[PATCH] ipconfig.c : implement DHCP Class-identifier

From: Rainer Jochem
Date: Thu Nov 08 2007 - 10:03:49 EST



This patch implements the DHCP Class identifier (see rfc1533) which is
used by DHCP clients to optionally identify the type and configuration of
a DHCP client which is send as a string to the server. For example, the
identifier may encode the client's hardware configuration. If the newly
introduced kernel-parameter 'dhcpclass' is set, then the kernel sends
the given string in its DHCP-request to the server.
If the option is omitted, the behaviour is as before without this patch.


Patch applies to:
Version: 2.6.23.1
File: net/ipv4/ipconfig.c


Signed-off-by: Rainer Jochem <rainer.jochem@xxxxxxxxxxxxx>

---

--- net/ipv4/ipconfig.c.orig 2007-11-08 14:54:11.001662860 +0100
+++ net/ipv4/ipconfig.c 2007-11-08 14:54:15.961480524 +0100
@@ -139,6 +139,8 @@ __be32 ic_servaddr = NONE; /* Boot serve
__be32 root_server_addr = NONE; /* Address of NFS server */
u8 root_server_path[256] = { 0, }; /* Path to mount as root */

+char vendor_class_identifier[256] = { 0, }; /* vendor class identifier */
+
/* Persistent data: */

static int ic_proto_used; /* Protocol used, if any */
@@ -620,6 +622,17 @@ ic_dhcp_init_options(u8 *options)
*e++ = sizeof(ic_req_params);
memcpy(e, ic_req_params, sizeof(ic_req_params));
e += sizeof(ic_req_params);
+
+ // Send it only if the according kernel parameter was set
+ if (*vendor_class_identifier) {
+ printk(KERN_INFO "Sending class identifier \"%s\"\n",
+ vendor_class_identifier);
+ *e++ = 60; /* Class-identifier */
+ *e++ = strlen(vendor_class_identifier);
+ memcpy(e, vendor_class_identifier,
+ strlen(vendor_class_identifier));
+ e += strlen(vendor_class_identifier);
+ }
}

*e++ = 255; /* End of the list */
@@ -1507,5 +1520,14 @@ static int __init nfsaddrs_config_setup(
return ip_auto_config_setup(addrs);
}

+static int __init vendor_class_identifier_setup(char *addrs)
+{
+ if (strlcpy(vendor_class_identifier, addrs, 250) > 250)
+ printk(KERN_WARNING "vendorclass too long, truncated to \"%s\"",
+ vendor_class_identifier);
+ return 1;
+}
+
__setup("ip=", ip_auto_config_setup);
__setup("nfsaddrs=", nfsaddrs_config_setup);
+__setup("dhcpclass=", vendor_class_identifier_setup);



--- ../linux-2.6.23.1/Documentation/kernel-parameters.txt 2007-10-12 18:43:44.000000000 +0200
+++ Documentation/kernel-parameters.txt 2007-10-24 17:02:22.441454955 +0200
@@ -533,6 +533,10 @@ and is between 256 and 4096 characters.
dhash_entries= [KNL]
Set number of hash buckets for dentry cache.

+ dhcpclass= [KNL]
+ Set DHCP Vendor Class Identifier to be sent
+ by the client.
+
digi= [HW,SERIAL]
IO parameters + enable/disable command.


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