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authorGravatar Christian Hesse <mail@eworm.de>2013-11-14 23:02:02 +0100
committerGravatar Christian Hesse <mail@eworm.de>2013-11-14 23:02:02 +0100
commit2afc18b5b49bfc1e3f21f62b458c367bc6e87bfb (patch)
treed7ab4fcd8f60772e37f375ed9e89742f3e142e9b
parentf45a34df0be309c62788f6b46024357505863743 (diff)
downloaddyndhcpd-2afc18b5b49bfc1e3f21f62b458c367bc6e87bfb.tar.gz
dyndhcpd-2afc18b5b49bfc1e3f21f62b458c367bc6e87bfb.tar.zst
bail on small networks, serve complete range and exclude self
-rw-r--r--dhcpd.conf6
-rw-r--r--dyndhcpd.c12
2 files changed, 12 insertions, 6 deletions
diff --git a/dhcpd.conf b/dhcpd.conf
index 6ec2a13..e0e295a 100644
--- a/dhcpd.conf
+++ b/dhcpd.conf
@@ -18,6 +18,12 @@ subnet __NETADDRESS__ netmask __NETMASK__ {
option time-servers __ADDRESS__;
range dynamic-bootp __MINHOST__ __MAXHOST__;
+
+ # make sure we do not serve our own address
+ host localhost {
+ hardware ethernet de:ad:00:be:ef:00;
+ fixed-address __ADDRESS__;
+ }
}
class "PXEClient" {
diff --git a/dyndhcpd.c b/dyndhcpd.c
index d6743f1..883349d 100644
--- a/dyndhcpd.c
+++ b/dyndhcpd.c
@@ -154,14 +154,14 @@ int main(int argc, char ** argv) {
s_broadcast.s_addr = v_host->s_addr |~ v_mask->s_addr;
s_netaddress.s_addr = v_host->s_addr & v_mask->s_addr;
- if (ntohl(s_broadcast.s_addr) - ntohl(v_host->s_addr) < ntohl(v_host->s_addr) - ntohl(s_netaddress.s_addr)) {
- s_minhost.s_addr = htonl(ntohl(s_netaddress.s_addr) + 1);
- s_maxhost.s_addr = htonl(ntohl(v_host->s_addr) - 1);
- } else {
- s_minhost.s_addr = htonl(ntohl(v_host->s_addr) + 1);
- s_maxhost.s_addr = htonl(ntohl(s_broadcast.s_addr) - 1);
+ if (ntohl(s_broadcast.s_addr) - ntohl(s_netaddress.s_addr) < 2) {
+ fprintf(stderr, "We do not have addresses to serve, need a netmask with 28 bit minimum.\n");
+ return EXIT_FAILURE;
}
+ s_minhost.s_addr = htonl(ntohl(s_netaddress.s_addr) + 1);
+ s_maxhost.s_addr = htonl(ntohl(s_broadcast.s_addr) - 1);
+
if (inet_ntop(AF_INET, &s_broadcast, c_broadcast, INET_ADDRSTRLEN) != NULL &&
inet_ntop(AF_INET, &s_netaddress, c_netaddress, INET_ADDRSTRLEN) != NULL &&
inet_ntop(AF_INET, &s_minhost, c_minhost, INET_ADDRSTRLEN) != NULL &&