From c6d85babd9e60d830c347eb2650df10804ba7d40 Mon Sep 17 00:00:00 2001
From: Jonas Gunz <himself@jonasgunz.de>
Date: Wed, 22 Sep 2021 22:44:56 +0200
Subject: add chaos testing

---
 Makefile               |  4 ++++
 scripts/chaos_dumps.sh | 32 ++++++++++++++++++++++++++++++++
 src/chaos.c            | 43 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 79 insertions(+)
 create mode 100755 scripts/chaos_dumps.sh
 create mode 100644 src/chaos.c

diff --git a/Makefile b/Makefile
index fa47130..e076f59 100644
--- a/Makefile
+++ b/Makefile
@@ -84,6 +84,10 @@ valgrind: $(DEFAULT)
 	@echo [EXEC] valgrind $(BUILDDIR)/$(OUTPUT) $(RUNARGS)
 	valgrind --leak-check=full $(BUILDDIR)/$(OUTPUT) $(RUNARGS)
 
+chaos: LDFLAGS += -ldl
+chaos: CFLAGS += -D_CHAOS -D_GNU_SOURCE
+chaos: clean debug
+
 .PHONY: clean
 clean:
 	@echo [ RM ] $(OBJ) $(TOBJS)
diff --git a/scripts/chaos_dumps.sh b/scripts/chaos_dumps.sh
new file mode 100755
index 0000000..d853e83
--- /dev/null
+++ b/scripts/chaos_dumps.sh
@@ -0,0 +1,32 @@
+#!/bin/bash
+
+CRASHCNT=0
+GOODCRASHES=0
+PROG=build/dnsd
+
+make chaos
+
+ulimit -S -c unlimited $PROG
+mkdir -p dumps
+
+while true; do
+	$PROG -p 5333 -z tests/zone.file > /dev/null &
+	PID=$!
+
+	for i in $(seq 50); do
+		dig -p 5333 test.example.com @localhost > /dev/null &
+	done
+
+	sleep 5
+
+	if ! kill -s 15 $PID ; then
+		CRASHCNT=$(( CRASHCNT + 1 ))
+
+		echo -n "Crash #$CRASHCNT"
+
+		if ! coredumpctl -o dumps/$CRASHCNT.core dump COREDUMP_PID=$PID "COREDUMP_EXE=$(realpath $PROG)" > /dev/null 2>&1; then
+			GOODCRASHES=$(( GOODCRASHES + 1 ))
+			echo " Good crash #$GOODCRASHES"
+		fi
+	fi
+done
diff --git a/src/chaos.c b/src/chaos.c
new file mode 100644
index 0000000..231c94a
--- /dev/null
+++ b/src/chaos.c
@@ -0,0 +1,43 @@
+/*
+ * src/chaos.c
+ * (c) 2021 Jonas Gunz <himself@jonasgunz.de>
+ * License: MIT
+ */
+
+/**
+ * Randomly inject errors in library functions to check resiliency
+ */
+
+#if defined(_CHAOS) && defined(_GNU_SOURCE)
+
+#warning "CHAOS Mode enabled"
+
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
+void* malloc (size_t size) {
+	int fd;
+	uint16_t rand;
+
+	void* (*realmalloc)(size_t size) =
+		(void* (*)(size_t size)) dlsym(RTLD_NEXT, "malloc");
+
+	fd = open("/dev/urandom", O_RDONLY);
+	read(fd, &rand, 2);
+	close(fd);
+
+	if( rand < 1000 ) {
+		errno = ENOMEM;
+		return NULL;
+	}
+
+	return realmalloc(size);
+}
+
+#endif
-- 
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