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59 lines
1.1 KiB
59 lines
1.1 KiB
/*
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* UCW Library -- Rate Limiting based on the Token Bucket Filter
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*
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* (c) 2009 Martin Mares <mj@ucw.cz>
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*
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* This software may be freely distributed and used according to the terms
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* of the GNU Lesser General Public License.
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*/
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#include <ucw/lib.h>
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#include <ucw/tbf.h>
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void
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tbf_init(struct token_bucket_filter *f)
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{
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if (!f->burst)
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f->burst = MAX(2*f->rate, 1);
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f->last_hit = 0;
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f->bucket = f->burst;
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}
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int
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tbf_limit(struct token_bucket_filter *f, timestamp_t now)
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{
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timestamp_t delta_t = now - f->last_hit;
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f->last_hit = now;
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double b = f->bucket + f->rate * delta_t / 1000;
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b = MIN(b, f->burst);
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if (b >= 1)
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{
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uint dropped = f->drop_count;
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f->bucket = b - 1;
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f->drop_count = 0;
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return dropped;
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}
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else
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{
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f->bucket = b;
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f->drop_count++;
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return -f->drop_count;
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}
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}
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#ifdef TEST
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int main(void)
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{
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struct token_bucket_filter t = { .rate = 1, .burst = 2 };
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tbf_init(&t);
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for (timestamp_t now = 0; now < 3000; now += 77)
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{
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int res = tbf_limit(&t, now);
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msg(L_DEBUG, "t=%u result=%d bucket=%f", (uint) now, res, t.bucket);
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}
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return 0;
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}
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#endif
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