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WIFI-3905-AP does not forward dhcp broadcast offer

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This patch will add fix to allow DHCP broadcast packets, so that AP can forward DHCP broadcast offer to clients

cause:
In the bridge source code, there is a mechanism to drop all the broadcast packets if the proxy arp is enabled, because of this dhcp clients which set broadcast flag to 1 while connecting toAP's interfaces are not able get the an ip address hence they are not connecting.

solution:
Added the code to the bridge source code, so that before dropping broadcast packets it first check whether it is dhcp braodcast packet or not. So that it won't drop dhcp broadcast packets. Hence DORA process will succeed and clients which set broadcast flag to 1 gets an ip address even though the proxy arp is enabled.

Signed-off-by: Nagendrababu <nagendrababu.bonkuri@connectus.ai>
This commit is contained in:
Nagendrababu
2021-09-10 15:01:35 -04:00
committed by Arif
parent 9b383148f8
commit b838bc9005
1 changed files with 84 additions and 0 deletions
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84
patches/0063-Allow-DHCP-broadcast-packets.patch Normal file
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@@ -0,0 +1,84 @@
From 2d71809001b7d05afbc6ebd98878826dda135659 Mon Sep 17 00:00:00 2001
From: Nagendrababu <nagendrababu.bonkuri@connectus.ai>
Date: Fri, 10 Sep 2021 12:47:12 -0400
Subject: [PATCH] WIFI-3905-AP does not forward dhcp broadcast offer
This patch will add fix to allow DHCP broadcast packets, so that AP can forward DHCP broadcast offer to clients
cause:
In the bridge source code, there is a mechanism to drop all the broadcast packets if the proxy arp is enabled, because of this dhcp clients which set broadcast flag to 1 while connecting toAP's interfaces are not able get an ip address hence they are not connecting
solution:
Added the code to the bridge source code so that before dropping broadcast packets it first checks, whether it is dhcp broadcast packet or not. So that it won't drop dhcp braodcast packets.Hence DORA process will succeed and clients which sets broadcast flag to 1 gets an ip address even though the proxy arp is enabled.
---
.../A00-Allow-DHCP-braodcast-packet.patch | 59 +++++++++++++++++++
1 file changed, 59 insertions(+)
create mode 100644 target/linux/ipq40xx/patches-4.14/A00-Allow-DHCP-braodcast-packet.patch
diff --git a/target/linux/ipq40xx/patches-4.14/A00-Allow-DHCP-braodcast-packet.patch b/target/linux/ipq40xx/patches-4.14/A00-Allow-DHCP-braodcast-packet.patch
new file mode 100644
index 0000000000..a7c9a8847a
--- /dev/null
+++ b/target/linux/ipq40xx/patches-4.14/A00-Allow-DHCP-braodcast-packet.patch
@@ -0,0 +1,59 @@
+Index: linux-4.14.187/net/bridge/br_forward.c
+===================================================================
+--- linux-4.14.187.orig/net/bridge/br_forward.c
++++ linux-4.14.187/net/bridge/br_forward.c
+@@ -20,6 +20,40 @@
+ #include <linux/if_vlan.h>
+ #include <linux/netfilter_bridge.h>
+ #include "br_private.h"
++#include <linux/ip.h>
++#include <linux/udp.h>
++
++static struct bootp_pkt { /* BOOTP packet format */
++ struct iphdr iph; /* IP header */
++ struct udphdr udph; /* UDP header */
++ u8 op; /* 1=request, 2=reply */
++ u8 htype; /* HW address type */
++ u8 hlen; /* HW address length */
++ u8 hops; /* Used only by gateways */
++ __be32 xid; /* Transaction ID */
++ __be16 secs; /* Seconds since we started */
++ __be16 flags; /* Just what it says */
++ __be32 client_ip; /* Client's IP address if known */
++ __be32 your_ip; /* Assigned IP address */
++ __be32 server_ip; /* (Next, e.g. NFS) Server's IP address */
++ __be32 relay_ip; /* IP address of BOOTP relay */
++ u8 hw_addr[16]; /* Client's HW address */
++ u8 serv_name[64]; /* Server host name */
++ u8 boot_file[128]; /* Name of boot file */
++ u8 exten[312]; /* DHCP options / BOOTP vendor extensions */
++};
++
++/* Before dropping broadcast packets first check whether the packets are
++ * dhcp packet or not */
++
++static bool dhcp_packet_check(struct sk_buff *skb)
++{
++ struct bootp_pkt *b;
++ b = (struct bootp_pkt *)skb_network_header(skb);
++ if (b->udph.source != htons(67) || b->udph.dest != htons(68))
++ return false;
++ return true;
++}
+
+ /* Don't forward packets to originating port or forwarding disabled */
+ static inline int should_deliver(const struct net_bridge_port *p,
+@@ -204,8 +238,12 @@ void br_flood(struct net_bridge *br, str
+ /* Do not flood to ports that enable proxy ARP */
+ if (p->flags & BR_PROXYARP)
+ continue;
++ /** Before dropping broadcast packets, check whether the packets are dhcp packet
++ * or not so that the dhcp packets won't drop, hence DORA process will succeed
++ * and dhcp clients which set broadcast flag to 1 get an ip address even though
++ * proxy arp is enabled */
+ if ((p->flags & BR_PROXYARP_WIFI) &&
+- BR_INPUT_SKB_CB(skb)->proxyarp_replied)
++ BR_INPUT_SKB_CB(skb)->proxyarp_replied && !dhcp_packet_check(skb))
+ continue;
+
+ prev = maybe_deliver(prev, p, skb, local_orig);
--
2.25.1