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authorStefano Brivio <sbrivio@redhat.com>2023-02-16 01:53:30 +0100
committerStefano Brivio <sbrivio@redhat.com>2023-02-16 17:33:57 +0100
commit77a6d976aa4571427ba832226a3232f92bfd169f (patch)
tree8a523cf4b20ea82282c5dc879f5b238d8edee7cf
parent7564b58a7f27bd926b0ce76b4fda145dca2d15dd (diff)
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dhcp: Fix netmask calculation for option 1 from prefix length
Similar to the conf_print() fix from commit 4129764ecaeb ("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: dd09cceaee21 ("Minor improvements to IPv4 netmask handling") Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
-rw-r--r--dhcp.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/dhcp.c b/dhcp.c
index 6088886..edab780 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -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));