From 51e61e39733931aee54ae23ab4eb16917cb1325e Mon Sep 17 00:00:00 2001
From: Justin Maggard <jmaggard@netgear.com>
Date: Fri, 31 Jul 2009 01:41:10 +0000
Subject: [PATCH] * Track MAC addresses in the client cache (when we can find
 them); so if we have an expired cache entry, but the MAC hasn't changed, we
 can assume the original ID is still valid.

---
 getifaddr.c     | 35 +++++++++++++++++++++++++++++++++++
 getifaddr.h     |  4 ++++
 minidlnatypes.h |  1 +
 upnphttp.c      | 33 ++++++++++++++++++++++++++-------
 4 files changed, 66 insertions(+), 7 deletions(-)

diff --git a/getifaddr.c b/getifaddr.c
index 18a5daf..35d3a3b 100644
--- a/getifaddr.c
+++ b/getifaddr.c
@@ -127,3 +127,38 @@ getifhwaddr(const char * ifname, char * buf, int len)
 	}
 	return 0;
 }
+
+int
+get_remote_mac(struct in_addr ip_addr, unsigned char * mac)
+{
+	struct in_addr arp_ent;
+	FILE * arp;
+	char remote_ip[16];
+	int matches, hwtype, flags;
+	memset(mac, 0xFF, 6);
+
+ 	arp = fopen("/proc/net/arp", "r");
+	if( !arp )
+		return 1;
+	while( !feof(arp) )
+	{
+	        matches = fscanf(arp, "%s 0x%X 0x%X %hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
+		                      remote_ip, &hwtype, &flags,
+		                      &mac[0], &mac[1], &mac[2], &mac[3], &mac[4], &mac[5]);
+		if( matches != 9 )
+			continue;
+		inet_pton(AF_INET, remote_ip, &arp_ent);
+		if( ip_addr.s_addr == arp_ent.s_addr )
+			break;
+		mac[0] = 0xFF;
+	}
+	fclose(arp);
+
+	if( mac[0] == 0xFF )
+	{
+		memset(mac, 0xFF, 6);
+		return 1;
+	}
+
+	return 0;
+}
diff --git a/getifaddr.h b/getifaddr.h
index 65a7668..d6651ad 100644
--- a/getifaddr.h
+++ b/getifaddr.h
@@ -6,6 +6,7 @@
 
 #ifndef __GETIFADDR_H__
 #define __GETIFADDR_H__
+#include <arpa/inet.h>
 
 /* getifaddr()
  * take a network interface name and write the
@@ -20,5 +21,8 @@ getsysaddr(char * buf, int len);
 int
 getifhwaddr(const char * ifname, char * buf, int len);
 
+int
+get_remote_mac(struct in_addr ip_addr, unsigned char * mac);
+
 #endif
 
diff --git a/minidlnatypes.h b/minidlnatypes.h
index 6560ca8..ec4f72b 100644
--- a/minidlnatypes.h
+++ b/minidlnatypes.h
@@ -58,6 +58,7 @@ struct album_art_name_s {
 
 struct client_cache_s {
 	struct in_addr addr;
+	unsigned char mac[6];
 	enum client_types type;
 	u_int32_t flags;
 	time_t age;
diff --git a/upnphttp.c b/upnphttp.c
index 4486c04..40dbbf3 100644
--- a/upnphttp.c
+++ b/upnphttp.c
@@ -30,9 +30,11 @@
 #include <fcntl.h>
 #include <errno.h>
 #include <sys/sendfile.h>
+#include <arpa/inet.h>
 
 #include "upnpglobalvars.h"
 #include "utils.h"
+#include "getifaddr.h"
 #include "image_utils.h"
 #include "log.h"
 #include "sql.h"
@@ -94,11 +96,22 @@ SearchClientCache(struct in_addr addr)
 	{
 		if( clients[i].addr.s_addr == addr.s_addr )
 		{
-			/* Invalidate this client cache if it's older than 2 hours */
-			if( (time(NULL) - clients[i].age) > 7200 )
+			/* Invalidate this client cache if it's older than 1 hour */
+			if( (time(NULL) - clients[i].age) > 3600 )
 			{
-				memset(&clients[i], 0, sizeof(struct client_cache_s));
-				return -1;
+				unsigned char mac[6];
+				if( get_remote_mac(addr, mac) == 0 &&
+				    memcmp(mac, clients[i].mac, 6) == 0 )
+				{
+					/* Same MAC as last time when we were able to identify the client,
+ 					 * so extend the timeout by another hour. */
+					clients[i].age = time(NULL);
+				}
+				else
+				{
+					memset(&clients[i], 0, sizeof(struct client_cache_s));
+					return -1;
+				}
 			}
 			DPRINTF(E_DEBUG, L_HTTP, "Client found in cache. [type %d/entry %d]\n", clients[i].type, i);
 			return i;
@@ -350,6 +363,9 @@ next_header:
 			h->req_chunklen = -1;
 		}
 	}
+	/* Don't bother checking client type until we have the whole request. */
+	if( (h->req_buflen - h->req_contentoff) < h->req_contentlen )
+		return;
 	/* If the client type wasn't found, search the cache.
 	 * This is done because a lot of clients like to send a
 	 * different User-Agent with different types of requests. */
@@ -363,15 +379,18 @@ next_header:
 			{
 				if( clients[n].addr.s_addr )
 					continue;
+				get_remote_mac(h->clientaddr, clients[n].mac);
 				clients[n].addr = h->clientaddr;
-				DPRINTF(E_DEBUG, L_HTTP, "Added client [%d/%X] to cache slot %d.\n",
-				                         h->req_client, clients[n].addr.s_addr, n);
+				DPRINTF(E_DEBUG, L_HTTP, "Added client [%d/%s/%02X:%02X:%02X:%02X:%02X:%02X] to cache slot %d.\n",
+				                         h->req_client, inet_ntoa(clients[n].addr),
+				                         clients[n].mac[0], clients[n].mac[1], clients[n].mac[2],
+				                         clients[n].mac[3], clients[n].mac[4], clients[n].mac[5], n);
 				break;
 			}
 		}
 		else if( (n < EStandardDLNA150) && (h->req_client == EStandardDLNA150) )
 		{
-			/* If we know the client, but our new detection is generic, use our cached info */
+			/* If we know the client and our new detection is generic, use our cached info */
 			h->reqflags |= clients[n].flags;
 			h->req_client = clients[n].type;
 			return;