Start wire-up of logging and tunnel system.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

WireGuardNetworkExtension/WireGuardGoWrapper.m

@@ -8,12 +8,17 @@
 
 #import "WireGuardGoWrapper.h"
 
+#include <os/log.h>
 #include "wireguard.h"
 
 /// Trampoline function
 static ssize_t do_read(const void *ctx, const unsigned char *buf, size_t len);
 /// Trampoline function
 static ssize_t do_write(const void *ctx, const unsigned char *buf, size_t len);
+/// Trampoline function
+static void do_log(int level, const char *tag, const char *msg);
+
+
 
 @interface WireGuardGoWrapper ()
 
@@ -26,6 +31,9 @@ static ssize_t do_write(const void *ctx, const unsigned char *buf, size_t len);
 
 - (void) turnOnWithInterfaceName: (NSString *)interfaceName settingsString: (NSString *)settingsString
 {
+
+    wgSetLogger(do_log);
+
     const char * ifName = [interfaceName UTF8String];
     const char * settings = [settingsString UTF8String];
 
@@ -38,6 +46,16 @@ static ssize_t do_write(const void *ctx, const unsigned char *buf, size_t len);
     wgTurnOff(self.handle);
 }
 
++ (os_log_t)log {
+    static os_log_t subLog = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        subLog = os_log_create("com.wireguard.ios.WireGuard.WireGuardNetworkExtension", "WireGuard-Go");
+    });
+
+    return subLog;
+}
+
 @end
 
 static ssize_t do_read(const void *ctx, const unsigned char *buf, size_t len)
@@ -45,6 +63,7 @@ static ssize_t do_read(const void *ctx, const unsigned char *buf, size_t len)
     WireGuardGoWrapper *wrapper = (__bridge WireGuardGoWrapper *)ctx;
     printf("Reading from instance with ctx %p into buffer %p of length %zu\n", ctx, buf, len);
     sleep(1);
+    // TODO received data from tunnel, write to Packetflow
     return wrapper.isClosed ? -1 : 0;
 }
 
@@ -54,3 +73,9 @@ static ssize_t do_write(const void *ctx, const unsigned char *buf, size_t len)
     printf("Writing from instance with ctx %p into buffer %p of length %zu\n", ctx, buf, len);
     return len;
 }
+
+static void do_log(int level, const char *tag, const char *msg)
+{
+    // TODO Get some details on the log level and distribute to matching log levels.
+    os_log([WireGuardGoWrapper log], "Log level %d for %s: %s", level, tag, msg);
+}