Added snotes for failed SASL authentication attempts if need_sasl flag is set

Many thanks to Shockk for this patch.

References commits:
 - 15dc12b76e76c6fa2ead773b6b40965223ad453f - Added snotes for failed SASL authentication attempts if need_sasl flag is set.
 - febd2e2aca27f7f1acfc522f3fda65d8be067edc - Updated help/opers/snomask to add +S snomask.

help/opers/snomask

@@ -16,6 +16,7 @@ Server notice masks: (? designates that the snomask is provided
        +n     - Local client nick changes
        +r     - Invalid usernames and dumb HTTP proxies
        +s     - Generic server messages and oper kills
+       +S     - Clients refused due to failed SASL auth
        +u     - Client connections without auth{} block
      ? +W     - Shows whenever someone does a local whois on you
        +x     - New server introduction and split messages

include/snomask.h

@@ -54,6 +54,7 @@
 #define SNO_EXTERNAL		0x00000400
 #define SNO_SPY			0x00000800
 #define SNO_OPERSPY		0x00001000
+#define SNO_SASLFAIL		0x00002000
 
 char *construct_snobuf(unsigned int val);
 unsigned int parse_snobuf_to_mask(unsigned int val, const char *sno);

src/s_user.c

@@ -355,6 +355,8 @@ register_local_user(struct Client *client_p, struct Client *source_p, const char
 
 	if(IsNeedSasl(aconf) && !*user->suser)
 	{
+		sendto_realops_snomask(SNO_SASLFAIL, L_ALL,
+				     "SASL authentication failed, rejecting %s[%s].", source_p->name, source_p->host);
 		ServerStats.is_ref++;
 		sendto_one_notice(source_p, ":*** Notice -- You need to identify via SASL to use this server");
 		exit_client(client_p, source_p, &me, "SASL access only");

src/snomask.c

@@ -62,7 +62,7 @@ int snomask_modes[256] = {
         0,                      /* P */
         0,		        /* Q */
         0,                      /* R */
-        0,		        /* S */
+        SNO_SASLFAIL,	        /* S */
         0,                      /* T */
         0,                      /* U */
         0,                      /* V */