Initial commitHEADmaster

1 files changed, 179 insertions, 0 deletions

diff --git a/server/rback.py b/server/rback.py
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+ #       Serial Backup Server
+ #       Copyright © 2015 Jeffrey Armstrong <jeff@rainbow-100.com>
+ #       http://jeff.rainbow-100.com/
+ #
+ #       This program is free software: you can redistribute it and/or modify
+ #       it under the terms of the GNU General Public License as published by
+ #       the Free Software Foundation, either version 3 of the License, or
+ #       (at your option) any later version.
+ #       
+ #       This program is distributed in the hope that it will be useful
+ #       but WITHOUT ANY WARRANTY; without even the implied warranty of
+ #       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ #       GNU General Public License for more details.
+ #       
+ #       You should have received a copy of the GNU General Public License
+ #       along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import time
+import serial
+import argparse
+import os
+import os.path
+
+DEFAULT_PORT = 19200
+DEFAULT_DEV = '/dev/ttyUSB0'
+
+OK = "OK"
+RETRY = "RETRY"
+ABORT = "ABORT"
+
+def respond(ser, msg):
+    """Writes a response message to the client"""
+    ser.write(msg)
+    ser.write(";")
+
+def fletcher16(data):
+    """Computes the Fletcher 16 checksum of a data stream"""
+    c0 = 0
+    c1 = 0
+        
+    for b in data:
+        c0 = (c0 + ord(b))
+        c1 = (c1 + c0)
+        
+    cb0 = 255 - ((c0+c1) % 255)
+    cb1 = 255 - ((c0 + cb0) % 255)
+    
+    return cb0, cb1
+
+def receive_file(ser, fp):
+    """Receives a file block from the client, determines its validity,
+    and responds accordingly."""
+    
+    file_contents = b''
+
+    length = ord(ser.read())
+    err = 0
+
+    while length > 0:
+        #print("    receiving {0} bytes".format(length))
+        bytes = b''
+        for i in range(0, length):
+            bytes = bytes + ser.read()
+        
+        fl1 = ser.read()
+        fl2 = ser.read()
+        
+        v1, v2 = fletcher16(bytes)
+
+        # print("Fletcher16 - Rainbow({0}, {1})  Python({2}, {3})".format(ord(fl1), ord(fl2), v1, v2))
+        
+        if (v1 == ord(fl1) and v2 == ord(fl2)):
+            fp.write(bytes)
+            respond(ser, OK)
+        elif err < 10:
+            respond(ser, RETRY)
+            err = err + 1
+            if err == 1:
+                fp.write(bytes)
+            print("  block retry {0}...".format(err))
+        else:
+            respond(ser, ABORT)
+            print("  block abort")
+            break
+            
+        length = ord(ser.read())
+
+def readtext(ser, bytes=1):
+    """Reads a string of bytes from the serial port and converts
+    them to a string if necessary (i.e. Python 3)"""
+    b = ser.read(bytes)
+    try:
+        return str(b,'ascii')
+    except TypeError:
+        return b
+    
+def init(ser):
+    """Waits for an initialization message from the client"""
+    print("Waiting for 'ONLINE'...")
+    while ser.inWaiting() < 6:
+        time.sleep(1)
+    
+    x = readtext(ser, 6)
+    if x == 'ONLINE':
+        print("Received 'ONLINE' message.  Awaiting files...")
+        return True
+        
+    return False
+    
+def readfilename(ser):
+    """Reads the next filename from the client"""
+    fname = b''
+    
+    b = ser.read()
+    while b != b';':
+        fname = fname + b
+        b = ser.read()
+    
+    try:    
+        return str(fname, 'ascii')
+    except TypeError:
+        return fname
+    
+def prepfile(filename):
+    """Returns an open file for writing based on the
+    reported DOS name"""
+    
+    newfile = filename.replace(':', '')
+    if os.sep != '\\':
+        newfile = newfile.replace('\\', os.sep)
+        
+    dirs = newfile.split(os.sep)
+    fullpath = ''
+    for d in dirs[:-1]:
+        fullpath = os.path.join(fullpath,d)
+        if not os.path.exists(fullpath):
+            os.mkdir(fullpath)
+            
+    return open(newfile, "w")
+    
+def main_transfer(ser):
+    """Main program loop"""
+    
+    # First wait for the online signal
+    if not init(ser):
+        print("Initialize failed. Quitting.")
+        return
+    
+    while True:
+        fname = readfilename(ser)
+        fp = prepfile(fname)
+        if fp is None:
+            break
+
+        print("Receiving {0}".format(fname))
+        respond(ser, OK)
+        receive_file(ser, fp)
+        fp.close()
+
+def main(port='/dev/ttyUSB0', speed=19200):
+    """Opens the serial port and starts the transfer"""
+    
+    ser = serial.Serial(port, speed)
+    
+    main_transfer(ser)
+    
+    ser.close()
+    
+if __name__ == '__main__':
+
+    parser = argparse.ArgumentParser()
+    
+    parser.add_argument('-p', '--port', dest='port', default='/dev/ttyUSB0')
+    parser.add_argument('-s', '--speed', dest='speed', type=int, default=19200)
+    
+    res = parser.parse_args()
+    
+    main(port=res.port, speed=res.speed)
+