nando/nando

#!/usr/bin/env python

import socket,sys,time,os,configobj

RC="/etc/nandorc"
BLOCK_SIZE=10240

def setup_options():
    ''' Setup the command line options '''
    from argparse import ArgumentParser

    parser=ArgumentParser(description="Alive notifier. Options first read from /etc/nandorc, and overriden by switches.")
    parser.add_argument("--host",action='store', dest='HOST',type=str,default=None,
                      help="Host name/IP of the server")
    parser.add_argument("--port", action='store', dest='PORT', default=None,type=int,
                      help="Port number of the server")
    parser.add_argument("-t",action='store', dest='TIMEOUT',default=5, type=int,
                      help="Connection timeout")
    parser.add_argument("-i",action='store', dest='INTERVAL',default=0, type=int,
                      help="Send signal every i seconds. If 0, send only once and exit.")
    parser.add_argument("-m",action='store', dest='MSGFILE',type=str,default=None,
                      help="Read a text file as description. Max length 512 chars")
    parser.add_argument("--query-ip",action='store', dest='QUERY_HOSTNAME',default=None,type=str,
                      help="Query the IP of a host name")
    parser.add_argument("--query-host",action='store', dest='QUERY_IP',default=None,type=str,
                      help="Query the hostname of an IP")
    parser.add_argument("command",type=str,action="store",default="",nargs="?",
                      choices=['','list','alive','lost'],
                      help="Command to send. If empty, send standard alive-notice. Commands: list, alive")
    options=parser.parse_args()
    if os.path.exists(RC):
        rc=configobj.ConfigObj(RC)
        if options.HOST is None:
            if "HOST" in rc.keys():
                options.HOST=rc['HOST']
        if options.PORT is None:
            if "PORT" in rc.keys():
                options.PORT=int(rc['PORT'])
        if options.MSGFILE is None:
            if "MSGFILE" in rc.keys():
                options.MSGFILE=rc['MSGFILE']
    
    if options.HOST is None:
        parser.error("Host name required")    
    if options.PORT is None:
        parser.error("Port number required")    
    return options


def print_table(data):
    lengths=[0,0,0,0]
    for row in data.split("\n"):
        cols=row.split("|",4)
        if len(cols)!=4:
            continue
        for c in range(4):
            lengths[c]=max(lengths[c], len(cols[c]))
    lengths=[str(x) for x in lengths]
    for row in data.split("\n"):
        cols=row.split("|",4)
        if len(cols)!=4:
            continue
        print(("{0:<"+lengths[0]+"} | {1:<"+lengths[1]+"} | {2:>"+lengths[2]+"} | {3}").format(*cols))

def query_ip(sock,opts):
    sock.sendto("list", (opts.HOST, opts.PORT))
    received = sock.recv(BLOCK_SIZE)
    for row in received.split("\n"):
        cols=row.split("|",4)
        if cols[0]==opts.QUERY_HOSTNAME:
            sys.stdout.write(cols[1])
            sys.exit(0)
    sys.exit(1)
    
def query_host(sock,opts):
    sock.sendto("list", (opts.HOST, opts.PORT))
    received = sock.recv(BLOCK_SIZE)
    for row in received.split("\n"):
        cols=row.split("|",4)
        if cols[1]==opts.QUERY_IP:
            sys.stdout.write(cols[0])
            sys.exit(0)
    sys.exit(1)

def read_desc(opts):
    
    if not opts.MSGFILE:
        return ""
    if not os.path.isfile(opts.MSGFILE):
        return ""
    
    DESC=open(opts.MSGFILE,"rb").read(1024)
    DESC=''.join([ c for c in DESC if c not in ['\n','\r','|'] ])
    return DESC

opts=setup_options()

errors=0
while True:
    try:
        MYNAME = socket.gethostname()
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        sock.settimeout(opts.TIMEOUT)
        sock.connect((opts.HOST,opts.PORT))
        MYIP=sock.getsockname()[0]
        
        if opts.QUERY_HOSTNAME:
            query_ip(sock,opts)
        if opts.QUERY_IP:
            query_host(sock,opts)
        
        if opts.command=="":
            DESC=read_desc(opts)
            MSG="{0}|{1}|{2}\n".format(MYNAME,MYIP,DESC)
        else:
            MSG=opts.command
        
        sock.sendto(MSG, (opts.HOST, opts.PORT))
        received = sock.recv(BLOCK_SIZE)
        if opts.command!="":
            print_table(received)
        if opts.INTERVAL==0 and opts.command=="":
            sock.sendto("list", (opts.HOST, opts.PORT))
            received = sock.recv(BLOCK_SIZE)
            print_table(received)
        errors=0
    except socket.error:
        print("Didn't get reply from {0}:{1}".format(opts.HOST,opts.PORT))
        errors=1
    except IndexError:
        print(received)
    if opts.INTERVAL==0:
        break
    time.sleep(opts.INTERVAL)

sys.exit(errors)