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protocol/protocol
Luis MartinGarcia d7cd420032 First public version of Protocol.
2014-08-15 01:27:27 +02:00

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#!/usr/bin/python
################################################################################
# ____ _ _ #
# | _ \ _ __ ___ | |_ ___ ___ ___ | | #
# | |_) | '__/ _ \| __/ _ \ / __/ _ \| | #
# | __/| | | (_) | || (_) | (_| (_) | | #
# |_| |_| \___/ \__\___/ \___\___/|_| #
# #
# == A Simple ASCII Header Generator for Network Protocols == #
# #
################################################################################
# #
# Written by: #
# #
# Luis MartinGarcia. #
# -> E-Mail: luis.mgarc@gmail.com #
# -> WWWW: http://www.luismg.com #
# -> GitHub: https://github.com/luismartingarcia #
# #
################################################################################
# #
# This file is part of Protocol. #
# #
# Copyright (C) 2014 Luis MartinGarcia (luis.mgarc@gmail.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/>. #
# #
# Please check file LICENSE.txt for the complete version of the license, #
# as this disclaimer does not contain the full information. Also, note #
# that although Protocol is licensed under the GNU GPL v3 license, it may #
# be possible to obtain copies of it under different, less restrictive, #
# alternative licenses. Requests will be studied on a case by case basis. #
# If you wish to obtain Protocol under a different license, please contact #
# the email address mentioned above. #
# #
################################################################################
# #
# Description: #
# #
# Protocol is a command-line tool that provides quick access to the most #
# common network protocol headers in ASCII (RFC-like) format. It also has the #
# ability to create ASCII headers for custom protocols defined by the user #
# through a very simple syntax. #
# #
################################################################################
# STANDARD LIBRARY IMPORTS
import sys
from datetime import date
# INTERNAL IMPORTS
from constants import *
import specs
# CLASS DEFINITIONS
class ProtocolException(Exception):
"""
This class represents exceptions raised by the Protocol class
"""
def __init__(self, errmsg):
self.errmsg=errmsg
def __str__(self):
return str(self.errmsg)
class Protocol():
"""
This class represents a network protocol header. Objects are constructed by
passing a textual protocol specification. Once that is done, instances
can be printed by converting them to a str type.
"""
def __init__(self, spec):
"""
Class constructor.
@param spec is the textual specification that describes the protocol.
"""
self.hdr_char_start="+" # Character for start of the border line
self.hdr_char_end="+" # Character for end of the border line
self.hdr_char_fill_odd="+" # Fill character for border odd positions
self.hdr_char_fill_even="-" # Fill character for border even positions
self.hdr_char_sep="|" # Field separator character
self.bits_per_line=32 # Number of bits per line
self.do_print_top_tens=True # True: print top numbers for bit tens
self.do_print_top_units=True # True: print top numbers for bit units
self.field_list=[] # Header fields to be printed out
self.parse_spec(spec) # Parse the received spec and populate self.field_list
def parse_spec(self, spec):
"""
Parses a textual protocol spec and stores the relevant internal state
so such spec can be later converted to a nice ASCII diagram.
@return the list of protocol fields, as a dictionary containing
keys 'len' and 'text'. The list is returned for completeness but no
caller is expected to store or use such list.
@raise ProtocolException in case the supplied spec is not valid
"""
if "?" in spec:
parts=spec.split("?")
fields=parts[0]
opts=parts[1]
if spec.count("?")>1:
raise ProtocolException("FATAL: Character '?' may only be used as an option separator.")
else:
fields=spec
opts=None
# Parse field spec
items=fields.split(",")
for item in items:
try:
text, bits = item.split(":")
bits=int(bits)
if bits<=0:
raise ProtocolException("FATAL: Fields must be at least one bit long (%s)" %spec)
except ProtocolException:
raise
except:
raise ProtocolException("FATAL: Invalid field_list specification (%s)" %spec)
self.field_list.append({"text":text, "len":bits})
# Parse options
if opts is not None:
opts=opts.split(",")
for opt in opts:
try:
var, value = opt.split("=")
if var.lower()=="bits":
self.bits_per_line=int(value)
if self.bits_per_line<=0:
raise ProtocolException("FATAL: Invalid value for 'bits' option (%s)" % value)
elif var.lower()=="numbers":
if value.lower() in ["0", "n", "no", "none", "false"]:
self.do_print_top_tens=False
self.do_print_top_units=False
elif value.lower() in ["1", "y", "yes", "none", "true"]:
self.do_print_top_tens=True
self.do_print_top_units=True
else:
raise ProtocolException("FATAL: Invalid value for 'numbers' option (%s)" % value)
elif var.lower() in ["oddchar", "evenchar", "startchar", "endchar", "sepchar"]:
if len(value)>1 or len(value)<=0:
raise ProtocolException("FATAL: Invalid value for '%s' option (%s)" % (var, value))
else:
if var.lower()=="oddchar":
self.hdr_char_fill_odd=value
elif var.lower()=="evenchar":
self.hdr_char_fill_even=value
elif var.lower()=="startchar":
self.hdr_char_start=value
elif var.lower()=="endchar":
self.hdr_char_end=value
elif var.lower()=="sepchar":
self.hdr_char_sep=value
except ProtocolException:
raise
except:
raise ProtocolException("FATAL: Invalid options specification (%s)" % opt)
return self.field_list
def _get_top_numbers(self):
"""
@return a string representing the bit units and bit tens on top of the
protocol header. Note that a proper string is only returned if one or
both self.do_print_top_tens and self.do_print_top_units is True.
The returned string is not \n terminated, but it may contain a newline
character in the middle.
"""
lines=["", ""]
if self.do_print_top_tens is True:
for i in range(0, self.bits_per_line):
if str(i)[-1:]=="0":
lines[0]+=" %s" % str(i)[0]
else:
lines[0]+=" "
lines[0]+="\n"
if self.do_print_top_units is True:
for i in range(0, self.bits_per_line):
lines[1]+=" %s" % str(i)[-1:]
#lines[1]+="\n"
result = "".join(lines)
return result if len(result)>0 else None
def _get_horizontal(self, width=None):
"""
@return the horizontal border line that separates field rows.
@param width controls how many field bits the line should cover. By
default, if no width is supplied, the line covers the hole length of
the header.
"""
if width is None:
width=self.bits_per_line
if width<=0:
return ""
else:
a="%s" % self.hdr_char_start
b=(self.hdr_char_fill_even+self.hdr_char_fill_odd)*(width-1)
c="%s%s" % (self.hdr_char_fill_even, self.hdr_char_end)
return a+b+c
def _get_separator(self, line_end=""):
"""
@return a string containing a protocol field separator. Returned string
is a single character and matches whatever is stored in self.hdr_char_sep
"""
return self.hdr_char_sep
def _process_field_list(self):
"""
Processes the list of protocol fields that we got from the spec and turns
it into something that we can print easily (useful for cases when we have
protocol fields that span more than one line). This is just a helper
function to make __str__()'s life easier.
"""
new_fields=[]
bits_in_line=0
i=0
while i < len(self.field_list):
# Extract all the info we need about the field
field=self.field_list[i]
field_text= field['text']
field_len= field['len']
field['MF']=False
available_in_line = self.bits_per_line - bits_in_line
# If we have enough space on this line to include the current field
# then just keep it as it is.
if available_in_line >= field_len:
new_fields.append(field)
bits_in_line+=field_len
i+=1
if bits_in_line==self.bits_per_line:
bits_in_line=0
# Otherwise, split the field into two parts, one blank and one with
# the actual field text
else:
# Case 1: We have a field that is perfectly aligned and it
# has a length that is multiple of our line length
if bits_in_line==0 and field_len%self.bits_per_line==0:
new_fields.append(field)
i+=1
bits_in_line=0
# Case 2: We weren't that lucky and the field is either not
# aligned or we can't print it using an exact number of full
# lines
else:
# If we have more space in the current line than in the next,
# then put the field text in this one
if available_in_line >= field_len-available_in_line:
new_field = {'text':field_text, 'len':available_in_line, "MF":True}
new_fields.append(new_field)
field['text']=""
field['len']=field_len-available_in_line
field['MF']=False
else:
new_field = {'text':"", 'len':available_in_line, "MF":True}
new_fields.append(new_field)
field['text']=field_text
field['len']=field_len-available_in_line
field['MF']=False
bits_in_line=0
continue
return new_fields
# Convert to string
def __str__(self):
"""
Converts the protocol specification stored in the object to a nice
ASCII diagram like the ones that appear in RFCs. Conversion supports
fields of any length, and supports field that span more than one
line in the diagram.
@return a string containing the ASCII representation of the protocol
header.
"""
# First of all, process our field list. This does some magic to make
# the algorithm work for fields that span more than one line
proto_fields = self._process_field_list()
lines=[]
numbers=self._get_top_numbers()
if numbers is not None:
lines.append(numbers)
lines.append(self._get_horizontal())
# Print all protocol fields
bits_in_line=0
current_line=""
fields_done=0
p=-1
while p < len(proto_fields)-1:
p+=1
# Extract all the info we need about the field
field = proto_fields[p]
field_text= field['text']
field_len= field['len']
field_mf = field['MF'] is True # Field has more fragments
# If the field text is too long, we truncate it, and add a dot
# at the end.
if len(field_text) > (field_len*2)-1:
field_text=field_text[0:(field_len*2)-1]
if len(field_text)>1:
field_text=field_text[0:-1]+"."
# If we have space for the whole field in the current line, go
# ahead and add it
if self.bits_per_line-bits_in_line >= field_len:
# If this is the first thing we print on a line, add the
# starting character
if bits_in_line==0:
current_line+=self._get_separator()
# Add the whole field
current_line+=str.center(field_text, (field_len*2)-1)
# Update counters
bits_in_line+=field_len
fields_done+=1
# If this is the last character in the line, store the line
if bits_in_line==self.bits_per_line:
current_line+=self._get_separator()
lines.append(current_line)
current_line=""
bits_in_line=0
# When we have a fragmented field, we may need to suppress
# the floor of the field, so the current line connects
# with the one that follows. E.g:
# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
# | field16 | |
# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
# | field |
# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
if field_mf is True:
if proto_fields[p+1]['len'] > self.bits_per_line - field_len:
# Print some +-+-+ to cover the previous field
line_left=self._get_horizontal(self.bits_per_line - field_len)
if len(line_left)==0:
line_left=self.hdr_char_start
# Now print some empty space to cover the part that
# we can join with the field below.
# Case 1: If the next field reaches the end of its
# line, then we need to print whitespace until the
# end our line
if proto_fields[p+1]['len'] >= self.bits_per_line:
line_center=" "* ((2*(field_len)-1))
line_right=self.hdr_char_end
# Case 2: the field in the next row is not big enough
# to cover all the space we'd like to join, so we
# just print whitespace to cover as much as we can
else:
line_center=" "* ((2*((proto_fields[p+1]['len']-(self.bits_per_line-field_len))))-1)
line_right=self._get_horizontal(self.bits_per_line-proto_fields[p+1]['len'])
lines.append(line_left+line_center+line_right)
else:
lines.append(self._get_horizontal())
else:
lines.append(self._get_horizontal())
# If this is not the last character of the line but we have no
# more fields to print, wrap up
elif fields_done==len(proto_fields):
current_line+=self._get_separator()
lines.append(current_line)
lines.append(self._get_horizontal(bits_in_line))
else:
# Add the separator character
current_line+=self.hdr_char_sep
# We don't have enough space for the field on this line.
else:
# Case 1: We are at the beginning of a new line and we need to
# span more than one line
if bits_in_line==0:
# Case 1a: We have a multiple of the number of bits per line
if field_len%self.bits_per_line==0:
# Compute how many lines in total we need to print for this
# big field.
lines_to_print = int(((field_len/self.bits_per_line)*2)-1)
# We print the field text in the central line
central_line=int(lines_to_print/2)
# Print all those lines
for i in range(0, lines_to_print):
# Let's figure out which character we need to use
# to start and end the current line
if i%2==1:
start_line=self.hdr_char_start
end_line=self.hdr_char_end
else:
start_line=self.hdr_char_sep
end_line=self.hdr_char_sep
# This is the line where we need to print the field
# text.
if i == central_line:
lines.append(start_line + str.center(field_text, (self.bits_per_line*2)-1) + end_line)
# This is a line we need to leave blank
else:
lines.append(start_line + (" " * ((self.bits_per_line*2)-1)) + end_line)
# If we just added the last line, add a horizontal separator
if i==lines_to_print-1:
lines.append(self._get_horizontal())
# Case 2: We are not at the beginning of the line and we need
# to print something that does not fit in the current line
else:
# This should never happen, since our _process_field_list()
# divides fields in chunks so we never have the case of
# something spanning lines in a weird manner
assert(False)
result= "\n".join(lines)
return result
class Main():
"""
This class does all the boring task of a command-line application. It parses
user input, displays usage, parses input files, etc.
"""
def __init__(self):
"""
Class constructor. Nothing fancy.
"""
self.cmd_line_args=None # Copy of the user argv
self.protocols=[] # List of protocols to print out
self.bits_per_line=None # Number of bits per line to print
self.skip_numbers=None # True to avoid printing bit units and tens
self.hdr_char_start=None # Character for start of the border line
self.hdr_char_end=None # Character for end of the border line
self.hdr_char_fill_odd=None # Fill character for border odd positions
self.hdr_char_fill_even=None # Fill character for border even positions
self.hdr_char_sep=None # Field separator character
def display_help(self):
"""
Displays command-line usage help to standard output.
"""
print("")
print("%s v%s" % (APPLICATION_NAME, APPLICATION_VERSION))
print("Copyright (C) %i, %s (%s)." % (max(2014, date.today().year), APPLICATION_AUTHOR, APPLICATION_AUTHOR_EMAIL))
print("This software comes with ABSOLUTELY NO WARRANTY.")
print("")
self.display_usage()
print("PARAMETERS:")
print(" <protocol> : Name of an existing protocol")
print(" <spec> : Field by field specification of non-existing protocol")
print("OPTIONS:")
print(" -b, --bits <n> : Number of bits per line")
print(" -f, --file : Read specs from a text file")
print(" -h, --help : Displays this help information")
print(" -n, --no-numbers : Do not print bit numbers on top of the header")
print(" -V, --version : Displays current version")
print(" --evenchar <char> : Character for the even positions of horizontal table borders")
print(" --oddchar <char> : Character for the odd positions of horizontal table borders")
print(" --startchar <char> : Character that starts horizontal table borders")
print(" --endchar <char> : Character that ends horizontal table borders")
print(" --sepchar <char> : Character that separates protocol fields")
def get_usage(self):
"""
@return a string containing application usage information
"""
return "Usage: %s {<protocol> or <spec>} [OPTIONS]" % self.cmd_line_args[0]
def display_usage(self):
"""
Prints usage information to standard output
"""
print(self.get_usage())
def parse_config_file(self, filename):
"""
This method parses the supplied configuration file and adds any protocols to our
list of protocols to print.
@return The number of protocols parsed
"""
i=0
# Read the contents of the whole file
try:
f = open(filename)
lines = f.readlines()
f.close()
except:
print("Error while reading file %s. Please make sure it exists and it's readable." % filename)
sys.exit(1)
# Parse protocol specs, line by line
for line in lines:
# Sanitize the line
line=line.strip()
# If it starts with #, or is an empty line ignore it
if line.startswith("#") or len(line)==0:
continue
# If we have something else, treat it as a protocol spec
proto=Protocol(line)
self.protocols.append(proto)
i+=1
return i
def parse_cmd_line_args(self, argv, is_config_file=False):
"""
Parses command-line arguments and stores any relevant information
internally
"""
# Store a reference to command line args for later use.
if is_config_file==False:
self.cmd_line_args = argv
# Check we have received enough command-line parameters
if len(argv) == 1 and is_config_file is False:
print(self.get_usage())
sys.exit(1)
else:
skip_arg=False
for i in range(1, len(argv)):
# Useful for args like -c <filename>. This avoids parsing the
# filename as it if was a command-line flag.
if skip_arg==True:
skip_arg=False
continue
# Spec file
if argv[i]=="-f" or argv[i]=="--file":
# Make sure we have an actual parameter after the flag
if (i+1)>=len(argv):
return OP_FAILURE, "Expected parameter after %s\n%s" % (argv[i], self.get_usage())
skip_arg=True
# Parse the config file
protos = self.parse_config_file(argv[i+1])
if protos <= 0:
return OP_FAILURE, "No protocol specifications found in the supplied file (%s)" % argv[i+1]
# Bits per line
elif argv[i]=="-b" or argv[i]=="--bits":
# Make sure we have an actual parameter after the flag
if (i+1)>=len(argv):
return OP_FAILURE, "Expected parameter after %s\n%s" % (argv[i], self.get_usage())
skip_arg=True
# Parse the config file
try:
self.bits_per_line=int(argv[i+1])
if self.bits_per_line<=0:
return OP_FAILURE, "Invalid number of bits per line supplied (%s)" % argv[i+1]
except:
return OP_FAILURE, "Invalid number of bits per line supplied (%s)" % argv[i+1]
# Avoid displaying numbers on top of the header
elif argv[i]=="-n" or argv[i]=="--no-numbers":
self.skip_numbers=True
# Character variations
elif argv[i] in ["--oddchar", "--evenchar", "--startchar", "--endchar", "--sepchar"]:
# Make sure we have an actual parameter after the flag
if (i+1)>=len(argv):
return OP_FAILURE, "Expected parameter after %s\n%s" % (argv[i], self.get_usage())
skip_arg=True
# Make sure we got a single character, not more
if len(argv[i+1])!=1:
return OP_FAILURE, "A single character is expected after %s\n%s" % (argv[i], self.get_usage())
# Now let's store whatever character spec we got
if argv[i]=="--oddchar":
self.hdr_char_fill_odd=argv[i+1]
elif argv[i]=="--evenchar":
self.hdr_char_fill_even=argv[i+1]
elif argv[i]=="--startchar":
self.hdr_char_start=argv[i+1]
elif argv[i]=="--endchar":
self.hdr_char_end=argv[i+1]
elif argv[i]=="--sepchar":
self.hdr_char_sep=argv[i+1]
# Display help
elif argv[i]=="-h" or argv[i]=="--help":
self.display_help()
sys.exit(0)
# Display version
elif argv[i]=="-V" or argv[i]=="--version":
print("%s v%s" % (APPLICATION_NAME, APPLICATION_VERSION))
sys.exit(0)
# Incorrect option supplied
elif argv[i].startswith("-"):
print("ERROR: Invalid option supplied (%s)" % argv[i])
sys.exit(1)
# Protocol name or protocol spec
else:
# If it contains ":" characters, we have a protocol spec
if argv[i].count(":")>0:
spec = argv[i]
# Otherwise, the user meant to display an existing protocol
else:
# If we got an exact match, end of story
if argv[i] in specs.protocols:
spec = specs.protocols[argv[i]]
# Otherwise, we may have received a partial match so
# we need to figure out which protocol the user meant.
# If the specification is ambiguous, we will error
else:
start_with_the_same=[]
for spec in specs.protocols:
if spec.startswith(argv[i]):
start_with_the_same.append(spec)
# If we only have one entry, it means we got some
# shortened version of the protocol name but no
# ambiguity. In that case, we will use the match.
if len(start_with_the_same)==1:
spec=specs.protocols[start_with_the_same[0]]
elif len(start_with_the_same)==0:
print("ERROR: supplied protocol '%s' does not exist." % argv[i]);
sys.exit(1)
else:
print("Ambiguous protocol specifier '%s'. Did you mean any of these?" % argv[i])
for spec in start_with_the_same:
print(" %s" % spec)
sys.exit(1)
# Finally, based on the spec, instance an actual protocol.
# Note that if the spec is incorect, the Protocol() consutrctor
# will call sys.exit() itself, so there is no need to do
# error checking here.
try:
proto = Protocol(spec)
self.protocols.append(proto)
except ProtocolException as e:
print("ERROR: %s" % str(e))
sys.exit(1)
if len(self.protocols)==0:
print("ERROR: Missing protocol")
sys.exit(1)
return OP_SUCCESS, None
def run(self):
"""
This is Protocol's 'core' method: parses command line argument and prints
any necessary protocol to standard output
"""
# Parse command-line arguments
code, err = self.parse_cmd_line_args(sys.argv)
if code!=OP_SUCCESS:
print("ERROR: %s" % err)
sys.exit(1)
# Print the appropriate protocol headers
for i in range(0, len(self.protocols)):
# Modify the properties of the object if the user passed any
# options that require it
if self.bits_per_line is not None:
self.protocols[i].bits_per_line = self.bits_per_line
if self.skip_numbers is not None:
if self.skip_numbers is True:
self.protocols[i].do_print_top_tens=False
self.protocols[i].do_print_top_units=False
else:
self.protocols[i].do_print_top_tens=True
self.protocols[i].do_print_top_units=True
if self.hdr_char_end is not None:
self.protocols[i].hdr_char_end=self.hdr_char_end
if self.hdr_char_start is not None:
self.protocols[i].hdr_char_start=self.hdr_char_start
if self.hdr_char_fill_even is not None:
self.protocols[i].hdr_char_fill_even=self.hdr_char_fill_even
if self.hdr_char_fill_odd is not None:
self.protocols[i].hdr_char_fill_odd=self.hdr_char_fill_odd
if self.hdr_char_sep is not None:
self.protocols[i].hdr_char_sep=self.hdr_char_sep
print(self.protocols[i])
if len(self.protocols)>1 and i!=len(self.protocols)-1:
print("")
# Main function
def main():
"""
Main function. Runs the Protocol program.
"""
# Instance our core class
program = Main()
# Do our magic
program.run()
# THIS IS THE START OF THE EXECUTION
if __name__ == "__main__":
main()
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