Add TrafficForwarder tests

unittest/vslib/Makefile.am

@@ -30,7 +30,8 @@ tests_SOURCES = main.cpp \
 				TestSaiUnittests.cpp \
 				TestSelectableFd.cpp \
 				TestSignal.cpp \
-				TestSwitchConfigContainer.cpp
+				TestSwitchConfigContainer.cpp \
+				TestTrafficForwarder.cpp
 
 tests_CXXFLAGS = $(DBGFLAGS) $(AM_CXXFLAGS) $(CXXFLAGS_COMMON)
 tests_LDADD = $(LDADD_GTEST) $(top_srcdir)/vslib/libSaiVS.a -lhiredis -lswsscommon -lnl-genl-3 -lnl-nf-3 -lnl-route-3 -lnl-3 \

unittest/vslib/TestTrafficForwarder.cpp

@@ -0,0 +1,66 @@
+#include "TrafficForwarder.h"
+
+#include <linux/if_packet.h>
+
+#include <gtest/gtest.h>
+
+using namespace saivs;
+
+typedef union _control
+{
+    char control_data[CMSG_SPACE(sizeof(tpacket_auxdata))];
+    struct cmsghdr cmsg;
+
+} control;
+
+static_assert(sizeof(cmsghdr) == 16, "header must be 8 bytes");
+static_assert(sizeof(control) >= (sizeof(cmsghdr) + sizeof(tpacket_auxdata)), "control must at least include both");
+
+TEST(TrafficForwarder, addVlanTag)
+{
+    uint8_t buffer[0x1000];
+
+    size_t length = 1;
+
+    struct msghdr hdr;
+
+    memset(&hdr, 0, sizeof(hdr));
+
+    EXPECT_FALSE(TrafficForwarder::addVlanTag(buffer, length, hdr));
+
+    control p;
+
+    memset(&p, 0, sizeof(p));
+
+    hdr.msg_controllen = sizeof(p);
+    hdr.msg_control = &p;
+
+    EXPECT_FALSE(TrafficForwarder::addVlanTag(buffer, length, hdr));
+
+    cmsghdr* cmsg = &p.cmsg;
+
+    cmsg->cmsg_level = SOL_PACKET;
+    cmsg->cmsg_type = PACKET_AUXDATA;
+
+    EXPECT_FALSE(TrafficForwarder::addVlanTag(buffer, length, hdr));
+
+    struct tpacket_auxdata* aux = (struct tpacket_auxdata*)CMSG_DATA(cmsg);
+
+    // https://en.wikipedia.org/wiki/IEEE_802.1Q
+    // 
+    // TPID(16) |          TCI(16)
+    //          |  PCP(3)  DEI(1) VID(12)
+
+    aux->tp_status |= TP_STATUS_VLAN_VALID;
+    aux->tp_status |= TP_STATUS_VLAN_TPID_VALID;
+
+    length = ETH_FRAME_BUFFER_SIZE;
+
+    EXPECT_THROW(TrafficForwarder::addVlanTag(buffer, length, hdr), std::runtime_error);
+
+    length = 64;
+
+    EXPECT_TRUE(TrafficForwarder::addVlanTag(buffer, length, hdr));
+
+    EXPECT_EQ(length, 68); 
+}

vslib/TrafficForwarder.cpp

@@ -23,7 +23,7 @@ using namespace saivs;
 #define MAC_ADDRESS_SIZE (6)
 #define VLAN_TAG_SIZE (4)
 
-void TrafficForwarder::addVlanTag(
+bool TrafficForwarder::addVlanTag(
         _Inout_ unsigned char *buffer,
         _Inout_ size_t &length,
         _Inout_ struct msghdr &msg)
@@ -65,9 +65,11 @@ void TrafficForwarder::addVlanTag(
 
             length += VLAN_TAG_SIZE;
 
-            break;
+            return true;
         }
     }
+
+    return false;
 }
 
 bool TrafficForwarder::sendTo(

vslib/TrafficForwarder.h

@@ -22,7 +22,7 @@ namespace saivs
 
         public:
 
-            static void addVlanTag(
+            static bool addVlanTag(
                     _Inout_ unsigned char *buffer,
                     _Inout_ size_t &length,
                     _Inout_ struct msghdr &msg);