
-    * Acquire a handle to the server credentials.
+    * We accept any service principal that's present in our keytab. This
+    * increases interoperability between kerberos implementations that see
+    * for example case sensitivity differently, while not really opening up
+    * any vector of attack.
     */
-   r = AcquireCredentialsHandle(NULL,
-                                "negotiate",
+   port->gss->cred = GSS_C_NO_CREDENTIAL;
+
+   /*
+    * Initialize sequence with an empty context
+    */
+   port->gss->ctx = GSS_C_NO_CONTEXT;
+
+   /*
+    * Loop through GSSAPI message exchange. This exchange can consist of
+    * multiple messags sent in both directions. First message is always from
+    * the client. All messages from client to server are password packets
+    * (type 'p').
+    */
+   do
+   {
+       mtype = pq_getbyte();
+       if (mtype != 'p')
+       {
+           /* Only log error if client didn't disconnect. */
+           if (mtype != EOF)
+               ereport(COMMERROR,
+                       (errcode(ERRCODE_PROTOCOL_VIOLATION),
+                        errmsg("expected GSS response, got message type %d",
+                               mtype)));
+           return STATUS_ERROR;
+       }
+
+       /* Get the actual GSS token */
+       initStringInfo(&buf);
+       if (pq_getmessage(&buf, 2000))
+       {
+           /* EOF - pq_getmessage already logged error */
+           pfree(buf.data);
+           return STATUS_ERROR;
+       }
+
+       /* Map to GSSAPI style buffer */
+       gbuf.length = buf.len;
+       gbuf.value = buf.data;
+
+       elog(DEBUG4, "Processing received GSS token of length %u",
+            (unsigned int) gbuf.length);
+
+       maj_stat = gss_accept_sec_context(
+                                         &min_stat,
+                                         &port->gss->ctx,
+                                         port->gss->cred,
+                                         &gbuf,
+                                         GSS_C_NO_CHANNEL_BINDINGS,
+                                         &port->gss->name,
+                                         NULL,
+                                         &port->gss->outbuf,
+                                         &gflags,
+                                         NULL,
+                                         NULL);
+
+       /* gbuf no longer used */
+       pfree(buf.data);
+
+       elog(DEBUG5, "gss_accept_sec_context major: %d, "
+            "minor: %d, outlen: %u, outflags: %x",
+            maj_stat, min_stat,
+            (unsigned int) port->gss->outbuf.length, gflags);
+
+       if (port->gss->outbuf.length != 0)
+       {
+           /*
+            * Negotiation generated data to be sent to the client.
+            */
+           OM_uint32   lmin_s;
+
+           elog(DEBUG4, "sending GSS response token of length %u",
+                (unsigned int) port->gss->outbuf.length);
+
+           sendAuthRequest(port, AUTH_REQ_GSS_CONT);
+
+           gss_release_buffer(&lmin_s, &port->gss->outbuf);
+       }
+
+       if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED)
+       {
+           OM_uint32   lmin_s;
+
+           gss_delete_sec_context(&lmin_s, &port->gss->ctx, GSS_C_NO_BUFFER);
+           pg_GSS_error(ERROR,
+                      gettext_noop("accepting GSS security context failed"),
+                        maj_stat, min_stat);
+       }
+
+       if (maj_stat == GSS_S_CONTINUE_NEEDED)
+           elog(DEBUG4, "GSS continue needed");
+
+   } while (maj_stat == GSS_S_CONTINUE_NEEDED);
+
+   if (port->gss->cred != GSS_C_NO_CREDENTIAL)
+   {
+       /*
+        * Release service principal credentials
+        */
+       gss_release_cred(&min_stat, &port->gss->cred);
+   }
+
+   /*
+    * GSS_S_COMPLETE indicates that authentication is now complete.
+    *
+    * Get the name of the user that authenticated, and compare it to the pg
+    * username that was specified for the connection.
+    */
+   maj_stat = gss_display_name(&min_stat, port->gss->name, &gbuf, NULL);
+   if (maj_stat != GSS_S_COMPLETE)
+       pg_GSS_error(ERROR,
+                    gettext_noop("retrieving GSS user name failed"),
+                    maj_stat, min_stat);
+
+   /*
+    * Split the username at the realm separator
+    */
+   if (strchr(gbuf.value, '@'))
+   {
+       char       *cp = strchr(gbuf.value, '@');
+
+       *cp = '\0';
+       cp++;
+
+       if (pg_krb_realm != NULL && strlen(pg_krb_realm))
+       {
+           /*
+            * Match the realm part of the name first
+            */
+           if (pg_krb_caseins_users)
+               ret = pg_strcasecmp(pg_krb_realm, cp);
+           else
+               ret = strcmp(pg_krb_realm, cp);
+
+           if (ret)
+           {
+               /* GSS realm does not match */
+               elog(DEBUG2,
+                  "GSSAPI realm (%s) and configured realm (%s) don't match",
+                    cp, pg_krb_realm);
+               gss_release_buffer(&lmin_s, &gbuf);
+               return STATUS_ERROR;
+           }
+       }
+   }
+   else if (pg_krb_realm && strlen(pg_krb_realm))
+   {
+       elog(DEBUG2,
+            "GSSAPI did not return realm but realm matching was requested");
+
+       gss_release_buffer(&lmin_s, &gbuf);
+       return STATUS_ERROR;
+   }
+
+   if (pg_krb_caseins_users)
+       ret = pg_strcasecmp(port->user_name, gbuf.value);
+   else
+       ret = strcmp(port->user_name, gbuf.value);
+
+   if (ret)
+   {
+       /* GSS name and PGUSER are not equivalent */
+       elog(DEBUG2,
+            "provided username (%s) and GSSAPI username (%s) don't match",
+            port->user_name, (char *) gbuf.value);
+
+       gss_release_buffer(&lmin_s, &gbuf);
+       return STATUS_ERROR;
+   }
+
+   gss_release_buffer(&lmin_s, &gbuf);
+
+   return STATUS_OK;
+}
+
+#else                          /* no ENABLE_GSS */
+
+static int
+pg_GSS_recvauth(Port *port)
+{
+   ereport(LOG,
+           (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+            errmsg("GSSAPI not implemented on this server")));
+   return STATUS_ERROR;
+}
+
+#endif   /* ENABLE_GSS */
+
+
+/*----------------------------------------------------------------
+ * SSPI authentication system
+ *----------------------------------------------------------------
+ */
+#ifdef ENABLE_SSPI
+static void
+pg_SSPI_error(int severity, char *errmsg, SECURITY_STATUS r)
+{
+   char        sysmsg[256];
+
+   if (FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, r, 0, sysmsg, sizeof(sysmsg), NULL) == 0)
+       ereport(severity,
+               (errmsg_internal("%s", errmsg),
+                errdetail("SSPI error %x", (unsigned int) r)));
+   else
+       ereport(severity,
+               (errmsg_internal("%s", errmsg),
+                errdetail("%s (%x)", sysmsg, (unsigned int) r)));
+}
+
+static int
+pg_SSPI_recvauth(Port *port)
+{
+   int         mtype;
+   StringInfoData buf;
+   SECURITY_STATUS r;
+   CredHandle  sspicred;
+   CtxtHandle *sspictx = NULL,
+               newctx;
+   TimeStamp   expiry;
+   ULONG       contextattr;
+   SecBufferDesc inbuf;
+   SecBufferDesc outbuf;
+   SecBuffer   OutBuffers[1];
+   SecBuffer   InBuffers[1];
+   HANDLE      token;
+   TOKEN_USER *tokenuser;
+   DWORD       retlen;
+   char        accountname[MAXPGPATH];
+   char        domainname[MAXPGPATH];
+   DWORD       accountnamesize = sizeof(accountname);
+   DWORD       domainnamesize = sizeof(domainname);
+   SID_NAME_USE accountnameuse;
+   HMODULE     secur32;
+   QUERY_SECURITY_CONTEXT_TOKEN_FN _QuerySecurityContextToken;
+
+   /*
+    * SSPI auth is not supported for protocol versions before 3, because it
+    * relies on the overall message length word to determine the SSPI payload
+    * size in AuthenticationGSSContinue and PasswordMessage messages.
+    * (This is, in fact, a design error in our SSPI support, because protocol
+    * messages are supposed to be parsable without relying on the length
+    * word; but it's not worth changing it now.)
+    */
+   if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
+       ereport(FATAL,
+               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                errmsg("SSPI is not supported in protocol version 2")));
+
+   /*
+    * Acquire a handle to the server credentials.
+    */
+   r = AcquireCredentialsHandle(NULL,
+                                "negotiate",
                                 SECPKG_CRED_INBOUND,
                                 NULL,
                                 NULL,
@@ -816,391 +1236,126 @@ pg_SSPI_recvauth(Port *port)
    } while (r == SEC_I_CONTINUE_NEEDED);
 
 
-   /*
-    * Release service principal credentials
-    */
-   FreeCredentialsHandle(&sspicred);
-
-
-   /*
-    * SEC_E_OK indicates that authentication is now complete.
-    *
-    * Get the name of the user that authenticated, and compare it to the pg
-    * username that was specified for the connection.
-    *
-    * MingW is missing the export for QuerySecurityContextToken in the
-    * secur32 library, so we have to load it dynamically.
-    */
-
-   secur32 = LoadLibrary("SECUR32.DLL");
-   if (secur32 == NULL)
-       ereport(ERROR,
-               (errmsg_internal("could not load secur32.dll: %d",
-                                (int) GetLastError())));
-
-   _QuerySecurityContextToken = (QUERY_SECURITY_CONTEXT_TOKEN_FN)
-       GetProcAddress(secur32, "QuerySecurityContextToken");
-   if (_QuerySecurityContextToken == NULL)
-   {
-       FreeLibrary(secur32);
-       ereport(ERROR,
-               (errmsg_internal("could not locate QuerySecurityContextToken in secur32.dll: %d",
-                                (int) GetLastError())));
-   }
-
-   r = (_QuerySecurityContextToken) (sspictx, &token);
-   if (r != SEC_E_OK)
-   {
-       FreeLibrary(secur32);
-       pg_SSPI_error(ERROR,
-              gettext_noop("could not get security token from context"), r);
-   }
-
-   FreeLibrary(secur32);
-
-   /*
-    * No longer need the security context, everything from here on uses the
-    * token instead.
-    */
-   DeleteSecurityContext(sspictx);
-   free(sspictx);
-
-   if (!GetTokenInformation(token, TokenUser, NULL, 0, &retlen) && GetLastError() != 122)
-       ereport(ERROR,
-            (errmsg_internal("could not get token user size: error code %d",
-                             (int) GetLastError())));
-
-   tokenuser = malloc(retlen);
-   if (tokenuser == NULL)
-       ereport(ERROR,
-               (errmsg("out of memory")));
-
-   if (!GetTokenInformation(token, TokenUser, tokenuser, retlen, &retlen))
-       ereport(ERROR,
-               (errmsg_internal("could not get user token: error code %d",
-                                (int) GetLastError())));
-
-   if (!LookupAccountSid(NULL, tokenuser->User.Sid, accountname, &accountnamesize,
-                         domainname, &domainnamesize, &accountnameuse))
-       ereport(ERROR,
-             (errmsg_internal("could not lookup acconut sid: error code %d",
-                              (int) GetLastError())));
-
-   free(tokenuser);
-
-   /*
-    * Compare realm/domain if requested. In SSPI, always compare case
-    * insensitive.
-    */
-   if (pg_krb_realm && strlen(pg_krb_realm))
-   {
-       if (pg_strcasecmp(pg_krb_realm, domainname))
-       {
-           elog(DEBUG2,
-                "SSPI domain (%s) and configured domain (%s) don't match",
-                domainname, pg_krb_realm);
-
-           return STATUS_ERROR;
-       }
-   }
-
-   /*
-    * We have the username (without domain/realm) in accountname, compare to
-    * the supplied value. In SSPI, always compare case insensitive.
-    */
-   if (pg_strcasecmp(port->user_name, accountname))
-   {
-       /* GSS name and PGUSER are not equivalent */
-       elog(DEBUG2,
-            "provided username (%s) and SSPI username (%s) don't match",
-            port->user_name, accountname);
-
-       return STATUS_ERROR;
-   }
-
-   return STATUS_OK;
-}
-
-#else                          /* no ENABLE_SSPI */
-
-static int
-pg_SSPI_recvauth(Port *port)
-{
-   ereport(LOG,
-           (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-            errmsg("SSPI not implemented on this server")));
-   return STATUS_ERROR;
-}
-
-#endif   /* ENABLE_SSPI */
-
-
-/*
- * Tell the user the authentication failed, but not (much about) why.
- *
- * There is a tradeoff here between security concerns and making life
- * unnecessarily difficult for legitimate users.  We would not, for example,
- * want to report the password we were expecting to receive...
- * But it seems useful to report the username and authorization method
- * in use, and these are items that must be presumed known to an attacker
- * anyway.
- * Note that many sorts of failure report additional information in the
- * postmaster log, which we hope is only readable by good guys.
- */
-static void
-auth_failed(Port *port, int status)
-{
-   const char *errstr;
-
-   /*
-    * If we failed due to EOF from client, just quit; there's no point in
-    * trying to send a message to the client, and not much point in logging
-    * the failure in the postmaster log.  (Logging the failure might be
-    * desirable, were it not for the fact that libpq closes the connection
-    * unceremoniously if challenged for a password when it hasn't got one to
-    * send.  We'll get a useless log entry for every psql connection under
-    * password auth, even if it's perfectly successful, if we log STATUS_EOF
-    * events.)
-    */
-   if (status == STATUS_EOF)
-       proc_exit(0);
-
-   switch (port->auth_method)
-   {
-       case uaReject:
-           errstr = gettext_noop("authentication failed for user \"%s\": host rejected");
-           break;
-       case uaKrb5:
-           errstr = gettext_noop("Kerberos 5 authentication failed for user \"%s\"");
-           break;
-       case uaGSS:
-           errstr = gettext_noop("GSSAPI authentication failed for user \"%s\"");
-           break;
-       case uaSSPI:
-           errstr = gettext_noop("SSPI authentication failed for user \"%s\"");
-           break;
-       case uaTrust:
-           errstr = gettext_noop("\"trust\" authentication failed for user \"%s\"");
-           break;
-       case uaIdent:
-           errstr = gettext_noop("Ident authentication failed for user \"%s\"");
-           break;
-       case uaMD5:
-       case uaCrypt:
-       case uaPassword:
-           errstr = gettext_noop("password authentication failed for user \"%s\"");
-           break;
-#ifdef USE_PAM
-       case uaPAM:
-           errstr = gettext_noop("PAM authentication failed for user \"%s\"");
-           break;
-#endif   /* USE_PAM */
-#ifdef USE_LDAP
-       case uaLDAP:
-           errstr = gettext_noop("LDAP authentication failed for user \"%s\"");
-           break;
-#endif   /* USE_LDAP */
-       default:
-           errstr = gettext_noop("authentication failed for user \"%s\": invalid authentication method");
-           break;
-   }
-
-   ereport(FATAL,
-           (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
-            errmsg(errstr, port->user_name)));
-   /* doesn't return */
-}
-
-
-/*
- * Client authentication starts here.  If there is an error, this
- * function does not return and the backend process is terminated.
- */
-void
-ClientAuthentication(Port *port)
-{
-   int         status = STATUS_ERROR;
-
-   /*
-    * Get the authentication method to use for this frontend/database
-    * combination.  Note: a failure return indicates a problem with the hba
-    * config file, not with the request.  hba.c should have dropped an error
-    * message into the postmaster logfile if it failed.
-    */
-   if (hba_getauthmethod(port) != STATUS_OK)
-       ereport(FATAL,
-               (errcode(ERRCODE_CONFIG_FILE_ERROR),
-                errmsg("missing or erroneous pg_hba.conf file"),
-                errhint("See server log for details.")));
-
-   switch (port->auth_method)
-   {
-       case uaReject:
-
-           /*
-            * This could have come from an explicit "reject" entry in
-            * pg_hba.conf, but more likely it means there was no matching
-            * entry.  Take pity on the poor user and issue a helpful error
-            * message.  NOTE: this is not a security breach, because all the
-            * info reported here is known at the frontend and must be assumed
-            * known to bad guys. We're merely helping out the less clueful
-            * good guys.
-            */
-           {
-               char        hostinfo[NI_MAXHOST];
-
-               pg_getnameinfo_all(&port->raddr.addr, port->raddr.salen,
-                                  hostinfo, sizeof(hostinfo),
-                                  NULL, 0,
-                                  NI_NUMERICHOST);
-
-#ifdef USE_SSL
-               ereport(FATAL,
-                       (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
-                        errmsg("no pg_hba.conf entry for host \"%s\", user \"%s\", database \"%s\", %s",
-                             hostinfo, port->user_name, port->database_name,
-                               port->ssl ? _("SSL on") : _("SSL off"))));
-#else
-               ereport(FATAL,
-                       (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
-                        errmsg("no pg_hba.conf entry for host \"%s\", user \"%s\", database \"%s\"",
-                          hostinfo, port->user_name, port->database_name)));
-#endif
-               break;
-           }
-
-       case uaKrb5:
-           sendAuthRequest(port, AUTH_REQ_KRB5);
-           status = pg_krb5_recvauth(port);
-           break;
-
-       case uaGSS:
-           sendAuthRequest(port, AUTH_REQ_GSS);
-           status = pg_GSS_recvauth(port);
-           break;
-
-       case uaSSPI:
-           sendAuthRequest(port, AUTH_REQ_SSPI);
-           status = pg_SSPI_recvauth(port);
-           break;
-
-       case uaIdent:
-
-           /*
-            * If we are doing ident on unix-domain sockets, use SCM_CREDS
-            * only if it is defined and SO_PEERCRED isn't.
-            */
-#if !defined(HAVE_GETPEEREID) && !defined(SO_PEERCRED) && \
-   (defined(HAVE_STRUCT_CMSGCRED) || defined(HAVE_STRUCT_FCRED) || \
-    (defined(HAVE_STRUCT_SOCKCRED) && defined(LOCAL_CREDS)))
-           if (port->raddr.addr.ss_family == AF_UNIX)
-           {
-#if defined(HAVE_STRUCT_FCRED) || defined(HAVE_STRUCT_SOCKCRED)
-
-               /*
-                * Receive credentials on next message receipt, BSD/OS,
-                * NetBSD. We need to set this before the client sends the
-                * next packet.
-                */
-               int         on = 1;
-
-               if (setsockopt(port->sock, 0, LOCAL_CREDS, &on, sizeof(on)) < 0)
-                   ereport(FATAL,
-                           (errcode_for_socket_access(),
-                      errmsg("could not enable credential reception: %m")));
-#endif
-
-               sendAuthRequest(port, AUTH_REQ_SCM_CREDS);
-           }
-#endif
-           status = authident(port);
-           break;
-
-       case uaMD5:
-           sendAuthRequest(port, AUTH_REQ_MD5);
-           status = recv_and_check_password_packet(port);
-           break;
+   /*
+    * Release service principal credentials
+    */
+   FreeCredentialsHandle(&sspicred);
 
-       case uaCrypt:
-           sendAuthRequest(port, AUTH_REQ_CRYPT);
-           status = recv_and_check_password_packet(port);
-           break;
 
-       case uaPassword:
-           sendAuthRequest(port, AUTH_REQ_PASSWORD);
-           status = recv_and_check_password_packet(port);
-           break;
+   /*
+    * SEC_E_OK indicates that authentication is now complete.
+    *
+    * Get the name of the user that authenticated, and compare it to the pg
+    * username that was specified for the connection.
+    *
+    * MingW is missing the export for QuerySecurityContextToken in the
+    * secur32 library, so we have to load it dynamically.
+    */
 
-#ifdef USE_PAM
-       case uaPAM:
-           pam_port_cludge = port;
-           status = CheckPAMAuth(port, port->user_name, "");
-           break;
-#endif   /* USE_PAM */
+   secur32 = LoadLibrary("SECUR32.DLL");
+   if (secur32 == NULL)
+       ereport(ERROR,
+               (errmsg_internal("could not load secur32.dll: %d",
+                                (int) GetLastError())));
 
-#ifdef USE_LDAP
-       case uaLDAP:
-           status = CheckLDAPAuth(port);
-           break;
-#endif
+   _QuerySecurityContextToken = (QUERY_SECURITY_CONTEXT_TOKEN_FN)
+       GetProcAddress(secur32, "QuerySecurityContextToken");
+   if (_QuerySecurityContextToken == NULL)
+   {
+       FreeLibrary(secur32);
+       ereport(ERROR,
+               (errmsg_internal("could not locate QuerySecurityContextToken in secur32.dll: %d",
+                                (int) GetLastError())));
+   }
 
-       case uaTrust:
-           status = STATUS_OK;
-           break;
+   r = (_QuerySecurityContextToken) (sspictx, &token);
+   if (r != SEC_E_OK)
+   {
+       FreeLibrary(secur32);
+       pg_SSPI_error(ERROR,
+              gettext_noop("could not get security token from context"), r);
    }
 
-   if (status == STATUS_OK)
-       sendAuthRequest(port, AUTH_REQ_OK);
-   else
-       auth_failed(port, status);
-}
+   FreeLibrary(secur32);
 
+   /*
+    * No longer need the security context, everything from here on uses the
+    * token instead.
+    */
+   DeleteSecurityContext(sspictx);
+   free(sspictx);
 
-/*
- * Send an authentication request packet to the frontend.
- */
-static void
-sendAuthRequest(Port *port, AuthRequest areq)
-{
-   StringInfoData buf;
+   if (!GetTokenInformation(token, TokenUser, NULL, 0, &retlen) && GetLastError() != 122)
+       ereport(ERROR,
+            (errmsg_internal("could not get token user size: error code %d",
+                             (int) GetLastError())));
 
-   pq_beginmessage(&buf, 'R');
-   pq_sendint(&buf, (int32) areq, sizeof(int32));
+   tokenuser = malloc(retlen);
+   if (tokenuser == NULL)
+       ereport(ERROR,
+               (errmsg("out of memory")));
 
-   /* Add the salt for encrypted passwords. */
-   if (areq == AUTH_REQ_MD5)
-       pq_sendbytes(&buf, port->md5Salt, 4);
-   else if (areq == AUTH_REQ_CRYPT)
-       pq_sendbytes(&buf, port->cryptSalt, 2);
+   if (!GetTokenInformation(token, TokenUser, tokenuser, retlen, &retlen))
+       ereport(ERROR,
+               (errmsg_internal("could not get user token: error code %d",
+                                (int) GetLastError())));
 
-#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
+   if (!LookupAccountSid(NULL, tokenuser->User.Sid, accountname, &accountnamesize,
+                         domainname, &domainnamesize, &accountnameuse))
+       ereport(ERROR,
+             (errmsg_internal("could not lookup acconut sid: error code %d",
+                              (int) GetLastError())));
+
+   free(tokenuser);
 
    /*
-    * Add the authentication data for the next step of the GSSAPI or SSPI
-    * negotiation.
+    * Compare realm/domain if requested. In SSPI, always compare case
+    * insensitive.
     */
-   else if (areq == AUTH_REQ_GSS_CONT)
+   if (pg_krb_realm && strlen(pg_krb_realm))
    {
-       if (port->gss->outbuf.length > 0)
+       if (pg_strcasecmp(pg_krb_realm, domainname))
        {
-           elog(DEBUG4, "sending GSS token of length %u",
-                (unsigned int) port->gss->outbuf.length);
+           elog(DEBUG2,
+                "SSPI domain (%s) and configured domain (%s) don't match",
+                domainname, pg_krb_realm);
 
-           pq_sendbytes(&buf, port->gss->outbuf.value, port->gss->outbuf.length);
+           return STATUS_ERROR;
        }
    }
-#endif
-
-   pq_endmessage(&buf);
 
    /*
-    * Flush message so client will see it, except for AUTH_REQ_OK, which need
-    * not be sent until we are ready for queries.
+    * We have the username (without domain/realm) in accountname, compare to
+    * the supplied value. In SSPI, always compare case insensitive.
     */
-   if (areq != AUTH_REQ_OK)
-       pq_flush();
+   if (pg_strcasecmp(port->user_name, accountname))
+   {
+       /* GSS name and PGUSER are not equivalent */
+       elog(DEBUG2,
+            "provided username (%s) and SSPI username (%s) don't match",
+            port->user_name, accountname);
+
+       return STATUS_ERROR;
+   }
+
+   return STATUS_OK;
+}
+
+#else                          /* no ENABLE_SSPI */
+
+static int
+pg_SSPI_recvauth(Port *port)
+{
+   ereport(LOG,
+           (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+            errmsg("SSPI not implemented on this server")));
+   return STATUS_ERROR;
 }
 
+#endif   /* ENABLE_SSPI */
+
+
+
 /*----------------------------------------------------------------
  * Ident authentication system
  *----------------------------------------------------------------
@@ -1655,7 +1810,6 @@ authident(hbaPort *port)
  * PAM authentication system
  *----------------------------------------------------------------
  */
-
 #ifdef USE_PAM
 
 /*
@@ -1835,6 +1989,11 @@ CheckPAMAuth(Port *port, char *user, char *password)
 #endif   /* USE_PAM */
 
 
+
+/*----------------------------------------------------------------
+ * LDAP authentication system
+ *----------------------------------------------------------------
+ */
 #ifdef USE_LDAP
 
 static int
@@ -2014,94 +2173,3 @@ CheckLDAPAuth(Port *port)
 }
 #endif   /* USE_LDAP */
 
-/*
- * Collect password response packet from frontend.
- *
- * Returns NULL if couldn't get password, else palloc'd string.
- */
-static char *
-recv_password_packet(Port *port)
-{
-   StringInfoData buf;
-
-   if (PG_PROTOCOL_MAJOR(port->proto) >= 3)
-   {
-       /* Expect 'p' message type */
-       int         mtype;
-
-       mtype = pq_getbyte();
-       if (mtype != 'p')
-       {
-           /*
-            * If the client just disconnects without offering a password,
-            * don't make a log entry.  This is legal per protocol spec and in
-            * fact commonly done by psql, so complaining just clutters the
-            * log.
-            */
-           if (mtype != EOF)
-               ereport(COMMERROR,
-                       (errcode(ERRCODE_PROTOCOL_VIOLATION),
-                   errmsg("expected password response, got message type %d",
-                          mtype)));
-           return NULL;        /* EOF or bad message type */
-       }
-   }
-   else
-   {
-       /* For pre-3.0 clients, avoid log entry if they just disconnect */
-       if (pq_peekbyte() == EOF)
-           return NULL;        /* EOF */
-   }
-
-   initStringInfo(&buf);
-   if (pq_getmessage(&buf, 1000))      /* receive password */
-   {
-       /* EOF - pq_getmessage already logged a suitable message */
-       pfree(buf.data);
-       return NULL;
-   }
-
-   /*
-    * Apply sanity check: password packet length should agree with length of
-    * contained string.  Note it is safe to use strlen here because
-    * StringInfo is guaranteed to have an appended '\0'.
-    */
-   if (strlen(buf.data) + 1 != buf.len)
-       ereport(COMMERROR,
-               (errcode(ERRCODE_PROTOCOL_VIOLATION),
-                errmsg("invalid password packet size")));
-
-   /* Do not echo password to logs, for security. */
-   ereport(DEBUG5,
-           (errmsg("received password packet")));
-
-   /*
-    * Return the received string.  Note we do not attempt to do any
-    * character-set conversion on it; since we don't yet know the client's
-    * encoding, there wouldn't be much point.
-    */
-   return buf.data;
-}
-
-
-/*
- * Called when we have sent an authorization request for a password.
- * Get the response and check it.
- */
-static int
-recv_and_check_password_packet(Port *port)
-{
-   char       *passwd;
-   int         result;
-
-   passwd = recv_password_packet(port);
-
-   if (passwd == NULL)
-       return STATUS_EOF;      /* client wouldn't send password */
-
-   result = md5_crypt_verify(port, port->user_name, passwd);
-
-   pfree(passwd);
-
-   return result;
-}