From patchwork Sat Jan 29 21:47:30 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sven Eckelmann X-Patchwork-Id: 795 Return-Path: Received: from v3-1039.vlinux.de (narfation.org [79.140.41.39]) by open-mesh.org (Postfix) with ESMTPS id A8017154630 for ; Sat, 29 Jan 2011 22:48:00 +0100 (CET) Received: from sven-desktop.home.narfation.org (unknown [88.130.181.181]) by v3-1039.vlinux.de (Postfix) with ESMTPSA id F17DB94057; Sat, 29 Jan 2011 22:48:32 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=narfation.org; s=mail; t=1296337713; bh=CSbQwL92vxpymqlZfi+dYHZHy0X2MV+omGLGrKMdOiA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References; b=oTQkcLeSnEdvZ734sMXnrRYuvNf9mVrMmpkauLt8nrX0hEgFYeVx1GGSdnuI9dsAN GIELEcqbML/jM/qNd5KZYj/ieKcWuX16RKsdoX50fWk+0i7M78LLOyoJZYJzGGrIC7 sEosf7vzUWogyuhY8HWhjmIyrIVxtsEprhJkXSjE= From: Sven Eckelmann To: davem@davemloft.net Date: Sat, 29 Jan 2011 22:47:30 +0100 Message-Id: <1296337660-12376-4-git-send-email-sven@narfation.org> X-Mailer: git-send-email 1.7.2.3 In-Reply-To: <1296337660-12376-1-git-send-email-sven@narfation.org> References: <1296337660-12376-1-git-send-email-sven@narfation.org> Cc: netdev@vger.kernel.org, b.a.t.m.a.n@lists.open-mesh.org Subject: [B.A.T.M.A.N.] [PATCH 03/13] batman-adv: Calculate correct size for merged packets X-BeenThere: b.a.t.m.a.n@lists.open-mesh.org X-Mailman-Version: 2.1.11 Precedence: list Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 29 Jan 2011 21:48:01 -0000 The routing algorithm must be able to decide if a fragment can be merged with the missing part and still be passed to a forwarding interface. The fragments can only differ by one byte in case that the original payload had an uneven length. In that situation the sender has to inform all possible receivers that the tail is one byte longer using the flag UNI_FRAG_LARGETAIL. The combination of UNI_FRAG_LARGETAIL and UNI_FRAG_HEAD flag makes it possible to calculate the correct length for even and uneven sized payloads. The original formula missed to add the unicast header at all and forgot to remove the fragment header of the second fragment. This made the results highly unreliable and only useful for machines with large differences between the configured MTUs. Reported-by: Russell Senior Reported-by: Marek Lindner Signed-off-by: Sven Eckelmann --- net/batman-adv/packet.h | 1 + net/batman-adv/routing.c | 2 +- net/batman-adv/unicast.c | 8 ++++++-- net/batman-adv/unicast.h | 23 +++++++++++++++++++++++ 4 files changed, 31 insertions(+), 3 deletions(-) diff --git a/net/batman-adv/packet.h b/net/batman-adv/packet.h index 2284e81..03ce0d3 100644 --- a/net/batman-adv/packet.h +++ b/net/batman-adv/packet.h @@ -50,6 +50,7 @@ /* fragmentation defines */ #define UNI_FRAG_HEAD 0x01 +#define UNI_FRAG_LARGETAIL 0x02 struct batman_packet { uint8_t packet_type; diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c index 8828edd..a8cd389 100644 --- a/net/batman-adv/routing.c +++ b/net/batman-adv/routing.c @@ -1193,7 +1193,7 @@ int route_unicast_packet(struct sk_buff *skb, struct batman_if *recv_if, dstaddr); if (unicast_packet->packet_type == BAT_UNICAST_FRAG && - 2 * skb->len - hdr_size <= batman_if->net_dev->mtu) { + frag_can_reassemble(skb, batman_if->net_dev->mtu)) { ret = frag_reassemble_skb(skb, bat_priv, &new_skb); diff --git a/net/batman-adv/unicast.c b/net/batman-adv/unicast.c index 811f7fc..fc77079 100644 --- a/net/batman-adv/unicast.c +++ b/net/batman-adv/unicast.c @@ -225,6 +225,7 @@ int frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv, int uc_hdr_len = sizeof(struct unicast_packet); int ucf_hdr_len = sizeof(struct unicast_frag_packet); int data_len = skb->len - uc_hdr_len; + int large_tail = 0; if (!bat_priv->primary_if) goto dropped; @@ -254,8 +255,11 @@ int frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv, memcpy(frag1->orig, bat_priv->primary_if->net_dev->dev_addr, ETH_ALEN); memcpy(frag2, frag1, sizeof(struct unicast_frag_packet)); - frag1->flags |= UNI_FRAG_HEAD; - frag2->flags &= ~UNI_FRAG_HEAD; + if (data_len & 1) + large_tail = UNI_FRAG_LARGETAIL; + + frag1->flags = UNI_FRAG_HEAD | large_tail; + frag2->flags = large_tail; frag1->seqno = htons((uint16_t)atomic_inc_return( &batman_if->frag_seqno)); diff --git a/net/batman-adv/unicast.h b/net/batman-adv/unicast.h index e32b786..e7211c2 100644 --- a/net/batman-adv/unicast.h +++ b/net/batman-adv/unicast.h @@ -22,6 +22,8 @@ #ifndef _NET_BATMAN_ADV_UNICAST_H_ #define _NET_BATMAN_ADV_UNICAST_H_ +#include "packet.h" + #define FRAG_TIMEOUT 10000 /* purge frag list entrys after time in ms */ #define FRAG_BUFFER_SIZE 6 /* number of list elements in buffer */ @@ -32,4 +34,25 @@ int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv); int frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv, struct batman_if *batman_if, uint8_t dstaddr[]); +static inline int frag_can_reassemble(struct sk_buff *skb, int mtu) +{ + struct unicast_frag_packet *unicast_packet; + int uneven_correction = 0; + unsigned int merged_size; + + unicast_packet = (struct unicast_frag_packet *)skb->data; + + if (unicast_packet->flags & UNI_FRAG_LARGETAIL) { + if (unicast_packet->flags & UNI_FRAG_HEAD) + uneven_correction = 1; + else + uneven_correction = -1; + } + + merged_size = (skb->len - sizeof(struct unicast_frag_packet)) * 2; + merged_size += sizeof(struct unicast_packet) + uneven_correction; + + return merged_size <= mtu; +} + #endif /* _NET_BATMAN_ADV_UNICAST_H_ */