On Thu, Feb 16, 2023 at 02:07:52AM +0100, Stefano Brivio wrote:
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(a)redhat.com>
Fixes: dd09cceaee21 ("Minor improvements to IPv4 netmask handling")
Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>
Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au>
---
dhcp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
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));
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson