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package loop
// Copyright (c) 2013-2017 The btcsuite developers
// Copyright (c) 2015-2016 The Decred developers
// Heavily inspired by
// Copyright (C) 2015-2020 The Lightning Network Developers
import (
// Commit stores the current commit hash of this build, this should be set
// using the -ldflags during compilation.
var Commit string
// semanticAlphabet is the allowed characters from the semantic versioning
// guidelines for pre-release version and build metadata strings. In particular
// they MUST only contain characters in semanticAlphabet.
const semanticAlphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-"
// These constants define the application version and follow the semantic
// versioning 2.0.0 spec (
const (
// Note: please update when you change these values.
appMajor uint = 0
appMinor uint = 11
appPatch uint = 1
// appPreRelease MUST only contain characters from semanticAlphabet per
// the semantic versioning spec.
appPreRelease = "beta"
// defaultAgentName is the default name of the software that is added as
// the first part of the user agent string.
defaultAgentName = "loopd"
// AgentName stores the name of the software that is added as the first part of
// the user agent string. This defaults to the value "loopd" when being run as
// a standalone component but can be overwritten by LiT for example when loopd
// is integrated into the UI.
var AgentName = defaultAgentName
// Version returns the application version as a properly formed string per the
// semantic versioning 2.0.0 spec ( and the commit it was
// built on.
func Version() string {
// Append commit hash of current build to version.
return fmt.Sprintf("%s commit=%s", semanticVersion(), Commit)
// UserAgent returns the full user agent string that identifies the software
// that is submitting swaps to the loop server.
func UserAgent(initiator string) string {
// We'll only allow "safe" characters in the initiator portion of the
// user agent string and spaces only if surrounded by other characters.
initiatorAlphabet := semanticAlphabet + ". "
cleanInitiator := normalizeVerString(
strings.TrimSpace(initiator), initiatorAlphabet,
if len(cleanInitiator) > 0 {
cleanInitiator = fmt.Sprintf(",initiator=%s", cleanInitiator)
// The whole user agent string is limited to 255 characters server side
// and also consists of the agent name, version and commit. So we only
// want to take up at most 150 characters for the initiator. Anything
// more will just be dropped.
strLen := len(cleanInitiator)
cleanInitiator = cleanInitiator[:int(math.Min(float64(strLen), 150))]
// Assemble full string, including the commit hash of current build.
return fmt.Sprintf(
"%s/v%s/commit=%s%s", AgentName, semanticVersion(), Commit,
// semanticVersion returns the SemVer part of the version.
func semanticVersion() string {
// Start with the major, minor, and patch versions.
version := fmt.Sprintf("%d.%d.%d", appMajor, appMinor, appPatch)
// Append pre-release version if there is one. The hyphen called for
// by the semantic versioning spec is automatically appended and should
// not be contained in the pre-release string. The pre-release version
// is not appended if it contains invalid characters.
preRelease := normalizeVerString(appPreRelease, semanticAlphabet)
if preRelease != "" {
version = fmt.Sprintf("%s-%s", version, preRelease)
return version
// normalizeVerString returns the passed string stripped of all characters
// which are not valid according to the given alphabet.
func normalizeVerString(str, alphabet string) string {
var result bytes.Buffer
for _, r := range str {
if strings.ContainsRune(alphabet, r) {
return result.String()