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39 lines
1.1 KiB
C
39 lines
1.1 KiB
C
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/*
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* BIRD -- Path Operations
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*
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* (c) 2000 Martin Mares <mj@ucw.cz>
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* (c) 2000 Pavel Machek <pavel@ucw.cz>
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*
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* Can be freely distributed and used under the terms of the GNU GPL.
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*/
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#include "nest/bird.h"
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#include "nest/route.h"
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#include "lib/resource.h"
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#include "lib/unaligned.h"
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struct adata *
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as_path_prepend(struct linpool *pool, struct adata *olda, int as)
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{
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struct adata *newa;
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if (olda->length && olda->data[0] == 2 && olda->data[1] < 255) /* Starting with sequence => just prepend the AS number */
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{
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newa = lp_alloc(pool, sizeof(struct adata) + olda->length + 2);
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newa->length = olda->length + 2;
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newa->data[0] = 2;
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newa->data[1] = olda->data[1] + 1;
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memcpy(newa->data+4, olda->data+2, olda->length-2);
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}
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else /* Create new path segment */
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{
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newa = lp_alloc(pool, sizeof(struct adata) + olda->length + 4);
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newa->length = olda->length + 4;
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newa->data[0] = 2;
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newa->data[1] = 1;
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memcpy(newa->data+4, olda->data, olda->length);
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}
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put_u16(newa->data+2, as);
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return newa;
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}
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