1 files changed, 51 insertions, 0 deletions
diff --git a/tests/test_igmp.cpp b/tests/test_igmp.cpp
new file mode 100644
index 0000000..b87d88d
--- /dev/null
+++ b/tests/test_igmp.cpp
@@ -0,0 +1,51 @@
+#include <doctest/doctest.h>
+
+#include <array>
+#include <vector>
+
+#include "packeteer/net/igmp.hpp"
+
+using namespace packeteer::net;
+
+TEST_CASE("parse_igmp decodes a general membership query with an all-zero group") {
+    std::vector<unsigned char> bytes = {0x11, 0x64, 0x00, 0x00, 0, 0, 0, 0};
+    auto igmp = parse_igmp(bytes);
+    REQUIRE(igmp.has_value());
+    CHECK(igmp->type == kIgmpMembershipQuery);
+    REQUIRE(igmp->group.has_value());
+    CHECK(igmp->group->bytes == std::array<unsigned char, 4>{0, 0, 0, 0});
+}
+
+TEST_CASE("parse_igmp decodes a v2 membership report with a real group address") {
+    std::vector<unsigned char> bytes = {0x16, 0x00, 0x00, 0x00, 239, 255, 255, 250};
+    auto igmp = parse_igmp(bytes);
+    REQUIRE(igmp.has_value());
+    CHECK(igmp->type == kIgmpV2MembershipReport);
+    REQUIRE(igmp->group.has_value());
+    CHECK(igmp->group->bytes == std::array<unsigned char, 4>{239, 255, 255, 250});
+}
+
+TEST_CASE("parse_igmp rejects a payload shorter than the fixed header") {
+    std::vector<unsigned char> bytes(4, 0);
+    CHECK_FALSE(parse_igmp(bytes).has_value());
+}
+
+TEST_CASE("parse_igmp leaves group unset for a v3 report, whose bytes[4:8] aren't an address") {
+    // Real capture from this exact bug: bytes[4:8] here are Reserved
+    // (2 bytes, zero) + Number of Group Records (2 bytes, = 1) --
+    // reading that as an IPv4 address produced the nonsense
+    // "group=0.0.0.1" before this was fixed. IGMPv3's actual group
+    // address(es) live inside the group records that follow, which
+    // this dissector doesn't decode (see the header comment).
+    std::vector<unsigned char> bytes = {0x22, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01};
+    auto igmp = parse_igmp(bytes);
+    REQUIRE(igmp.has_value());
+    CHECK(igmp->type == kIgmpV3MembershipReport);
+    CHECK_FALSE(igmp->group.has_value());
+}
+
+TEST_CASE("igmp_type_name names known types and falls back to hex for unknown ones") {
+    CHECK(igmp_type_name(kIgmpMembershipQuery) == "Membership Query");
+    CHECK(igmp_type_name(kIgmpLeaveGroup) == "Leave Group");
+    CHECK(igmp_type_name(0x99) == "type=0x99");
+}