From 7be2b0da6e89ddf61b78b3fa0b9ff952d52594c4 Mon Sep 17 00:00:00 2001
From: luigi__ <luigi__@users.sf.net>
Date: Fri, 24 Sep 2010 22:34:20 +0000
Subject: [PATCH] Wifi: for the Adhoc interface, generate a MAC address from
 the computer's IP and the process ID as to prevent MAC collisions in any
 case.

---
 desmume/src/driver.h         |  2 ++
 desmume/src/firmware.cpp     |  6 ++++++
 desmume/src/firmware.h       |  1 +
 desmume/src/wifi.cpp         | 18 ++++++++++++++----
 desmume/src/windows/main.cpp | 29 +++++++++++++++++++++++++++++
 5 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/desmume/src/driver.h b/desmume/src/driver.h
index 073cedbdb..3e1b7d08f 100644
--- a/desmume/src/driver.h
+++ b/desmume/src/driver.h
@@ -49,6 +49,8 @@ public:
 	virtual bool WIFI_SocketsAvailable() { return true; }
 	virtual bool WIFI_PCapAvailable() { return false; }
 
+	virtual void WIFI_GetUniqueMAC(u8* mac) {}
+
 	virtual bool WIFI_WFCWarning() { return false; }
 
 	virtual int PCAP_findalldevs(pcap_if_t** alldevs, char* errbuf) { return -1; }
diff --git a/desmume/src/firmware.cpp b/desmume/src/firmware.cpp
index 9456bcf4d..8d50dd35e 100644
--- a/desmume/src/firmware.cpp
+++ b/desmume/src/firmware.cpp
@@ -869,3 +869,9 @@ void NDS_FillDefaultFirmwareConfigData( struct NDS_fw_config_data *fw_config) {
 	fw_config->touch_cal[1].screen_x = 0xe0 + 1;
 	fw_config->touch_cal[1].screen_y = 0x80 + 1;
 }
+
+void NDS_PatchFirmwareMAC()
+{
+	memcpy((MMU.fw.data + 0x36), FW_Mac, sizeof(FW_Mac));
+	(*(u16*)(MMU.fw.data + 0x2A)) = calc_CRC16(0, (MMU.fw.data + 0x2C), 0x138);
+}
diff --git a/desmume/src/firmware.h b/desmume/src/firmware.h
index 2db38fe3e..2a4888544 100644
--- a/desmume/src/firmware.h
+++ b/desmume/src/firmware.h
@@ -80,6 +80,7 @@ public:
 int copy_firmware_user_data( u8 *dest_buffer, const u8 *fw_data);
 int NDS_CreateDummyFirmware( struct NDS_fw_config_data *user_settings);
 void NDS_FillDefaultFirmwareConfigData( struct NDS_fw_config_data *fw_config);
+void NDS_PatchFirmwareMAC();
 
 #endif
 
diff --git a/desmume/src/wifi.cpp b/desmume/src/wifi.cpp
index 07eebd479..79027a8ad 100644
--- a/desmume/src/wifi.cpp
+++ b/desmume/src/wifi.cpp
@@ -1631,10 +1631,9 @@ typedef struct _Adhoc_FrameHeader
 
 bool Adhoc_Init()
 {
+	BOOL opt_true = TRUE;
 	int res;
 
-	Adhoc.usecCounter = 0;
-
 	if (!driver->WIFI_SocketsAvailable())
 	{
 		WIFI_LOG(1, "Ad-hoc: failed to initialize sockets.\n");
@@ -1650,6 +1649,10 @@ bool Adhoc_Init()
 		return false;
 	}
 
+	// Enable the socket to be bound to an address/port that is already in use
+	// This enables us to communicate with another DeSmuME instance running on the same computer.
+	res = setsockopt(wifi_socket, SOL_SOCKET, SO_REUSEADDR, (const char*)&opt_true, sizeof(BOOL));
+
 	// Bind the socket to any address on port 7000
 	sockaddr_t saddr;
 	saddr.sa_family = AF_INET;
@@ -1665,8 +1668,7 @@ bool Adhoc_Init()
 
 	// Enable broadcast mode
 	// Not doing so results in failure when sendto'ing to broadcast address
-	BOOL opt = TRUE;
-	res = setsockopt(wifi_socket, SOL_SOCKET, SO_BROADCAST, (const char*)&opt, sizeof(BOOL));
+	res = setsockopt(wifi_socket, SOL_SOCKET, SO_BROADCAST, (const char*)&opt_true, sizeof(BOOL));
 	if (res < 0)
 	{
 		WIFI_LOG(1, "Ad-hoc: failed to enable broadcast mode.\n");
@@ -1679,6 +1681,8 @@ bool Adhoc_Init()
 	*(u32*)&sendAddr.sa_data[2] = htonl(INADDR_BROADCAST); 
 	*(u16*)&sendAddr.sa_data[0] = htons(BASEPORT);
 
+	Adhoc_Reset();
+
 	WIFI_LOG(1, "Ad-hoc: initialization successful.\n");
 
 	return true;
@@ -1693,6 +1697,12 @@ void Adhoc_DeInit()
 void Adhoc_Reset()
 {
 	Adhoc.usecCounter = 0;
+
+	driver->WIFI_GetUniqueMAC(FW_Mac);
+	NDS_PatchFirmwareMAC();
+
+	printf("WIFI: ADHOC: MAC = %02X:%02X:%02X:%02X:%02X:%02X\n",
+		FW_Mac[0], FW_Mac[1], FW_Mac[2], FW_Mac[3], FW_Mac[4], FW_Mac[5]);
 }
 
 void Adhoc_SendPacket(u8* packet, u32 len)
diff --git a/desmume/src/windows/main.cpp b/desmume/src/windows/main.cpp
index b23ccdca2..972f83211 100644
--- a/desmume/src/windows/main.cpp
+++ b/desmume/src/windows/main.cpp
@@ -2256,6 +2256,35 @@ class WinDriver : public BaseDriver
 	virtual bool WIFI_SocketsAvailable() { return bSocketsAvailable; }
 	virtual bool WIFI_PCapAvailable() { return bWinPCapAvailable; }
 
+	virtual void WIFI_GetUniqueMAC(u8* mac)
+	{
+		if (mac == NULL) return;
+
+		char hostname[256];
+		if (gethostname(hostname, 256) != 0)
+			strncpy(hostname, "127.0.0.1", 256);
+
+		hostent* he = gethostbyname(hostname);
+		unsigned long ipaddr;
+		if (he == NULL)
+			ipaddr = 0x0100007F; // 127.0.0.1
+		else
+			ipaddr = *(unsigned long*)he->h_addr_list[0];
+
+		unsigned long pid = GetCurrentProcessId();
+
+		unsigned long hash = pid;
+		while ((hash & 0xFF000000) == 0)
+			hash <<= 1;
+		hash >>= 1;
+		hash += ipaddr >> 8;
+		hash &= 0x00FFFFFF;
+
+		mac[3] = hash >> 16;
+		mac[4] = (hash >> 8) & 0xFF;
+		mac[5] = hash & 0xFF;
+	}
+
 	virtual bool WIFI_WFCWarning()
 	{
 		return MessageBox(NULL,	"You are trying to connect to the Nintendo WFC servers.\n"