lti

README

This project is under development. There are no API stabiltiy guarantees at this point.

Go-LTI

Implementation of LTI 1.0 Protocol in Go.

Currently there are a few major missing features such as the implementation of Tool Consumer, common cartridge parsing, proper nonce and timestamp verification.

Tool Provider Usage

Tool Provider wraps a http.Request and provides easy access to LTI headers, Validation of LTI requests and creation of return URLS.

LTI headers are deserialized into a LTIStdHeaders struct which can be accessed from the LTIHeaders attribute of an LTIToolProvider.

func Handler(w http.ResponseWriter, r *http.Request) {
	
    // Create a new LTIToolProvider
	ltiRequest, err := lti.NewLTIToolProvider(r)
    
    // Validate LTI request
    valid, err := ltiRequest.ValidateRequest(secretKey, false, false)
    
	if valid == true {
    
        // Access some LTI Header
    	fmt.Println(ltiRequest.LTIHeaders.LISPersonFamilyName)
        
    } else {
    
    	// Redirect to return URL
        returnUrl, _ = ltiRequest.CreateReturnURL()
        http.Redirect(w, r, returnUrl.String(), http.StatusMovedPermanently)
    
    }
}

Documentation

Overview

Implementation of LTI 1.0 Protocol in Go.

Currently there are a few major missing features such as the implementation of Tool Consumer, common cartridge parsing, proper nonce and timestamp verification.

Tool Provider Usage

Tool Provider wraps a http.Request and provides easy access to LTI headers, Validation of LTI requests and creation of return URLS.

LTI headers are deserialized into a LTIStdHeaders struct which can be accessed from the LTIHeaders attribute of an LTIToolProvider.

func Handler(w http.ResponseWriter, r *http.Request) {

    // Create a new LTIToolProvider
	ltiRequest, err := lti.NewLTIToolProvider(r)

    // Validate LTI request
    valid, err := ltiRequest.ValidateRequest(secretKey, false, false)

	if valid == true {

        // Access some LTI Header
    	fmt.Println(ltiRequest.LTIHeaders.LISPersonFamilyName)

    } else {

    	// Redirect to return URL
        returnUrl, _ = ltiRequest.CreateReturnURL()
        http.Redirect(w, r, returnUrl.String(), http.StatusMovedPermanently)

    }
}

Index

• Constants
• Variables
• type LTIStdHeaders
  • func ParseXMLEncodedFile(filename string) (*LTIStdHeaders, error)
• type LTIStdResponse
  • func NewLTIErrorResponse(errMsg, logMsg string, statusCode int) *LTIStdResponse
  • func NewLTIStdResponse(respMsg, logMsg string, statusCode int) *LTIStdResponse
  • func (l *LTIStdResponse) Serialize() (string, error)
• type LTIToolConsumer
  • func NewLTIToolConsumer() *LTIToolConsumer
  • func (c *LTIToolConsumer) SendLTIReqeust(l *LTIStdHeaders) (*http.Response, error)
• type LTIToolProvider
  • func NewLTIToolProvider(r *http.Request) (*LTIToolProvider, error)
  • func (tp *LTIToolProvider) CreateReturnURL() (*url.URL, error)
  • func (tp *LTIToolProvider) SetProxyPathPrefix(proxyPath string)
  • func (tp *LTIToolProvider) SetProxyScheme(scheme string)
  • func (tp *LTIToolProvider) ValidateRequest(consumerSecret string, checkTimestamp, checkNonce bool, forceTLS bool, ...) (bool, error)

Constants

const (
	ContextID    = "context_id"
	ContextLabel = "context_label"
	ContextTitle = "context_title"
	ContextType  = "context_type"

	LaunchPresHeight    = "launch_presentation_height"
	LaunchPresLocale    = "launch_presentation_locale"
	LaunchPresTarget    = "launch_presentation_document_target"
	LaunchPresReturnURL = "launch_presentation_return_url"
	LaunchPresWidth     = "launch_presentation_width"

	LISCourseOfferingSID = "lis_course_offering_sourcedid"
	LISCourseSectionSID  = "lis_course_section_sourcedid"

	LISPersonFamilyName   = "lis_person_name_family"
	LISPersonFullName     = "lis_person_name_full"
	LISPersonGivenName    = "lis_person_name_given"
	LISPersonPrimaryEmail = "lis_person_contact_email_primary"
	LISPersonSID          = "lis_person_sourcedid"

	LISResultSID = "lis_result_souredid"

	LTIMessageType = "lti_message_type"
	LTIVersion     = "lti_version"

	OAuthCallback        = "oauth_callback"
	OAuthConsumerKey     = "oauth_consumer_key"
	OAuthNonce           = "oauth_nonce"
	OAuthSignature       = "oauth_signature"
	OAuthSignatureMethod = "oauth_signature_method"
	OAuthTimestamp       = "oauth_timestamp"
	OAuthVersion         = "oauth_version"

	ResourceLinkID    = "resource_link_id"
	ResourceLinkTitle = "resource_link_title"
	ResourceLinkDesc  = "resource_link_description"

	Roles = "roles"

	ToolConsumerInstGUID         = "tool_consumer_instance_guid"
	ToolConsumerInstName         = "tool_consumer_instance_name"
	ToolConsumerInstDesc         = "tool_consumer_instance_description"
	ToolConsumerInstURL          = "tool_consumer_instance_url"
	ToolConsumerInstContactEmail = "tool_consumer_instance_contact_email"

	UserId    = "user_id"
	UserImage = "user_image"
)

Variables

var (
	// Resource Link ID errors
	ErrLogUnknownResourceLinkId = errors.New(errLogBase + "Provided Resource Link ID does not have an associated resource.")
)

Exported errors

var OAuthTimestampValidationRange time.Duration = time.Minute * 10

Types

type LTIStdHeaders

type LTIStdHeaders struct {
	ContextID    string                `json:"context_id" url:"context_id,omitempty"`
	ContextLabel string                `json:"context_label" url:"context_label,omitempty"`
	ContextTitle string                `json:"context_title" url:"context_title,omitempty"`
	ContextType  *types.LTIContextType `json:"context_type" url:"context_type,omitempty"`

	LaunchPresHeight    string `json:"launch_presentation_height" url:"launch_presentation_height,omitempty"`
	LaunchPresLocale    string `json:"launch_presentation_locale" url:"launch_presentation_locale,omitempty"`
	LaunchPresTarget    string `json:"launch_presentation_document_target" url:"launch_presentation_document_target,omitempty"`
	LaunchPresReturnURL string `json:"launch_presentation_return_url" url:"launch_presentation_return_url,omitempty"`
	LaunchPresWidth     string `json:"launch_presentation_width" url:"launch_presentation_width,omitempty"`

	LISCourseOfferingSID string `json:"lis_course_offering_sourcedid" url:"lis_course_offering_sourcedid,omitempty"`
	LISCourseSectionSID  string `json:"lis_course_section_sourcedid" url:"lis_course_section_sourcedid,omitempty"`

	LISPersonFamilyName   string `json:"lis_person_name_family" url:"lis_person_name_family,omitempty"`
	LISPersonFullName     string `json:"lis_person_name_full" url:"lis_person_name_full,omitempty"`
	LISPersonGivenName    string `json:"lis_person_name_given" url:",omitempty"`
	LISPersonPrimaryEmail string `json:"lis_person_contact_email_primary" url:"lis_person_contact_email_primary,omitempty"`
	LISPersonSID          string `json:"lis_person_sourcedid" url:"lis_person_sourcedid,omitempty"`

	LISResultSID string `json:"lis_result_souredid" url:"lis_result_souredid,omitempty"`

	LTIMessageType types.LTIMessage `json:"lti_message_type" url:"lti_message_type,omitempty"`
	LTIVersion     types.LTIVersion `json:"lti_version" url:"lti_version,omitempty"`

	OAuthCallback        string `json:"oauth_callback" url:"oauth_callback,omitempty"`
	OAuthConsumerKey     string `json:"oauth_consumer_key" url:"oauth_consumer_key,omitempty"`
	OAuthNonce           string `json:"oauth_nonce" url:"oauth_nonce,omitempty"`
	OAuthSignature       string `json:"oauth_signature" url:"oauth_signature,omitempty"`
	OAuthSignatureMethod string `json:"oauth_signature_method" url:"oauth_signature_method,omitempty"`
	OAuthTimestamp       int    `json:"oauth_timestamp" url:"oauth_timestamp,omitempty"`
	OAuthVersion         string `json:"oauth_version" url:"oauth_version,omitempty"`

	ResourceLinkID    string `json:"resource_link_id" url:"resource_link_id,omitempty"`
	ResourceLinkTitle string `json:"resource_link_title" url:"resource_link_title,omitempty"`
	ResourceLinkDesc  string `json:"resource_link_description" url:"resource_link_description,omitempty"`

	Roles *types.LTIRoles `json:"roles" url:"roles,omitempty"`

	ToolConsumerInstGUID         string `json:"tool_consumer_instance_guid" url:"tool_consumer_instance_guid,omitempty"`
	ToolConsumerInstName         string `json:"tool_consumer_instance_name" url:"tool_consumer_instance_name,omitempty"`
	ToolConsumerInstDesc         string `json:"tool_consumer_instance_description" url:"tool_consumer_instance_description,omitempty"`
	ToolConsumerInstURL          string `json:"tool_consumer_instance_url" url:"tool_consumer_instance_url,omitempty"`
	ToolConsumerInstContactEmail string `json:"tool_consumer_instance_contact_email" url:"tool_consumer_instance_contact_email,omitempty"`

	UserId    string `json:"user_id" schema:"user_id" url:"user_id,omitempty"`
	UserImage string `json:"user_image" schema:"user_image" url:"user_image,omitempty"`
}

func ParseXMLEncodedFile

func ParseXMLEncodedFile(filename string) (*LTIStdHeaders, error)

**Not implemented**

type LTIStdResponse

type LTIStdResponse struct {
	LTIMessage      string `url:"lti_msg,omitempty"`
	LTIErrorMessage string `url:"lti_errormsg,omitempty"`
	LTILog          string `url:"lti_log,omitempty"`
	LTIErrorLog     string `url:"lti_errorlog,omitempty"`

	StatusCode int `url:"-"`
}

LTIStdResponse provides ability to serialize LTI response messages per LTI 1.0 spec.

func NewLTIErrorResponse

func NewLTIErrorResponse(errMsg, logMsg string, statusCode int) *LTIStdResponse

Create a new LTI response with provided user error message, error log message and error status code.

func NewLTIStdResponse

func NewLTIStdResponse(respMsg, logMsg string, statusCode int) *LTIStdResponse

Create a new LTI response with provided user message, log message and status code.

func (*LTIStdResponse) Serialize

func (l *LTIStdResponse) Serialize() (string, error)

Serialize LTI response fields into encoded URL query string.

type LTIToolConsumer

type LTIToolConsumer struct {
	LTIHeaders LTIStdHeaders
}

Tool consumer is not yet implemnted.

func NewLTIToolConsumer

func NewLTIToolConsumer() *LTIToolConsumer

**Not implemented**

func (*LTIToolConsumer) SendLTIReqeust

func (c *LTIToolConsumer) SendLTIReqeust(l *LTIStdHeaders) (*http.Response, error)

**Not implemented**

type LTIToolProvider

type LTIToolProvider struct {
	LTIHeaders  *LTIStdHeaders
	LTIResponse *LTIStdResponse
	// contains filtered or unexported fields
}

Tool provider wraps a provided http.Request, parses the LTI headers and allows for access to standard LTI Header fields as well as validation of LTI request.

func NewLTIToolProvider

func NewLTIToolProvider(r *http.Request) (*LTIToolProvider, error)

Create a new LTIToolProvide and set the LTIHeaders attribute to the parsed http.Request payload. Accepts URL encoded forms per LTI 1.0 spec and additionally supports also JSON payloads.

func (*LTIToolProvider) CreateReturnURL

func (tp *LTIToolProvider) CreateReturnURL() (*url.URL, error)

If the LTI request provided a return URL, serialize the LTIResponse and create a return URL from it.

func (*LTIToolProvider) SetProxyPathPrefix

func (tp *LTIToolProvider) SetProxyPathPrefix(proxyPath string)

IF a request is being proxied passed, the original request host information is overwritten by the proxying host. Use this to correctly set the desired host.

TODO remove this, pull proxy path from headers

func (*LTIToolProvider) SetProxyScheme

func (tp *LTIToolProvider) SetProxyScheme(scheme string)

func (*LTIToolProvider) ValidateRequest

func (tp *LTIToolProvider) ValidateRequest(consumerSecret string, checkTimestamp, checkNonce bool, forceTLS bool, transformPath func(string) string) (bool, error)

Validate that the LTI request was signed with the provided consumer secret.

TODO Implement nonce checking and better timestamp checking.