[1350] Support for DHCPv4 END option added.

src/lib/dhcp/libdhcp.cc

@@ -17,6 +17,7 @@
 #include <util/buffer.h>
 #include <dhcp/libdhcp.h>
 #include "config.h"
+#include <dhcp/dhcp4.h>
 #include <dhcp/dhcp6.h>
 #include <dhcp/option.h>
 #include <dhcp/option6_ia.h>
@@ -90,8 +91,17 @@ LibDHCP::unpackOptions4(const std::vector<uint8_t>& buf,
     size_t offset = 0;
 
     // 2 - header of DHCPv4 option
-    while (offset + 2 <= buf.size()) {
+    while (offset + 1 <= buf.size()) {
         uint8_t opt_type = buf[offset++];
+        if (offset + 1 == buf.size()) {
+            if (opt_type == DHO_END)
+                return; // just return. Don't need to add DHO_END option
+            else {
+                isc_throw(OutOfRange, "Attempt to parse truncated option "
+                          << opt_type);
+            }
+        }
+
         uint8_t opt_len =  buf[offset++];
         if (offset + opt_len > buf.size() ) {
             isc_throw(OutOfRange, "Option parse failed. Tried to parse "

src/lib/dhcp/pkt4.cc

@@ -117,6 +117,10 @@ Pkt4::pack() {
 
     LibDHCP::packOptions(bufferOut_, options_);
 
+    // add END option that indicates end of options
+    // (End option is very simple, just a 255 octet)
+    bufferOut_.writeUint8(DHO_END);
+
     return (true);
 }
 bool

src/lib/dhcp/tests/pkt4_unittest.cc

@@ -487,13 +487,15 @@ TEST(Pkt4Test, options) {
 
     const OutputBuffer& buf = pkt->getBuffer();
     // check that all options are stored, they should take sizeof(v4Opts)
-    ASSERT_EQ(static_cast<size_t>(Pkt4::DHCPV4_PKT_HDR_LEN) + sizeof(v4Opts),
+    // there also should be OPTION_END added (just one byte)
+    ASSERT_EQ(static_cast<size_t>(Pkt4::DHCPV4_PKT_HDR_LEN) + sizeof(v4Opts) + 1,
               buf.getLength());
 
     // that that this extra data actually contain our options
     const uint8_t* ptr = static_cast<const uint8_t*>(buf.getData());
     ptr += Pkt4::DHCPV4_PKT_HDR_LEN; // rewind to end of fixed part
     EXPECT_EQ(0, memcmp(ptr, v4Opts, sizeof(v4Opts)));
+    EXPECT_EQ(DHO_END, static_cast<uint8_t>(*(ptr + sizeof(v4Opts))));
 
     EXPECT_NO_THROW(
         delete pkt;