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util: Add be32_prefix_mask().

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Shifting a 32-bit entity by 32 bits is undefined behavior.  As we have 2
cases where we may hit this, it is a time to introduce a helper for
this.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
This commit is contained in:
Jarno Rajahalme
2014-11-11 15:50:51 -08:00
parent b393b7f042
commit 526a7c85d1
3 changed files with 13 additions and 6 deletions
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2
lib/classifier.c
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@@ -1829,7 +1829,7 @@ find_match_wc(const struct cls_subtable *subtable, const struct flow *flow,
trie_lookup_value(subtable->ports_trie, &value, 32, &mbits);
((OVS_FORCE ovs_be32 *)&wc->masks)[TP_PORTS_OFS32] |=
mask & htonl(~0 << (32 - mbits));
mask & be32_prefix_mask(mbits);
ofs.start = TP_PORTS_OFS32;
goto range_out;

8
lib/meta-flow.c
View File

@@ -33,6 +33,7 @@
#include "shash.h"
#include "socket-util.h"
#include "unaligned.h"
#include "util.h"
#include "vlog.h"
VLOG_DEFINE_THIS_MODULE(meta_flow);
@@ -2405,13 +2406,10 @@ mf_from_ipv4_string(const struct mf_field *mf, const char *s,
/* OK. */
} else if (ovs_scan(s, IP_SCAN_FMT"/%d", IP_SCAN_ARGS(ip), &prefix)) {
if (prefix <= 0 || prefix > 32) {
return xasprintf("%s: network prefix bits not between 1 and "
return xasprintf("%s: network prefix bits not between 0 and "
"32", s);
} else if (prefix == 32) {
*mask = OVS_BE32_MAX;
} else {
*mask = htonl(((1u << prefix) - 1) << (32 - prefix));
}
*mask = be32_prefix_mask(prefix);
} else if (ovs_scan(s, IP_SCAN_FMT, IP_SCAN_ARGS(ip))) {
*mask = OVS_BE32_MAX;
} else {

9
lib/util.h
View File

@@ -26,6 +26,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "byte-order.h"
#include "compiler.h"
#include "openvswitch/types.h"
@@ -478,6 +479,14 @@ leftmost_1bit_idx(uint32_t x)
{
return x ? log_2_floor(x) : 32;
}
/* Return a ovs_be32 prefix in network byte order with 'plen' highest bits set.
* Shift with 32 is undefined behavior, but we rather use 64-bit shift than
* compare. */
static inline ovs_be32 be32_prefix_mask(int plen)
{
return htonl((uint64_t)UINT32_MAX << (32 - plen));
}
bool is_all_zeros(const uint8_t *, size_t);
bool is_all_ones(const uint8_t *, size_t);