pkg/util/*: Add missing function comments.

See,

$ gometalinter --vendor --deadline 10m --disable-all --enable=golint  ./...
encoding.go:15:1:warning: comment on exported function GetRandomString should be of the form "GetRandomString ..." (golint)
encoding.go:30:1:warning: exported function EncodePassword should have comment or be unexported (golint)
encoding.go:35:1:warning: comment on exported function EncodeMd5 should be of the form "EncodeMd5 ..." (golint)
encoding.go:42:1:warning: comment on exported function PBKDF2 should be of the form "PBKDF2 ..." (golint)
encoding.go:80:1:warning: exported function GetBasicAuthHeader should have comment or be unexported (golint)
encoding.go:85:1:warning: exported function DecodeBasicAuthHeader should have comment or be unexported (golint)
encoding.go:105:1:warning: exported function RandomHex should have comment or be unexported (golint)
encryption.go:14:1:warning: exported function Decrypt should have comment or be unexported (golint)
encryption.go:39:1:warning: exported function Encrypt should have comment or be unexported (golint)
ip.go:7:1:warning: exported function SplitIpPort should have comment or be unexported (golint)
json.go:3:6:warning: exported type DynMap should have comment or be unexported (golint)
md5.go:22:1:warning: comment on exported function Md5SumString should be of the form "Md5SumString ..." (golint)
strings.go:10:1:warning: exported function StringsFallback2 should have comment or be unexported (golint)
strings.go:14:1:warning: exported function StringsFallback3 should have comment or be unexported (golint)
strings.go:27:1:warning: exported function SplitString should have comment or be unexported (golint)
strings.go:35:1:warning: exported function GetAgeString should have comment or be unexported (golint)
url.go:8:6:warning: exported type UrlQueryReader should have comment or be unexported (golint)
url.go:12:1:warning: exported function NewUrlQueryReader should have comment or be unexported (golint)
url.go:23:1:warning: exported method UrlQueryReader.Get should have comment or be unexported (golint)
url.go:32:1:warning: exported function JoinUrlFragments should have comment or be unexported (golint)
validation.go:16:1:warning: exported function IsEmail should have comment or be unexported (golint)

pkg/util/encoding.go

@@ -12,6 +12,7 @@ import (
 	"strings"
 )
 
+// GetRandomString generate random string by specify chars.
 // source: https://github.com/gogits/gogs/blob/9ee80e3e5426821f03a4e99fad34418f5c736413/modules/base/tool.go#L58
 func GetRandomString(n int, alphabets ...byte) string {
 	const alphanum = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
@@ -27,18 +28,21 @@ func GetRandomString(n int, alphabets ...byte) string {
 	return string(bytes)
 }
 
+// EncodePassword encodes a password using PBKDF2.
 func EncodePassword(password string, salt string) string {
 	newPasswd := PBKDF2([]byte(password), []byte(salt), 10000, 50, sha256.New)
 	return hex.EncodeToString(newPasswd)
 }
 
-// Encode string to md5 hex value.
+// EncodeMd5 encodes a string to md5 hex value.
 func EncodeMd5(str string) string {
 	m := md5.New()
 	m.Write([]byte(str))
 	return hex.EncodeToString(m.Sum(nil))
 }
 
+// PBKDF2 implements Password-Based Key Derivation Function 2), aimed to reduce
+// the vulnerability of encrypted keys to brute force attacks.
 // http://code.google.com/p/go/source/browse/pbkdf2/pbkdf2.go?repo=crypto
 func PBKDF2(password, salt []byte, iter, keyLen int, h func() hash.Hash) []byte {
 	prf := hmac.New(h, password)
@@ -77,11 +81,13 @@ func PBKDF2(password, salt []byte, iter, keyLen int, h func() hash.Hash) []byte
 	return dk[:keyLen]
 }
 
+// GetBasicAuthHeader returns a base64 encoded string from user and password.
 func GetBasicAuthHeader(user string, password string) string {
 	var userAndPass = user + ":" + password
 	return "Basic " + base64.StdEncoding.EncodeToString([]byte(userAndPass))
 }
 
+// DecodeBasicAuthHeader decodes user and password from a basic auth header.
 func DecodeBasicAuthHeader(header string) (string, string, error) {
 	var code string
 	parts := strings.SplitN(header, " ", 2)
@@ -102,6 +108,7 @@ func DecodeBasicAuthHeader(header string) (string, string, error) {
 	return userAndPass[0], userAndPass[1], nil
 }
 
+// RandomHex returns a random string from a n seed.
 func RandomHex(n int) (string, error) {
 	bytes := make([]byte, n)
 	if _, err := rand.Read(bytes); err != nil {

pkg/util/encryption.go

@@ -11,6 +11,7 @@ import (
 
 const saltLength = 8
 
+// Decrypt decrypts a payload with a given secret.
 func Decrypt(payload []byte, secret string) ([]byte, error) {
 	salt := payload[:saltLength]
 	key := encryptionKeyToBytes(secret, string(salt))
@@ -36,6 +37,7 @@ func Decrypt(payload []byte, secret string) ([]byte, error) {
 	return payloadDst, nil
 }
 
+// Encrypt encrypts a payload with a given secret.
 func Encrypt(payload []byte, secret string) ([]byte, error) {
 	salt := GetRandomString(saltLength)
 

pkg/util/ip.go

@@ -4,6 +4,7 @@ import (
 	"net"
 )
 
+// SplitIpPort splits the ip string and port.
 func SplitIpPort(ipStr string, portDefault string) (ip string, port string, err error) {
 	ipAddr := net.ParseIP(ipStr)
 

pkg/util/json.go

 package util
 
+// DynMap defines a dynamic map interface.
 type DynMap map[string]interface{}

pkg/util/md5.go

@@ -19,7 +19,7 @@ func Md5Sum(reader io.Reader) (string, error) {
 	return returnMD5String, nil
 }
 
-// Md5Sum calculates the md5sum of a string
+// Md5SumString calculates the md5sum of a string
 func Md5SumString(input string) (string, error) {
 	buffer := strings.NewReader(input)
 	return Md5Sum(buffer)

pkg/util/strings.go

@@ -7,10 +7,12 @@ import (
 	"time"
 )
 
+// StringsFallback2 returns the first of two not empty strings.
 func StringsFallback2(val1 string, val2 string) string {
 	return stringsFallback(val1, val2)
 }
 
+// StringsFallback3 returns the first of three not empty strings.
 func StringsFallback3(val1 string, val2 string, val3 string) string {
 	return stringsFallback(val1, val2, val3)
 }
@@ -24,6 +26,7 @@ func stringsFallback(vals ...string) string {
 	return ""
 }
 
+// SplitString splits a string by commas or empty spaces.
 func SplitString(str string) []string {
 	if len(str) == 0 {
 		return []string{}
@@ -32,6 +35,7 @@ func SplitString(str string) []string {
 	return regexp.MustCompile("[, ]+").Split(str, -1)
 }
 
+// GetAgeString returns a string representing certain time from years to minutes.
 func GetAgeString(t time.Time) string {
 	if t.IsZero() {
 		return "?"

pkg/util/url.go

@@ -5,10 +5,12 @@ import (
 	"strings"
 )
 
+// UrlQueryReader is a URL query type.
 type UrlQueryReader struct {
 	values url.Values
 }
 
+// NewUrlQueryReader parses a raw query and returns it as a UrlQueryReader type.
 func NewUrlQueryReader(urlInfo *url.URL) (*UrlQueryReader, error) {
 	u, err := url.ParseQuery(urlInfo.RawQuery)
 	if err != nil {
@@ -20,6 +22,8 @@ func NewUrlQueryReader(urlInfo *url.URL) (*UrlQueryReader, error) {
 	}, nil
 }
 
+// Get parse parameters from an URL. If the parameter does not exist, it returns
+// the default value.
 func (r *UrlQueryReader) Get(name string, def string) string {
 	val := r.values[name]
 	if len(val) == 0 {
@@ -29,6 +33,7 @@ func (r *UrlQueryReader) Get(name string, def string) string {
 	return val[0]
 }
 
+// JoinUrlFragments joins two URL fragments into only one URL string.
 func JoinUrlFragments(a, b string) string {
 	aslash := strings.HasSuffix(a, "/")
 	bslash := strings.HasPrefix(b, "/")

pkg/util/validation.go

@@ -13,6 +13,7 @@ var (
 	regexEmail = regexp.MustCompile(emailRegexPattern)
 )
 
+// IsEmail checks if a string is a valid email address.
 func IsEmail(str string) bool {
 	return regexEmail.MatchString(strings.ToLower(str))
 }