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bgpd: Use IEEE-754 Floating Point for storing extcommunity bandwidth

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https://datatracker.ietf.org/doc/html/draft-ietf-idr-link-bandwidth-07 says:

The bandwidth of the link is expressed as 4
   octets in IEEE floating point format, units being bytes (not bits!)
   per second.  It is carried in the Local Administrator subfield of the
   Value Field.

Before:

```
	  Extended Community (16), length: 8, Flags [OT]:
	    unknown extd community typecode (0x0004), Flags [none]
	      0x0000:  0004 fdeb 0001 e848
	    0x0000:  0004 fdeb 0001 e848
	  Updated routes:
	    172.16.16.1/32
```

0001 e848 - means 125000 (1Mbps), which is encoded incorrect.

After:

```
	  Extended Community (16), length: 8, Flags [OT]:
	    unknown extd community typecode (0x0004), Flags [none]
	      0x0000:  0004 fdeb 47f4 2400
	    0x0000:  0004 fdeb 47f4 2400
	  Updated routes:
	    172.16.16.1/32
```

47f4 2400 - means the same, but in floating point format.

Signed-off-by: Donatas Abraitis <donatas.abraitis@gmail.com>
This commit is contained in:
Donatas Abraitis 2021-08-24 10:58:20 +03:00
parent 26bf593efb
commit 8bcaad3ded
2 changed files with 34 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
bgpd/bgp_ecommunity.c
View File

@ -836,11 +836,22 @@ static int ecommunity_rt_soo_str(char *buf, size_t bufsz, const uint8_t *pnt,
ECOMMUNITY_SIZE);
}
/* Helper function to convert IEEE-754 Floating Point to uint32 */
static uint32_t ieee_float_uint32_to_uint32(uint32_t u)
{
union {
float r;
uint32_t d;
} f = {.d = u};
return (uint32_t)f.r;
}
static int ecommunity_lb_str(char *buf, size_t bufsz, const uint8_t *pnt)
{
int len = 0;
as_t as;
uint32_t bw;
uint32_t bw_tmp, bw;
char bps_buf[20] = {0};
#define ONE_GBPS_BYTES (1000 * 1000 * 1000 / 8)
@ -849,7 +860,10 @@ static int ecommunity_lb_str(char *buf, size_t bufsz, const uint8_t *pnt)
as = (*pnt++ << 8);
as |= (*pnt++);
(void)ptr_get_be32(pnt, &bw);
(void)ptr_get_be32(pnt, &bw_tmp);
bw = ieee_float_uint32_to_uint32(bw_tmp);
if (bw >= ONE_GBPS_BYTES)
snprintf(bps_buf, sizeof(bps_buf), "%.3f Gbps",
(float)(bw / ONE_GBPS_BYTES));
@ -1533,7 +1547,7 @@ const uint8_t *ecommunity_linkbw_present(struct ecommunity *ecom, uint32_t *bw)
pnt = ptr_get_be32(pnt, &bwval);
(void)pnt; /* consume value */
if (bw)
*bw = bwval;
*bw = ieee_float_uint32_to_uint32(bwval);
return eval;
}
}

21
bgpd/bgp_ecommunity.h
View File

@ -198,6 +198,17 @@ static inline void encode_route_target_as4(as_t as, uint16_t val,
eval->val[7] = val & 0xff;
}
/* Helper function to convert uint32 to IEEE-754 Floating Point */
static uint32_t uint32_to_ieee_float_uint32(uint32_t u)
{
union {
float r;
uint32_t d;
} f = {.r = (float)u};
return f.d;
}
/*
* Encode BGP Link Bandwidth extended community
* bandwidth (bw) is in bytes-per-sec
@ -205,6 +216,8 @@ static inline void encode_route_target_as4(as_t as, uint16_t val,
static inline void encode_lb_extcomm(as_t as, uint32_t bw, bool non_trans,
struct ecommunity_val *eval)
{
uint32_t bandwidth = uint32_to_ieee_float_uint32(bw);
memset(eval, 0, sizeof(*eval));
eval->val[0] = ECOMMUNITY_ENCODE_AS;
if (non_trans)
@ -212,10 +225,10 @@ static inline void encode_lb_extcomm(as_t as, uint32_t bw, bool non_trans,
eval->val[1] = ECOMMUNITY_LINK_BANDWIDTH;
eval->val[2] = (as >> 8) & 0xff;
eval->val[3] = as & 0xff;
eval->val[4] = (bw >> 24) & 0xff;
eval->val[5] = (bw >> 16) & 0xff;
eval->val[6] = (bw >> 8) & 0xff;
eval->val[7] = bw & 0xff;
eval->val[4] = (bandwidth >> 24) & 0xff;
eval->val[5] = (bandwidth >> 16) & 0xff;
eval->val[6] = (bandwidth >> 8) & 0xff;
eval->val[7] = bandwidth & 0xff;
}
extern void ecommunity_init(void);