[sr-dev] git:master: Added new mode to sr_init that modifies the way the pseudo-random generator behaves

Module: sip-router Branch: master Commit: 7f839dab108423e47660e06459591efef41f81a3 URL: http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commit;h=7f839da… Author: Marius Zbihlei &lt;marius.zbihlei(a)1and1.ro&gt; Committer: Marius Zbihlei &lt;marius.zbihlei(a)1and1.ro&gt; Date: Tue Apr 10 17:17:56 2012 +0300 Added new mode to sr_init that modifies the way the pseudo-random generator behaves Now it can use a LFSR (Linear Feedback Shift Register) to generate pseudo random numbers --- lib/srutils/sruid.c | 36 ++++++++++++++++++++++++++++++++++-- lib/srutils/sruid.h | 5 ++++- modules_k/kex/kex_mod.c | 4 ++-- 3 files changed, 40 insertions(+), 5 deletions(-) diff --git a/lib/srutils/sruid.c b/lib/srutils/sruid.c index 682a244..d9efec8 100644 --- a/lib/srutils/sruid.c +++ b/lib/srutils/sruid.c @@ -34,10 +34,38 @@ #include "sruid.h" +/* starting polynomials */ +#define MASK_32 0xb4bcd35c +#define MASK_31 0x7a5bc2e3 + +unsigned int lfsr32, lfsr31; + +int shift_lfsr(unsigned int *lfsr, unsigned int mask){ + int feedback; + feedback = *lfsr & 0x1; + *lfsr >>=1; + if (feedback == 1) + *lfsr ^= mask; + return *lfsr; +} + +void init_lfsr(void){ + lfsr32 = (unsigned int)time(NULL); + lfsr31 = (unsigned int)getpid(); +} + +/* + * returns a 32 bit random integer + * + */ +int get_random(){ + return (shift_lfsr(&lfsr32, MASK_32) ^ shift_lfsr(&lfsr31, MASK_31)) & 0xffffffff; +} + /** * */ -int sruid_init(sruid_t *sid, char sep, char *cid) +int sruid_init(sruid_t *sid, char sep, char *cid, int mode) { int i; @@ -67,6 +95,7 @@ int sruid_init(sruid_t *sid, char sep, char *cid) } sid->out = sid->buf + i + 5; sid->uid.s = sid->buf; + sid->mode = (sruid_mode_t)mode; LM_DBG("root for sruid is [%.*s] (%u / %d)\n", i+5, sid->uid.s, sid->counter, i+5); return 0; @@ -88,7 +117,10 @@ int sruid_next(sruid_t *sid) if(sid->counter==0) sid->counter=1; - val = sid->counter; + if(sid->mode == SRUID_LFSR) + val = get_random(); + else + val = sid->counter; i = 0; while(val!=0) { diff --git a/lib/srutils/sruid.h b/lib/srutils/sruid.h index b7c49ee..16ac116 100644 --- a/lib/srutils/sruid.h +++ b/lib/srutils/sruid.h @@ -29,14 +29,17 @@ #define SRUID_SIZE 40 +typedef enum {SRUID_INC=0, SRUID_LFSR=1} sruid_mode_t; + typedef struct sruid { char buf[SRUID_SIZE]; char *out; str uid; unsigned int counter; + sruid_mode_t mode; } sruid_t; -int sruid_init(sruid_t *sid, char sep, char *cid); +int sruid_init(sruid_t *sid, char sep, char *cid, int mode); int sruid_next(sruid_t *sid); #endif diff --git a/modules_k/kex/kex_mod.c b/modules_k/kex/kex_mod.c index 82165f5..ad3cc1d 100644 --- a/modules_k/kex/kex_mod.c +++ b/modules_k/kex/kex_mod.c @@ -137,7 +137,7 @@ struct module_exports exports= { */ static int mod_init(void) { - if(sruid_init(&_kex_sruid, '-', NULL)<0) + if(sruid_init(&_kex_sruid, '-', NULL, 0)<0) return -1; if(init_mi_core()<0) return -1; @@ -158,7 +158,7 @@ static int mod_init(void) static int child_init(int rank) { LM_DBG("rank is (%d)\n", rank); - if(sruid_init(&_kex_sruid, '-', NULL)<0) + if(sruid_init(&_kex_sruid, '-', NULL, 0)<0) return -1; if (rank==PROC_INIT) return pkg_proc_stats_init();