One can set a dhclient-script to ignore things and then call
the real dhclient-script, but I like this diff better.
Penned by Kenneth R Westerback on 20120726 21:43.39, we have:
| I like this on first read. In fact I thought this already existed.
| I'll actually look more closely at the code tomorrow.
|
| .... Ken
|
| On Thu, Jul 26, 2012 at 10:09:28PM -0400, Ted Unangst wrote:
| > I have a system with two network interfaces (em0 and em1), running dhcp
| > on both. Both dhcp servers provide me with a nameserver, but only one
| > of them works (I can't fix this). There is a config file for dhclient
| > I can use, but it only supports the supersede keyword. I don't want
| > to statically configure a nameserver override for em1, because the
| > whole point is that the good nameserver on em0 can change. I just
| > want to say "pretend this option did not arrive."
| >
| > Diff below adds a little support for an ignore keyword. Like
| > supersede, except don't actually use the supplied value.
| >
| > Index: clparse.c
| > ===================================================================
| > RCS file: /cvs/src/sbin/dhclient/clparse.c,v
| > retrieving revision 1.38
| > diff -u -p -r1.38 clparse.c
| > --- clparse.c 10 Dec 2011 17:15:27 -0000 1.38
| > +++ clparse.c 27 Jul 2012 01:59:10 -0000
| > @@ -170,6 +170,11 @@ parse_client_statement(FILE *cfile)
| > if (code != -1)
| > config->default_actions[code] = ACTION_SUPERSEDE;
| > return;
| > + case TOK_IGNORE:
| > + code = parse_option_decl(cfile, &config->defaults[0]);
| > + if (code != -1)
| > + config->default_actions[code] = ACTION_IGNORE;
| > + return;
| > case TOK_APPEND:
| > code = parse_option_decl(cfile, &config->defaults[0]);
| > if (code != -1)
| > Index: conflex.c
| > ===================================================================
| > RCS file: /cvs/src/sbin/dhclient/conflex.c,v
| > retrieving revision 1.14
| > diff -u -p -r1.14 conflex.c
| > --- conflex.c 10 Dec 2011 17:36:40 -0000 1.14
| > +++ conflex.c 27 Jul 2012 01:15:19 -0000
| > @@ -337,6 +337,7 @@ static const struct keywords {
| > { "filename", TOK_FILENAME },
| > { "fixed-address", TOK_FIXED_ADDR },
| > { "hardware", TOK_HARDWARE },
| > + { "ignore", TOK_IGNORE },
| > { "initial-interval", TOK_INITIAL_INTERVAL },
| > { "interface", TOK_INTERFACE },
| > { "lease", TOK_LEASE },
| > Index: dhclient.c
| > ===================================================================
| > RCS file: /cvs/src/sbin/dhclient/dhclient.c,v
| > retrieving revision 1.146
| > diff -u -p -r1.146 dhclient.c
| > --- dhclient.c 9 Jul 2012 16:21:21 -0000 1.146
| > +++ dhclient.c 27 Jul 2012 01:59:35 -0000
| > @@ -1535,6 +1535,9 @@ priv_script_write_params(char *prefix, s
| > if (config->defaults[i].len) {
| > if (lease->options[i].len) {
| > switch (config->default_actions[i]) {
| > + case ACTION_IGNORE:
| > + /* handled below */
| > + break;
| > case ACTION_DEFAULT:
| > dp = lease->options[i].data;
| > len = lease->options[i].len;
| > @@ -1588,6 +1591,9 @@ supersede:
| > len = lease->options[i].len;
| > dp = lease->options[i].data;
| > } else {
| > + len = 0;
| > + }
| > + if (len && config->default_actions[i] == ACTION_IGNORE) {
| > len = 0;
| > }
| > if (len) {
| > Index: dhclient.conf.5
| > ===================================================================
| > RCS file: /cvs/src/sbin/dhclient/dhclient.conf.5,v
| > retrieving revision 1.21
| > diff -u -p -r1.21 dhclient.conf.5
| > --- dhclient.conf.5 9 Apr 2011 19:53:00 -0000 1.21
| > +++ dhclient.conf.5 27 Jul 2012 02:05:28 -0000
| > @@ -244,6 +244,14 @@ in the
| > .Ic supersede
| > statement.
| > .It Xo
| > +.Ic ignore No { Op Ar option declaration
| > +.Oo , Ar ... option declaration Oc }
| > +.Xc
| > +If for some set of options the client should always ignore the
| > +value supplied by the server, these values can be defined in the
| > +.Ic ignore
| > +statement.
| > +.It Xo
| > .Ic prepend No { Op Ar option declaration
| > .Oo , Ar ... option declaration Oc }
| > .Xc
| > Index: dhcpd.h
| > ===================================================================
| > RCS file: /cvs/src/sbin/dhclient/dhcpd.h,v
| > retrieving revision 1.76
| > diff -u -p -r1.76 dhcpd.h
| > --- dhcpd.h 9 Jul 2012 16:21:21 -0000 1.76
| > +++ dhcpd.h 27 Jul 2012 01:18:18 -0000
| > @@ -130,6 +130,7 @@ struct client_config {
| > struct option_data defaults[256];
| > enum {
| > ACTION_DEFAULT,
| > + ACTION_IGNORE,
| > ACTION_SUPERSEDE,
| > ACTION_PREPEND,
| > ACTION_APPEND
| > Index: dhctoken.h
| > ===================================================================
| > RCS file: /cvs/src/sbin/dhclient/dhctoken.h,v
| > retrieving revision 1.5
| > diff -u -p -r1.5 dhctoken.h
| > --- dhctoken.h 15 May 2006 08:10:57 -0000 1.5
| > +++ dhctoken.h 27 Jul 2012 01:15:54 -0000
| > @@ -79,6 +79,7 @@
| > #define TOK_REJECT 292
| > #define TOK_FDDI 293
| > #define TOK_LINK_TIMEOUT 294
| > +#define TOK_IGNORE 295
| >
| > #define is_identifier(x) ((x) >= TOK_FIRST_TOKEN && \
| > (x) != TOK_STRING && \
--
Todd Fries .. [email protected]
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