Routed subinterface enhancements (sonic-net#2017)

* Routed subinterface library implementation

Author: preetham-singh

lib/subintf.cpp

@@ -0,0 +1,113 @@
+#include <cerrno>
+#include <cstring>
+#include <array>
+#include <net/if.h>
+#include "subintf.h"
+
+using namespace swss;
+
+subIntf::subIntf(const std::string &ifName)
+{
+    alias = ifName;
+    size_t found = alias.find(VLAN_SUB_INTERFACE_SEPARATOR);
+    if (found != std::string::npos)
+    {
+        parentIf = alias.substr(0, found);
+        if (!parentIf.compare(0, strlen("Eth"), "Eth"))
+        {
+            std::string parentIfName;
+            if (!parentIf.compare(0, strlen("Ethernet"), "Ethernet"))
+            {
+                parentIfShortName = "Eth" + parentIf.substr(strlen("Ethernet"));
+                isCompressed = false;
+                parentIfName = "Ethernet" + parentIf.substr(strlen("Ethernet"));
+            }
+            else
+            {
+                parentIfShortName = "Eth" + parentIf.substr(strlen("Eth"));
+                isCompressed = true;
+                parentIfName = "Ethernet" + parentIf.substr(strlen("Eth"));
+            }
+            parentIf = parentIfName;
+            subIfIdx = alias.substr(found + 1);
+        }
+        else if (!parentIf.compare(0, strlen("Po"), "Po"))
+        {
+            if (!parentIf.compare(0, strlen("PortChannel"), "PortChannel"))
+            {
+                isCompressed = false;
+                parentIfShortName = "Po" + parentIf.substr(strlen("PortChannel"));
+                parentIf = "PortChannel" + parentIf.substr(strlen("PortChannel"));
+            }
+            else
+            {
+                isCompressed = true;
+                parentIfShortName = "Po" + parentIf.substr(strlen("Po"));
+                parentIf = "PortChannel" + parentIf.substr(strlen("Po"));
+            }
+            subIfIdx = alias.substr(found + 1);
+        }
+        else
+        {
+            subIfIdx = "";
+        }
+    }
+}
+
+bool subIntf::isValid() const
+{
+    if (subIfIdx == "")
+    {
+        return false;
+    }
+    else if (alias.length() >= IFNAMSIZ)
+    {
+        return false;
+    }
+
+    return true;
+}
+
+std::string subIntf::parentIntf() const
+{
+    return parentIf;
+}
+
+int subIntf::subIntfIdx() const
+{
+    uint16_t id;
+    try
+    {
+        id = static_cast<uint16_t>(stoul(subIfIdx));
+    }
+    catch (const std::invalid_argument &e)
+    {
+        return -1;
+    }
+    catch (const std::out_of_range &e)
+    {
+        return -1;
+    }
+    return id;
+}
+
+std::string subIntf::longName() const
+{
+    if (isValid() == false)
+        return "";
+
+    return (parentIf + VLAN_SUB_INTERFACE_SEPARATOR + subIfIdx);
+}
+
+std::string subIntf::shortName() const
+{
+    if (isValid() == false)
+        return "";
+
+    return (parentIfShortName + VLAN_SUB_INTERFACE_SEPARATOR + subIfIdx);
+}
+
+bool subIntf::isShortName() const
+{
+    return ((isCompressed == true) ? true : false);
+}

lib/subintf.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#define VLAN_SUB_INTERFACE_SEPARATOR   "."
+namespace swss {
+	class subIntf
+	{
+		public:
+			subIntf(const std::string &ifName);
+			bool isValid() const;
+			std::string parentIntf() const;
+			int subIntfIdx() const;
+			std::string longName() const;
+			std::string shortName() const;
+			bool isShortName() const;
+
+        private:
+			std::string alias;
+			std::string subIfIdx;
+			std::string parentIf;
+			std::string parentIfShortName;
+			bool isCompressed = false;
+	};
+}