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List:       linux-wpan
Subject:    Re: [PATCH v3 5/5] 6lowpan: Use netdev addr_len to determine lladdr len
From:       Stefan Schmidt <stefan () osg ! samsung ! com>
Date:       2017-02-20 22:15:54
Message-ID: 4995f54a-6288-f2e0-8a1d-a763349ee5f9 () osg ! samsung ! com
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Hello.

On 02/17/2017 04:50 PM, Luiz Augusto von Dentz wrote:
> From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
>
> This allow technologies such as Bluetooth to use its native lladdr which
> is eui48 instead of eui64 which was expected by functions like
> lowpan_header_decompress and lowpan_header_compress.
>
> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> ---
>  include/net/6lowpan.h   | 19 +++++++++++++++++++
>  net/6lowpan/iphc.c      | 49 +++++++++++++++++++++++++++++++++++++------------
>  net/bluetooth/6lowpan.c | 42 ++++++------------------------------------
>  3 files changed, 62 insertions(+), 48 deletions(-)
>
> diff --git a/include/net/6lowpan.h b/include/net/6lowpan.h
> index 5ab4c99..c5792cb 100644
> --- a/include/net/6lowpan.h
> +++ b/include/net/6lowpan.h
> @@ -198,6 +198,25 @@ static inline void lowpan_iphc_uncompress_eui64_lladdr(struct in6_addr *ipaddr,
>  	ipaddr->s6_addr[8] ^= 0x02;
>  }
>
> +static inline void lowpan_iphc_uncompress_eui48_lladdr(struct in6_addr *ipaddr,
> +						       const void *lladdr)
> +{
> +	/* fe:80::XXXX:XXff:feXX:XXXX
> +	 *        \_________________/
> +	 *              hwaddr
> +	 */
> +	ipaddr->s6_addr[0] = 0xFE;
> +	ipaddr->s6_addr[1] = 0x80;
> +	memcpy(&ipaddr->s6_addr[8], lladdr, 3);
> +	ipaddr->s6_addr[11] = 0xFF;
> +	ipaddr->s6_addr[12] = 0xFE;
> +	memcpy(&ipaddr->s6_addr[13], lladdr + 3, 3);
> +	/* second bit-flip (Universe/Local)
> +	 * is done according RFC2464
> +	 */
> +	ipaddr->s6_addr[8] ^= 0x02;
> +}
> +
>  #ifdef DEBUG
>  /* print data in line */
>  static inline void raw_dump_inline(const char *caller, char *msg,
> diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c
> index fb5f6fa..ddbeeb7 100644
> --- a/net/6lowpan/iphc.c
> +++ b/net/6lowpan/iphc.c
> @@ -278,6 +278,22 @@ lowpan_iphc_ctx_get_by_mcast_addr(const struct net_device *dev,
>  	return ret;
>  }
>
> +static void lowpan_iphc_uncompress_lladdr(const struct net_device *dev,
> +					  struct in6_addr *ipaddr,
> +					  const void *lladdr)
> +{
> +	switch (dev->addr_len) {
> +	case ETH_ALEN:
> +		lowpan_iphc_uncompress_eui48_lladdr(ipaddr, lladdr);
> +		break;
> +	case EUI64_ADDR_LEN:
> +		lowpan_iphc_uncompress_eui64_lladdr(ipaddr, lladdr);
> +		break;
> +	default:
> +		WARN_ON_ONCE(1);
> +	}
> +}
> +
>  /* Uncompress address function for source and
>   * destination address(non-multicast).
>   *
> @@ -320,8 +336,7 @@ static int lowpan_iphc_uncompress_addr(struct sk_buff *skb,
>  			lowpan_iphc_uncompress_802154_lladdr(ipaddr, lladdr);
>  			break;
>  		default:
> -			lowpan_iphc_uncompress_eui64_lladdr(ipaddr, lladdr);
> -			break;
> +			lowpan_iphc_uncompress_lladdr(dev, ipaddr, lladdr);

You removed the break statement here while keeping it in the next hunk. 
It does not make a difference in he end but for consistency you should 
either keep the break statements or remove all similar ones (in the 
default cases)

>  		}
>  		break;
>  	default:
> @@ -381,7 +396,7 @@ static int lowpan_iphc_uncompress_ctx_addr(struct sk_buff *skb,
>  			lowpan_iphc_uncompress_802154_lladdr(ipaddr, lladdr);
>  			break;
>  		default:
> -			lowpan_iphc_uncompress_eui64_lladdr(ipaddr, lladdr);
> +			lowpan_iphc_uncompress_lladdr(dev, ipaddr, lladdr);
>  			break;
>  		}
>  		ipv6_addr_prefix_copy(ipaddr, &ctx->pfx, ctx->plen);
> @@ -810,6 +825,21 @@ lowpan_iphc_compress_ctx_802154_lladdr(const struct in6_addr *ipaddr,
>  	return lladdr_compress;
>  }
>
> +static bool lowpan_iphc_addr_equal(const struct net_device *dev,
> +				   const struct lowpan_iphc_ctx *ctx,
> +				   const struct in6_addr *ipaddr,
> +				   const void *lladdr)
> +{
> +	struct in6_addr tmp = {};
> +
> +	lowpan_iphc_uncompress_lladdr(dev, &tmp, lladdr);
> +
> +	if (ctx)
> +		ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
> +
> +	return ipv6_addr_equal(&tmp, ipaddr);
> +}
> +
>  static u8 lowpan_compress_ctx_addr(u8 **hc_ptr, const struct net_device *dev,
>  				   const struct in6_addr *ipaddr,
>  				   const struct lowpan_iphc_ctx *ctx,
> @@ -827,13 +857,7 @@ static u8 lowpan_compress_ctx_addr(u8 **hc_ptr, const struct net_device *dev,
>  		}
>  		break;
>  	default:
> -		/* check for SAM/DAM = 11 */
> -		memcpy(&tmp.s6_addr[8], lladdr, EUI64_ADDR_LEN);
> -		/* second bit-flip (Universe/Local) is done according RFC2464 */
> -		tmp.s6_addr[8] ^= 0x02;
> -		/* context information are always used */
> -		ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
> -		if (ipv6_addr_equal(&tmp, ipaddr)) {
> +		if (lowpan_iphc_addr_equal(dev, ctx, ipaddr, lladdr)) {
>  			dam = LOWPAN_IPHC_DAM_11;
>  			goto out;
>  		}
> @@ -929,11 +953,12 @@ static u8 lowpan_compress_addr_64(u8 **hc_ptr, const struct net_device *dev,
>  		}
>  		break;
>  	default:
> -		if (is_addr_mac_addr_based(ipaddr, lladdr)) {
> -			dam = LOWPAN_IPHC_DAM_11; /* 0-bits */
> +		if (lowpan_iphc_addr_equal(dev, NULL, ipaddr, lladdr)) {
> +			dam = LOWPAN_IPHC_DAM_11;
>  			pr_debug("address compression 0 bits\n");
>  			goto out;
>  		}
> +
>  		break;
>  	}
>
> diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
> index 1456b01..0b68cfc 100644
> --- a/net/bluetooth/6lowpan.c
> +++ b/net/bluetooth/6lowpan.c
> @@ -64,7 +64,7 @@ struct lowpan_peer {
>  	struct l2cap_chan *chan;
>
>  	/* peer addresses in various formats */
> -	unsigned char eui64_addr[EUI64_ADDR_LEN];
> +	unsigned char lladdr[ETH_ALEN];
>  	struct in6_addr peer_addr;
>  };
>
> @@ -80,8 +80,6 @@ struct lowpan_btle_dev {
>  	struct delayed_work notify_peers;
>  };
>
> -static void set_addr(u8 *eui, u8 *addr, u8 addr_type);
> -
>  static inline struct lowpan_btle_dev *
>  lowpan_btle_dev(const struct net_device *netdev)
>  {
> @@ -277,7 +275,6 @@ static int iphc_decompress(struct sk_buff *skb, struct net_device *netdev,
>  	const u8 *saddr;
>  	struct lowpan_btle_dev *dev;
>  	struct lowpan_peer *peer;
> -	unsigned char eui64_daddr[EUI64_ADDR_LEN];
>
>  	dev = lowpan_btle_dev(netdev);
>
> @@ -287,10 +284,9 @@ static int iphc_decompress(struct sk_buff *skb, struct net_device *netdev,
>  	if (!peer)
>  		return -EINVAL;
>
> -	saddr = peer->eui64_addr;
> -	set_addr(&eui64_daddr[0], chan->src.b, chan->src_type);
> +	saddr = peer->lladdr;
>
> -	return lowpan_header_decompress(skb, netdev, &eui64_daddr, saddr);
> +	return lowpan_header_decompress(skb, netdev, netdev->dev_addr, saddr);
>  }
>
>  static int recv_pkt(struct sk_buff *skb, struct net_device *dev,
> @@ -477,7 +473,7 @@ static int setup_header(struct sk_buff *skb, struct net_device *netdev,
>  			}
>  		}
>
> -		daddr = peer->eui64_addr;
> +		daddr = peer->lladdr;
>  		*peer_addr = addr;
>  		*peer_addr_type = addr_type;
>  		lowpan_cb(skb)->chan = peer->chan;
> @@ -663,27 +659,6 @@ static struct device_type bt_type = {
>  	.name	= "bluetooth",
>  };
>
> -static void set_addr(u8 *eui, u8 *addr, u8 addr_type)
> -{
> -	/* addr is the BT address in little-endian format */
> -	eui[0] = addr[5];
> -	eui[1] = addr[4];
> -	eui[2] = addr[3];
> -	eui[3] = 0xFF;
> -	eui[4] = 0xFE;
> -	eui[5] = addr[2];
> -	eui[6] = addr[1];
> -	eui[7] = addr[0];
> -
> -	/* Universal/local bit set, BT 6lowpan draft ch. 3.2.1 */
> -	if (addr_type == BDADDR_LE_PUBLIC)
> -		eui[0] &= ~0x02;
> -	else
> -		eui[0] |= 0x02;
> -
> -	BT_DBG("type %d addr %*phC", addr_type, 8, eui);
> -}
> -
>  static void ifup(struct net_device *netdev)
>  {
>  	int err;
> @@ -762,14 +737,9 @@ static struct l2cap_chan *add_peer_chan(struct l2cap_chan *chan,
>  	peer->chan = chan;
>  	memset(&peer->peer_addr, 0, sizeof(struct in6_addr));
>
> -	/* RFC 2464 ch. 5 */
> -	peer->peer_addr.s6_addr[0] = 0xFE;
> -	peer->peer_addr.s6_addr[1] = 0x80;
> -	set_addr((u8 *)&peer->peer_addr.s6_addr + 8, chan->dst.b,
> -		 chan->dst_type);
> +	baswap((void *)peer->lladdr, &chan->dst);
>
> -	memcpy(&peer->eui64_addr, (u8 *)&peer->peer_addr.s6_addr + 8,
> -	       EUI64_ADDR_LEN);
> +	lowpan_iphc_uncompress_eui48_lladdr(&peer->peer_addr, peer->lladdr);
>
>  	/* IPv6 address needs to have the U/L bit set properly so toggle
>  	 * it back here.
>

With the nitpicks from above:

Reviewed-by: Stefan Schmidt <stefan@osg.samsung.com>

regards
Stefan Schmidt
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