1 files changed, 188 insertions, 0 deletions
diff --git a/src/objective-c/GRPCClient/private/GRPCConnectivityMonitor.m b/src/objective-c/GRPCClient/private/GRPCConnectivityMonitor.m
new file mode 100644
index 0000000000..f66a77c9b2
--- /dev/null
+++ b/src/objective-c/GRPCClient/private/GRPCConnectivityMonitor.m
@@ -0,0 +1,188 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#import "GRPCConnectivityMonitor.h"
+
+#pragma mark Flags
+
+@implementation GRPCReachabilityFlags {
+  SCNetworkReachabilityFlags _flags;
+}
+
++ (instancetype)flagsWithFlags:(SCNetworkReachabilityFlags)flags {
+  return [[self alloc] initWithFlags:flags];
+}
+
+- (instancetype)initWithFlags:(SCNetworkReachabilityFlags)flags {
+  if ((self = [super init])) {
+    _flags = flags;
+  }
+  return self;
+}
+
+/*
+ * One accessor method implementation per flag. Example:
+
+- (BOOL)isCell { \
+  return !!(_flags & kSCNetworkReachabilityFlagsIsWWAN); \
+}
+
+ */
+#define GRPC_XMACRO_ITEM(methodName, FlagName) \
+- (BOOL)methodName { \
+  return !!(_flags & kSCNetworkReachabilityFlags ## FlagName); \
+}
+#include "GRPCReachabilityFlagNames.xmacro.h"
+#undef GRPC_XMACRO_ITEM
+
+- (BOOL)isHostReachable {
+  // Note: connectionOnDemand means it'll be reachable only if using the CFSocketStream API or APIs
+  // on top of it.
+  // connectionRequired means we can't tell until a connection is attempted (e.g. for VPN on
+  // demand).
+  return self.reachable && !self.interventionRequired && !self.connectionOnDemand;
+}
+
+- (NSString *)description {
+  NSMutableArray *activeOptions = [NSMutableArray arrayWithCapacity:9];
+
+  /*
+   * For each flag, add its name to the array if it's ON. Example:
+
+  if (self.isCell) {
+    [activeOptions addObject:@"isCell"];
+  }
+
+   */
+#define GRPC_XMACRO_ITEM(methodName, FlagName) \
+  if (self.methodName) { \
+    [activeOptions addObject:@#methodName]; \
+  }
+#include "GRPCReachabilityFlagNames.xmacro.h"
+#undef GRPC_XMACRO_ITEM
+
+  return activeOptions.count == 0 ? @"(none)" : [activeOptions componentsJoinedByString:@", "];
+}
+
+- (BOOL)isEqual:(id)object {
+  return [object isKindOfClass:[GRPCReachabilityFlags class]] &&
+      _flags == ((GRPCReachabilityFlags *)object)->_flags;
+}
+
+- (NSUInteger)hash {
+  return _flags;
+}
+@end
+
+#pragma mark Connectivity Monitor
+
+// Assumes the third argument is a block that accepts SCNetworkReachabilityFlags, and passes the
+// received ones to it.
+static void PassFlagsToContextInfoBlock(SCNetworkReachabilityRef target,
+                                        SCNetworkReachabilityFlags flags,
+                                        void *info) {
+  #pragma unused (target)
+  ((__bridge void (^)(SCNetworkReachabilityFlags))info)(flags);
+}
+
+@implementation GRPCConnectivityMonitor {
+  SCNetworkReachabilityRef _reachabilityRef;
+}
+
+- (nullable instancetype)initWithReachability:(nullable SCNetworkReachabilityRef)reachability {
+  if (!reachability) {
+    return nil;
+  }
+  if ((self = [super init])) {
+    _reachabilityRef = CFRetain(reachability);
+    _queue = dispatch_get_main_queue();
+  }
+  return self;
+}
+
++ (nullable instancetype)monitorWithHost:(nonnull NSString *)host {
+  const char *hostName = host.UTF8String;
+  if (!hostName) {
+    [NSException raise:NSInvalidArgumentException
+                format:@"host.UTF8String returns NULL for %@", host];
+  }
+  SCNetworkReachabilityRef reachability =
+      SCNetworkReachabilityCreateWithName(NULL, hostName);
+
+  GRPCConnectivityMonitor *returnValue = [[self alloc] initWithReachability:reachability];
+  if (reachability) {
+    CFRelease(reachability);
+  }
+  return returnValue;
+}
+
+- (void)handleLossWithHandler:(void (^)())handler {
+  __weak typeof(self) weakSelf = self;
+  [self startListeningWithHandler:^(GRPCReachabilityFlags *flags) {
+    if (!flags.isHostReachable) {
+      [weakSelf stopListening];
+      handler();
+    }
+  }];
+}
+
+- (void)startListeningWithHandler:(void (^)(GRPCReachabilityFlags *))handler {
+  SCNetworkReachabilityContext context = {
+    .version = 0,
+    .info = (__bridge_retained void *)^(SCNetworkReachabilityFlags flags){
+      // Pass the flags as as Objective-C wrapper.
+      handler([[GRPCReachabilityFlags alloc] initWithFlags:flags]);
+    },
+    .release = CFRelease
+  };
+  SCNetworkReachabilitySetCallback(_reachabilityRef, PassFlagsToContextInfoBlock, &context);
+  SCNetworkReachabilitySetDispatchQueue(_reachabilityRef, _queue);
+}
+
+- (void)stopListening {
+  SCNetworkReachabilitySetCallback(_reachabilityRef, NULL, NULL);
+  SCNetworkReachabilitySetDispatchQueue(_reachabilityRef, NULL);
+}
+
+- (void)setQueue:(dispatch_queue_t)queue {
+  _queue = queue ?: dispatch_get_main_queue();
+}
+
+- (void)dealloc {
+  if (_reachabilityRef) {
+    [self stopListening];
+    CFRelease(_reachabilityRef);
+  }
+}
+
+@end