Add a helper to read the interface state

This helper doesn't really distinguish between "I failed to read the
state" and "state is down" but I think that if we cannot observe
the interface to be up, it may as well be down.

Bug: 31337216
Test: Compiles
Change-Id: Id48968844fea120bc0a4c439693db58d72feb4a1

3 files changed, 38 insertions, 9 deletions

diff --git a/libwifi_system/include/wifi_system/interface_tool.h b/libwifi_system/include/wifi_system/interface_tool.h
index 2e58379a1..aabdd9a52 100644
--- a/libwifi_system/include/wifi_system/interface_tool.h
+++ b/libwifi_system/include/wifi_system/interface_tool.h
@@ -25,6 +25,10 @@ class InterfaceTool {
   InterfaceTool() = default;
   virtual ~InterfaceTool() = default;
 
+  // Get the interface state of |if_name|.
+  // Returns true iff the interface is up.
+  virtual bool GetUpState(const char* if_name);
+
   // Set the interface named by |if_name| up or down.
   // Returns true on success, false otherwise.
   virtual bool SetUpState(const char* if_name, bool request_up);
diff --git a/libwifi_system/interface_tool.cpp b/libwifi_system/interface_tool.cpp
index af9cc0805..f0d40efd4 100644
--- a/libwifi_system/interface_tool.cpp
+++ b/libwifi_system/interface_tool.cpp
@@ -31,9 +31,26 @@ namespace {
 
 const char kWlan0InterfaceName[] = "wlan0";
 
+bool GetIfState(const char* if_name, int sock, struct ifreq* ifr) {
+  memset(ifr, 0, sizeof(*ifr));
+  if (strlcpy(ifr->ifr_name, if_name, sizeof(ifr->ifr_name)) >=
+      sizeof(ifr->ifr_name)) {
+    LOG(ERROR) << "Interface name is too long: " << if_name;
+    return false;
+  }
+
+  if (TEMP_FAILURE_RETRY(ioctl(sock, SIOCGIFFLAGS, ifr)) != 0) {
+    LOG(ERROR) << "Could not read interface state for " << if_name
+               << " (" << strerror(errno) << ")";
+    return false;
+  }
+
+  return true;
+}
+
 }  // namespace
 
-bool InterfaceTool::SetUpState(const char* if_name, bool request_up) {
+bool InterfaceTool::GetUpState(const char* if_name) {
   base::unique_fd sock(socket(PF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0));
   if (sock.get() < 0) {
     LOG(ERROR) << "Failed to open socket to set up/down state ("
@@ -42,19 +59,26 @@ bool InterfaceTool::SetUpState(const char* if_name, bool request_up) {
   }
 
   struct ifreq ifr;
-  memset(&ifr, 0, sizeof(ifr));
-  if (strlcpy(ifr.ifr_name, if_name, sizeof(ifr.ifr_name)) >=
-      sizeof(ifr.ifr_name)) {
-    LOG(ERROR) << "Interface name is too long: " << if_name;
-    return false;
+  if (!GetIfState(if_name, sock.get(), &ifr)) {
+    return false;  // logging done internally
   }
 
-  if (TEMP_FAILURE_RETRY(ioctl(sock.get(), SIOCGIFFLAGS, &ifr)) != 0) {
-    LOG(ERROR) << "Could not read interface state for " << if_name
-               << " (" << strerror(errno) << ")";
+  return ifr.ifr_flags & IFF_UP;
+}
+
+bool InterfaceTool::SetUpState(const char* if_name, bool request_up) {
+  base::unique_fd sock(socket(PF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0));
+  if (sock.get() < 0) {
+    LOG(ERROR) << "Failed to open socket to set up/down state ("
+               << strerror(errno) << ")";
     return false;
   }
 
+  struct ifreq ifr;
+  if (!GetIfState(if_name, sock.get(), &ifr)) {
+    return false;  // logging done internally
+  }
+
   const bool currently_up = ifr.ifr_flags & IFF_UP;
   if (currently_up == request_up) {
     return true;
diff --git a/libwifi_system/testlib/include/wifi_system_test/mock_interface_tool.h b/libwifi_system/testlib/include/wifi_system_test/mock_interface_tool.h
index 13e67807a..b9926c938 100644
--- a/libwifi_system/testlib/include/wifi_system_test/mock_interface_tool.h
+++ b/libwifi_system/testlib/include/wifi_system_test/mock_interface_tool.h
@@ -26,6 +26,7 @@ class MockInterfaceTool : public InterfaceTool {
  public:
   ~MockInterfaceTool() override = default;
 
+  MOCK_METHOD1(GetUpState, bool(const char* if_name));
   MOCK_METHOD2(SetUpState, bool(const char* if_name, bool request_up));
   MOCK_METHOD1(SetWifiUpState, bool(bool request_up));