Hello,

i've written a small rough diff against dhcpd, which adds the ability to
reload dhcpd.conf upon receiving SIGHUP (like done with various daemons,
instead of doing pkill daemon && daemon)

Currently, it only makes cfile a static instance, opened only once at
the first start of the daemon, and never closed (this was needed as
dhcpd chroots), and then calls readconf() upon SIGHUP.

This is a first patch, which may need several improvements, as i didn't
read the whole code of dhcpd, but it seems to work fine here for basic
operations (i.e add a host to dhcpd.conf, kill -HUP the daemon, dhclient
on the new host, it works) - i'd like people to test it, and comment about it.

I don't think the same trick is to do on the lease file, as it is
normally not edited by users.

Am i in the right direction, or is it the wrong approach to handle this ?

Thanks,

Landry
? dhcp-options.cat5
? dhcpd
? dhcpd.cat8
? dhcpd.conf.cat5
? dhcpd.leases.cat5
Index: confpars.c
================================================== =================
RCS file: /cvs/src/usr.sbin/dhcpd/confpars.c,v
retrieving revision 1.16
diff -u -r1.16 confpars.c
--- confpars.c 17 Dec 2006 18:03:33 -0000 1.16
+++ confpars.c 15 Jul 2007 14:26:41 -0000
@@ -41,6 +41,7 @@
#include "dhcpd.h"
#include "dhctoken.h"

+static FILE* cfile = NULL;
/* conf-file :== parameters declarations EOF
parameters :== <nil> | parameter | parameters parameter
declarations :== <nil> | declaration | declarations declaration */
@@ -48,7 +49,6 @@
int
readconf(void)
{
- FILE *cfile;
char *val;
int token;
int declaration = 0;
@@ -67,7 +67,7 @@
root_group.allow_booting = 1;
root_group.authoritative = 1;

- if ((cfile = fopen(path_dhcpd_conf, "r")) == NULL)
+ if (cfile == NULL && (cfile = fopen(path_dhcpd_conf, "r")) == NULL)
error("Can't open %s: %m", path_dhcpd_conf);

do {
@@ -80,7 +80,7 @@
declaration);
} while (1);
token = next_token(&val, cfile); /* Clear the peek buffer */
- fclose(cfile);
+ /* fclose(cfile); */

return !warnings_occurred;
}
Index: dhcpd.c
================================================== =================
RCS file: /cvs/src/usr.sbin/dhcpd/dhcpd.c,v
retrieving revision 1.32
diff -u -r1.32 dhcpd.c
--- dhcpd.c 17 Feb 2007 18:27:38 -0000 1.32
+++ dhcpd.c 15 Jul 2007 14:26:41 -0000
@@ -126,6 +126,9 @@

tzset();

+ /* Register a handler to reload the configuration file upon SIGHUP */
+ (void) signal(SIGHUP, sighup);
+
time(&cur_time);
if (!readconf())
error("Configuration file errors encountered");
@@ -193,6 +196,14 @@
fprintf(stderr, " [-l lease-file]\n");
fprintf(stderr, "\t[if0 [...ifN]]\n");
exit(1);
+}
+
+void
+sighup (int signal)
+{
+ note("Recieived SIGHUP, reloading configuration file");
+ if (!readconf())
+ error("Configuration file errors encountered");
}

void
Index: dhcpd.h
================================================== =================
RCS file: /cvs/src/usr.sbin/dhcpd/dhcpd.h,v
retrieving revision 1.33
diff -u -r1.33 dhcpd.h
--- dhcpd.h 22 Feb 2007 07:02:31 -0000 1.33
+++ dhcpd.h 15 Jul 2007 14:26:42 -0000
@@ -499,6 +499,7 @@
extern char *path_dhcpd_db;

int main(int, char *[]);
+void sighup(int);
void cleanup(void);
void lease_pinged(struct iaddr, u_int8_t *, int);
void lease_ping_timeout(void *);