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Fix resolve behaviour on subsequent callback invocations for Windows

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hensm
2026-03-02 20:50:37 +00:00
committed by Matt Hensman
parent 318b586e49
commit 75f0a1bb1c
2 changed files with 62 additions and 43 deletions
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19
bridge/src/dns_sd/native/dns_sd_platform_browser_unix.cc
View File

@@ -158,7 +158,6 @@ void DnsSdPlatformBrowser::Impl::event_loop()
.tv_sec = 0, .tv_usec = 250000
}; // 250ms
int result = select(max_fd + 1, &read_fds, nullptr, nullptr, &tv);
if (result <= 0 || !is_started)
continue;
@@ -230,10 +229,10 @@ void DNSSD_API DnsSdPlatformBrowser::Impl::resolve_callback(DNSServiceRef, DNSSe
return;
}
DnsSdService info;
info.name = ctx->service_name;
info.host = hosttarget;
info.port = ntohs(port);
DnsSdService service;
service.name = ctx->service_name;
service.host = hosttarget;
service.port = ntohs(port);
// Parse TXT record into key-value map
{
@@ -245,7 +244,7 @@ void DNSSD_API DnsSdPlatformBrowser::Impl::resolve_callback(DNSServiceRef, DNSSe
auto err = TXTRecordGetItemAtIndex(
txt_len, txt_record, i, sizeof(key), key, &value_len, &value);
if (err == kDNSServiceErr_NoError) {
info.txt_record[key] = (value && value_len > 0)
service.txt_record[key] = (value && value_len > 0)
? std::string(static_cast<const char*>(value), value_len)
: "";
}
@@ -253,10 +252,10 @@ void DNSSD_API DnsSdPlatformBrowser::Impl::resolve_callback(DNSServiceRef, DNSSe
}
// Resolve v4/v6 addresses via getaddrinfo
resolve_addresses(hosttarget, info.address4, info.address6);
resolve_addresses(hosttarget, service.address4, service.address6);
DEBUG_LOG("resolved: %s -> %s:%d (%s / %s)", info.name.c_str(), info.host.c_str(), info.port,
info.address4.c_str(), info.address6.c_str());
ctx->impl->delegate.on_service_up(info);
DEBUG_LOG("resolved: %s -> %s:%d (%s / %s)", service.name.c_str(), service.host.c_str(),
service.port, service.address4.c_str(), service.address6.c_str());
ctx->impl->delegate.on_service_up(service);
ctx->destroyed = true;
}

86
bridge/src/dns_sd/native/dns_sd_platform_browser_win.cc
View File

@@ -1,8 +1,8 @@
/**
* DNS-SD browser implementation for Windows.
*
* Uses the DNS-SD functions of the Windows DNS API (Windns.h) available on Windows 10+ without any
* third-party dependencies like Bonjour.
* Uses the DnsService* functions of the Windows DNS API (windns.h) available on Windows 10+ without
* any third-party dependencies like Bonjour.
*/
#include "dns_sd_platform_browser.h"
@@ -17,7 +17,6 @@
#include <chrono>
#include <condition_variable>
#include <map>
#include <set>
#include <thread>
namespace {
@@ -76,7 +75,6 @@ struct DnsSdPlatformBrowser::Impl {
/** Represents a resolve operation triggered by the current browse operation. */
struct ResolveContext {
Impl* impl;
bool cancelled;
DWORD ttl;
std::string service_name;
std::wstring query_name;
@@ -85,20 +83,20 @@ struct DnsSdPlatformBrowser::Impl {
ResolveContext()
: impl(nullptr)
, cancelled(false)
, ttl(0)
, resolve_request {}
, resolve_cancel {}
{
}
};
// Stored contexts for ongoing resolve operations
std::set<ResolveContext*> active_resolves;
// Stored contexts for ongoing resolve operations (keyed by service name)
std::map<std::string, ResolveContext*> active_resolves;
std::mutex active_resolves_mutex;
// WinDNS doesn't have a builtin mechanism to notify us when a service disappears, so we
// keep a record of found services and expire them (emitting a `service_down` event) based on
// their TTL unless they're refreshed by a subsequent browse callback.
// The Windows DNS API doesn't have a builtin mechanism to notify us when a service disappears,
// so we keep a record of found services (keyed by service name) and expire them (emitting a
// `service_down` event) based on their TTL unless they're refreshed by a subsequent browse
// callback.
std::map<std::string, std::chrono::steady_clock::time_point> expiring_services;
std::mutex expiring_services_mutex;
std::thread expiry_thread;
@@ -175,16 +173,15 @@ void DnsSdPlatformBrowser::Impl::stop()
// Cancel browse operation
DnsServiceBrowseCancel(&browse.cancel);
// Cancel and cleanup active resolves
// Cancel active resolve operation(s). We make a copy of the map here to avoid a deadlock when
// DnsServiceResolveCancel invokes the resolve callback with an ERROR_CANCELLED status.
std::map<std::string, ResolveContext*> resolves_to_cancel;
{
std::scoped_lock lock(active_resolves_mutex);
for (auto* ctx : active_resolves) {
if (!ctx->cancelled) {
ctx->cancelled = true;
DnsServiceResolveCancel(&ctx->resolve_cancel);
}
}
active_resolves.clear();
resolves_to_cancel = active_resolves;
}
for (auto& [name, ctx] : resolves_to_cancel) {
DnsServiceResolveCancel(&ctx->resolve_cancel);
}
// Wake and join expiry thread
@@ -261,18 +258,43 @@ void WINAPI DnsSdPlatformBrowser::Impl::browse_callback(
if (record->wType != DNS_TYPE_PTR)
continue;
std::string instance_name = wide_to_utf8(record->Data.PTR.pNameHost);
// Strip everything after (and including) the first dot to get the service name
size_t first_dot_index = instance_name.find('.');
std::string service_name = (first_dot_index != std::string::npos)
? instance_name.substr(0, first_dot_index)
: instance_name;
// If we've already resolved this service, just refresh its TTL expiry without starting
// another resolve operation.
{
std::scoped_lock lock(impl->expiring_services_mutex);
if (impl->expiring_services.count(service_name) > 0) {
impl->expiring_services[service_name]
= std::chrono::steady_clock::now() + std::chrono::seconds(record->dwTtl);
DEBUG_LOG("refreshed TTL for %s (ttl=%lu)", service_name.c_str(), record->dwTtl);
impl->expiry_cv.notify_one();
continue;
}
}
// Ensure we don't have an active resolve operation for this service already
{
std::scoped_lock lock(impl->active_resolves_mutex);
if (impl->active_resolves.count(service_name) > 0) {
DEBUG_LOG("resolve already in progress for %s, skipping", service_name.c_str());
continue;
}
}
DEBUG_LOG("browse found: %s (ttl=%lu)", instance_name.c_str(), record->dwTtl);
// Create a new resolve context for this service
auto* resolve_ctx = new ResolveContext();
resolve_ctx->impl = impl;
resolve_ctx->ttl = record->dwTtl;
std::string instance_name = wide_to_utf8(record->Data.PTR.pNameHost);
DEBUG_LOG("browse found: %s (ttl=%lu)", instance_name.c_str(), record->dwTtl);
// Strip everything after (and including) the first dot to get the service name
size_t dot = instance_name.find('.');
resolve_ctx->service_name
= (dot != std::string::npos) ? instance_name.substr(0, dot) : instance_name;
resolve_ctx->service_name = std::move(service_name);
resolve_ctx->query_name = utf8_to_wide(instance_name);
// Populate resolve request
@@ -290,7 +312,7 @@ void WINAPI DnsSdPlatformBrowser::Impl::browse_callback(
switch (resolve_status) {
case ERROR_SUCCESS:
case DNS_REQUEST_PENDING:
impl->active_resolves.insert(resolve_ctx);
impl->active_resolves[resolve_ctx->service_name] = resolve_ctx;
break;
default:
delete resolve_ctx;
@@ -311,15 +333,13 @@ void WINAPI DnsSdPlatformBrowser::Impl::resolve_callback(
DnsServiceFreeInstance(service_instance);
{
std::scoped_lock lock(impl->active_resolves_mutex);
impl->active_resolves.erase(resolve_ctx);
impl->active_resolves.erase(resolve_ctx->service_name);
}
delete resolve_ctx;
} };
// If the browse operation is still active, the resolve operation was not cancelled, and we got
// a valid result, emit a service_up event
if (impl->is_started && !resolve_ctx->cancelled && status == ERROR_SUCCESS
&& service_instance) {
// If the browse operation is still active and we got a valid result, emit a service_up event
if (impl->is_started && status == ERROR_SUCCESS && service_instance) {
DnsSdService service;
service.name = resolve_ctx->service_name;
service.host = wide_to_utf8(service_instance->pszHostName);