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

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

[Rainer Jochem]

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@mpi-sb.mpg.de>

---

--- 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.

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

[Patrick McHardy]

Rainer Jochem wrote:
> --- 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 */

static please, no need to initialize.

> +
>  /* 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);

Seems like useless noise.

> +			*e++ = 60;	/* Class-identifier */
> +			*e++ = strlen(vendor_class_identifier);
> +			memcpy(e, vendor_class_identifier,
> +			       strlen(vendor_class_identifier));
> +			e += strlen(vendor_class_identifier);

You could avoid these three strlen calls by using a temporary
variable to hold the length.

> +		}
>  	}
>  
>  	*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)

sizeof(vendor_class_identifier). Why are you using 250 but the
array is 256 bytes large?

> +		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]

[IP_PNP]

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

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

[Ilpo Järvinen]

On Thu, 8 Nov 2007, Rainer Jochem wrote:

> @@ -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

No C99 comments please. Though I'm not sure if this comment is that 
necessary anyway...

> +		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 */

-- 
 i.

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

[Rainer Jochem]

Corrected version below.

> >+			printk(KERN_INFO "Sending class identifier \"%s\"\n",
> >+			       vendor_class_identifier);
> 
> Seems like useless noise.

This information is only sent in the case that the option is actually used.
And in this case it might be useful for the user to see to which string the 
option was set.


--- net/ipv4/ipconfig.c.orig	2007-11-14 09:16:15.800566536 +0100
+++ net/ipv4/ipconfig.c	2007-11-14 09:16:20.200403710 +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 */
 
+static char vendor_class_identifier[253]; /* vendor class identifier */
+
 /* Persistent data: */
 
 static int ic_proto_used;			/* Protocol used, if any */
@@ -580,6 +582,7 @@ ic_dhcp_init_options(u8 *options)
 	u8 mt = ((ic_servaddr == NONE)
 		 ? DHCPDISCOVER : DHCPREQUEST);
 	u8 *e = options;
+	int len = 0;
 
 #ifdef IPCONFIG_DEBUG
 	printk("DHCP: Sending message type %d\n", mt);
@@ -620,6 +623,16 @@ 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);
+
+		if (*vendor_class_identifier) {
+			printk(KERN_INFO "Sending class identifier \"%s\"\n",
+			       vendor_class_identifier);
+			*e++ = 60;	/* Class-identifier */
+			len = strlen(vendor_class_identifier);
+			*e++ = len;
+			memcpy(e, vendor_class_identifier, len);
+			e += len;
+		}
 	}
 
 	*e++ = 255;	/* End of the list */
@@ -1507,5 +1520,16 @@ 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,
+		    sizeof(vendor_class_identifier))
+	    > sizeof(vendor_class_identifier))
+		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=	[IP_PNP]
+			Set DHCP Vendor Class Identifier to be sent
+			by the client.
+
 	digi=		[HW,SERIAL]
 			IO parameters + enable/disable command.

Signed-off-by: Rainer Jochem <rainer.jochem@mpi-sb.mpg.de>

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

[Patrick McHardy]

Rainer Jochem wrote:
> Corrected version below.
> 
>>> +			printk(KERN_INFO "Sending class identifier \"%s\"\n",
>>> +			       vendor_class_identifier);
>> Seems like useless noise.
> 
> This information is only sent in the case that the option is actually used.
> And in this case it might be useful for the user to see to which string the 
> option was set.


I don't think its very useful since you can simply get this information
from /proc/cmdline in case something goes wrong, but if you insist at
least give it a meaningful prefix.

> @@ -580,6 +582,7 @@ ic_dhcp_init_options(u8 *options)
>  	u8 mt = ((ic_servaddr == NONE)
>  		 ? DHCPDISCOVER : DHCPREQUEST);
>  	u8 *e = options;
> +	int len = 0;

The initialization is unnecessary.

>  #ifdef IPCONFIG_DEBUG
>  	printk("DHCP: Sending message type %d\n", mt);
> @@ -620,6 +623,16 @@ 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);
> +
> +		if (*vendor_class_identifier) {
> +			printk(KERN_INFO "Sending class identifier \"%s\"\n",
> +			       vendor_class_identifier);
> +			*e++ = 60;	/* Class-identifier */
> +			len = strlen(vendor_class_identifier);
> +			*e++ = len;
> +			memcpy(e, vendor_class_identifier, len);
> +			e += len;
> +		}
>  	}
>  
>  	*e++ = 255;	/* End of the list */
> @@ -1507,5 +1520,16 @@ 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,
> +		    sizeof(vendor_class_identifier))
> +	    > sizeof(vendor_class_identifier))
> +		printk(KERN_WARNING "vendorclass too long, truncated to \"%s\"",
> +		       vendor_class_identifier);

Should be >= I think.

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

[Rainer Jochem]

> I don't think its very useful since you can simply get this information
> from /proc/cmdline in case something goes wrong, but if you insist at
> least give it a meaningful prefix.

Added.

> The initialization is unnecessary.

Removed.

> Should be >= I think.

Fixed.


Regards,
 Rainer

----

--- net/ipv4/ipconfig.c.orig	2007-11-14 09:16:15.800566536 +0100
+++ net/ipv4/ipconfig.c	2007-11-14 10:34:22.471219274 +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 */
 
+static char vendor_class_identifier[253]; /* vendor class identifier */
+
 /* Persistent data: */
 
 static int ic_proto_used;			/* Protocol used, if any */
@@ -580,6 +582,7 @@ ic_dhcp_init_options(u8 *options)
 	u8 mt = ((ic_servaddr == NONE)
 		 ? DHCPDISCOVER : DHCPREQUEST);
 	u8 *e = options;
+	int len;
 
 #ifdef IPCONFIG_DEBUG
 	printk("DHCP: Sending message type %d\n", mt);
@@ -620,6 +623,16 @@ 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);
+
+		if (*vendor_class_identifier) {
+			printk(KERN_INFO "DHCP: sending class identifier \"%s\"\n",
+			       vendor_class_identifier);
+			*e++ = 60;	/* Class-identifier */
+			len = strlen(vendor_class_identifier);
+			*e++ = len;
+			memcpy(e, vendor_class_identifier, len);
+			e += len;
+		}
 	}
 
 	*e++ = 255;	/* End of the list */
@@ -1507,5 +1520,16 @@ 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,
+		    sizeof(vendor_class_identifier))
+	    >= sizeof(vendor_class_identifier))
+		printk(KERN_WARNING "DHCP: 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);

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

[Patrick McHardy]

Rainer Jochem wrote:
> 
>> I don't think its very useful since you can simply get this information
>> from /proc/cmdline in case something goes wrong, but if you insist at
>> least give it a meaningful prefix.
> 
> Added.
> 
>> The initialization is unnecessary.
> 
> Removed.
> 
>> Should be >= I think.
> 
> Fixed.


Looks fine, thanks.

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

[David Miller]

From: Patrick McHardy <kaber@trash.net>
Date: Wed, 14 Nov 2007 10:48:43 +0100

> Rainer Jochem wrote:
> > 
> >> I don't think its very useful since you can simply get this information
> >> from /proc/cmdline in case something goes wrong, but if you insist at
> >> least give it a meaningful prefix.
> > 
> > Added.
> > 
> >> The initialization is unnecessary.
> > 
> > Removed.
> > 
> >> Should be >= I think.
> > 
> > Fixed.
> 
> Looks fine, thanks.

Applied to net-2.6.25, thanks everyone.

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

[Francois Romieu]

Rainer Jochem <rainer.jochem@mpi-sb.mpg.de> :
[...]
> --- net/ipv4/ipconfig.c.orig	2007-11-14 09:16:15.800566536 +0100
> +++ net/ipv4/ipconfig.c	2007-11-14 10:34:22.471219274 +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 */
>  
> +static char vendor_class_identifier[253]; /* vendor class identifier */
> +

ic_dhcp_init_options is __init. Should it not be __initdata ?

-- 
Ueimor

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

[David Miller]

From: Francois Romieu <romieu@fr.zoreil.com>
Date: Wed, 14 Nov 2007 23:11:19 +0100

> Rainer Jochem <rainer.jochem@mpi-sb.mpg.de> :
> [...]
> > --- net/ipv4/ipconfig.c.orig	2007-11-14 09:16:15.800566536 +0100
> > +++ net/ipv4/ipconfig.c	2007-11-14 10:34:22.471219274 +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 */
> >  
> > +static char vendor_class_identifier[253]; /* vendor class identifier */
> > +
> 
> ic_dhcp_init_options is __init. Should it not be __initdata ?

I think so and I've made that change in net-2.6.25, thanks.