From 43676ab590c3f8686fd047d34c3e33803eef71f0 Mon Sep 17 00:00:00 2001 From: Antonio Quartulli Date: Tue, 26 Apr 2011 21:31:45 +0200 Subject: batman-adv: improved gateway tq-based selection 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 Signed-off-by: Marek Lindner Signed-off-by: Sven Eckelmann --- net/batman-adv/gateway_client.c | 94 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 92 insertions(+), 2 deletions(-) (limited to 'net/batman-adv/gateway_client.c') diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c index 6381864..8b25b52 100644 --- a/net/batman-adv/gateway_client.c +++ b/net/batman-adv/gateway_client.c @@ -25,11 +25,17 @@ #include "gateway_common.h" #include "hard-interface.h" #include "originator.h" +#include "routing.h" #include #include #include #include +/* 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_ref(struct gw_node *gw_node) { if (atomic_dec_and_test(&gw_node->refcount)) @@ -509,14 +515,75 @@ 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; + p += 2; + + /* check if the message type is what we need */ + if (*p == DHCP_REQUEST) + ret = true; + break; + } 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; @@ -584,7 +651,30 @@ 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; } -- cgit v1.1