--- zzzz-none-000/linux-2.4.17/net/ipv4/netfilter/ipt_limit.c 2001-09-30 19:26:08.000000000 +0000 +++ sangam-fb-322/linux-2.4.17/net/ipv4/netfilter/ipt_limit.c 2004-11-24 13:22:08.000000000 +0000 @@ -1,136 +1,136 @@ -/* Kernel module to control the rate - * - * Jérôme de Vivie - * Hervé Eychenne - * - * 2 September 1999: Changed from the target RATE to the match - * `limit', removed logging. Did I mention that - * Alexey is a fucking genius? - * Rusty Russell (rusty@rustcorp.com.au). */ -#include -#include -#include -#include - -#include -#include - -/* The algorithm used is the Simple Token Bucket Filter (TBF) - * see net/sched/sch_tbf.c in the linux source tree - */ - -static spinlock_t limit_lock = SPIN_LOCK_UNLOCKED; - -/* Rusty: This is my (non-mathematically-inclined) understanding of - this algorithm. The `average rate' in jiffies becomes your initial - amount of credit `credit' and the most credit you can ever have - `credit_cap'. The `peak rate' becomes the cost of passing the - test, `cost'. - - `prev' tracks the last packet hit: you gain one credit per jiffy. - If you get credit balance more than this, the extra credit is - discarded. Every time the match passes, you lose `cost' credits; - if you don't have that many, the test fails. - - See Alexey's formal explanation in net/sched/sch_tbf.c. - - To avoid underflow, we multiply by 128 (ie. you get 128 credits per - jiffy). Hence a cost of 2^32-1, means one pass per 32768 seconds - at 1024HZ (or one every 9 hours). A cost of 1 means 12800 passes - per second at 100HZ. */ - -#define CREDITS_PER_JIFFY 128 - -static int -ipt_limit_match(const struct sk_buff *skb, - const struct net_device *in, - const struct net_device *out, - const void *matchinfo, - int offset, - const void *hdr, - u_int16_t datalen, - int *hotdrop) -{ - struct ipt_rateinfo *r = ((struct ipt_rateinfo *)matchinfo)->master; - unsigned long now = jiffies; - - spin_lock_bh(&limit_lock); - r->credit += (now - xchg(&r->prev, now)) * CREDITS_PER_JIFFY; - if (r->credit > r->credit_cap) - r->credit = r->credit_cap; - - if (r->credit >= r->cost) { - /* We're not limited. */ - r->credit -= r->cost; - spin_unlock_bh(&limit_lock); - return 1; - } - - spin_unlock_bh(&limit_lock); - return 0; -} - -/* Precision saver. */ -static u_int32_t -user2credits(u_int32_t user) -{ - /* If multiplying would overflow... */ - if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY)) - /* Divide first. */ - return (user / IPT_LIMIT_SCALE) * HZ * CREDITS_PER_JIFFY; - - return (user * HZ * CREDITS_PER_JIFFY) / IPT_LIMIT_SCALE; -} - -static int -ipt_limit_checkentry(const char *tablename, - const struct ipt_ip *ip, - void *matchinfo, - unsigned int matchsize, - unsigned int hook_mask) -{ - struct ipt_rateinfo *r = matchinfo; - - if (matchsize != IPT_ALIGN(sizeof(struct ipt_rateinfo))) - return 0; - - /* Check for overflow. */ - if (r->burst == 0 - || user2credits(r->avg * r->burst) < user2credits(r->avg)) { - printk("Call rusty: overflow in ipt_limit: %u/%u\n", - r->avg, r->burst); - return 0; - } - - /* User avg in seconds * IPT_LIMIT_SCALE: convert to jiffies * - 128. */ - r->prev = jiffies; - r->credit = user2credits(r->avg * r->burst); /* Credits full. */ - r->credit_cap = user2credits(r->avg * r->burst); /* Credits full. */ - r->cost = user2credits(r->avg); - - /* For SMP, we only want to use one set of counters. */ - r->master = r; - - return 1; -} - -static struct ipt_match ipt_limit_reg -= { { NULL, NULL }, "limit", ipt_limit_match, ipt_limit_checkentry, NULL, - THIS_MODULE }; - -static int __init init(void) -{ - if (ipt_register_match(&ipt_limit_reg)) - return -EINVAL; - return 0; -} - -static void __exit fini(void) -{ - ipt_unregister_match(&ipt_limit_reg); -} - -module_init(init); -module_exit(fini); -MODULE_LICENSE("GPL"); +/* Kernel module to control the rate + * + * Jérôme de Vivie + * Hervé Eychenne + * + * 2 September 1999: Changed from the target RATE to the match + * `limit', removed logging. Did I mention that + * Alexey is a fucking genius? + * Rusty Russell (rusty@rustcorp.com.au). */ +#include +#include +#include +#include + +#include +#include + +/* The algorithm used is the Simple Token Bucket Filter (TBF) + * see net/sched/sch_tbf.c in the linux source tree + */ + +static spinlock_t limit_lock = SPIN_LOCK_UNLOCKED; + +/* Rusty: This is my (non-mathematically-inclined) understanding of + this algorithm. The `average rate' in jiffies becomes your initial + amount of credit `credit' and the most credit you can ever have + `credit_cap'. The `peak rate' becomes the cost of passing the + test, `cost'. + + `prev' tracks the last packet hit: you gain one credit per jiffy. + If you get credit balance more than this, the extra credit is + discarded. Every time the match passes, you lose `cost' credits; + if you don't have that many, the test fails. + + See Alexey's formal explanation in net/sched/sch_tbf.c. + + To avoid underflow, we multiply by 128 (ie. you get 128 credits per + jiffy). Hence a cost of 2^32-1, means one pass per 32768 seconds + at 1024HZ (or one every 9 hours). A cost of 1 means 12800 passes + per second at 100HZ. */ + +#define CREDITS_PER_JIFFY 128 + +static int +ipt_limit_match(const struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + const void *matchinfo, + int offset, + const void *hdr, + u_int16_t datalen, + int *hotdrop) +{ + struct ipt_rateinfo *r = ((struct ipt_rateinfo *)matchinfo)->master; + unsigned long now = jiffies; + + spin_lock_bh(&limit_lock); + r->credit += (now - xchg(&r->prev, now)) * CREDITS_PER_JIFFY; + if (r->credit > r->credit_cap) + r->credit = r->credit_cap; + + if (r->credit >= r->cost) { + /* We're not limited. */ + r->credit -= r->cost; + spin_unlock_bh(&limit_lock); + return 1; + } + + spin_unlock_bh(&limit_lock); + return 0; +} + +/* Precision saver. */ +static u_int32_t +user2credits(u_int32_t user) +{ + /* If multiplying would overflow... */ + if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY)) + /* Divide first. */ + return (user / IPT_LIMIT_SCALE) * HZ * CREDITS_PER_JIFFY; + + return (user * HZ * CREDITS_PER_JIFFY) / IPT_LIMIT_SCALE; +} + +static int +ipt_limit_checkentry(const char *tablename, + const struct ipt_ip *ip, + void *matchinfo, + unsigned int matchsize, + unsigned int hook_mask) +{ + struct ipt_rateinfo *r = matchinfo; + + if (matchsize != IPT_ALIGN(sizeof(struct ipt_rateinfo))) + return 0; + + /* Check for overflow. */ + if (r->burst == 0 + || user2credits(r->avg * r->burst) < user2credits(r->avg)) { + printk("Call rusty: overflow in ipt_limit: %u/%u\n", + r->avg, r->burst); + return 0; + } + + /* User avg in seconds * IPT_LIMIT_SCALE: convert to jiffies * + 128. */ + r->prev = jiffies; + r->credit = user2credits(r->avg * r->burst); /* Credits full. */ + r->credit_cap = user2credits(r->avg * r->burst); /* Credits full. */ + r->cost = user2credits(r->avg); + + /* For SMP, we only want to use one set of counters. */ + r->master = r; + + return 1; +} + +static struct ipt_match ipt_limit_reg += { { NULL, NULL }, "limit", ipt_limit_match, ipt_limit_checkentry, NULL, + THIS_MODULE }; + +static int __init init(void) +{ + if (ipt_register_match(&ipt_limit_reg)) + return -EINVAL; + return 0; +} + +static void __exit fini(void) +{ + ipt_unregister_match(&ipt_limit_reg); +} + +module_init(init); +module_exit(fini); +MODULE_LICENSE("GPL");