Need help understanding python snippet with regex and cURL

Question

EDIT - Just added entire cURL function for reference/more information but need help with if statements - regex

Looking for help to understand the if statements in this cURL. I've read through some python documentation and I understand each of the pieces, that this is searching with regex and replacing. Just hoping someone might be able to help give a bigger picture explanation. I don't really understand the .groups.

To give a little more background this script is accessing another site via cURL it stores a cookie and when ran checks if cookie is valid, if not it grabs a new one after posting username/password. The site recently changed and I'm trying to figure out what I need to change to get this working again.

#get auth cookie for sso
def getAuthCookie( self ):
    buffer = BytesIO()
    c = pycurl.Curl()
    c.setopt(c.SSL_VERIFYPEER, False)
    c.setopt(c.FOLLOWLOCATION, True)
    c.setopt(c.TIMEOUT, 60)
    c.setopt(c.USERPWD, self.user+":"+cred.getpasswd( self.encPasswd ) )
    c.setopt(c.URL, 'https://sso.sample.com')
    c.setopt(c.COOKIEJAR, self.cookieDir)
    c.setopt(c.COOKIEFILE, self.cookieDir )
    c.setopt(c.WRITEFUNCTION, buffer.write)
    c.perform()
    c.unsetopt(c.USERPWD)
    c.setopt(c.URL, 'https://sample.com')
    c.perform()
    html = str(buffer.getvalue())    

----------------------------------------------------------
if "RelayState" in html:
    rex = re.compile( "input type=\"hidden\" name=\"RelayState\" value=\"(.*)\"" )
    RELAY = rex.search( html ).groups()[0]
if "SAMLResponse" in html:
    rex = re.compile( "input type=\"hidden\" name=\"SAMLResponse\" value=\"(.*)\"" )
    SAML =  rex.search( html ).groups()[0]
    datastuff = {'SAMLResponse':SAML,'RelayState':RELAY,'redirect':'Redirect','show_button':'true'}
if "form method=\"POST\" action=" in html:
    rex = re.compile( "form method=\"POST\" action=\"(.*)\" " )
    postUrl = rex.search( html ).groups()[0]
---------------------------------------------------------- 

#post our saml obtained, get to our final dest
    c.setopt(c.URL, postUrl )
    c.setopt(c.POST, True)
    c.setopt(c.POSTFIELDS, urlencode( datastuff ))
    c.perform()
    c.close()

Answer 1

See the comments I have injected in the code:

#get auth cookie for sso
def getAuthCookie( self ):
    buffer = BytesIO()
    c = pycurl.Curl()
    c.setopt(c.SSL_VERIFYPEER, False)
    c.setopt(c.FOLLOWLOCATION, True)
    c.setopt(c.TIMEOUT, 60)
    c.setopt(c.USERPWD, self.user+":"+cred.getpasswd( self.encPasswd ) )
    # curling sso.sample.com, which I assume promts a login dialog box and curl will set that with the varible provide above
    c.setopt(c.URL, 'https://sso.sample.com')
    # save the cookie to cookieDir
    c.setopt(c.COOKIEJAR, self.cookieDir)
    c.setopt(c.COOKIEFILE, self.cookieDir )
    c.setopt(c.WRITEFUNCTION, buffer.write)
    # perform all the previous curl commands
    c.perform()
    c.unsetopt(c.USERPWD)
    # curl new site sample.com
    c.setopt(c.URL, 'https://sample.com')
    c.perform()
    # save output as html var
    html = str(buffer.getvalue())    

----------------------------------------------------------
# The following three if statments
# if "some string is found" in varible-html: then do the lines indented lines that follow
if "RelayState" in html:
    # setup a regex to look for "input type="hidden" name="RelayState" value="[and captures everything here this will become the RELAY var]"
    rex = re.compile( "input type=\"hidden\" name=\"RelayState\" value=\"(.*)\"" )
    # this executes the regex expression on the html var
    RELAY = rex.search( html ).groups()[0]
if "SAMLResponse" in html:
    rex = re.compile( "input type=\"hidden\" name=\"SAMLResponse\" value=\"(.*)\"" )
    # same thing is happening here capturing the value as SAML
    SAML =  rex.search( html ).groups()[0]
    # contructing a new var with strings and the newly contructed vars
    datastuff = {'SAMLResponse':SAML,'RelayState':RELAY,'redirect':'Redirect','show_button':'true'}
if "form method=\"POST\" action=" in html:
    rex = re.compile( "form method=\"POST\" action=\"(.*)\" " )
    # again action="[postURL]"
    postUrl = rex.search( html ).groups()[0]
---------------------------------------------------------- 

#post our saml obtained, get to our final dest
    c.setopt(c.URL, postUrl ) # setup curl with url found above
    c.setopt(c.POST, True) # use post method
    c.setopt(c.POSTFIELDS, urlencode( datastuff )) # post fields found above with newly contructed vars
    c.perform()
    c.close()

If something changed and you are now getting an error, I would try print html after the html = str(buffer.getvalue()) to see if your still hitting the same page where it is expecting to find the regex's performed.