Golang SMPP v3.4 Library

Overview

This is a golang library for SMPP v3.4 message generation and parsing.

Usage

The library is in the package smpp. There are two basic object types: smpp.Parameter and smpp.PDU. One may Encode a PDU object to an octet stream in network byte order, and may Decode an octet stream in network byte order into a PDU.

An SMPP v3.4 PDU has a header and one or more Parameters. Parameters are Mandatory or Optional. Mandatory Parameters are at fixed offsets in a PDU, based on the PDU type, and are either of fixed size, or are null terminated (or it is a short_message, which is treated specially, as described below). Optional Parameters are TLV (Tag/Length/Value) encoded. There are different constructors for different Paramter types:

p := smpp.NewFLParameter(value interface{})
p := smpp.NewCOctetStringParameter(value string)
p := smpp.NewOctetStringFromString(value string)
p := smpp.NewTLVParameter(tag uint16, value interface{})

NewFLParameter is for fixed length parameters, and the length and encoding is inferred from the value type, which may be uint8, uint16 or uint32. NetCOctetStringParameter is for C-Octet-Strings (which are null--that is, byte with a value of 0--terminated). OctetStringFromString produces an Octet-String (which is not null terminated) from a string. The only Parameter type that uses this is short_messsage, which must be preceded by an sm_length Parameter that provides the short_message length. NewTLVParameter generates an Optional Parameter. The Length of the TLV is inferred from type of value, which may be uint8, uint16, uint32, string or []byte.

None of the Parameter constructors return an error, so that they can be used inline with a PDU constructor. They will, however, return nil if something goes wrong.

To create a PDU:

pdu := smpp.NewPDU(id smpp.CommandIDType, status uint32, sequence uint32, mandatoryParams []*smpp.Parameter, optionalParams []*smpp.Parameter)

To decode an incoming byte stream (which must be a complete PDU):

pdu, err := smpp.DecodePDU(stream []byte)

Examples

There are examples in the examples/ directory.

Status

In pdu.go, the global variable pduTypeDefinition maps the Mandatory Parameters for each PDU type. Particularly, neither SubmitMulti nor SubmitMultiResp are implemented, and messages of this type will neither encode nor decode properly. It requires a bit of extra logic in the code to support these. Additionally, there are no unit tests for a subset of the message types, so their encode/decode methods are not thoroughly tested.