Comms refactor (prerequisite of libproxmark work) (#371)

* Refactor the comms code only from PR#346, without comms_globals.h.
* OSX: Add note for example serial port

client/comms.c

@@ -0,0 +1,325 @@
+//-----------------------------------------------------------------------------
+// Copyright (C) 2009 Michael Gernoth <michael at gernoth.net>
+// Copyright (C) 2010 iZsh <izsh at fail0verflow.com>
+//
+// This code is licensed to you under the terms of the GNU GPL, version 2 or,
+// at your option, any later version. See the LICENSE.txt file for the text of
+// the license.
+//-----------------------------------------------------------------------------
+// Code for communicating with the proxmark3 hardware.
+//-----------------------------------------------------------------------------
+
+#include <pthread.h>
+
+#include "comms.h"
+#include "uart.h"
+#include "ui.h"
+#include "common.h"
+#include "data.h"
+#include "util_posix.h"
+
+// Declare globals.
+
+// Serial port that we are communicating with the PM3 on.
+static serial_port* port;
+
+// If TRUE, then there is no active connection to the PM3, and we will drop commands sent.
+static bool offline;
+
+// Transmit buffer.
+// TODO: Use locks and execute this on the main thread, rather than the receiver
+// thread.  Running on the main thread means we need to be careful in the
+// flasher, as it means SendCommand is no longer async, and can't be used as a
+// buffer for a pending command when the connection is re-established.
+static UsbCommand txcmd;
+static bool txcmd_pending;
+
+// Used by UsbReceiveCommand as a ring buffer for messages that are yet to be
+// processed by a command handler (WaitForResponse{,Timeout})
+static UsbCommand cmdBuffer[CMD_BUFFER_SIZE];
+
+// Points to the next empty position to write to
+static int cmd_head = 0;
+
+// Points to the position of the last unread command
+static int cmd_tail = 0;
+
+// to lock cmdBuffer operations from different threads
+static pthread_mutex_t cmdBufferMutex = PTHREAD_MUTEX_INITIALIZER;
+
+// These wrappers are required because it is not possible to access a static
+// global variable outside of the context of a single file.
+
+void SetSerialPort(serial_port* new_port) {
+	port = new_port;
+}
+
+serial_port* GetSerialPort() {
+	return port;
+}
+
+void SetOffline(bool new_offline) {
+	offline = new_offline;
+}
+
+bool IsOffline() {
+	return offline;
+}
+
+void SendCommand(UsbCommand *c) {
+	#ifdef COMMS_DEBUG
+	printf("Sending %04x cmd\n", c->cmd);
+	#endif
+
+	if (offline) {
+      PrintAndLog("Sending bytes to proxmark failed - offline");
+      return;
+    }
+  /**
+	The while-loop below causes hangups at times, when the pm3 unit is unresponsive
+	or disconnected. The main console thread is alive, but comm thread just spins here.
+	Not good.../holiman
+	**/
+	while(txcmd_pending);
+	txcmd = *c;
+	txcmd_pending = true;
+}
+
+/**
+ * @brief This method should be called when sending a new command to the pm3. In case any old
+ *  responses from previous commands are stored in the buffer, a call to this method should clear them.
+ *  A better method could have been to have explicit command-ACKS, so we can know which ACK goes to which
+ *  operation. Right now we'll just have to live with this.
+ */
+void clearCommandBuffer()
+{
+	//This is a very simple operation
+	pthread_mutex_lock(&cmdBufferMutex);
+	cmd_tail = cmd_head;
+	pthread_mutex_unlock(&cmdBufferMutex);
+}
+
+/**
+ * @brief storeCommand stores a USB command in a circular buffer
+ * @param UC
+ */
+void storeCommand(UsbCommand *command)
+{
+	pthread_mutex_lock(&cmdBufferMutex);
+	if( (cmd_head+1) % CMD_BUFFER_SIZE == cmd_tail)
+	{
+		// If these two are equal, we're about to overwrite in the
+		// circular buffer.
+		PrintAndLog("WARNING: Command buffer about to overwrite command! This needs to be fixed!");
+	}
+
+	// Store the command at the 'head' location
+	UsbCommand* destination = &cmdBuffer[cmd_head];
+	memcpy(destination, command, sizeof(UsbCommand));
+
+	cmd_head = (cmd_head +1) % CMD_BUFFER_SIZE; //increment head and wrap
+	pthread_mutex_unlock(&cmdBufferMutex);
+}
+
+
+/**
+ * @brief getCommand gets a command from an internal circular buffer.
+ * @param response location to write command
+ * @return 1 if response was returned, 0 if nothing has been received
+ */
+int getCommand(UsbCommand* response)
+{
+	pthread_mutex_lock(&cmdBufferMutex);
+	//If head == tail, there's nothing to read, or if we just got initialized
+	if (cmd_head == cmd_tail){
+		pthread_mutex_unlock(&cmdBufferMutex);
+		return 0;
+	}
+
+	//Pick out the next unread command
+	UsbCommand* last_unread = &cmdBuffer[cmd_tail];
+	memcpy(response, last_unread, sizeof(UsbCommand));
+	//Increment tail - this is a circular buffer, so modulo buffer size
+	cmd_tail = (cmd_tail + 1) % CMD_BUFFER_SIZE;
+
+	pthread_mutex_unlock(&cmdBufferMutex);
+	return 1;
+}
+
+//-----------------------------------------------------------------------------
+// Entry point into our code: called whenever we received a packet over USB
+// that we weren't necessarily expecting, for example a debug print.
+//-----------------------------------------------------------------------------
+void UsbCommandReceived(UsbCommand *UC)
+{
+	switch(UC->cmd) {
+
+	// First check if we are handling a debug message
+	case CMD_DEBUG_PRINT_STRING: {
+		char s[USB_CMD_DATA_SIZE+1];
+		memset(s, 0x00, sizeof(s));
+		size_t len = MIN(UC->arg[0],USB_CMD_DATA_SIZE);
+		memcpy(s,UC->d.asBytes,len);
+		PrintAndLog("#db# %s", s);
+		return;
+	}
+
+	case CMD_DEBUG_PRINT_INTEGERS: {
+		PrintAndLog("#db# %08x, %08x, %08x       \r\n", UC->arg[0], UC->arg[1], UC->arg[2]);
+		return;
+	}
+
+	case CMD_DOWNLOADED_RAW_ADC_SAMPLES_125K: {
+		// FIXME: This does unsanitised copies into memory when we don't know
+		// the size of the buffer.
+		if (sample_buf) {
+			memcpy(sample_buf+(UC->arg[0]),UC->d.asBytes,UC->arg[1]);
+		}
+		return;
+	}
+
+	default: {
+		storeCommand(UC);
+		return;
+	}
+	}
+}
+
+// Gets a single command from a proxmark3 device. This should never be used
+// with the full client.
+//
+// @param conn A receiver_arg structure.
+// @param command A buffer to store the received command.
+bool ReceiveCommand(receiver_arg* conn, UsbCommand* command) {
+	// Local recieve buffer
+	size_t rxlen;
+	byte_t rx[sizeof(UsbCommand)];
+	byte_t* prx = rx;
+
+	while (conn->run) {
+		rxlen = 0;
+		if (uart_receive(port, prx, sizeof(UsbCommand) - (prx-rx), &rxlen) && rxlen) {
+			prx += rxlen;
+			if (prx-rx < sizeof(UsbCommand)) {
+				// Keep reading until we have a completed response.
+				continue;
+			}
+
+			// We have a completed response.
+			memcpy(command, rx, sizeof(UsbCommand));
+			return true;
+		}
+
+		if (prx == rx) {
+			// We got no complete command while waiting, give up control
+			return false;
+		}
+	}
+
+	// did not get a complete command before being cancelled.
+	return false;
+}
+
+// Worker thread for processing incoming events from the PM3
+void *uart_receiver(void *targ) {
+	receiver_arg *conn = (receiver_arg*)targ;
+	UsbCommand rx;
+
+	while (conn->run) {
+		#ifdef COMMS_DEBUG
+		printf("uart_receiver: get lock\n");
+		#endif
+		// Lock up receives, in case they try to take it away from us.
+		pthread_mutex_lock(&conn->recv_lock);
+		#ifdef COMMS_DEBUG
+		printf("uart_receiver: lock acquired\n");
+		#endif
+
+		if (port == NULL) {
+			#ifdef COMMS_DEBUG
+			printf("uart_receiver: port disappeared\n");
+			#endif
+			// Our port disappeared, stall. This code path matters for the flasher,
+			// where it is fiddling with the serial port under us.
+			pthread_mutex_unlock(&conn->recv_lock);
+			msleep(10);
+			continue;
+		}
+
+		bool got_command = ReceiveCommand(conn, &rx);
+		#ifdef COMMS_DEBUG
+		printf("uart_receiver: got command\n");
+		#endif
+		pthread_mutex_unlock(&conn->recv_lock);
+
+		if (got_command) {
+			UsbCommandReceived(&rx);
+		}
+
+		// We aren't normally trying to transmit in the flasher when the port would
+		// be reset, so we can just keep going at this point.
+		if (txcmd_pending) {
+			if (!uart_send(port, (byte_t*) &txcmd, sizeof(UsbCommand))) {
+				PrintAndLog("Sending bytes to proxmark failed");
+			}
+			txcmd_pending = false;
+		}
+	}
+
+	pthread_exit(NULL);
+	return NULL;
+}
+
+/**
+ * Waits for a certain response type. This method waits for a maximum of
+ * ms_timeout milliseconds for a specified response command.
+ *@brief WaitForResponseTimeout
+ * @param cmd command to wait for, or CMD_ANY to take any command.
+ * @param response struct to copy received command into.
+ * @param ms_timeout
+ * @param show_warning
+ * @return true if command was returned, otherwise false
+ */
+bool WaitForResponseTimeoutW(uint64_t cmd, UsbCommand* response, size_t ms_timeout, bool show_warning) {
+	UsbCommand resp;
+
+	#ifdef COMMS_DEBUG
+	printf("Waiting for %04x cmd\n", cmd);
+	#endif
+	
+	if (response == NULL) {
+		response = &resp;
+	}
+
+	uint64_t start_time = msclock();
+
+	// Wait until the command is received
+	for (;;) {
+		while(getCommand(response)) {
+			if (cmd == CMD_ANY || response->cmd == cmd) {
+				return true;
+			}
+		}
+		
+		if (msclock() - start_time > ms_timeout) {
+			// We timed out.
+			break;
+		}
+		
+		if (msclock() - start_time > 2000 && show_warning) {
+			// 2 seconds elapsed (but this doesn't mean the timeout was exceeded)
+			PrintAndLog("Waiting for a response from the proxmark...");
+			PrintAndLog("Don't forget to cancel its operation first by pressing on the button");
+			break;
+		}
+	}
+	return false;
+}
+
+bool WaitForResponseTimeout(uint64_t cmd, UsbCommand* response, size_t ms_timeout) {
+	return WaitForResponseTimeoutW(cmd, response, ms_timeout, true);
+}
+
+bool WaitForResponse(uint64_t cmd, UsbCommand* response) {
+	return WaitForResponseTimeout(cmd, response, -1);
+}