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65 lines
1.9 KiB
C
65 lines
1.9 KiB
C
/*
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* BIRD Internet Routing Daemon -- MPLS manipulation
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*
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* (c) 2016 Jan Matejka <mq@ucw.cz>
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* (c) 2016 CZ.NIC z.s.p.o.
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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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#ifndef _BIRD_MPLS_H_
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#define _BIRD_MPLS_H_
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#define MPLS_STACK_LENGTH 8 /* Adjust this if you need deeper MPLS stack */
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#define MPLS_PXLEN 20 /* Length of the label in bits. Constant. */
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#define MPLS_LABEL_MAX ((1<<MPLS_PXLEN)-1) /* Maximal possible label value. */
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/*
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* RFC 3032 updated by RFC 5462:
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*
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* 0 1 2 3
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* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label
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* | Label | TC |S| TTL | Stack
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* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Entry
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*
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* Label: Label Value, 20 bits
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* TC: Traffic Class, 3 bits
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* S: Bottom of Stack, 1 bit
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* TTL: Time to Live, 8 bits
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*/
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typedef struct mpls_stack {
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u8 len;
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u32 label[MPLS_STACK_LENGTH];
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} mpls_stack;
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static inline char * const mpls_hton(mpls_stack s) {
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static char buf[MPLS_STACK_LENGTH*4];
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int i;
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for (i = 0; i < s.len; i++) {
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buf[i*4 + 0] = s.label[i] >> 12;
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buf[i*4 + 1] = s.label[i] >> 4;
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buf[i*4 + 2] = (s.label[i] << 4) | (i == s.len - 1 ? 0x1 : 0);
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buf[i*4 + 3] = 0;
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}
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return buf;
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}
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static inline int mpls_buflen(const char *buf) {
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// Looking for the Bottom of Stack set to 4.
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int i;
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for (i = 0; !(buf[i++*4 + 2] & 0x1); );
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return i*4;
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}
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static inline mpls_stack mpls_ntoh(const char *buf) {
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mpls_stack s = { .len = mpls_buflen(buf) };
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int i;
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for (i = 0; i < s.len; i++)
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s.label[i] = (buf[i*4 + 0] << 12) | (buf[i*4 + 1] << 4) | (buf[i*4 + 2] >> 4);
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return s;
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}
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#endif
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