355 lines
6.2 KiB
C
355 lines
6.2 KiB
C
/*
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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 "nest/attrs.h"
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#include "lib/resource.h"
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#include "lib/unaligned.h"
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#include "lib/string.h"
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/* Global AS4 support, shared by all BGP instances.
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* This specifies whether BA_AS_PATH attributes contain 2 or 4 B per ASN
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*/
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int bgp_as4_support = 1;
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static void
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put_as(byte *data, u32 as)
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{
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if (bgp_as4_support)
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put_u32(data, as);
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else if (as <= 0xFFFF)
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put_u16(data, as);
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else
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bug("put_as: Try to put 32bit AS to 16bit AS Path");
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}
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static inline u32
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get_as(byte *data)
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{
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return bgp_as4_support ? get_u32(data) : get_u16(data);
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}
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struct adata *
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as_path_prepend(struct linpool *pool, struct adata *olda, u32 as)
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{
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int bs = bgp_as4_support ? 4 : 2;
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struct adata *newa;
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if (olda->length && olda->data[0] == AS_PATH_SEQUENCE && olda->data[1] < 255)
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/* Starting with sequence => just prepend the AS number */
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{
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int nl = olda->length + bs;
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newa = lp_alloc(pool, sizeof(struct adata) + nl);
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newa->length = nl;
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newa->data[0] = AS_PATH_SEQUENCE;
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newa->data[1] = olda->data[1] + 1;
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memcpy(newa->data + bs + 2, 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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int nl = olda->length + bs + 2;
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newa = lp_alloc(pool, sizeof(struct adata) + nl);
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newa->length = nl;
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newa->data[0] = AS_PATH_SEQUENCE;
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newa->data[1] = 1;
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memcpy(newa->data + bs + 2, olda->data, olda->length);
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}
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put_as(newa->data + 2, as);
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return newa;
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}
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int
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as_path_convert_to_old(struct adata *path, byte *dst, int *new_used)
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{
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byte *src = path->data;
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byte *src_end = src + path->length;
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byte *dst_start = dst;
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u32 as;
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int i, n;
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*new_used = 0;
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while (src < src_end)
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{
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n = src[1];
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*dst++ = *src++;
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*dst++ = *src++;
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for(i=0; i<n; i++)
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{
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as = get_u32(src);
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if (as > 0xFFFF)
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{
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as = AS_TRANS;
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*new_used = 1;
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}
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put_u16(dst, as);
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src += 4;
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dst += 2;
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}
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}
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return dst - dst_start;
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}
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int
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as_path_convert_to_new(struct adata *path, byte *dst, int req_as)
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{
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byte *src = path->data;
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byte *src_end = src + path->length;
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byte *dst_start = dst;
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u32 as;
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int i, t, n;
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while ((src < src_end) && (req_as > 0))
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{
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t = *src++;
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n = *src++;
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if (t == AS_PATH_SEQUENCE)
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{
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if (n > req_as)
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n = req_as;
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req_as -= n;
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}
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else // t == AS_PATH_SET
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req_as--;
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*dst++ = t;
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*dst++ = n;
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for(i=0; i<n; i++)
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{
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as = get_u16(src);
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put_u32(dst, as);
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src += 2;
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dst += 4;
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}
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}
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return dst - dst_start;
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}
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void
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as_path_format(struct adata *path, byte *buf, unsigned int size)
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{
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int bs = bgp_as4_support ? 4 : 2;
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byte *p = path->data;
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byte *e = p + path->length;
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byte *end = buf + size - 16;
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int sp = 1;
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int l, isset;
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while (p < e)
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{
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if (buf > end)
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{
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strcpy(buf, " ...");
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return;
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}
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isset = (*p++ == AS_PATH_SET);
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l = *p++;
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if (isset)
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{
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if (!sp)
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*buf++ = ' ';
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*buf++ = '{';
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sp = 0;
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}
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while (l-- && buf <= end)
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{
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if (!sp)
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*buf++ = ' ';
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buf += bsprintf(buf, "%u", get_as(p));
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p += bs;
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sp = 0;
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}
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if (isset)
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{
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*buf++ = ' ';
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*buf++ = '}';
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sp = 0;
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}
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}
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*buf = 0;
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}
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int
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as_path_getlen(struct adata *path)
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{
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int bs = bgp_as4_support ? 4 : 2;
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int res = 0;
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u8 *p = path->data;
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u8 *q = p+path->length;
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int len;
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while (p<q)
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{
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switch (*p++)
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{
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case AS_PATH_SET: len = *p++; res++; p += bs * len; break;
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case AS_PATH_SEQUENCE: len = *p++; res += len; p += bs * len; break;
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default: bug("as_path_getlen: Invalid path segment");
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}
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}
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return res;
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}
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int
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as_path_get_first(struct adata *path, u32 *orig_as)
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{
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int bs = bgp_as4_support ? 4 : 2;
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int found = 0;
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u32 res = 0;
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u8 *p = path->data;
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u8 *q = p+path->length;
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int len;
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while (p<q)
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{
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switch (*p++)
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{
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case AS_PATH_SET:
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if (len = *p++)
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{
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found = 1;
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res = get_as(p);
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p += bs * len;
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}
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break;
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case AS_PATH_SEQUENCE:
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if (len = *p++)
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{
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found = 1;
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res = get_as(p + bs * (len - 1));
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p += bs * len;
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}
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break;
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default: bug("as_path_get_first: Invalid path segment");
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}
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}
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*orig_as = res;
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return found;
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}
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int
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as_path_get_last(struct adata *path, u32 *last_as)
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{
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u8 *p = path->data;
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if ((path->length == 0) || (p[0] != AS_PATH_SEQUENCE) || (p[1] == 0))
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return 0;
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else
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{
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*last_as = get_as(p+2);
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return 1;
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}
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}
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int
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as_path_is_member(struct adata *path, u32 as)
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{
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int bs = bgp_as4_support ? 4 : 2;
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u8 *p = path->data;
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u8 *q = p+path->length;
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int i, n;
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while (p<q)
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{
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n = p[1];
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p += 2;
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for(i=0; i<n; i++)
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{
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if (get_as(p) == as)
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return 1;
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p += bs;
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}
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}
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return 0;
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}
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#define MASK_PLUS do { mask = mask->next; if (!mask) return next == q; \
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asterisk = mask->any; \
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if (asterisk) { mask = mask->next; if (!mask) { return 1; } } \
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} while(0)
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int
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as_path_match(struct adata *path, struct f_path_mask *mask)
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{
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int bs = bgp_as4_support ? 4 : 2;
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int i;
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int asterisk = 0;
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u8 *p = path->data;
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u8 *q = p+path->length;
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int len;
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u8 *next;
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u32 as;
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asterisk = mask->any;
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if (asterisk)
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{ mask = mask->next; if (!mask) return 1; }
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while (p<q) {
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switch (*p++) {
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case AS_PATH_SET:
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len = *p++;
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{
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u8 *p_save = p;
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next = p_save + bs * len;
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retry:
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p = p_save;
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for (i=0; i<len; i++) {
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as = get_as(p);
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if (asterisk && (as == mask->val)) {
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MASK_PLUS;
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goto retry;
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}
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if (!asterisk && (as == mask->val)) {
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p = next;
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MASK_PLUS;
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goto okay;
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}
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p += bs;
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}
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if (!asterisk)
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return 0;
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okay: ;
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}
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break;
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case AS_PATH_SEQUENCE:
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len = *p++;
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for (i=0; i<len; i++) {
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next = p + bs;
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as = get_as(p);
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if (asterisk && (as == mask->val))
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MASK_PLUS;
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else if (!asterisk) {
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if (as != mask->val)
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return 0;
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MASK_PLUS;
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}
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p += bs;
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}
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break;
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default:
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bug("as_path_match: Invalid path component");
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}
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}
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return 0;
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}
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