Fix for telnet gateway to UNIX telnetd (using unixgate.bin) by sending

"DONT TERMINAL TYPE" Telnet command before passing through traffic from the
remote server (allowing renegotiation of the Terminal Type from the telnet client).

src/sbbs3/telgate.cpp

@@ -133,6 +133,9 @@ void sbbs_t::telnet_gate(char* destaddr, ulong mode)
 		l=p-(char*)buf;
 		sendsocket(remote_socket,(char*)buf,l);
 	}
+	
+	/* This is required for gating to Unix telnetd */
+	send_telnet_cmd(TELNET_DONT,TELNET_TERM_TYPE);	// Re-negotiation of terminal type
 
 	/* Text/NVT mode by default */
 	send_telnet_cmd(TELNET_DONT,TELNET_BINARY);
@@ -143,6 +146,16 @@ void sbbs_t::telnet_gate(char* destaddr, ulong mode)
 			gettimeleft();
 		rd=RingBufRead(&inbuf,buf,sizeof(buf));
 		if(rd) {
+#if 0
+			if(memchr(buf,TELNET_IAC,rd)) {
+				char dump[2048];
+				dump[0];
+				p=dump;
+				for(int i=0;i<rd;i++)
+					p+=sprintf(p,"%u ",buf[i]);
+				lprintf(LOG_DEBUG,"Node %d Telnet cmd from client: %s", cfg.node_num, dump);
+			}
+#endif
 			if(!(telnet_mode&TELNET_MODE_BIN_RX)) {
 				if(*buf==0x1d) { // ^]
 					save_console=console;
@@ -228,6 +241,16 @@ void sbbs_t::telnet_gate(char* destaddr, ulong mode)
 			lprintf(LOG_INFO,"Node %d Telnet gate disconnected",cfg.node_num);
 			break;
 		}
+#if 0
+		if(memchr(buf,TELNET_IAC,rd)) {
+			char dump[2048];
+			dump[0];
+			p=dump;
+			for(int i=0;i<rd;i++)
+				p+=sprintf(p,"%u ",buf[i]);
+			lprintf(LOG_DEBUG,"Node %d Telnet cmd from remote: %s", cfg.node_num, dump);
+		}
+#endif
 		RingBufWrite(&outbuf,buf,rd);
 	}
 	console&=~CON_RAW_IN;