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Use NWPathMonitor for modern Apple reachability with legacy fallback #1431

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4b62d73
Migrate Apple reachability from SCNetworkReachability to NWPathMonitor
bmehta001 Apr 29, 2026
3906d9e
Restore ODWReachabilityTests includes to keep #1431 focused
bmehta001 Apr 29, 2026
12d8958
Restore ODWReachability.m header section to match main
bmehta001 Apr 29, 2026
7702508
Use NWPathMonitor in ODWReachability
bmehta001 May 2, 2026
675cad4
Clarify modern WWAN reachability handling
bmehta001 May 2, 2026
366f87a
Avoid blocking Apple reachability construction
bmehta001 May 2, 2026
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220 changes: 124 additions & 96 deletions lib/pal/posix/NetworkInformationImpl.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@
class NetworkInformation : public NetworkInformationImpl,
public std::enable_shared_from_this<NetworkInformation>
{
public:
public:
/// <summary>
///
/// </summary>
Expand Down Expand Up @@ -59,21 +59,27 @@ virtual NetworkCost GetNetworkCost()
/// <summary>
/// Setup initial network information and start net monitor if requested.
/// This cannot be put in constructor because we need to use shared_from_this.
/// </summary>
void SetupNetDetect();
/// </summary>
void SetupNetDetect();

private:
void UpdateType(NetworkType type) noexcept;
void UpdateCost(NetworkCost cost) noexcept;
std::string m_network_provider {};
private:
void SetupModernNetDetect() API_AVAILABLE(macos(10.14), ios(12.0));
#if ODW_LEGACY_REACHABILITY_REQUIRED
void SetupLegacyNetDetect();
#endif
void UpdateType(NetworkType type) noexcept;
void UpdateCost(NetworkCost cost) noexcept;
std::string m_network_provider {};

// iOS 12 and newer
nw_path_monitor_t m_monitor = nil;
// iOS 12+ / macOS 10.14+
nw_path_monitor_t m_monitor = nil;

// iOS 11 and older
ODWReachability* m_reach = nil;
id m_notificationId = nil;
};
#if ODW_LEGACY_REACHABILITY_REQUIRED
// Older Apple deployment targets still need the legacy fallback.
ODWReachability* m_reach = nil;
id m_notificationId = nil;
#endif
};

NetworkInformation::NetworkInformation(IRuntimeConfig& configuration) :
NetworkInformationImpl(configuration)
Expand All @@ -84,6 +90,7 @@ virtual NetworkCost GetNetworkCost()

NetworkInformation::~NetworkInformation() noexcept
{
#if ODW_LEGACY_REACHABILITY_REQUIRED
if (@available(macOS 10.14, iOS 12.0, *))
{
if (m_isNetDetectEnabled)
Expand All @@ -99,108 +106,130 @@ virtual NetworkCost GetNetworkCost()
[m_reach stopNotifier];
}
}
#else
if (m_isNetDetectEnabled)
{
nw_path_monitor_cancel(m_monitor);
}
#endif
}

void NetworkInformation::SetupNetDetect()
void NetworkInformation::SetupModernNetDetect()
{
if (@available(macOS 10.14, iOS 12.0, *))
auto weak_this = std::weak_ptr<NetworkInformation>(shared_from_this());

m_monitor = nw_path_monitor_create();
nw_path_monitor_set_queue(m_monitor, dispatch_get_global_queue(QOS_CLASS_BACKGROUND, 0));
nw_path_monitor_set_update_handler(m_monitor, ^(nw_path_t path)
{
auto weak_this = std::weak_ptr<NetworkInformation>(shared_from_this());
auto strong_this = weak_this.lock();
if (!strong_this)
{
return;
}

m_monitor = nw_path_monitor_create();
nw_path_monitor_set_queue(m_monitor, dispatch_get_global_queue(QOS_CLASS_BACKGROUND, 0));
nw_path_monitor_set_update_handler(m_monitor, ^(nw_path_t path)
NetworkType type = NetworkType_Unknown;
NetworkCost cost = NetworkCost_Unknown;
nw_path_status_t status = nw_path_get_status(path);
bool connected = status == nw_path_status_satisfied || status == nw_path_status_satisfiable;
if (connected)
{
auto strong_this = weak_this.lock();
if (!strong_this)
if (nw_path_uses_interface_type(path, nw_interface_type_wifi))
{
return;
type = NetworkType_Wifi;
}

NetworkType type = NetworkType_Unknown;
NetworkCost cost = NetworkCost_Unknown;
nw_path_status_t status = nw_path_get_status(path);
bool connected = status == nw_path_status_satisfied || status == nw_path_status_satisfiable;
if (connected)
else if (nw_path_uses_interface_type(path, nw_interface_type_cellular))
{
if (nw_path_uses_interface_type(path, nw_interface_type_wifi))
{
type = NetworkType_Wifi;
}
else if (nw_path_uses_interface_type(path, nw_interface_type_cellular))
{
type = NetworkType_WWAN;
}
else if (nw_path_uses_interface_type(path, nw_interface_type_wired))
{
type = NetworkType_Wired;
}
cost = nw_path_is_expensive(path) ? NetworkCost_Metered : NetworkCost_Unmetered;
if (@available(macOS 10.15, iOS 13.0, *))
type = NetworkType_WWAN;
}
else if (nw_path_uses_interface_type(path, nw_interface_type_wired))
{
type = NetworkType_Wired;
}
cost = nw_path_is_expensive(path) ? NetworkCost_Metered : NetworkCost_Unmetered;
if (@available(macOS 10.15, iOS 13.0, *))
{
if (nw_path_is_constrained(path))
{
if (nw_path_is_constrained(path))
{
cost = NetworkCost_Roaming;
}
cost = NetworkCost_Roaming;
}
}
strong_this->UpdateType(type);
strong_this->UpdateCost(cost);
});
nw_path_monitor_start(m_monitor);

// nw_path_monitor_start will invoke the callback for once. So if
// we don't want to listen for changes, we can just start the
// monitor and stop it right away.
if (!m_isNetDetectEnabled)
{
nw_path_monitor_cancel(m_monitor);
}
}
else
strong_this->UpdateType(type);
strong_this->UpdateCost(cost);
});
nw_path_monitor_start(m_monitor);

// nw_path_monitor_start will invoke the callback for once. So if
// we don't want to listen for changes, we can just start the
// monitor and stop it right away.
if (!m_isNetDetectEnabled)
{
auto weak_this = std::weak_ptr<NetworkInformation>(shared_from_this());
nw_path_monitor_cancel(m_monitor);
}
}

m_reach = [ODWReachability reachabilityForInternetConnection];
void (^block)(NSNotification*) = ^(NSNotification*)
{
auto strong_this = weak_this.lock();
if (!strong_this)
{
return;
}
#if ODW_LEGACY_REACHABILITY_REQUIRED
void NetworkInformation::SetupLegacyNetDetect()
{
auto weak_this = std::weak_ptr<NetworkInformation>(shared_from_this());

// NetworkCost information is not available until iOS 12.
// Just make the best guess here.
switch (m_reach.currentReachabilityStatus)
{
case NotReachable:
strong_this->UpdateType(NetworkType_Unknown);
strong_this->UpdateCost(NetworkCost_Unknown);
break;
case ReachableViaWiFi:
strong_this->UpdateType(NetworkType_Wifi);
strong_this->UpdateCost(NetworkCost_Unmetered);
break;
case ReachableViaWWAN:
strong_this->UpdateType(NetworkType_WWAN);
strong_this->UpdateCost(NetworkCost_Metered);
break;
}
};
block(nil); // Update the initial status.
m_reach = [ODWReachability reachabilityForInternetConnection];
void (^block)(NSNotification*) = ^(NSNotification*)
{
auto strong_this = weak_this.lock();
if (!strong_this)
{
return;
}

if (m_isNetDetectEnabled)
// NetworkCost information is not available until iOS 12.
// Just make the best guess here.
switch (m_reach.currentReachabilityStatus)
{
m_notificationId =
[[NSNotificationCenter defaultCenter]
addObserverForName: kNetworkReachabilityChangedNotification
object: nil
queue: nil
usingBlock: block];
[m_reach startNotifier];
case NotReachable:
strong_this->UpdateType(NetworkType_Unknown);
strong_this->UpdateCost(NetworkCost_Unknown);
break;
case ReachableViaWiFi:
strong_this->UpdateType(NetworkType_Wifi);
strong_this->UpdateCost(NetworkCost_Unmetered);
break;
case ReachableViaWWAN:
strong_this->UpdateType(NetworkType_WWAN);
strong_this->UpdateCost(NetworkCost_Metered);
break;
}
};
block(nil); // Update the initial status.

if (m_isNetDetectEnabled)
{
m_notificationId =
[[NSNotificationCenter defaultCenter]
addObserverForName: kNetworkReachabilityChangedNotification
object: nil
queue: nil
usingBlock: block];
[m_reach startNotifier];
}
}
#endif

void NetworkInformation::SetupNetDetect()
{
#if ODW_LEGACY_REACHABILITY_REQUIRED
if (@available(macOS 10.14, iOS 12.0, *))
{
SetupModernNetDetect();
}
else
{
SetupLegacyNetDetect();
}
#else
SetupModernNetDetect();
#endif
}

void NetworkInformation::UpdateType(NetworkType type) noexcept
Expand Down Expand Up @@ -229,4 +258,3 @@ virtual NetworkCost GetNetworkCost()
}

} PAL_NS_END

12 changes: 12 additions & 0 deletions third_party/Reachability/ODWReachability.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,8 +25,10 @@
POSSIBILITY OF SUCH DAMAGE.
*/

#import <AvailabilityMacros.h>
#import <Foundation/Foundation.h>
#import <SystemConfiguration/SystemConfiguration.h>
#import <TargetConditionals.h>


/**
Expand All @@ -40,6 +42,16 @@

extern NSString* const kNetworkReachabilityChangedNotification;

// Older Apple deployment targets still need the legacy SCNetworkReachability
// backend at runtime. Newer targets can compile directly to the modern path.
#if TARGET_OS_IPHONE
#define ODW_LEGACY_REACHABILITY_REQUIRED (__IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_12_0)
#elif TARGET_OS_OSX
#define ODW_LEGACY_REACHABILITY_REQUIRED (__MAC_OS_X_VERSION_MIN_REQUIRED < __MAC_10_14)
#else
#define ODW_LEGACY_REACHABILITY_REQUIRED 0
#endif

typedef NS_ENUM(NSInteger, ODWNetworkStatus) {
// Apple NetworkStatus Compatible Names.
NotReachable = 0,
Expand Down
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