prologic-saltyim/lookup.go

package saltyim

import (
	"crypto/sha256"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"strings"

	log "github.com/sirupsen/logrus"
)

// Addr represents a Salty IM User's Address
type Addr struct {
	User   string
	Domain string
}

// IsZero returns true if the address is empty
func (a Addr) IsZero() bool {
	return a.User == "" && a.Domain == ""
}

func (a Addr) String() string {
	return fmt.Sprintf("%s@%s", a.User, a.Domain)
}

// Formatted returns a formatted user used in the Salty Message Format
// <timestamp\t(<user>) <message>\n
func (a Addr) Formatted() string {
	return fmt.Sprintf("(%s)", a)
}

// URI returns the Well-Known URI for this Addr
func (a Addr) URI() string {
	return fmt.Sprintf("https://%s/.well-known/salty/%s.json", a.Domain, a.User)
}

// HashURI returns the Well-Known HashURI for this Addr
func (a Addr) HashURI() string {
	return fmt.Sprintf("https://%s/.well-known/salty/%x.json", a.Domain, sha256.Sum256([]byte(a.String())))
}

// ParseAddr parsers a Salty Address for a user into it's user and domain
// parts and returns an Addr object with the User and Domain and a method
// for returning the expected User's Well-Known URI
func ParseAddr(addr string) (Addr, error) {
	parts := strings.Split(addr, "@")
	if len(parts) != 2 {
		return Addr{}, fmt.Errorf("expected nick@domain found %q", addr)
	}

	return Addr{parts[0], parts[1]}, nil
}

// Lookup looks up a Salty Address for a User by parsing the user's domain and
// making a request to the user's Well-Known URI expected to be located at
// https://domain/.well-known/salty/<user>.json
func Lookup(addr string) (Config, error) {
	a, err := ParseAddr(addr)
	if err != nil {
		log.WithError(err).Errorf("error parsing addr %q", addr)
		return Config{}, err
	}

	// Attempt using hash
	res, err := Request(http.MethodGet, a.HashURI(), nil, nil)
	if err != nil {
		// Fallback to plain user nick
		res, err = Request(http.MethodGet, a.URI(), nil, nil)
	}
	if err != nil {
		log.WithError(err).Error("error requesting well-known uri")
		return Config{}, err
	}

	data, err := ioutil.ReadAll(res.Body)
	if err != nil {
		log.WithError(err).Errorf("error reading well-known config")
		return Config{}, err
	}

	var config Config
	if err := json.Unmarshal(data, &config); err != nil {
		log.WithError(err).Error("error parsing well-known config")
		return Config{}, err
	}

	return config, err
}