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

[proxmark3-svn] / client / comms.c

//-----------------------------------------------------------------------------
// 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);
}