Re: [PATCH 2/4] NFS: Support raw IPv6 address hostnames during NFS mount operation

[Peter Staubach <staubach@redhat.com>]

Chuck Lever wrote:
> Traditionally the mount command has looked for a ":" to separate the
> server's hostname from the export path in the mounted on device name,
> like this:
>
> 	mount server:/export /mounted/on/dir
>
> The server's hostname is "server" and the export path is "/export".
>
> You can also substitute a specific IPv4 network address for the server
> hostname, like this:
>
> 	mount 192.168.0.55:/export /mounted/on/dir
>
> Raw IPv6 addresses present a problem, however, because they look
> something like this:
>
> 	fe80::200:5aff:fe00:30b
>
> Note the use of colons.
>
> To get around the presence of colons, copy the Solaris convention used for
> mounting IPv6 servers by address: wrap a raw IPv6 address with square
> brackets.
>
>   

It seems unfortunate that the convention couldn't have been to
look for the first instance of ":/" and break the strings there.

       ps

> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>
>  fs/nfs/super.c |   90 +++++++++++++++++++++++++++++++++++++++++++++++++++-----
>  1 files changed, 82 insertions(+), 8 deletions(-)
>
>
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index 5e0eefa..98c8110 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -1215,14 +1215,9 @@ static int nfs_try_mount(struct nfs_parsed_mount_data *args,
>  	return status;
>  }
>  
> -/*
> - * Split "dev_name" into "hostname:export_path".
> - *
> - * Note: caller frees hostname and export path, even on error.
> - */
> -static int nfs_parse_devname(const char *dev_name,
> -			     char **hostname, size_t maxnamlen,
> -			     char **export_path, size_t maxpathlen)
> +static int nfs_parse_simple_hostname(const char *dev_name,
> +				     char **hostname, size_t maxnamlen,
> +				     char **export_path, size_t maxpathlen)
>  {
>  	size_t len;
>  	char *colon, *comma;
> @@ -1277,6 +1272,85 @@ out_path:
>  }
>  
>  /*
> + * Hostname has square brackets around it because it contains one or
> + * more colons.  We look for the first closing square bracket, and a
> + * colon must follow it.
> + */
> +static int nfs_parse_protected_hostname(const char *dev_name,
> +					char **hostname, size_t maxnamlen,
> +					char **export_path, size_t maxpathlen)
> +{
> +	size_t len;
> +	char *start, *end;
> +
> +	start = (char *)(dev_name + 1);
> +
> +	end = strchr(start, ']');
> +	if (end == NULL)
> +		goto out_bad_devname;
> +	if (*(end + 1) != ':')
> +		goto out_bad_devname;
> +
> +	len = end - start;
> +	if (len > maxnamlen)
> +		goto out_hostname;
> +
> +	/* N.B. caller will free nfs_server.hostname in all cases */
> +	*hostname = kstrndup(start, len, GFP_KERNEL);
> +	if (*hostname == NULL)
> +		goto out_nomem;
> +
> +	end += 2;
> +	len = strlen(end);
> +	if (len > maxpathlen)
> +		goto out_path;
> +	*export_path = kstrndup(end, len, GFP_KERNEL);
> +	if (!*export_path)
> +		goto out_nomem;
> +
> +	return 0;
> +
> +out_bad_devname:
> +	dfprintk(MOUNT, "NFS: device name not in host:path format\n");
> +	return -EINVAL;
> +
> +out_nomem:
> +	dfprintk(MOUNT, "NFS: not enough memory to parse device name\n");
> +	return -ENOMEM;
> +
> +out_hostname:
> +	dfprintk(MOUNT, "NFS: server hostname too long\n");
> +	return -ENAMETOOLONG;
> +
> +out_path:
> +	dfprintk(MOUNT, "NFS: export pathname too long\n");
> +	return -ENAMETOOLONG;
> +}
> +
> +/*
> + * Split "dev_name" into "hostname:export_path".
> + *
> + * The leftmost colon demarks the split between the server's hostname
> + * and the export path.  If the hostname starts with a left square
> + * bracket, then it may contain colons.
> + *
> + * Note: caller frees hostname and export path, even on error.
> + */
> +static int nfs_parse_devname(const char *dev_name,
> +			     char **hostname, size_t maxnamlen,
> +			     char **export_path, size_t maxpathlen)
> +{
> +	if (*dev_name == '[')
> +		return nfs_parse_protected_hostname(dev_name,
> +						    hostname, maxnamlen,
> +						    export_path, maxpathlen);
> +
> +	return nfs_parse_simple_hostname(dev_name,
> +					 hostname, maxnamlen,
> +					 export_path, maxpathlen);
> +}
> +
> +/*
>   * Validate the NFS2/NFS3 mount data
>   * - fills in the mount root filehandle
>   *
>
> --
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