CODEWITHSUNDEEP
pythonpython-2.7sip
Mohamed Ilyess Mezghich
Mohamed Ilyess Mezghich

Reputation: 53

Extracting some SIP headers

I am using this regular expression for SIP (Session Initiation Protocol) URIs to extract the different internal variables.

_syntax = re.compile('^(?P<scheme>[a-zA-Z][a-zA-Z0-9\+\-\.]*):'  # scheme
    + '(?:(?:(?P<user>[a-zA-Z0-9\-\_\.\!\~\*\'\(\)&=\+\$,;\?\/\%]+)' # user
    + '(?::(?P<password>[^:@;\?]+))?)@)?' # password
    + '(?:(?:(?P<host>[^;\?:]*)(?::(?P<port>[\d]+))?))'  # host, port
    + '(?:;(?P<params>[^\?]*))?' # parameters
    + '(?:\?(?P<headers>.*))?$') # headers
m = URI._syntax.match(value)
    if m: 
        self.scheme, self.user, self.password, self.host, self.port, params, headers = m.groups()

and i want to extract specific header like the header via,branch,contact,callID or Cseq. The general form of a sip message is:

OPTIONS sip:172.16.18.35:5060 SIP/2.0
Content-Length: 0
Via: SIP/2.0/UDP 172.16.18.90:5060
From: "fake" <sip:[email protected]>
Supported: replaces, timer
User-Agent: SIPPing
To: <sip:172.16.18.35:5060>
Contact: <sip:[email protected]:5060>
CSeq: 1 OPTIONS
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH
Call-ID: [email protected]
Date: Thu, 25 Apr 2013 003024 +0000
Max-Forwards: 70

Upvotes: 1

Views: 1191

Answers (1)

Charles Duffy
Charles Duffy

Reputation: 295443

I would suggest taking advantage of the intentional similarities between SIP header format and RFC822.

from email.parser import Parser
msg = Parser().parsestr(m.group('headers'))

...thereafter:

>>> msg.keys()
['Content-Length', 'Via', 'From', 'Supported', 'User-Agent', 'To', 'Contact', 'CSeq', 'Allow', 'Call-ID', 'Date', 'Max-Forwards']
>>> msg['To']
'<sip:172.16.18.35:5060>'
>>> msg['Date']
'Thu, 25 Apr 2013 003024 +0000'

...etc. See the documentation for the Python standard-library email module for more details.

Upvotes: 2

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