Strip the scope id from address string before passing to inet_pton.

On some platforms, like FreeBSD, inet_pton fails if the address
string includes trailing characters like a scope id.

asio/include/asio/detail/impl/socket_ops.ipp

diff --git a/asio/include/asio/detail/impl/socket_ops.ipp b/asio/include/asio/detail/impl/socket_ops.ipp
index d4f0e0b..7488dd8 100644
--- a/asio/include/asio/detail/impl/socket_ops.ipp
+++ b/asio/include/asio/detail/impl/socket_ops.ipp
@@ -2272,14 +2272,34 @@
 
   return result == socket_error_retval ? -1 : 1;
 #else // defined(ASIO_WINDOWS) || defined(__CYGWIN__)
-  int result = error_wrapper(::inet_pton(af, src, dest), ec);
+  using namespace std; // For strchr, memcpy and atoi.
+
+  // On some platforms, inet_pton fails if an address string contains a scope
+  // id. Detect and remove the scope id before passing the string to inet_pton.
+  const bool is_v6 = (af == ASIO_OS_DEF(AF_INET6));
+  const char* if_name = is_v6 ? strchr(src, '%') : 0;
+  char src_buf[max_addr_v6_str_len + 1];
+  const char* src_ptr = src;
+  if (if_name != 0)
+  {
+    if (if_name - src > max_addr_v6_str_len)
+    {
+      ec = asio::error::invalid_argument;
+      return 0;
+    }
+    memcpy(src_buf, src, if_name - src);
+    src_buf[if_name - src] = 0;
+    src_ptr = src_buf;
+  }
+
+  int result = error_wrapper(::inet_pton(af, src_ptr, dest), ec);
   if (result <= 0 && !ec)
     ec = asio::error::invalid_argument;
-  if (result > 0 && af == ASIO_OS_DEF(AF_INET6) && scope_id)
+  if (result > 0 && is_v6 && scope_id)
   {
     using namespace std; // For strchr and atoi.
     *scope_id = 0;
-    if (const char* if_name = strchr(src, '%'))
+    if (if_name != 0)
     {
       in6_addr_type* ipv6_address = static_cast<in6_addr_type*>(dest);
       bool is_link_local = ((ipv6_address->s6_addr[0] == 0xfe)