Validate the client address

Address could be hostname or IPaddress,Address validation
is being done by calling the gethostbyname system function.

Change-Id: I7d7eecd164c471c80af0b440a4b541badd2f966f
Signed-off-by: Ratan Gupta <ratagupt@in.ibm.com>
diff --git a/snmp_conf_manager.cpp b/snmp_conf_manager.cpp
index 30d0815..3c7eaa6 100644
--- a/snmp_conf_manager.cpp
+++ b/snmp_conf_manager.cpp
@@ -1,9 +1,15 @@
 #include "config.h"
 #include "snmp_conf_manager.hpp"
+#include "snmp_util.hpp"
+#include "xyz/openbmc_project/Common/error.hpp"
+
+#include <phosphor-logging/elog-errors.hpp>
 #include <phosphor-logging/log.hpp>
 
 #include <experimental/filesystem>
 
+#include <arpa/inet.h>
+
 namespace phosphor
 {
 namespace network
@@ -12,6 +18,8 @@
 {
 
 using namespace phosphor::logging;
+using namespace sdbusplus::xyz::openbmc_project::Common::Error;
+using Argument = xyz::openbmc_project::Common::InvalidArgument;
 
 ConfManager::ConfManager(sdbusplus::bus::bus& bus, const char* objPath) :
     details::CreateIface(bus, objPath, true), bus(bus), objectPath(objPath)
@@ -21,16 +29,31 @@
 void ConfManager::client(std::string address, uint16_t port)
 {
     auto clientEntry = this->clients.find(address);
-    if (clientEntry == this->clients.end())
+    if (clientEntry != this->clients.end())
     {
-        std::experimental::filesystem::path objPath;
-        objPath /= objectPath;
-        objPath /= generateId(address, port);
-
-        this->clients.emplace(
-            address, std::make_unique<phosphor::network::snmp::Client>(
-                         bus, objPath.string().c_str(), *this, address, port));
+        // address is already there
+        return;
     }
+    try
+    {
+        // just to check whether given address is valid or not.
+        resolveAddress(address);
+    }
+    catch (InternalFailure& e)
+    {
+        log<level::ERR>("Not a valid address"),
+            entry("ADDRESS=%s", address.c_str());
+        elog<InvalidArgument>(Argument::ARGUMENT_NAME("Address"),
+                              Argument::ARGUMENT_VALUE(address.c_str()));
+    }
+    // create the D-Bus object
+    std::experimental::filesystem::path objPath;
+    objPath /= objectPath;
+    objPath /= generateId(address, port);
+
+    this->clients.emplace(
+        address, std::make_unique<phosphor::network::snmp::Client>(
+                     bus, objPath.string().c_str(), *this, address, port));
 }
 
 std::string ConfManager::generateId(const std::string& address, uint16_t port)