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dhcp: Fix netmask calculation for option 1 from prefix length

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Similar to the conf_print() fix from commit 4129764eca ("conf: Fix
mask calculation from prefix_len in conf_print()"): to calculate an
IPv4 netmask from the prefix length, we need to left shift 32 all-one
bits by 32 minus the prefix length -- not by the prefix length
itself.

Reported-by: Yalan Zhang <yalzhang@redhat.com>
Fixes: dd09cceaee ("Minor improvements to IPv4 netmask handling")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Stefano Brivio 2023-02-16 01:53:30 +01:00
parent 7564b58a7f
commit 77a6d976aa
1 changed files with 1 additions and 1 deletions
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2
dhcp.c
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@ -335,7 +335,7 @@ int dhcp(const struct ctx *c, const struct pool *p)
m->chaddr[3], m->chaddr[4], m->chaddr[5]);
m->yiaddr = c->ip4.addr;
mask.s_addr = htonl(0xffffffff << c->ip4.prefix_len);
mask.s_addr = htonl(0xffffffff << (32 - c->ip4.prefix_len));
memcpy(opts[1].s, &mask, sizeof(mask));
memcpy(opts[3].s, &c->ip4.gw, sizeof(c->ip4.gw));
memcpy(opts[54].s, &c->ip4.gw, sizeof(c->ip4.gw));