If a client issues a DHCPREQUEST for renewal, the packet is dropped if the old destination (the old gateway for the client) TQ is smaller than the current best gateway TQ less GW_THRESHOLD
Signed-off-by: Antonio Quartulli <[email protected]> --- 1) Following Andrew's suggestion, the dhcp unicast packet type is now checked to ensure it is a DHCPREQUEST. 2) Comments corrections Thanks gateway_client.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++++++++- gateway_client.h | 3 +- main.h | 3 +- soft-interface.c | 10 ++++- 4 files changed, 104 insertions(+), 6 deletions(-) diff --git a/gateway_client.c b/gateway_client.c index 8a7090c..da2bc8d 100644 --- a/gateway_client.c +++ b/gateway_client.c @@ -25,11 +25,17 @@ #include "gateway_common.h" #include "hard-interface.h" #include "originator.h" +#include "routing.h" #include <linux/ip.h> #include <linux/ipv6.h> #include <linux/udp.h> #include <linux/if_vlan.h> +/* This is the offset of the options field in a dhcp packet starting at + * the beginning of the dhcp header */ +#define DHCP_OPTIONS_OFFSET 240 +#define DHCP_REQUEST 3 + static void gw_node_free_rcu(struct rcu_head *rcu) { struct gw_node *gw_node; @@ -505,14 +511,75 @@ out: return ret; } -int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb) +static bool is_type_dhcprequest(struct sk_buff *skb, int header_len) +{ + int ret = false; + unsigned char *p; + int pkt_len; + + if (skb_linearize(skb) < 0) + goto out; + + pkt_len = skb_headlen(skb); + + if (pkt_len < header_len + DHCP_OPTIONS_OFFSET + 1) + goto out; + + p = skb->data + header_len + DHCP_OPTIONS_OFFSET; + pkt_len -= header_len + DHCP_OPTIONS_OFFSET + 1; + + /* Access the dhcp option lists. Each entry is made up by: + * - octect 1: option type + * - octect 2: option data len (only if type != 255 and 0) + * - octect 3: option data */ + while (*p != 255 && !ret) { + /* p now points to the first octect: option type */ + if (*p == 53) { + /* type 53 is the message type option. + * Jump the len octect and go to the data octect */ + if (pkt_len < 2) + goto out; + pkt_len -= 2; + p += 2; + + /* check if the message type is what we need */ + if (*p == DHCP_REQUEST) + ret = true; + } else if (*p == 0) { + /* option type 0 (padding), just go forward */ + if (pkt_len < 1) + goto out; + pkt_len--; + p++; + } else { + /* This is any other option. So we get the length... */ + if (pkt_len < 1) + goto out; + pkt_len--; + p++; + + /* ...and then we jump over the data */ + if (pkt_len < *p) + goto out; + pkt_len -= *p; + p += (*p); + } + } +out: + return ret; +} + +int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb, + struct orig_node *old_gw) { struct ethhdr *ethhdr; struct iphdr *iphdr; struct ipv6hdr *ipv6hdr; struct udphdr *udphdr; struct gw_node *curr_gw; + struct neigh_node *neigh_curr = NULL, *neigh_old = NULL; unsigned int header_len = 0; + int ret = 1; if (atomic_read(&bat_priv->gw_mode) == GW_MODE_OFF) return 0; @@ -580,7 +647,30 @@ int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb) if (!curr_gw) return 0; + /* If old_gw != NULL then this packet is unicast. + * So, at this point we have to check the message type: if it is a + * DHCPREQUEST we have to decide whether to drop it or not */ + if (old_gw && curr_gw->orig_node != old_gw) { + if (is_type_dhcprequest(skb, header_len)) { + /* If the dhcp packet has been sent to a different gw, + * we have to evaluate whether the old gw is still + * reliable enough */ + neigh_curr = find_router(bat_priv, curr_gw->orig_node, + NULL); + neigh_old = find_router(bat_priv, old_gw, NULL); + if (!neigh_curr || !neigh_old) + goto free_neigh; + if (neigh_curr->tq_avg - neigh_old->tq_avg < + GW_THRESHOLD) + ret = -1; + } + } +free_neigh: + if (neigh_old) + neigh_node_free_ref(neigh_old); + if (neigh_curr) + neigh_node_free_ref(neigh_curr); if (curr_gw) gw_node_free_ref(curr_gw); - return 1; + return ret; } diff --git a/gateway_client.h b/gateway_client.h index 1ce8c60..b9b983c 100644 --- a/gateway_client.h +++ b/gateway_client.h @@ -31,6 +31,7 @@ void gw_node_update(struct bat_priv *bat_priv, void gw_node_delete(struct bat_priv *bat_priv, struct orig_node *orig_node); void gw_node_purge(struct bat_priv *bat_priv); int gw_client_seq_print_text(struct seq_file *seq, void *offset); -int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb); +int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb, + struct orig_node *old_gw); #endif /* _NET_BATMAN_ADV_GATEWAY_CLIENT_H_ */ diff --git a/main.h b/main.h index 4f9991d..fbd7d37 100644 --- a/main.h +++ b/main.h @@ -79,7 +79,6 @@ #define BCAST_QUEUE_LEN 256 #define BATMAN_QUEUE_LEN 256 - enum uev_action { UEV_ADD = 0, UEV_DEL, @@ -90,6 +89,8 @@ enum uev_type { UEV_GW = 0 }; +#define GW_THRESHOLD 25 + /* * Debug Messages */ diff --git a/soft-interface.c b/soft-interface.c index c76a33e..6d02d92 100644 --- a/soft-interface.c +++ b/soft-interface.c @@ -30,6 +30,7 @@ #include "gateway_common.h" #include "gateway_client.h" #include "bat_sysfs.h" +#include "originator.h" #include <linux/slab.h> #include <linux/ethtool.h> #include <linux/etherdevice.h> @@ -569,6 +570,7 @@ int interface_tx(struct sk_buff *skb, struct net_device *soft_iface) struct bcast_packet *bcast_packet; struct vlan_ethhdr *vhdr; struct softif_neigh *curr_softif_neigh = NULL; + struct orig_node *orig_node; int data_len = skb->len, ret; short vid = -1; bool do_bcast = false; @@ -603,8 +605,10 @@ int interface_tx(struct sk_buff *skb, struct net_device *soft_iface) /* TODO: check this for locks */ tt_local_add(soft_iface, ethhdr->h_source); - if (is_multicast_ether_addr(ethhdr->h_dest)) { - ret = gw_is_target(bat_priv, skb); + orig_node = transtable_search(bat_priv, ethhdr->h_dest); + if (is_multicast_ether_addr(ethhdr->h_dest) || + (orig_node && orig_node->gw_flags)) { + ret = gw_is_target(bat_priv, skb, orig_node); if (ret < 0) goto dropped; @@ -612,6 +616,8 @@ int interface_tx(struct sk_buff *skb, struct net_device *soft_iface) if (ret == 0) do_bcast = true; } + if (orig_node) + orig_node_free_ref(orig_node); /* ethernet packet should be broadcasted */ if (do_bcast) { -- 1.7.3.4
