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

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Date:	Thu, 08 Nov 2007 16:45:35 +0100
From:	Patrick McHardy <kaber@...sh.net>
To:	Rainer Jochem <rainer.jochem@...-sb.mpg.de>
CC:	davem@...emloft.net, kuznet@....inr.ac.ru, jmorris@...ei.org,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	pcernko@...-sws.mpg.de
Subject: Re: [PATCH] ipconfig.c : implement DHCP Class-identifier

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.
> 
> 

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