1 files changed, 31 insertions, 0 deletions
diff --git a/tests/test_net.cpp b/tests/test_net.cpp
index 2702758..64db07f 100644
--- a/tests/test_net.cpp
+++ b/tests/test_net.cpp
@@ -134,6 +134,37 @@ TEST_CASE("parse_ipv4 honors IHL > 5 (options present)") {
     CHECK(ip->payload.empty());
 }
 
+TEST_CASE("parse_ipv4 decodes an unfragmented packet with fragment_offset zero") {
+    std::vector<unsigned char> bytes(20, 0);
+    bytes[0] = 0x45;
+    auto ip = parse_ipv4(bytes);
+    REQUIRE(ip.has_value());
+    CHECK_FALSE(ip->header.more_fragments);
+    CHECK(ip->header.fragment_offset == 0);
+}
+
+TEST_CASE("parse_ipv4 decodes the identification field and More Fragments flag") {
+    std::vector<unsigned char> bytes(20, 0);
+    bytes[0] = 0x45;
+    bytes[4] = 0x12; bytes[5] = 0x34;  // identification = 0x1234
+    bytes[6] = 0x20; bytes[7] = 0x00;  // flags: MF=1, fragment_offset=0 (first fragment)
+    auto ip = parse_ipv4(bytes);
+    REQUIRE(ip.has_value());
+    CHECK(ip->header.identification == 0x1234);
+    CHECK(ip->header.more_fragments);
+    CHECK(ip->header.fragment_offset == 0);
+}
+
+TEST_CASE("parse_ipv4 decodes a nonzero fragment_offset in 8-byte units") {
+    std::vector<unsigned char> bytes(20, 0);
+    bytes[0] = 0x45;
+    bytes[6] = 0x00; bytes[7] = 0x08;  // fragment_offset = 8 (i.e. byte offset 64), MF=0 (last fragment)
+    auto ip = parse_ipv4(bytes);
+    REQUIRE(ip.has_value());
+    CHECK_FALSE(ip->header.more_fragments);
+    CHECK(ip->header.fragment_offset == 8);
+}
+
 TEST_CASE("parse_tcp decodes header fields and flags") {
     std::vector<unsigned char> bytes(20, 0);
     bytes[0] = 0x00; bytes[1] = 0x50;  // src port 80