android: fix permission issue on getifaddrs

Author: jaimecbernardo

deps/uv/include/uv/android-ifaddrs.h

@@ -26,23 +26,7 @@
 #ifndef	_IFADDRS_H_
 #define	_IFADDRS_H_
 
-struct ifaddrs {
-	struct ifaddrs  *ifa_next;
-	char		*ifa_name;
-	unsigned int	 ifa_flags;
-	struct sockaddr	*ifa_addr;
-	struct sockaddr	*ifa_netmask;
-	struct sockaddr	*ifa_dstaddr;
-	void		*ifa_data;
-};
-
-/*
- * This may have been defined in <net/if.h>.  Note that if <net/if.h> is
- * to be included it must be included before this header file.
- */
-#ifndef	ifa_broadaddr
-#define	ifa_broadaddr	ifa_dstaddr	/* broadcast address interface */
-#endif
+#include <ifaddrs.h>
 
 #include <sys/cdefs.h>
 

deps/uv/src/unix/android-ifaddrs.c

@@ -36,6 +36,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
 #include <linux/if_packet.h>
+#include <dlfcn.h>
 
 typedef struct NetlinkList
 {
@@ -534,7 +535,7 @@ static int interpretAddr(struct nlmsghdr *p_hdr, struct ifaddrs **p_resultList,
                 {
                     if(l_entry->ifa_addr)
                     {
-                        l_entry->ifa_dstaddr = (struct sockaddr *)l_addr;
+                        l_entry->ifa_ifu.ifu_dstaddr = (struct sockaddr *)l_addr;
                     }
                     else
                     {
@@ -545,7 +546,7 @@ static int interpretAddr(struct nlmsghdr *p_hdr, struct ifaddrs **p_resultList,
                 {
                     if(l_entry->ifa_addr)
                     {
-                        l_entry->ifa_dstaddr = l_entry->ifa_addr;
+                        l_entry->ifa_ifu.ifu_dstaddr = l_entry->ifa_addr;
                     }
                     l_entry->ifa_addr = (struct sockaddr *)l_addr;
                 }
@@ -652,8 +653,52 @@ static int interpretAddrs(int p_socket, pid_t p_pid, NetlinkList *p_netlinkList,
     return 0;
 }
 
+// Tries to get the system's getifaddrs if it's available.
+void *_dlopen_ifaddrs_handle = NULL;
+void init_dlopen_ifaddrs_handle(void) __attribute__((constructor));
+void destroy_dlopen_ifaddrs_handle(void) __attribute__((destructor));
+
+void init_dlopen_ifaddrs_handle(void)
+{
+    _dlopen_ifaddrs_handle = dlopen("libc.so", RTLD_NOW|RTLD_LOCAL);
+}
+
+void destroy_dlopen_ifaddrs_handle(void)
+{
+    if (_dlopen_ifaddrs_handle != NULL)
+    {
+        dlclose(_dlopen_ifaddrs_handle);
+        _dlopen_ifaddrs_handle = NULL;
+    }
+}
+
+int (*get_getifaddrs_native_func(void))(struct ifaddrs **)
+{
+    if (!_dlopen_ifaddrs_handle)
+    {
+        return NULL;
+    }
+    return dlsym(_dlopen_ifaddrs_handle, "getifaddrs");
+}
+
+void (*get_freeifaddrs_native_func(void))(struct ifaddrs *)
+{
+    if (!_dlopen_ifaddrs_handle)
+    {
+        return NULL;
+    }
+    return dlsym(_dlopen_ifaddrs_handle, "freeifaddrs");
+}
+
 int getifaddrs(struct ifaddrs **ifap)
 {
+    // If the native getifaddrs is available, call it.
+    int (*getifaddrs_native)(struct ifaddrs **) = get_getifaddrs_native_func();
+    if (getifaddrs_native != NULL)
+    {
+        return getifaddrs_native(ifap);
+    }
+
     int l_socket;
     int l_result;
     int l_numLinks;
@@ -703,6 +748,14 @@ int getifaddrs(struct ifaddrs **ifap)
 
 void freeifaddrs(struct ifaddrs *ifa)
 {
+    // If the native freeifaddrs is available, call it.
+    void (*freeifaddrs_native)(struct ifaddrs *) = get_freeifaddrs_native_func();
+    if (freeifaddrs_native != NULL)
+    {
+        freeifaddrs_native(ifa);
+        return;
+    }
+
     struct ifaddrs *l_cur;
     while(ifa)
     {