WIP: Replacing KDNSSD with mdns.h

KDNSSD only works with Avahi (so, only on Linux) while mdns.h is a
header-only library [1] that implements mdns from scratch and should
work on all platforms.

[1] https://github.com/mjansson/mdns
This commit is contained in:
Albert Vaca Cintora 2023-07-05 21:09:28 +02:00
parent 20750b7d99
commit 9a0b7ef78b
6 changed files with 2494 additions and 59 deletions

View file

@ -12,6 +12,7 @@ if (MDNS_ENABLED)
set(backends_kdeconnect_SRCS set(backends_kdeconnect_SRCS
${backends_kdeconnect_SRCS} ${backends_kdeconnect_SRCS}
backends/lan/mdnsdiscovery.cpp backends/lan/mdnsdiscovery.cpp
backends/lan/mdns_wrapper.cpp
) )
endif() endif()

1618
core/backends/lan/mdns.h Normal file

File diff suppressed because it is too large Load diff

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@ -0,0 +1,796 @@
/**
* SPDX-FileCopyrightText: 2023 Albert Vaca Cintora <albertvaka@gmail.com>
*
* SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/
#include "mdns_wrapper.h"
#include "core_debug.h"
#include "mdns.h"
#include <errno.h>
#include <signal.h>
#ifdef _WIN32
#include <iphlpapi.h>
#include <winsock2.h>
#else
#include <ifaddrs.h>
#include <net/if.h>
#include <netdb.h>
#include <sys/time.h>
#endif
#include <QNetworkInterface>
#include <QSocketNotifier>
const char *recordTypeToStr(int rtype)
{
switch (rtype) {
case MDNS_RECORDTYPE_PTR: return "PTR";
case MDNS_RECORDTYPE_SRV: return "SRV";
case MDNS_RECORDTYPE_TXT: return "TXT";
case MDNS_RECORDTYPE_A: return "A";
case MDNS_RECORDTYPE_AAAA: return "AAAA";
case MDNS_RECORDTYPE_ANY: return "ANY";
default: return "UNKNOWN";
}
}
const char *entryTypeToStr(int entry)
{
switch (entry) {
case MDNS_ENTRYTYPE_QUESTION: return "QUESTION";
case MDNS_ENTRYTYPE_ANSWER: return "ANSWER";
case MDNS_ENTRYTYPE_AUTHORITY: return "AUTHORITY";
case MDNS_ENTRYTYPE_ADDITIONAL: return "ADDITIONAL";
default: return "UNKNOWN";
}
}
// Callback that handles responses to a query
static int query_callback(int sock, const struct sockaddr* from, size_t addrlen, mdns_entry_type_t entry_type,
uint16_t query_id, uint16_t record_type, uint16_t rclass, uint32_t ttl, const void* data,
size_t size, size_t name_offset, size_t name_length, size_t record_offset,
size_t record_length, void* user_data) {
Q_UNUSED(sock);
Q_UNUSED(addrlen);
Q_UNUSED(query_id);
Q_UNUSED(entry_type);
Q_UNUSED(rclass);
Q_UNUSED(ttl);
Q_UNUSED(name_offset);
Q_UNUSED(name_length);
//qCDebug(KDECONNECT_CORE) << "Received DNS record of type" << recordTypeToStr(record_type) << "from socket" << sock << "with type" << entryTypeToStr(entry_type);
MdnsWrapper::MdnsService *discoveredService = (MdnsWrapper::MdnsService *)user_data;
switch (record_type) {
case MDNS_RECORDTYPE_PTR: {
mdns_string_pair_t namePos = mdns_get_next_substring(data, size, record_offset);
discoveredService->serviceName = QString::fromLatin1((char *)data + namePos.offset, namePos.length);
if (discoveredService->address == QHostAddress::Null) {
discoveredService->address = QHostAddress(from); // In case we don't receive a A record, use from as address
}
} break;
case MDNS_RECORDTYPE_SRV: {
static char auxBuffer[256];
mdns_record_srv_t record = mdns_record_parse_srv(data, size, record_offset, record_length, auxBuffer, sizeof(auxBuffer));
discoveredService->port = record.port;
} break;
case MDNS_RECORDTYPE_A: {
sockaddr_in addr;
mdns_record_parse_a(data, size, record_offset, record_length, &addr);
discoveredService->address = QHostAddress(ntohl(addr.sin_addr.s_addr));
} break;
case MDNS_RECORDTYPE_AAAA:
// Ignore IPv6 for now
break;
case MDNS_RECORDTYPE_TXT: {
mdns_record_txt_t records[24];
size_t parsed = mdns_record_parse_txt(data, size, record_offset, record_length, records, sizeof(records) / sizeof(mdns_record_txt_t));
for (size_t itxt = 0; itxt < parsed; ++itxt) {
QString key = QString::fromLatin1(records[itxt].key.str, records[itxt].key.length);
QString value = QString::fromLatin1(records[itxt].value.str, records[itxt].value.length);
discoveredService->txtRecords[key] = value;
}
} break;
default:
// Ignore unknown record types
break;
}
return 0;
}
void MdnsWrapper::startDiscovering(const char *serviceName)
{
int num_sockets = listenForQueryResponses();
if (num_sockets <= 0) {
qWarning() << "Failed to open any client sockets";
} else {
sendQuery(serviceName);
}
}
void MdnsWrapper::stopDiscovering()
{
stopListeningForQueryResponses();
}
void MdnsWrapper::stopListeningForQueryResponses()
{
qCDebug(KDECONNECT_CORE) << "Closing" << responseSocketNotifiers.size() << "sockets";
for (QSocketNotifier *socketNotifier : responseSocketNotifiers) {
mdns_socket_close(socketNotifier->socket());
delete socketNotifier;
}
responseSocketNotifiers.clear();
}
int MdnsWrapper::listenForQueryResponses()
{
// Open a socket for each interface
QVector<int> sockets;
for (const QNetworkInterface &iface : QNetworkInterface::allInterfaces()) {
int flags = iface.flags();
if (!(flags & QNetworkInterface::IsUp) || !(flags & QNetworkInterface::CanMulticast) || (flags & QNetworkInterface::IsLoopBack)) {
continue;
}
for (const QNetworkAddressEntry &ifaceAddress : iface.addressEntries()) {
QHostAddress sourceAddress = ifaceAddress.ip();
if (sourceAddress.protocol() == QAbstractSocket::IPv4Protocol && sourceAddress != QHostAddress::LocalHost) {
qCDebug(KDECONNECT_CORE) << "Opening socket for address" << sourceAddress;
struct sockaddr_in saddr;
memset(&saddr, 0, sizeof(saddr));
saddr.sin_family = AF_INET;
saddr.sin_port = 0;
saddr.sin_addr.s_addr = htonl(sourceAddress.toIPv4Address());
int socket = mdns_socket_open_ipv4(&saddr);
sockets.append(socket);
}
// Ignore IPv6 interfaces for now
}
}
// Start listening on all sockets
for (int socket : sockets) {
QSocketNotifier *socketNotifier = new QSocketNotifier(socket, QSocketNotifier::Read);
QObject::connect(socketNotifier, &QSocketNotifier::activated, [this](QSocketDescriptor socket) {
MdnsService discoveredService;
size_t capacity = 2048;
void *buffer = malloc(capacity);
size_t num_records = mdns_query_recv(socket, buffer, capacity, query_callback, (void *)&discoveredService, 0);
free(buffer);
// qCDebug(KDECONNECT_CORE) << "Discovered service" << discoveredService.serviceName << "at" << discoveredService.address << "in" << num_records <<
// "records via socket" << socket;
Q_EMIT serviceFound(discoveredService);
});
responseSocketNotifiers.append(socketNotifier);
}
qCDebug(KDECONNECT_CORE) << "Opened" << sockets.size() << "sockets to listen for MDNS query responses";
return sockets.size();
}
void MdnsWrapper::sendQuery(const char *serviceName)
{
qCDebug(KDECONNECT_CORE) << "Sending MDNS query for service" << serviceName;
mdns_query_t query;
query.name = serviceName;
query.length = strlen(serviceName);
query.type = MDNS_RECORDTYPE_PTR;
size_t capacity = 2048;
void *buffer = malloc(capacity);
for (QSocketNotifier *socketNotifier : responseSocketNotifiers) {
int socket = socketNotifier->socket();
qCDebug(KDECONNECT_CORE) << "Sending mDNS query via socket" << socket;
int ret = mdns_multiquery_send(socket, &query, 1, buffer, capacity, 0);
if (ret < 0) {
qWarning() << "Failed to send mDNS query:" << strerror(errno);
}
}
free(buffer);
}
// Those are the IPs we will announce. They are the first IP we find. Maybe we should announce all our IPs instead?
struct sockaddr_in service_address_ipv4;
struct sockaddr_in6 service_address_ipv6;
static mdns_string_t ipv4_address_to_string(char* buffer, size_t capacity, const struct sockaddr_in* addr,
size_t addrlen) {
char host[NI_MAXHOST] = {0};
char service[NI_MAXSERV] = {0};
int ret = getnameinfo((const struct sockaddr*)addr, (socklen_t)addrlen, host, NI_MAXHOST,
service, NI_MAXSERV, NI_NUMERICSERV | NI_NUMERICHOST);
int len = 0;
if (ret == 0) {
if (addr->sin_port != 0)
len = snprintf(buffer, capacity, "%s:%s", host, service);
else
len = snprintf(buffer, capacity, "%s", host);
}
if (len >= (int)capacity)
len = (int)capacity - 1;
mdns_string_t str;
str.str = buffer;
str.length = len;
return str;
}
static mdns_string_t ipv6_address_to_string(char* buffer, size_t capacity, const struct sockaddr_in6* addr,
size_t addrlen) {
char host[NI_MAXHOST] = {0};
char service[NI_MAXSERV] = {0};
int ret = getnameinfo((const struct sockaddr*)addr, (socklen_t)addrlen, host, NI_MAXHOST,
service, NI_MAXSERV, NI_NUMERICSERV | NI_NUMERICHOST);
int len = 0;
if (ret == 0) {
if (addr->sin6_port != 0)
len = snprintf(buffer, capacity, "[%s]:%s", host, service);
else
len = snprintf(buffer, capacity, "%s", host);
}
if (len >= (int)capacity)
len = (int)capacity - 1;
mdns_string_t str;
str.str = buffer;
str.length = len;
return str;
}
static mdns_string_t ip_address_to_string(char* buffer, size_t capacity, const struct sockaddr* addr, size_t addrlen) {
if (addr->sa_family == AF_INET6)
return ipv6_address_to_string(buffer, capacity, (const struct sockaddr_in6*)addr, addrlen);
return ipv4_address_to_string(buffer, capacity, (const struct sockaddr_in*)addr, addrlen);
}
char service_instance_buffer[256] = {0};
char qualified_hostname_buffer[256] = {0};
// Data for our service including the mDNS records
typedef struct {
mdns_string_t service;
mdns_string_t hostname;
mdns_string_t service_instance;
mdns_string_t hostname_qualified;
struct sockaddr_in address_ipv4;
struct sockaddr_in6 address_ipv6;
int port;
mdns_record_t record_ptr;
mdns_record_t record_srv;
mdns_record_t record_a;
mdns_record_t record_aaaa;
mdns_record_t txt_record[2];
} service_t;
service_t service = {};
// Open sockets to listen to incoming mDNS queries on port 5353
static int open_service_sockets(int* sockets)
{
// When recieving, each socket can recieve data from all network interfaces
// Thus we only need to open one socket for each address family
int num_sockets = 0;
{
struct sockaddr_in sock_addr;
memset(&sock_addr, 0, sizeof(struct sockaddr_in));
sock_addr.sin_family = AF_INET;
#ifdef _WIN32
sock_addr.sin_addr = in4addr_any;
#else
sock_addr.sin_addr.s_addr = INADDR_ANY;
#endif
sock_addr.sin_port = htons(MDNS_PORT);
#ifdef __APPLE__
sock_addr.sin_len = sizeof(struct sockaddr_in);
#endif
int sock = mdns_socket_open_ipv4(&sock_addr);
if (sock >= 0)
sockets[num_sockets++] = sock;
}
{
struct sockaddr_in6 sock_addr;
memset(&sock_addr, 0, sizeof(struct sockaddr_in6));
sock_addr.sin6_family = AF_INET6;
sock_addr.sin6_addr = in6addr_any;
sock_addr.sin6_port = htons(MDNS_PORT);
#ifdef __APPLE__
sock_addr.sin6_len = sizeof(struct sockaddr_in6);
#endif
int sock = mdns_socket_open_ipv6(&sock_addr);
if (sock >= 0)
sockets[num_sockets++] = sock;
}
return num_sockets;
}
static char sendbuffer[1024];
// Callback handling questions incoming on service sockets
static int service_callback(int sock, const struct sockaddr* from, size_t addrlen, mdns_entry_type_t entry,
uint16_t query_id, uint16_t rtype_int, uint16_t rclass, uint32_t ttl, const void* data,
size_t size, size_t name_offset, size_t name_length, size_t record_offset,
size_t record_length, void* user_data) {
static mdns_record_txt_t txtbuffer[128];
static char addrbuffer[64];
static char entrybuffer[256];
static char namebuffer[256];
mdns_record_type_t rtype = (mdns_record_type_t)rtype_int;
(void)sizeof(ttl);
if (entry != MDNS_ENTRYTYPE_QUESTION)
return 0;
const char dns_sd[] = "_services._dns-sd._udp.local.";
mdns_string_t fromaddrstr = ip_address_to_string(addrbuffer, sizeof(addrbuffer), from, addrlen);
size_t offset = name_offset;
mdns_string_t name = mdns_string_extract(data, size, &offset, namebuffer, sizeof(namebuffer));
const char* record_name = 0;
if (rtype == MDNS_RECORDTYPE_PTR)
record_name = "PTR";
else if (rtype == MDNS_RECORDTYPE_SRV)
record_name = "SRV";
else if (rtype == MDNS_RECORDTYPE_A)
record_name = "A";
else if (rtype == MDNS_RECORDTYPE_AAAA)
record_name = "AAAA";
else if (rtype == MDNS_RECORDTYPE_TXT)
record_name = "TXT";
else if (rtype == MDNS_RECORDTYPE_ANY)
record_name = "ANY";
else
return 0;
printf("Query %s %.*s\n", record_name, MDNS_STRING_FORMAT(name));
if ((name.length == (sizeof(dns_sd) - 1)) &&
(strncmp(name.str, dns_sd, sizeof(dns_sd) - 1) == 0)) {
if ((rtype == MDNS_RECORDTYPE_PTR) || (rtype == MDNS_RECORDTYPE_ANY)) {
// The PTR query was for the DNS-SD domain, send answer with a PTR record for the
// service name we advertise, typically on the "<_service-name>._tcp.local." format
// Answer PTR record reverse mapping "<_service-name>._tcp.local." to
// "<hostname>.<_service-name>._tcp.local."
mdns_record_t answer = {
.name = name, .type = MDNS_RECORDTYPE_PTR, .data.ptr.name = service.service};
// Send the answer, unicast or multicast depending on flag in query
uint16_t unicast = (rclass & MDNS_UNICAST_RESPONSE);
printf(" --> answer %.*s (%s)\n", MDNS_STRING_FORMAT(answer.data.ptr.name),
(unicast ? "unicast" : "multicast"));
if (unicast) {
mdns_query_answer_unicast(sock, (void*)from, addrlen, (void*)sendbuffer, sizeof(sendbuffer),
query_id, rtype, name.str, name.length, answer, NULL, 0, NULL, 0);
} else {
mdns_query_answer_multicast(sock, sendbuffer, sizeof(sendbuffer), answer, 0, 0, 0,
0);
}
}
} else if ((name.length == service.service.length) &&
(strncmp(name.str, service.service.str, name.length) == 0)) {
if ((rtype == MDNS_RECORDTYPE_PTR) || (rtype == MDNS_RECORDTYPE_ANY)) {
// The PTR query was for our service (usually "<_service-name._tcp.local"), answer a PTR
// record reverse mapping the queried service name to our service instance name
// (typically on the "<hostname>.<_service-name>._tcp.local." format), and add
// additional records containing the SRV record mapping the service instance name to our
// qualified hostname (typically "<hostname>.local.") and port, as well as any IPv4/IPv6
// address for the hostname as A/AAAA records, and two test TXT records
// Answer PTR record reverse mapping "<_service-name>._tcp.local." to
// "<hostname>.<_service-name>._tcp.local."
mdns_record_t answer = service.record_ptr;
mdns_record_t additional[5] = {0};
size_t additional_count = 0;
// SRV record mapping "<hostname>.<_service-name>._tcp.local." to
// "<hostname>.local." with port. Set weight & priority to 0.
additional[additional_count++] = service.record_srv;
// A/AAAA records mapping "<hostname>.local." to IPv4/IPv6 addresses
if (service.address_ipv4.sin_family == AF_INET)
additional[additional_count++] = service.record_a;
if (service.address_ipv6.sin6_family == AF_INET6)
additional[additional_count++] = service.record_aaaa;
// Add two test TXT records for our service instance name, will be coalesced into
// one record with both key-value pair strings by the library
additional[additional_count++] = service.txt_record[0];
additional[additional_count++] = service.txt_record[1];
// Send the answer, unicast or multicast depending on flag in query
uint16_t unicast = (rclass & MDNS_UNICAST_RESPONSE);
printf(" --> answer %.*s (%s)\n",
MDNS_STRING_FORMAT(service.record_ptr.data.ptr.name),
(unicast ? "unicast" : "multicast"));
if (unicast) {
mdns_query_answer_unicast(sock, from, addrlen, sendbuffer, sizeof(sendbuffer),
query_id, rtype, name.str, name.length, answer, 0, 0,
additional, additional_count);
} else {
mdns_query_answer_multicast(sock, sendbuffer, sizeof(sendbuffer), answer, 0, 0,
additional, additional_count);
}
}
} else if ((name.length == service.service_instance.length) &&
(strncmp(name.str, service.service_instance.str, name.length) == 0)) {
if ((rtype == MDNS_RECORDTYPE_SRV) || (rtype == MDNS_RECORDTYPE_ANY)) {
// The SRV query was for our service instance (usually
// "<hostname>.<_service-name._tcp.local"), answer a SRV record mapping the service
// instance name to our qualified hostname (typically "<hostname>.local.") and port, as
// well as any IPv4/IPv6 address for the hostname as A/AAAA records, and two test TXT
// records
// Answer PTR record reverse mapping "<_service-name>._tcp.local." to
// "<hostname>.<_service-name>._tcp.local."
mdns_record_t answer = service.record_srv;
mdns_record_t additional[5] = {0};
size_t additional_count = 0;
// A/AAAA records mapping "<hostname>.local." to IPv4/IPv6 addresses
if (service.address_ipv4.sin_family == AF_INET)
additional[additional_count++] = service.record_a;
if (service.address_ipv6.sin6_family == AF_INET6)
additional[additional_count++] = service.record_aaaa;
// Add two test TXT records for our service instance name, will be coalesced into
// one record with both key-value pair strings by the library
additional[additional_count++] = service.txt_record[0];
additional[additional_count++] = service.txt_record[1];
// Send the answer, unicast or multicast depending on flag in query
uint16_t unicast = (rclass & MDNS_UNICAST_RESPONSE);
printf(" --> answer %.*s port %d (%s)\n",
MDNS_STRING_FORMAT(service.record_srv.data.srv.name), service.port,
(unicast ? "unicast" : "multicast"));
if (unicast) {
mdns_query_answer_unicast(sock, from, addrlen, sendbuffer, sizeof(sendbuffer),
query_id, rtype, name.str, name.length, answer, 0, 0,
additional, additional_count);
} else {
mdns_query_answer_multicast(sock, sendbuffer, sizeof(sendbuffer), answer, 0, 0,
additional, additional_count);
}
}
} else {
qWarning() << "Is this for me?" << name.str << "VS" << service.hostname_qualified.str << "i" << service.address_ipv4.sin_family;
if ((name.length == service.hostname_qualified.length) &&
(strncmp(name.str, service.hostname_qualified.str, name.length) == 0)) {
if (((rtype == MDNS_RECORDTYPE_A) || (rtype == MDNS_RECORDTYPE_ANY)) &&
(service.address_ipv4.sin_family == AF_INET)) {
// The A query was for our qualified hostname (typically "<hostname>.local.") and we
// have an IPv4 address, answer with an A record mappiing the hostname to an IPv4
// address, as well as any IPv6 address for the hostname, and two test TXT records
// Answer A records mapping "<hostname>.local." to IPv4 address
mdns_record_t answer = service.record_a;
mdns_record_t additional[5] = {0};
size_t additional_count = 0;
// AAAA record mapping "<hostname>.local." to IPv6 addresses
if (service.address_ipv6.sin6_family == AF_INET6)
additional[additional_count++] = service.record_aaaa;
// Add two test TXT records for our service instance name, will be coalesced into
// one record with both key-value pair strings by the library
additional[additional_count++] = service.txt_record[0];
additional[additional_count++] = service.txt_record[1];
// Send the answer, unicast or multicast depending on flag in query
uint16_t unicast = (rclass & MDNS_UNICAST_RESPONSE);
mdns_string_t addrstr = ip_address_to_string(
addrbuffer, sizeof(addrbuffer), (struct sockaddr*)&service.record_a.data.a.addr,
sizeof(service.record_a.data.a.addr));
printf(" --> answer %.*s IPv4 %.*s (%s)\n", MDNS_STRING_FORMAT(service.record_a.name),
MDNS_STRING_FORMAT(addrstr), (unicast ? "unicast" : "multicast"));
if (unicast) {
mdns_query_answer_unicast(sock, from, addrlen, sendbuffer, sizeof(sendbuffer),
query_id, rtype, name.str, name.length, answer, 0, 0,
additional, additional_count);
} else {
mdns_query_answer_multicast(sock, sendbuffer, sizeof(sendbuffer), answer, 0, 0,
additional, additional_count);
}
} else if (((rtype == MDNS_RECORDTYPE_AAAA) || (rtype == MDNS_RECORDTYPE_ANY)) &&
(service.address_ipv6.sin6_family == AF_INET6)) {
// The AAAA query was for our qualified hostname (typically "<hostname>.local.") and we
// have an IPv6 address, answer with an AAAA record mappiing the hostname to an IPv6
// address, as well as any IPv4 address for the hostname, and two test TXT records
// Answer AAAA records mapping "<hostname>.local." to IPv6 address
mdns_record_t answer = service.record_aaaa;
mdns_record_t additional[5] = {0};
size_t additional_count = 0;
// A record mapping "<hostname>.local." to IPv4 addresses
if (service.address_ipv4.sin_family == AF_INET)
additional[additional_count++] = service.record_a;
// Add two test TXT records for our service instance name, will be coalesced into
// one record with both key-value pair strings by the library
additional[additional_count++] = service.txt_record[0];
additional[additional_count++] = service.txt_record[1];
// Send the answer, unicast or multicast depending on flag in query
uint16_t unicast = (rclass & MDNS_UNICAST_RESPONSE);
mdns_string_t addrstr =
ip_address_to_string(addrbuffer, sizeof(addrbuffer),
(struct sockaddr*)&service.record_aaaa.data.aaaa.addr,
sizeof(service.record_aaaa.data.aaaa.addr));
printf(" --> answer %.*s IPv6 %.*s (%s)\n",
MDNS_STRING_FORMAT(service.record_aaaa.name), MDNS_STRING_FORMAT(addrstr),
(unicast ? "unicast" : "multicast"));
if (unicast) {
mdns_query_answer_unicast(sock, from, addrlen, sendbuffer, sizeof(sendbuffer),
query_id, rtype, name.str, name.length, answer, 0, 0,
additional, additional_count);
} else {
mdns_query_answer_multicast(sock, sendbuffer, sizeof(sendbuffer), answer, 0, 0,
additional, additional_count);
}
}
}
}
return 0;
}
int sockets[32];
int MdnsWrapper::startAnnouncing(const char* hostname, const char* service_name, int service_port)
{
int num_sockets = open_service_sockets(sockets);
if (num_sockets <= 0) {
printf("Failed to open any client sockets\n");
return -1;
}
printf("Opened %d socket%s for mDNS service\n", num_sockets, num_sockets ? "s" : "");
size_t service_name_length = strlen(service_name);
if (!service_name_length) {
printf("Invalid service name\n");
return -1;
}
char* service_name_buffer = (char*)malloc(service_name_length + 2);
memcpy(service_name_buffer, service_name, service_name_length);
if (service_name_buffer[service_name_length - 1] != '.')
service_name_buffer[service_name_length++] = '.';
service_name_buffer[service_name_length] = 0;
service_name = service_name_buffer;
printf("Service mDNS: %s:%d\n", service_name, service_port);
printf("Hostname: %s\n", hostname);
size_t capacity = 2048;
void* buffer = malloc(capacity);
mdns_string_t service_string = (mdns_string_t){service_name, strlen(service_name)};
mdns_string_t hostname_string = (mdns_string_t){hostname, strlen(hostname)};
// Build the service instance "<hostname>.<_service-name>._tcp.local." string
snprintf(service_instance_buffer, sizeof(service_instance_buffer) - 1, "%.*s.%.*s",
MDNS_STRING_FORMAT(hostname_string), MDNS_STRING_FORMAT(service_string));
qWarning() << service_instance_buffer;
// Build the "<hostname>.local." string
snprintf(qualified_hostname_buffer, sizeof(qualified_hostname_buffer) - 1, "%.*s.local.",
MDNS_STRING_FORMAT(hostname_string));
memset(&service, 0, sizeof(service));
service.service.str = service_name;
service.service.length = strlen(service_name);
service.hostname.str = hostname;
service.hostname.length = strlen(hostname);
service.service_instance.str = service_instance_buffer;
service.service_instance.length = strlen(service_instance_buffer);
service.hostname_qualified.str = qualified_hostname_buffer;
service.hostname_qualified.length = strlen(qualified_hostname_buffer);
service.address_ipv4 = service_address_ipv4;
service.address_ipv6 = service_address_ipv6;
service.port = service_port;
// Setup our mDNS records
// PTR record reverse mapping "<_service-name>._tcp.local." to
// "<hostname>.<_service-name>._tcp.local."
service.record_ptr = (mdns_record_t){.name = service.service,
.type = MDNS_RECORDTYPE_PTR,
.data.ptr.name = service.service_instance,
.rclass = 0,
.ttl = 0};
// SRV record mapping "<hostname>.<_service-name>._tcp.local." to
// "<hostname>.local." with port. Set weight & priority to 0.
service.record_srv = (mdns_record_t){.name = service.service_instance,
.type = MDNS_RECORDTYPE_SRV,
.data.srv.name = service.hostname_qualified,
.data.srv.port = (uint16_t)service.port,
.data.srv.priority = 0,
.data.srv.weight = 0,
.rclass = 0,
.ttl = 0};
// A/AAAA records mapping "<hostname>.local." to IPv4/IPv6 addresses
service.record_a = (mdns_record_t){.name = service.hostname_qualified,
.type = MDNS_RECORDTYPE_A,
.data.a.addr = service.address_ipv4,
.rclass = 0,
.ttl = 0};
service.record_aaaa = (mdns_record_t){.name = service.hostname_qualified,
.type = MDNS_RECORDTYPE_AAAA,
.data.aaaa.addr = service.address_ipv6,
.rclass = 0,
.ttl = 0};
// Add two test TXT records for our service instance name, will be coalesced into
// one record with both key-value pair strings by the library
service.txt_record[0] = (mdns_record_t){.name = service.service_instance,
.type = MDNS_RECORDTYPE_TXT,
.data.txt.key = {MDNS_STRING_CONST("test")},
.data.txt.value = {MDNS_STRING_CONST("1")},
.rclass = 0,
.ttl = 0};
service.txt_record[1] = (mdns_record_t){.name = service.service_instance,
.type = MDNS_RECORDTYPE_TXT,
.data.txt.key = {MDNS_STRING_CONST("other")},
.data.txt.value = {MDNS_STRING_CONST("value")},
.rclass = 0,
.ttl = 0};
// Send an announcement on startup of service
{
printf("Sending announce\n");
mdns_record_t additional[5] = {0};
size_t additional_count = 0;
additional[additional_count++] = service.record_srv;
if (service.address_ipv4.sin_family == AF_INET)
additional[additional_count++] = service.record_a;
if (service.address_ipv6.sin6_family == AF_INET6)
additional[additional_count++] = service.record_aaaa;
additional[additional_count++] = service.txt_record[0];
additional[additional_count++] = service.txt_record[1];
for (int isock = 0; isock < num_sockets; ++isock)
mdns_announce_multicast(sockets[isock], buffer, capacity, service.record_ptr, 0, 0,
additional, additional_count);
}
// This is a crude implementation that checks for incoming queries
while (true) {
int nfds = 0;
fd_set readfs;
FD_ZERO(&readfs);
for (int isock = 0; isock < num_sockets; ++isock) {
if (sockets[isock] >= nfds)
nfds = sockets[isock] + 1;
FD_SET(sockets[isock], &readfs);
}
struct timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = 100000;
if (select(nfds, &readfs, 0, 0, &timeout) >= 0) {
for (int isock = 0; isock < num_sockets; ++isock) {
if (FD_ISSET(sockets[isock], &readfs)) {
mdns_socket_listen(sockets[isock], buffer, capacity, service_callback,
&service);
}
FD_SET(sockets[isock], &readfs);
}
} else {
break;
}
}
free(buffer);
free(service_name_buffer);
return 0;
}
void MdnsWrapper::stopAnnouncing()
{
printf("Sending goodbye\n");
mdns_record_t additional[5] = {};
size_t additional_count = 0;
additional[additional_count++] = service.record_srv;
if (service.address_ipv4.sin_family == AF_INET)
additional[additional_count++] = service.record_a;
if (service.address_ipv6.sin6_family == AF_INET6)
additional[additional_count++] = service.record_aaaa;
additional[additional_count++] = service.txt_record[0];
additional[additional_count++] = service.txt_record[1];
size_t capacity = 2048;
void *buffer = malloc(capacity);
int num_sockets = 2; // FIXME
for (int isock = 0; isock < num_sockets; ++isock) {
mdns_goodbye_multicast(sockets[isock], buffer, capacity, service.record_ptr, 0, 0, additional, additional_count);
}
for (int isock = 0; isock < num_sockets; ++isock) {
mdns_socket_close(sockets[isock]);
}
free(buffer);
printf("Closed socket%s\n", num_sockets ? "s" : "");
}

View file

@ -0,0 +1,50 @@
/**
* SPDX-FileCopyrightText: 2023 Albert Vaca Cintora <albertvaka@gmail.com>
*
* SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/
#ifndef KDECONNECT_MDNS_WRAPPER_H
#define KDECONNECT_MDNS_WRAPPER_H
#include <QHostAddress>
#include <QMap>
#include <QSocketNotifier>
#include <QString>
#include <QVector>
/*
* A Qt wrapper for the mdns.h header-only library
* from https://github.com/mjansson/mdns
*/
class MdnsWrapper : public QObject
{
Q_OBJECT
public:
struct MdnsService {
QString serviceName;
int port;
QHostAddress address;
QMap<QString, QString> txtRecords;
};
int startAnnouncing(const char *hostname, const char *service_name, int service_port);
void stopAnnouncing();
void startDiscovering(const char *serviceName);
void stopDiscovering();
void sendQuery(const char *serviceName);
Q_SIGNALS:
void serviceFound(const MdnsService &service);
private:
int listenForQueryResponses();
void stopListeningForQueryResponses();
QVector<QSocketNotifier *> responseSocketNotifiers;
};
#endif

View file

@ -10,26 +10,22 @@
#include "kdeconnectconfig.h" #include "kdeconnectconfig.h"
#include "lanlinkprovider.h" #include "lanlinkprovider.h"
#include <KDNSSD/DNSSD/PublicService> #include "mdns_wrapper.h"
#include <KDNSSD/DNSSD/RemoteService>
#include <KDNSSD/DNSSD/ServiceBrowser>
const QString kServiceName = QStringLiteral("_kdeconnect._udp"); #include <QHostInfo>
const char *kServiceName = "_kdeconnect._udp.local";
MdnsDiscovery::MdnsDiscovery(LanLinkProvider *lanLinkProvider) MdnsDiscovery::MdnsDiscovery(LanLinkProvider *lanLinkProvider)
: lanLinkProvider(lanLinkProvider) : lanLinkProvider(lanLinkProvider)
{ {
switch (KDNSSD::ServiceBrowser::isAvailable()) { connect(&mdnsWrapper, &MdnsWrapper::serviceFound, [lanLinkProvider](const MdnsWrapper::MdnsService &service) {
case KDNSSD::ServiceBrowser::Stopped: if (KdeConnectConfig::instance().deviceId() == service.serviceName) {
qCWarning(KDECONNECT_CORE) << "mDNS or Avahi daemons are not running, mDNS discovery not available"; qCDebug(KDECONNECT_CORE) << "Discovered myself, ignoring";
break; return;
case KDNSSD::ServiceBrowser::Working:
qCDebug(KDECONNECT_CORE) << "mDNS discovery is available";
break;
case KDNSSD::ServiceBrowser::Unsupported:
qCWarning(KDECONNECT_CORE) << "mDNS discovery not available (library built without DNS-SD support)";
break;
} }
qCDebug(KDECONNECT_CORE) << "Discovered" << service.serviceName << "at" << service.address;
lanLinkProvider->sendUdpIdentityPacket(QList<QHostAddress>{service.address});
});
} }
MdnsDiscovery::~MdnsDiscovery() MdnsDiscovery::~MdnsDiscovery()
@ -38,8 +34,13 @@ MdnsDiscovery::~MdnsDiscovery()
stopDiscovering(); stopDiscovering();
} }
QString hostName = QHostInfo::localHostName();
void MdnsDiscovery::startAnnouncing() void MdnsDiscovery::startAnnouncing()
{ {
// mdnsWrapper.startAnnouncing(hostName.toLatin1().data(), kServiceName, LanLinkProvider::UDP_PORT);
/*
if (m_publisher != nullptr) { if (m_publisher != nullptr) {
qCDebug(KDECONNECT_CORE) << "MDNS already announcing"; qCDebug(KDECONNECT_CORE) << "MDNS already announcing";
return; return;
@ -68,53 +69,26 @@ void MdnsDiscovery::startAnnouncing()
}); });
m_publisher->publishAsync(); m_publisher->publishAsync();
*/
} }
void MdnsDiscovery::stopAnnouncing() void MdnsDiscovery::stopAnnouncing()
{ {
if (m_publisher != nullptr) { // mdnsWrapper.stopAnnouncing();
qCDebug(KDECONNECT_CORE) << "MDNS stop announcing";
delete m_publisher; // if (m_publisher != nullptr) {
m_publisher = nullptr; // qCDebug(KDECONNECT_CORE) << "MDNS stop announcing";
} // delete m_publisher;
// m_publisher = nullptr;
// }
} }
void MdnsDiscovery::startDiscovering() void MdnsDiscovery::startDiscovering()
{ {
if (m_serviceBrowser != nullptr) { mdnsWrapper.startDiscovering(kServiceName);
qCDebug(KDECONNECT_CORE) << "MDNS already discovering";
return;
}
qCDebug(KDECONNECT_CORE) << "MDNS start discovering";
m_serviceBrowser = new KDNSSD::ServiceBrowser(kServiceName, true);
connect(m_serviceBrowser, &KDNSSD::ServiceBrowser::serviceAdded, [this](KDNSSD::RemoteService::Ptr service) {
if (KdeConnectConfig::instance().deviceId() == service->serviceName()) {
qCDebug(KDECONNECT_CORE) << "Discovered myself, ignoring";
return;
}
qCDebug(KDECONNECT_CORE) << "Discovered " << service->serviceName() << " at " << service->hostName();
QHostAddress address(service->hostName());
lanLinkProvider->sendUdpIdentityPacket(QList<QHostAddress>{address});
});
connect(m_serviceBrowser, &KDNSSD::ServiceBrowser::serviceRemoved, [](KDNSSD::RemoteService::Ptr service) {
qCDebug(KDECONNECT_CORE) << "Lost " << service->serviceName();
});
connect(m_serviceBrowser, &KDNSSD::ServiceBrowser::finished, []() {
qCDebug(KDECONNECT_CORE) << "Finished discovery";
});
m_serviceBrowser->startBrowse();
} }
void MdnsDiscovery::stopDiscovering() void MdnsDiscovery::stopDiscovering()
{ {
if (m_serviceBrowser != nullptr) { mdnsWrapper.stopDiscovering();
qCDebug(KDECONNECT_CORE) << "MDNS stop discovering";
delete m_serviceBrowser;
m_serviceBrowser = nullptr;
}
} }

View file

@ -11,12 +11,9 @@
#include "kdeconnectcore_export.h" #include "kdeconnectcore_export.h"
#include "mdns_wrapper.h"
class LanLinkProvider; class LanLinkProvider;
namespace KDNSSD
{
class PublicService;
class ServiceBrowser;
};
class KDECONNECTCORE_EXPORT MdnsDiscovery : public QObject class KDECONNECTCORE_EXPORT MdnsDiscovery : public QObject
{ {
@ -34,8 +31,7 @@ public:
private: private:
LanLinkProvider *lanLinkProvider = nullptr; LanLinkProvider *lanLinkProvider = nullptr;
KDNSSD::PublicService *m_publisher = nullptr; MdnsWrapper mdnsWrapper;
KDNSSD::ServiceBrowser *m_serviceBrowser = nullptr;
}; };
#endif // KDECONNECT_SERVER_H #endif // KDECONNECT_SERVER_H