Non-broadcast packets larger than MTU are fragmented and sent with an encapsulating header. Up to 16 fragments are supported, which are sent in reverse order on the wire.
Signed-off-by: Martin Hundebøll <[email protected]> --- fragmentation.c | 121 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ fragmentation.h | 3 ++ send.c | 21 ++++++++-- soft-interface.c | 7 ++++ types.h | 3 ++ 5 files changed, 151 insertions(+), 4 deletions(-) diff --git a/fragmentation.c b/fragmentation.c index 1c1ed2d..a7c3218 100644 --- a/fragmentation.c +++ b/fragmentation.c @@ -370,3 +370,124 @@ out: batadv_neigh_node_free_ref(neigh_node); return ret; } + +/** + * batadv_frag_create() - Create a fragment from skb. + * @skb: skb to create fragment from. + * @frag_head: header to use in new fragment. + * @mtu: Size of new fragment. + * + * Split the passed skb into two fragments: A new one with size matching the + * passed mtu and the old one with the rest. The new skb contains data from the + * tail of the old skb. + * + * Returns the new fragment, NULL on error. + */ +static struct sk_buff *batadv_frag_create(struct sk_buff *skb, + struct batadv_frag_packet *frag_head, + unsigned int mtu) +{ + struct sk_buff *skb_fragment; + unsigned header_size = sizeof(*frag_head); + unsigned fragment_size = mtu - header_size - ETH_HLEN; + + skb_fragment = dev_alloc_skb(mtu); + if (!skb_fragment) + goto out_err; + + /* Eat the last mtu-bytes of the skb */ + skb_reserve(skb_fragment, header_size); + skb_split(skb, skb_fragment, skb->len - fragment_size); + + /* Add the header */ + skb_push(skb_fragment, header_size); + memcpy(skb_fragment->data, frag_head, header_size); + + return skb_fragment; + +out_err: + return NULL; +} + +/** + * batadv_frag_send_packet() - Create up to 16 fragments from the passed skb. + * @skb: skb to create fragments from. + * @orig_node: Final destination of the created fragments. + * @neigh_node: Next-hop of the created fragments. + * + * Returns true on success, false otherwise. + */ +bool batadv_frag_send_packet(struct sk_buff *skb, + struct batadv_orig_node *orig_node, + struct batadv_neigh_node *neigh_node) +{ + struct batadv_priv *bat_priv; + struct batadv_hard_iface *primary_if; + struct batadv_frag_packet frag_header; + struct sk_buff *skb_fragment; + unsigned mtu = neigh_node->if_incoming->net_dev->mtu; + unsigned header_size = sizeof(frag_header); + unsigned max_fragment_size, max_packet_size; + + /* To avoid merge and refragmentation at next-hops we never send + * fragments larger than BATADV_FRAG_MAX_FRAG_SIZE + */ + mtu = min_t(int, mtu, BATADV_FRAG_MAX_FRAG_SIZE); + max_fragment_size = (mtu - header_size - ETH_HLEN); + max_packet_size = max_fragment_size*BATADV_FRAG_MAX_FRAGMENTS; + + /* Don't even try to fragment, if we need more than 16 fragments */ + if (skb->len > max_packet_size) + goto out_err; + + bat_priv = orig_node->bat_priv; + primary_if = batadv_primary_if_get_selected(bat_priv); + if (!primary_if) + goto out_err; + + /* Create one header to be copied to all fragments */ + frag_header.header.packet_type = BATADV_UNICAST_FRAG; + frag_header.header.version = BATADV_COMPAT_VERSION; + frag_header.header.ttl = BATADV_TTL; + frag_header.seqno = htons(atomic_inc_return(&bat_priv->frag_seqno)); + frag_header.reserved = 0; + frag_header.no = 0; + frag_header.total_size = htons(skb->len); + memcpy(frag_header.orig, primary_if->net_dev->dev_addr, ETH_ALEN); + memcpy(frag_header.dest, orig_node->orig, ETH_ALEN); + + /* Eat and send fragments from the tail of skb */ + while (skb->len > max_fragment_size) { + skb_fragment = batadv_frag_create(skb, &frag_header, mtu); + if (!skb_fragment) + goto out_err; + + batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX); + batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES, + skb_fragment->len + ETH_HLEN); + batadv_send_skb_packet(skb_fragment, neigh_node->if_incoming, + neigh_node->addr); + frag_header.no++; + + /* The initial check in this function should cover this case */ + if (frag_header.no == BATADV_FRAG_MAX_FRAGMENTS - 1) + goto out_err; + } + + /* Make room for the fragment header. */ + if (batadv_skb_head_push(skb, header_size) < 0 || + pskb_expand_head(skb, header_size + ETH_HLEN, 0, GFP_ATOMIC) < 0) + goto out_err; + + memcpy(skb->data, &frag_header, header_size); + + /* Send the last fragment */ + batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX); + batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES, + skb->len + ETH_HLEN); + batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr); + + return true; +out_err: + return false; +} diff --git a/fragmentation.h b/fragmentation.h index 16d1a62..ed85d97 100644 --- a/fragmentation.h +++ b/fragmentation.h @@ -27,5 +27,8 @@ bool batadv_frag_skb_fwd(struct sk_buff *skb, struct batadv_orig_node *orig_node_src); bool batadv_frag_skb_buffer(struct sk_buff **skb, struct batadv_orig_node *orig_node); +bool batadv_frag_send_packet(struct sk_buff *skb, + struct batadv_orig_node *orig_node, + struct batadv_neigh_node *neigh_node); #endif /* _NET_BATMAN_ADV_FRAGMENTATION_H_ */ diff --git a/send.c b/send.c index 21ba70d..6fc812a 100644 --- a/send.c +++ b/send.c @@ -28,8 +28,7 @@ #include "gateway_client.h" #include "originator.h" #include "network-coding.h" - -#include <linux/if_ether.h> +#include "fragmentation.h" static void batadv_send_outstanding_bcast_packet(struct work_struct *work); @@ -110,7 +109,19 @@ int batadv_send_skb_to_orig(struct sk_buff *skb, /* batadv_find_router() increases neigh_nodes refcount if found. */ neigh_node = batadv_find_router(bat_priv, orig_node, recv_if); if (!neigh_node) - return ret; + goto out; + + /* Check if the skb is too large to send in one piece and fragment + * it if needed. + */ + if (atomic_read(&bat_priv->fragmentation) && + skb->len + ETH_HLEN > neigh_node->if_incoming->net_dev->mtu) { + /* Fragment and send packet. */ + if (batadv_frag_send_packet(skb, orig_node, neigh_node)) + ret = NET_XMIT_SUCCESS; + + goto out; + } /* try to network code the packet, if it is received on an interface * (i.e. being forwarded). If the packet originates from this node or if @@ -124,7 +135,9 @@ int batadv_send_skb_to_orig(struct sk_buff *skb, ret = NET_XMIT_SUCCESS; } - batadv_neigh_node_free_ref(neigh_node); +out: + if (neigh_node) + batadv_neigh_node_free_ref(neigh_node); return ret; } diff --git a/soft-interface.c b/soft-interface.c index bcbb6fc..5d08c6c 100644 --- a/soft-interface.c +++ b/soft-interface.c @@ -431,6 +431,7 @@ static void batadv_softif_destroy_finish(struct work_struct *work) static int batadv_softif_init_late(struct net_device *dev) { struct batadv_priv *bat_priv; + uint32_t random_seqno; int ret; size_t cnt_len = sizeof(uint64_t) * BATADV_CNT_NUM; @@ -479,6 +480,10 @@ static int batadv_softif_init_late(struct net_device *dev) bat_priv->tt.last_changeset = NULL; bat_priv->tt.last_changeset_len = 0; + /* randomize initial seqno to avoid collision */ + get_random_bytes(&random_seqno, sizeof(random_seqno)); + atomic_set(&bat_priv->frag_seqno, random_seqno); + bat_priv->primary_if = NULL; bat_priv->num_ifaces = 0; @@ -746,6 +751,8 @@ static const struct { { "mgmt_tx_bytes" }, { "mgmt_rx" }, { "mgmt_rx_bytes" }, + { "frag_tx" }, + { "frag_tx_bytes" }, { "frag_rx" }, { "frag_rx_bytes" }, { "frag_fwd" }, diff --git a/types.h b/types.h index ee6e5d5..b9bc2b6 100644 --- a/types.h +++ b/types.h @@ -336,6 +336,8 @@ enum batadv_counters { BATADV_CNT_MGMT_TX_BYTES, BATADV_CNT_MGMT_RX, BATADV_CNT_MGMT_RX_BYTES, + BATADV_CNT_FRAG_TX, + BATADV_CNT_FRAG_TX_BYTES, BATADV_CNT_FRAG_RX, BATADV_CNT_FRAG_RX_BYTES, BATADV_CNT_FRAG_FWD, @@ -577,6 +579,7 @@ struct batadv_priv { atomic_t aggregated_ogms; atomic_t bonding; atomic_t fragmentation; + atomic_t frag_seqno; atomic_t ap_isolation; #ifdef CONFIG_BATMAN_ADV_BLA atomic_t bridge_loop_avoidance; -- 1.8.2.1
