neighbor: Refactor out netlink code
This will allow us to re-use the generic netlink bits for other netlink
request operations.
Adds test coverage to the netlink message parsing routines for sanity
and regression prevention.
Tested:
Neighbor population still works when static neighbors are created on
the BMC.
Change-Id: I755e86eb76a8f6f825616c13279328134de87da9
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/netlink.hpp b/netlink.hpp
new file mode 100644
index 0000000..e1a8253
--- /dev/null
+++ b/netlink.hpp
@@ -0,0 +1,69 @@
+#pragma once
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+
+#include <functional>
+#include <string_view>
+#include <tuple>
+#include <type_traits>
+
+namespace phosphor
+{
+namespace network
+{
+namespace netlink
+{
+
+/* @brief Called on each nlmsg received on the socket
+ */
+using ReceiveCallback = std::function<void(const nlmsghdr&, std::string_view)>;
+
+namespace detail
+{
+
+void processMsg(std::string_view& msgs, bool& done, const ReceiveCallback& cb);
+
+void performRequest(int protocol, void* data, size_t size,
+ const ReceiveCallback& cb);
+
+} // namespace detail
+
+/* @brief Call on a block of rtattrs to parse a single one out
+ * Updates the input to remove the attr parsed out.
+ *
+ * @param[in,out] attrs - The buffer holding rtattrs to parse
+ * @return A tuple of rtattr header + data buffer for the attr
+ */
+std::tuple<rtattr, std::string_view> extractRtAttr(std::string_view& data);
+
+/** @brief Performs a netlink request of the specified type with the given
+ * message Calls the callback upon receiving
+ *
+ * @param[in] protocol - The netlink protocol to use when opening the socket
+ * @param[in] type - The netlink message type
+ * @param[in] flags - Additional netlink flags for the request
+ * @param[in] msg - The message payload for the request
+ * @param[in] cb - Called for each response message payload
+ */
+template <typename T>
+void performRequest(int protocol, uint16_t type, uint16_t flags, const T& msg,
+ const ReceiveCallback& cb)
+{
+ static_assert(std::is_trivially_copyable_v<T>);
+
+ struct
+ {
+ nlmsghdr hdr;
+ T msg;
+ } data{};
+ data.hdr.nlmsg_len = sizeof(data);
+ data.hdr.nlmsg_type = type;
+ data.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | flags;
+ data.msg = msg;
+
+ detail::performRequest(protocol, &data, sizeof(data), cb);
+}
+
+} // namespace netlink
+} // namespace network
+} // namespace phosphor