Add wrapper functions of SendPacketAndGetResponses

This can help simplify the existing code of handling netlink
responses.

BUG=31111084
TEST=compile

Change-Id: I9a48ddb9af805c59c2733b7c1e2413b3f049edda

2 files changed, 63 insertions, 1 deletions

diff --git a/net/netlink_manager.cpp b/net/netlink_manager.cpp
index 9d816dd..73b97df 100644
--- a/net/netlink_manager.cpp
+++ b/net/netlink_manager.cpp
@@ -288,6 +288,50 @@ bool NetlinkManager::SendMessageAndGetResponses(
   return true;
 }
 
+bool NetlinkManager::SendMessageAndGetSingleResponse(
+    const NL80211Packet& packet,
+    unique_ptr<const NL80211Packet>* response) {
+  vector<unique_ptr<const NL80211Packet>> response_vec;
+  if (!SendMessageAndGetResponses(packet, &response_vec)) {
+    return false;
+  }
+  if (response_vec.size() != 1) {
+    LOG(ERROR) << "Unexpected repsonse size: " << response_vec.size();
+    return false;
+  }
+
+  *response = std::move(response_vec[0]);
+  return true;
+}
+
+bool NetlinkManager::SendMessageAndGetAckOrError(const NL80211Packet& packet,
+                                                 int* error_code) {
+  unique_ptr<const NL80211Packet> response;
+  if (!SendMessageAndGetSingleResponse(packet, &response)) {
+    return false;
+  }
+  uint16_t type = response->GetMessageType();
+  if (type != NLMSG_ERROR) {
+    LOG(ERROR) << "Receive unexpected message type :" << type;
+    return false;
+  }
+
+  *error_code = response->GetErrorCode();
+  return true;
+}
+
+bool NetlinkManager::SendMessageAndGetAck(const NL80211Packet& packet) {
+  int error_code;
+  if (!SendMessageAndGetAckOrError(packet, &error_code)) {
+    return false;
+  }
+  if (error_code != 0) {
+    LOG(ERROR) << "Received error messsage: " << strerror(error_code);
+    return false;
+  }
+
+  return true;
+}
 
 bool NetlinkManager::SendMessageInternal(const NL80211Packet& packet, int fd) {
   const vector<uint8_t>& data = packet.GetConstData();
diff --git a/net/netlink_manager.h b/net/netlink_manager.h
index 47cb98c..36f2772 100644
--- a/net/netlink_manager.h
+++ b/net/netlink_manager.h
@@ -71,6 +71,7 @@ class NetlinkManager {
   virtual uint32_t GetSequenceNumber();
   // Get NL80211 netlink family id,
   virtual uint16_t GetFamilyId();
+
   // Send |packet| to kernel.
   // This works in an asynchronous way.
   // |handler| will be run when we receive a valid reply from kernel.
@@ -80,10 +81,27 @@ class NetlinkManager {
       std::function<void(std::unique_ptr<const NL80211Packet>)> handler);
   // Synchronous version of |RegisterHandlerAndSendMessage|.
   // Returns true on successfully receiving an valid reply.
-  // Reply packets will be stored in |response|.
+  // Reply packets will be stored in |*response|.
   virtual bool SendMessageAndGetResponses(
       const NL80211Packet& packet,
       std::vector<std::unique_ptr<const NL80211Packet>>* response);
+  // Wrapper of |SendMessageAndGetResponses| for messages with a single
+  // response.
+  // Returns true on successfully receiving an valid reply.
+  // Reply packet will be stored in |*response|.
+  virtual bool SendMessageAndGetSingleResponse(
+      const NL80211Packet& packet,
+      std::unique_ptr<const NL80211Packet>* response);
+  // Wrapper of |SendMessageAndGetResponses| for messages that trigger
+  // only a NLMSG_ERROR response
+  // Returns true if the message is successfully sent and a NLMSG_ERROR response
+  // comes back, regardless of the error code.
+  // Error code will be stored in |*error_code|
+  virtual bool SendMessageAndGetAckOrError(const NL80211Packet& packet,
+                                           int* error_code);
+  // Wrapper of |SendMessageAndGetResponses| that returns true iff the response
+  // is an ACK.
+  virtual bool SendMessageAndGetAck(const NL80211Packet& packet);
 
   // Sign up to receive and log multicast events of a specific type.
   // |group| is one of the string NL80211_MULTICAST_GROUP_* in nl80211.h.