mirror of
https://github.com/DCC-EX/CommandStation-EX.git
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198 lines
6.2 KiB
C++
198 lines
6.2 KiB
C++
/*
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* © 2024 Harald Barth
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* All rights reserved.
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*
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* This file is part of CommandStation-EX
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*
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* This is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* It is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include <Arduino.h>
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#include "EthernetInterface.h"
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#ifdef DO_MDNS
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#include "EXmDNS.h"
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// fixed values for mDNS
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static IPAddress mdnsMulticastIPAddr = IPAddress(224, 0, 0, 251);
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#define MDNS_SERVER_PORT 5353
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// dotToLen()
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// converts stings of form ".foo.barbar.x" to a string with the
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// dots replaced with lenght. So string above would result in
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// "\x03foo\x06barbar\x01x" in C notation. If not NULL, *substr
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// will point to the beginning of the last component, in this
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// example that would be "\x01x".
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//
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static void dotToLen(char *str, char **substr) {
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char *dotplace = NULL;
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char *s;
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byte charcount = 0;
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for (s = str;/*see break*/ ; s++) {
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if (*s == '.' || *s == '\0') {
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// take care of accumulated
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if (dotplace != NULL && charcount != 0) {
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*dotplace = charcount;
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}
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if (*s == '\0')
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break;
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if (substr && *s == '.')
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*substr = s;
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// set new values
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dotplace = s;
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charcount = 0;
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} else {
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charcount++;
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}
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}
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}
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MDNS::MDNS(EthernetUDP& udp) {
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_udp = &udp;
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}
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MDNS::~MDNS() {
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_udp->stop();
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if (_name) free(_name);
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if (_serviceName) free(_serviceName);
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if (_serviceProto) free(_serviceProto);
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}
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int MDNS::begin(const IPAddress& ip, char* name) {
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// if we were called very soon after the board was booted, we need to give the
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// EthernetShield (WIZnet) some time to come up. Hence, we delay until millis() is at
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// least 3000. This is necessary, so that if we need to add a service record directly
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// after begin, the announce packet does not get lost in the bowels of the WIZnet chip.
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//while (millis() < 3000)
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// delay(100);
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_ipAddress = ip;
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_name = (char *)malloc(strlen(name)+2);
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byte n;
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for(n = 0; n<strlen(name); n++)
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_name[n+1] = name[n];
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_name[n+1] = '\0';
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_name[0] = '.';
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dotToLen(_name, NULL);
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return _udp->beginMulticast(mdnsMulticastIPAddr, MDNS_SERVER_PORT);
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}
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int MDNS::addServiceRecord(const char* name, uint16_t port, MDNSServiceProtocol_t proto) {
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// we ignore proto, assume TCP
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_serviceName = (char *)malloc(strlen(name)+2);
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byte n;
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for(n = 0; n<strlen(name); n++)
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_serviceName[n+1] = name[n];
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_serviceName[n+1] = '\0';
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_serviceName[0] = '.';
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_serviceProto = NULL; //to be filled in
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dotToLen(_serviceName, &_serviceProto);
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_servicePort = port;
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return 1;
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}
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static char dns_rr_services[] = "\x09_services\x07_dns-sd\x04_udp\x05local";
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static char dns_rr_tcplocal[] = "\x04_tcp\x05local";
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static char *dns_rr_local = dns_rr_tcplocal + dns_rr_tcplocal[0] + 1;
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typedef struct _DNSHeader_t
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{
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uint16_t xid;
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uint16_t flags; // flags condensed
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uint16_t queryCount;
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uint16_t answerCount;
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uint16_t authorityCount;
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uint16_t additionalCount;
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} __attribute__((__packed__)) DNSHeader_t;
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//
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// MDNS::run()
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// This broadcasts whatever we got evey BROADCASTTIME seconds.
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// Why? Too much brokenness i all mDNS implementations available
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//
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void MDNS::run() {
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static long int lastrun = BROADCASTTIME * 1000UL;
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unsigned long int now = millis();
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if (!(now - lastrun > BROADCASTTIME * 1000UL)) {
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return;
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}
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lastrun = now;
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DNSHeader_t dnsHeader = { 0 };
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_udp->beginPacket(mdnsMulticastIPAddr, MDNS_SERVER_PORT);
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// dns header
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dnsHeader.flags = lwip_htons(0x8400); // Response, authorative
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dnsHeader.answerCount = lwip_htons(4 /*5 if TXT but we do not do that */);
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_udp->write((uint8_t*)&dnsHeader, sizeof(DNSHeader_t));
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// rr #1, the PTR record from generic _services.x.local to service.x.local
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_udp->write((uint8_t*)dns_rr_services, sizeof(dns_rr_services));
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byte buf[10];
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buf[0] = 0x00;
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buf[1] = 0x0c; //PTR
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buf[2] = 0x00;
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buf[3] = 0x01; //IN
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*((uint32_t*)(buf+4)) = lwip_htonl(120); //TTL in sec
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*((uint16_t*)(buf+8)) = lwip_htons( _serviceProto[0] + 1 + strlen(dns_rr_tcplocal) + 1);
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_udp->write(buf, 10);
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_udp->write(_serviceProto,_serviceProto[0]+1);
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_udp->write(dns_rr_tcplocal, strlen(dns_rr_tcplocal)+1);
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// rr #2, the PTR record from proto.x to name.proto.x
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_udp->write(_serviceProto,_serviceProto[0]+1);
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_udp->write(dns_rr_tcplocal, strlen(dns_rr_tcplocal)+1);
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*((uint16_t*)(buf+8)) = lwip_htons(strlen(_serviceName) + strlen(dns_rr_tcplocal) + 1); // recycle most of buf
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_udp->write(buf, 10);
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_udp->write(_serviceName, strlen(_serviceName));
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_udp->write(dns_rr_tcplocal, strlen(dns_rr_tcplocal)+1);
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// rr #3, the SRV record for the service that points to local name
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_udp->write(_serviceName, strlen(_serviceName));
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_udp->write(dns_rr_tcplocal, strlen(dns_rr_tcplocal)+1);
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buf[1] = 0x21; // recycle most of buf but here SRV
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buf[2] = 0x80; // cache flush
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*((uint16_t*)(buf+8)) = lwip_htons(strlen(_name) + strlen(dns_rr_local) + 1 + 6);
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_udp->write(buf, 10);
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byte srv[6];
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// priority and weight
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srv[0] = srv[1] = srv[2] = srv[3] = 0;
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// port
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*((uint16_t*)(srv+4)) = lwip_htons(_servicePort);
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_udp->write(srv, 6);
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// target
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_udp->write(_name, _name[0]+1);
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_udp->write(dns_rr_local, strlen(dns_rr_local)+1);
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// rr #4, the A record for the name.local
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_udp->write(_name, _name[0]+1);
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_udp->write(dns_rr_local, strlen(dns_rr_local)+1);
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buf[1] = 0x01; // recycle most of buf but here A
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*((uint16_t*)(buf+8)) = lwip_htons(4);
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_udp->write(buf, 10);
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byte ip[4];
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ip[0] = _ipAddress[0];
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ip[1] = _ipAddress[1];
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ip[2] = _ipAddress[2];
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ip[3] = _ipAddress[3];
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_udp->write(ip, 4);
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_udp->endPacket();
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_udp->flush();
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//
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}
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#endif //DO_MDNS
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