JSON marshaling panics on specs with empty extended bitmap

[krishishah]

The official ISO8583 spec consists of an extended bitmap in DE 65. In practice, this is left empty in the vast majority of the use cases. JSON marshaling panics on a nil pointer reference on specs with this field defined.

In particular, it panics here because the underlying utils.Bitmap is nil at runtime:

 func (f *Bitmap) Bytes() ([]byte, error) {                                                                                                                                                                                                                                                                                                                                      
     return f.bitmap.Bytes(), nil                                                                                                                                                              
 } 

Adding a nil check before referencing the underlying bitmap fixes this issue.

Does this library have support for extended bitmaps?

[alovak]

@krishishah bitmap dynamically reads all bitmaps from the message as following:

• if 1st bit in the primary bitmap is set - it reads the secondary bitmap
• if 1st bit in the secondary bitmap is set - it reads the tertiary bitmap

I see that DE 65 is 1 bit (in some specs) but not sure what's the value of it.

May I ask you to share your code (you can do this privately) so I can better understand why it panics?

[alovak]

@krishishah I've fixed a tiny issue related to JSON Marshalling here https://github.com/moov-io/iso8583/pull/87

maybe it will fix your issue? :)

[krishishah]

@alovak it's actually 8 bytes on the official ISO spec and for the scheme we are integrating against as well. It indicates the presence of a 3rd segment of the message.

The scheme we are integrating against always has it populated as 0 but the only code change we made was to add it to the message spec as a Bitmap field against index 65.

Your change fixed the issue, great work!