afl: add define to disable rand_r use

The randomness affects AFL. It creates variable test cases, which
we need to avoid.

src/defrag-hash.c

@@ -132,10 +132,11 @@ void DefragInitConfig(char quiet)
     SC_ATOMIC_INIT(defragtracker_prune_idx);
     DefragTrackerQueueInit(&defragtracker_spare_q);
 
+#ifndef AFLFUZZ_NO_RANDOM
     unsigned int seed = RandomTimePreseed();
     /* set defaults */
     defrag_config.hash_rand   = (int)(DEFRAG_DEFAULT_HASHSIZE * (rand_r(&seed) / RAND_MAX + 1.0));
-
+#endif
     defrag_config.hash_size   = DEFRAG_DEFAULT_HASHSIZE;
     defrag_config.memcap      = DEFRAG_DEFAULT_MEMCAP;
     defrag_config.prealloc    = DEFRAG_DEFAULT_PREALLOC;

src/flow.c

@@ -355,10 +355,11 @@ void FlowInitConfig(char quiet)
     FlowQueueInit(&flow_spare_q);
     FlowQueueInit(&flow_recycle_q);
 
+#ifndef AFLFUZZ_NO_RANDOM
     unsigned int seed = RandomTimePreseed();
     /* set defaults */
     flow_config.hash_rand   = (int)( FLOW_DEFAULT_HASHSIZE * (rand_r(&seed) / RAND_MAX + 1.0));
-
+#endif
     flow_config.hash_size   = FLOW_DEFAULT_HASHSIZE;
     flow_config.memcap      = FLOW_DEFAULT_MEMCAP;
     flow_config.prealloc    = FLOW_DEFAULT_PREALLOC;

src/host.c

@@ -141,10 +141,11 @@ void HostInitConfig(char quiet)
     SC_ATOMIC_INIT(host_prune_idx);
     HostQueueInit(&host_spare_q);
 
+#ifndef AFLFUZZ_NO_RANDOM
     unsigned int seed = RandomTimePreseed();
     /* set defaults */
     host_config.hash_rand   = (int)( HOST_DEFAULT_HASHSIZE * (rand_r(&seed) / RAND_MAX + 1.0));
-
+#endif
     host_config.hash_size   = HOST_DEFAULT_HASHSIZE;
     host_config.memcap      = HOST_DEFAULT_MEMCAP;
     host_config.prealloc    = HOST_DEFAULT_PREALLOC;

src/ippair.c

@@ -137,10 +137,11 @@ void IPPairInitConfig(char quiet)
     SC_ATOMIC_INIT(ippair_prune_idx);
     IPPairQueueInit(&ippair_spare_q);
 
+#ifndef AFLFUZZ_NO_RANDOM
     unsigned int seed = RandomTimePreseed();
     /* set defaults */
     ippair_config.hash_rand   = (int)( IPPAIR_DEFAULT_HASHSIZE * (rand_r(&seed) / RAND_MAX + 1.0));
-
+#endif
     ippair_config.hash_size   = IPPAIR_DEFAULT_HASHSIZE;
     ippair_config.memcap      = IPPAIR_DEFAULT_MEMCAP;
     ippair_config.prealloc    = IPPAIR_DEFAULT_PREALLOC;

src/suricata-common.h

@@ -228,6 +228,8 @@
 #endif
 #endif
 
+#define AFLFUZZ_NO_RANDOM 1
+
 /* we need this to stringify the defines which are supplied at compiletime see:
    http://gcc.gnu.org/onlinedocs/gcc-3.4.1/cpp/Stringification.html#Stringification */
 #define xstr(s) str(s)