tests: cover additional safeguards and document PR 40 comparison

Add standalone regression coverage for DHCPv6 parsing/replies, RADIUS
response authentication/signing, VRF/CoA name bounds, LCP Echo MTU and
pool reuse. Document all 20 reference commits, upstream coverage, author
credits, adaptations and validation limits.

Validation: default userspace Debug build; five standalone suites with
ASan/UBSan (LCP UBSan only), including LeakSanitizer for ASan tests;
existing IPv6 DNS test; git diff --check. All passed.
Baseline duplicate Rapid-Commit and forged Access-Accept assertions fail
as expected. Full privileged session integration was not run.

1 files changed, 38 insertions, 0 deletions

diff --git a/tests/unit/mempool_safeguards_test.c b/tests/unit/mempool_safeguards_test.c
new file mode 100644
index 00000000..b0c6a3dc
--- /dev/null
+++ b/tests/unit/mempool_safeguards_test.c
@@ -0,0 +1,38 @@
+/* Pool reuse must not expose the previous object's payload. */
+#include <assert.h>
+#include <pthread.h>
+#include "triton.h"
+#undef __init
+#define __init
+#include "../../accel-pppd/triton/mempool.c"
+
+void triton_log_error(const char *fmt, ...) {}
+void triton_stat_mempool_allocated_add(uint64_t v) {}
+void triton_stat_mempool_allocated_sub(uint64_t v) {}
+void triton_stat_mempool_available_add(uint64_t v) {}
+void triton_stat_mempool_available_sub(uint64_t v) {}
+
+int main(void)
+{
+	mempool_t *pool;
+	unsigned char *p, *q;
+	int i;
+
+	spinlock_init(&pools_lock);
+	pool = mempool_create(128);
+	p = mempool_alloc(pool);
+	assert(p);
+	memset(p, 0xa5, 128);
+	mempool_free(p);
+	q = mempool_alloc(pool);
+	assert(q == p);
+	for (i = 0; i < 128; i++)
+		assert(!q[i]);
+	memset(q, 0x5a, 128);
+	mempool_free(q);
+	mempool_clean();
+	list_del(&((struct _mempool_t *)pool)->entry);
+	free(pool);
+	puts("Mempool safeguards: PASS");
+	return 0;
+}