OAuth signature_invalid error using PesaPal API with Ruby - php

Question

I'm having a real nightmare trying to get the PesaPal API to work for me using Ruby...
I appreciate that it's probably not the most commonly used API but if there's anybody online here who has more experience using OAuth, and/or PHP experience who could offer a fresh pair of eyes I'd appreciate it.
So the PesaPal developer site is here: http://developer.pesapal.com
Their API docs don't give away too many clues about how to use OAuth with their site and I don't understand PHP well enough to be sure I've read their PHP sample correctly.
Here's my attempt at implementing this in Ruby:
require 'oauth'
require 'uri'
key = '<my sandbox key>'
sec = '<my sandbox secret>'
API_DOMAIN = 'https://demo.pesapal.com'
# An XML string of param data to include with our request
RAW_XML = %{<?xml version=\"1.0\" encoding=\"utf-8\"?><PesapalDirectOrderInfo xmlns:xsi=\"http://www.w3.org/2001/XMLSchemainstance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" Amount=\"12.34\" Description=\"Bob Test 1\" Type=\"MERCHANT\" Reference=\"808\" FirstName=\"Bo\" LastName=\"Tester\" Email=\"bodacious#bodacious.com\" xmlns=\"http://www.pesapal.com\" />}
# Escape the XML
#post_xml = URI.escape(RAW_XML)
# Create a new OAuth Consumer
#consumer = OAuth::Consumer.new(key, sec, {
site: API_DOMAIN,
scheme: :query_string
})
# The signed request object
#signed_request = #consumer.create_signed_request('get', "#{API_DOMAIN}/API/PostPesapalDirectOrderV4")
# Join the pesapal_request_data and oauth_callback with '&' for valid URL params
#params = {
oauth_callback: URI.escape('http://localhost:3000'),
pesapal_request_data: #post_xml,
}.map { |k,v| "#{k}=#{v}" }.join('&')
# This is the URL we should redirect to
puts redirect_url = "#{#signed_request.path}&#{#params}"
When I try to visit the URL returned by this code, I get: Problem: signature_invalid | Advice: > | back from the API.
Can anyone think of what I'm doing wrong here?
Thanks

Answer 1

Check out the pesapal RubyGem here ... https://rubygems.org/gems/pesapal ... it handles all that stuff for you.

Answer 2

I had the same problem and I solved it by creating a method to manually sign the url. create your own method to get the oauth_nonce like this.
def nonce
Array.new( 5 ) { rand(256) }.pack('C*').unpack('H*').first
end
The signature method looks like this:
def signature
key = percent_encode( #consumer_secret ) + '&' + percent_encode( #token_secret )
digest = OpenSSL::Digest::Digest.new( 'sha1' )
hmac = OpenSSL::HMAC.digest( digest, key, #base_str )
Base64.encode64( hmac ).chomp.gsub( /\n/, '' )
end
This is the #base_str instance variable:
#base_str = [#req_method,
percent_encode( req_url ),
percent_encode( query_string )
].join( '&' )
This is the query_string method:
def query_string
pairs = []
#params.sort.each { | key, val |
pairs.push( "#{ percent_encode( key ) }=#{ percent_encode( val.to_s ) }" )
}
pairs.join '&'
end
You can then use the signature method above to get the oauth_signature param to use in the resulting url

Answer 3

I know the OP was interested in a solution that addresses the Ruby domain, but I feel it may be helpful to note that I was getting a similar problem on PHP and the solution was to ensure I had no white space in the XML post data structure.
WRONG:
<?xml version="1.0" encoding="utf-8"?>
<PesapalDirectOrderInfo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
Amount="200"
Currency="KES"
Description="Computer Accessory"
Type="MERCHANT"
Reference="dd19f9ede4db6f0a13b7053111f02825"
FirstName="Stack"
LastName="Overflow"
Email="so#stackoverflow.com"
PhoneNumber=""
xmlns="http://www.pesapal.com" >
<lineitems>
<lineitem uniqueid="29"
particulars="Keyboard"
quantity="1"
unitcost="200"
subtotal="200.00" >
</lineitem>
</lineitems>
</PesapalDirectOrderInfo>
CORRECT:
<?xml version="1.0" encoding="utf-8"?><PesapalDirectOrderInfo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" Amount="200" Currency="KES" Description="Computer Accessory" Type="MERCHANT" Reference="dd19f9ede4db6f0a13b7053111f02825" FirstName="Stack" LastName="Overflow" Email="so#stackoverflow.com" PhoneNumber="" xmlns="http://www.pesapal.com" ><lineitems><lineitem uniqueid="29" particulars="Keyboard" quantity="1" unitcost="200" subtotal="200.00" ></lineitem></lineitems></PesapalDirectOrderInfo>