ircd/listener: return a fatal TLS alert for early rejected TLS clients

This is in furtherance of commit 3fdf26aa19 which added
functionality to reply with a TLS record layer alert for D-Lined TLS
clients. It turns out that there are other plaintext error messages
in this same function that should receive the same treatment.

Also move another error string to a variable and use a compile-time
optimised-out strlen for it too, to use the same approach as an
existing error string.

Finally, use a different alert (internal_error) for the case where
IRCd is simply unable to accept more connections.

include/reject.h

@@ -28,7 +28,7 @@
 #define DELAYED_EXIT_TIME	10
 
 void init_reject(void);
-int check_reject(rb_fde_t *F, struct sockaddr *addr);
+int check_reject(rb_fde_t *F, struct sockaddr *addr, bool ssl);
 void add_reject(struct Client *, const char *mask1, const char *mask2, struct ConfItem *aconf, const char *reason);
 int is_reject_ip(struct sockaddr *addr);
 void flush_reject(void);

ircd/listener.c

@@ -581,13 +581,19 @@ accept_precallback(rb_fde_t *F, struct sockaddr *addr, rb_socklen_t addrlen, voi
 	static time_t last_oper_notice = 0;
 	int len;
 
+	static const char *allinuse = "ERROR :All connections in use\r\n";
 	static const char *toofast = "ERROR :Reconnecting too fast, throttled.\r\n";
 
-	static const unsigned char sslerrcode[] = {
+	static const unsigned char ssldeniederrcode[] = {
 		// SSLv3.0 Fatal Alert: Access Denied
 		0x15, 0x03, 0x00, 0x00, 0x02, 0x02, 0x31
 	};
 
+	static const unsigned char sslinternalerrcode[] = {
+		// SSLv3.0 Fatal Alert: Internal Error
+		0x15, 0x03, 0x00, 0x00, 0x02, 0x02, 0x50
+	};
+
 	if(listener->ssl && (!ircd_ssl_ok || !get_ssld_count()))
 	{
 		rb_close(F);
@@ -608,7 +614,11 @@ accept_precallback(rb_fde_t *F, struct sockaddr *addr, rb_socklen_t addrlen, voi
 			last_oper_notice = rb_current_time();
 		}
 
-		rb_write(F, "ERROR :All connections in use\r\n", 31);
+		if(listener->ssl)
+			rb_write(F, sslinternalerrcode, sizeof(sslinternalerrcode));
+		else
+			rb_write(F, allinuse, strlen(allinuse));
+
 		rb_close(F);
 		return 0;
 	}
@@ -625,7 +635,7 @@ accept_precallback(rb_fde_t *F, struct sockaddr *addr, rb_socklen_t addrlen, voi
 
 		if(listener->ssl)
 		{
-			rb_write(F, sslerrcode, sizeof(sslerrcode));
+			rb_write(F, ssldeniederrcode, sizeof(ssldeniederrcode));
 		}
 		else if(ConfigFileEntry.dline_with_reason)
 		{
@@ -648,7 +658,7 @@ accept_precallback(rb_fde_t *F, struct sockaddr *addr, rb_socklen_t addrlen, voi
 		return 0;
 	}
 
-	if(check_reject(F, addr)) {
+	if(check_reject(F, addr, listener->ssl)) {
 		/* Reject the connection without closing the socket
 		 * because it is now on the delay_exit list. */
 		return 0;
@@ -656,7 +666,11 @@ accept_precallback(rb_fde_t *F, struct sockaddr *addr, rb_socklen_t addrlen, voi
 
 	if(throttle_add(addr))
 	{
-		rb_write(F, toofast, strlen(toofast));
+		if(listener->ssl)
+			rb_write(F, ssldeniederrcode, sizeof(ssldeniederrcode));
+		else
+			rb_write(F, toofast, strlen(toofast));
+
 		rb_close(F);
 		return 0;
 	}

ircd/reject.c

@@ -58,6 +58,7 @@ typedef struct _delay_data
 	rb_fde_t *F;
 	struct ConfItem *aconf;
 	const char *reason;
+	bool ssl;
 } delay_t;
 
 typedef struct _throttle
@@ -92,28 +93,39 @@ reject_exit(void *unused)
 	delay_t *ddata;
 	static const char *errbuf = "ERROR :Closing Link: (*** Banned (cache))\r\n";
 
+	static const unsigned char ssldeniederrcode[] = {
+		// SSLv3.0 Fatal Alert: Access Denied
+		0x15, 0x03, 0x00, 0x00, 0x02, 0x02, 0x31
+	};
+
 	RB_DLINK_FOREACH_SAFE(ptr, ptr_next, delay_exit.head)
 	{
 		ddata = ptr->data;
 
-		*dynamic_reason = '\0';
+		if (ddata->ssl)
+		{
+			rb_write(ddata->F, ssldeniederrcode, sizeof(ssldeniederrcode));
+		}
+		else
+		{
+			*dynamic_reason = '\0';
+
+			if (ddata->aconf)
+				snprintf(dynamic_reason, sizeof dynamic_reason, form_str(ERR_YOUREBANNEDCREEP) "\r\n",
+					me.name, "*", get_user_ban_reason(ddata->aconf));
+			else if (ddata->reason)
+				snprintf(dynamic_reason, sizeof dynamic_reason, ":%s 465 %s :%s\r\n",
+					me.name, "*", ddata->reason);
+
+			if (*dynamic_reason)
+				rb_write(ddata->F, dynamic_reason, strlen(dynamic_reason));
+
+			rb_write(ddata->F, errbuf, strlen(errbuf));
+		}
 
 		if (ddata->aconf)
-		{
-			snprintf(dynamic_reason, sizeof dynamic_reason, form_str(ERR_YOUREBANNEDCREEP) "\r\n",
-				me.name, "*", get_user_ban_reason(ddata->aconf));
-			rb_write(ddata->F, dynamic_reason, strlen(dynamic_reason));
-
 			deref_conf(ddata->aconf);
-		}
-		else if (ddata->reason)
-		{
-			snprintf(dynamic_reason, sizeof dynamic_reason, ":%s 465 %s :%s\r\n",
-				me.name, "*", ddata->reason);
-			rb_write(ddata->F, dynamic_reason, strlen(dynamic_reason));
-		}
 
-		rb_write(ddata->F, errbuf, strlen(errbuf));
 		rb_close(ddata->F);
 		rb_free(ddata);
 	}
@@ -228,7 +240,7 @@ add_reject(struct Client *client_p, const char *mask1, const char *mask2, struct
 }
 
 int
-check_reject(rb_fde_t *F, struct sockaddr *addr)
+check_reject(rb_fde_t *F, struct sockaddr *addr, bool ssl)
 {
 	rb_patricia_node_t *pnode;
 	reject_t *rdata;
@@ -276,6 +288,7 @@ check_reject(rb_fde_t *F, struct sockaddr *addr)
 		ddata->reason = NULL;
 	}
 	ddata->F = F;
+	ddata->ssl = ssl;
 	rb_dlinkAdd(ddata, &ddata->node, &delay_exit);
 	return 1;
 }