Fix replies dropped when flood.max.unscoped is low

test/test_routing_policy/test_routing_policy.cpp

@@ -0,0 +1,110 @@
+#include <gtest/gtest.h>
+#include "helpers/RoutingPolicy.h"
+
+using namespace mesh;
+
+static Packet makeFlood(uint8_t route_type, uint8_t payload_type, uint8_t hops) {
+    Packet p;
+    p.header = route_type | (payload_type << PH_TYPE_SHIFT);
+    p.setPathHashSizeAndCount(1, hops);
+    p.payload_len = 1;
+    return p;
+}
+
+TEST(FloodHopLimit, UnscopedFloodIsDroppedAtFirstHopWhenMaxUnscopedIsZero) {
+    auto pkt = makeFlood(ROUTE_TYPE_FLOOD, PAYLOAD_TYPE_RESPONSE, 0);
+    EXPECT_TRUE(isFloodHopLimitExceeded(&pkt, 64, 0, 8));
+}
+
+TEST(FloodHopLimit, ScopedFloodIsForwardedWhenMaxUnscopedIsZero) {
+    for (uint8_t hops = 0; hops < 4; hops++) {
+        auto pkt = makeFlood(ROUTE_TYPE_TRANSPORT_FLOOD, PAYLOAD_TYPE_RESPONSE, hops);
+        EXPECT_FALSE(isFloodHopLimitExceeded(&pkt, 64, 0, 8)) << "hops=" << (int)hops;
+    }
+}
+
+TEST(FloodHopLimit, UnscopedFloodSurvivesUpToMaxUnscopedHops) {
+    // matches the reported workaround: raising flood.max.unscoped to the expected hop count
+    auto ok = makeFlood(ROUTE_TYPE_FLOOD, PAYLOAD_TYPE_RESPONSE, 2);
+    EXPECT_FALSE(isFloodHopLimitExceeded(&ok, 64, 3, 8));
+
+    auto too_far = makeFlood(ROUTE_TYPE_FLOOD, PAYLOAD_TYPE_RESPONSE, 3);
+    EXPECT_TRUE(isFloodHopLimitExceeded(&too_far, 64, 3, 8));
+}
+
+TEST(FloodHopLimit, ScopedFloodStillHonoursFloodMaxAndAdvertMax) {
+    auto beyond_max = makeFlood(ROUTE_TYPE_TRANSPORT_FLOOD, PAYLOAD_TYPE_RESPONSE, 5);
+    EXPECT_TRUE(isFloodHopLimitExceeded(&beyond_max, 5, 64, 8));
+
+    auto advert = makeFlood(ROUTE_TYPE_TRANSPORT_FLOOD, PAYLOAD_TYPE_ADVERT, 8);
+    EXPECT_TRUE(isFloodHopLimitExceeded(&advert, 64, 64, 8));
+}
+
+// flood.max.unscoped=0 hits adverts too, well before flood_max_advert applies: a node
+// still advertising un-scoped is invisible past its immediate neighbours
+TEST(FloodHopLimit, UnscopedAdvertIsAlsoDroppedAtHopZero) {
+    auto advert = makeFlood(ROUTE_TYPE_FLOOD, PAYLOAD_TYPE_ADVERT, 0);
+    EXPECT_TRUE(isFloodHopLimitExceeded(&advert, 64, 0, 8));
+
+    auto scoped = makeFlood(ROUTE_TYPE_TRANSPORT_FLOOD, PAYLOAD_TYPE_ADVERT, 0);
+    EXPECT_FALSE(isFloodHopLimitExceeded(&scoped, 64, 0, 8));
+}
+
+TEST(ReplyRoute, FloodRequestGetsAPathReturn) {
+    EXPECT_EQ(REPLY_ROUTE_PATH_RETURN,
+              chooseReplyRoute(true, false, false));
+    EXPECT_EQ(REPLY_ROUTE_PATH_RETURN,
+              chooseReplyRoute(true, false, true));
+}
+
+TEST(ReplyRoute, DirectRequestWithSuppliedPathRepliesDirect) {
+    EXPECT_EQ(REPLY_ROUTE_DIRECT_SUPPLIED, chooseReplyRoute(false, true, false));
+}
+
+// the reported bug: a DIRECT login (app already has a path) was answered by flooding, even
+// with an out_path stored. Under flood.max.unscoped=0 that reply never arrives.
+TEST(ReplyRoute, DirectRequestWithKnownOutPathRepliesDirect) {
+    EXPECT_EQ(REPLY_ROUTE_DIRECT_OUT_PATH,
+              chooseReplyRoute(false, false, true));
+}
+
+TEST(ReplyRoute, SuppliedPathWinsOverStoredOutPath) {
+    EXPECT_EQ(REPLY_ROUTE_DIRECT_SUPPLIED, chooseReplyRoute(false, true, true));
+}
+
+TEST(ReplyRoute, DirectRequestWithNoReturnPathFallsBackToFlood) {
+    EXPECT_EQ(REPLY_ROUTE_FLOOD, chooseReplyRoute(false, false, false));
+}
+
+TEST(ReplyScope, MirrorsTheRequestScopeWhenKnown) {
+    EXPECT_EQ(REPLY_SCOPE_REQUEST, chooseReplyScope(true,
+                                                    false,
+                                                    false));
+    EXPECT_EQ(REPLY_SCOPE_REQUEST, chooseReplyScope(true, false, true));
+}
+
+// un-scoped is itself a known scope, so mirror it. Replying scoped would change a path that
+// works today, and repeaters not holding our default Region would drop it anyway.
+TEST(ReplyScope, RepliesUnscopedToAnUnscopedFloodEvenWhenADefaultScopeExists) {
+    EXPECT_EQ(REPLY_SCOPE_NONE, chooseReplyScope(false,
+                                                 true,
+                                                 true));
+}
+
+// second half of the bug: a DIRECT request carries no transport codes, so recv_pkt_region is
+// always NULL. Un-scoped is dropped under flood.max.unscoped=0, and floods the mesh otherwise.
+TEST(ReplyScope, FallsBackToDefaultScopeWhenRequestScopeUnknown) {
+    EXPECT_EQ(REPLY_SCOPE_DEFAULT, chooseReplyScope(false,
+                                                    false,
+                                                    true));
+}
+
+TEST(ReplyScope, SendsUnscopedOnlyWhenNoScopeIsAvailableAtAll) {
+    EXPECT_EQ(REPLY_SCOPE_NONE, chooseReplyScope(false, false, false));
+    EXPECT_EQ(REPLY_SCOPE_NONE, chooseReplyScope(false, true, false));
+}
+
+int main(int argc, char** argv) {
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}