From 9275b10557d7d5632c8f00bf5aabb0d6836465e8 Mon Sep 17 00:00:00 2001
From: Roy Marples <roy@marples.name>
Date: Wed, 19 Feb 2020 18:14:28 +0000
Subject: [PATCH] DHCP: Add support for the Microsoft User Class option

Along with advice on how to set correctly the Vendor Class ID.
Also note this is not RFC compliant.
---
 src/dhcpcd.conf.5.in | 13 +++++++++++--
 src/if-options.c     | 17 +++++++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/dhcpcd.conf.5.in b/src/dhcpcd.conf.5.in
index e7988304..71c70499 100644
--- a/src/dhcpcd.conf.5.in
+++ b/src/dhcpcd.conf.5.in
@@ -24,7 +24,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd January 22, 2020
+.Dd February 19, 2020
 .Dt DHCPCD.CONF 5
 .Os
 .Sh NAME
@@ -690,8 +690,17 @@ If using IPv4LL then
 start the IPv4LL process after the timeout and then wait a little longer
 before really timing out.
 .It Ic userclass Ar string
-Tag the DHCPv4 messages with the userclass.
+Tag the DHCPv4 message with the userclass.
 You can specify more than one.
+.It Ic msuserclass Ar string
+Tag the DHCPv4 mesasge with the Microsoft userclass.
+Unlike the
+.Ic userclass
+option, this one can only be added once.
+It should only be used for Microsoft DHCP servers and the
+.Ic vendorclassid
+should be set to "MSFT 98" or "MSFT 5.0".
+This option is not RFC compliant.
 .It Ic vendor Ar code , Ns Ar value
 Add an encapsulated vendor option.
 .Ar code
diff --git a/src/if-options.c b/src/if-options.c
index b3026491..2358abb5 100644
--- a/src/if-options.c
+++ b/src/if-options.c
@@ -106,6 +106,7 @@
 #define O_LASTLEASE_EXTEND	O_BASE + 46
 #define O_INACTIVE		O_BASE + 47
 #define	O_MUDURL		O_BASE + 48
+#define	O_MSUSERCLASS		O_BASE + 49
 
 const struct option cf_options[] = {
 	{"background",      no_argument,       NULL, 'b'},
@@ -129,6 +130,9 @@ const struct option cf_options[] = {
 	{"inform6",         optional_argument, NULL, O_INFORM6},
 	{"timeout",         required_argument, NULL, 't'},
 	{"userclass",       required_argument, NULL, 'u'},
+#ifndef SMALL
+	{"msuserclass",     required_argument, NULL, O_MSUSERCLASS},
+#endif
 	{"vendor",          required_argument, NULL, 'v'},
 	{"waitip",          optional_argument, NULL, 'w'},
 	{"exit",            no_argument,       NULL, 'x'},
@@ -894,6 +898,19 @@ parse_option(struct dhcpcd_ctx *ctx, const char *ifname, struct if_options *ifo,
 			ifo->userclass[0] = (uint8_t)(ifo->userclass[0] + s +1);
 		}
 		break;
+#ifndef SMALL
+	case O_MSUSERCLASS:
+		/* Some Microsoft DHCP servers expect userclass to be an
+		 * opaque blob. This is not RFC 3004 compliant. */
+		s = parse_string((char *)ifo->userclass + 1,
+		    sizeof(ifo->userclass) - 1, arg);
+		if (s == -1) {
+			logerr("msuserclass");
+			return -1;
+		}
+		ifo->userclass[0] = (uint8_t)s;
+		break;
+#endif
 	case 'v':
 		ARG_REQUIRED;
 		p = strchr(arg, ',');
-- 
2.47.3