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/
marshal.go
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/
marshal.go
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package rfc5424
import (
"bytes"
"fmt"
"unicode/utf8"
)
// allowLongSdNames is true to allow names longer than the RFC-specified limit
// of 32-characters. (When true, this violates RFC-5424).
const allowLongSdNames = true
// RFC5424TimeOffsetNum is the timestamp defined by RFC-5424 with the
// NUMOFFSET instead of Z.
const RFC5424TimeOffsetNum = "2006-01-02T15:04:05.999999-07:00"
// RFC5424TimeOffsetUTC is the timestamp defined by RFC-5424 with the offset
// set to 0 for UTC.
const RFC5424TimeOffsetUTC = "2006-01-02T15:04:05.999999Z"
// ErrInvalidValue is returned when a log message cannot be emitted because one
// of the values is invalid.
type ErrInvalidValue struct {
Property string
Value interface{}
}
func (e ErrInvalidValue) Error() string {
return fmt.Sprintf("Message cannot be serialized because %s is invalid: %v",
e.Property, e.Value)
}
// invalidValue returns an invalid value error with the given property
func invalidValue(property string, value interface{}) error {
return ErrInvalidValue{Property: property, Value: value}
}
func nilify(x string) string {
if x == "" {
return "-"
}
return x
}
func escapeSDParam(s string) string {
escapeCount := 0
for i := 0; i < len(s); i++ {
switch s[i] {
case '\\', '"', ']':
escapeCount++
}
}
if escapeCount == 0 {
return s
}
t := make([]byte, len(s)+escapeCount)
j := 0
for i := 0; i < len(s); i++ {
switch c := s[i]; c {
case '\\', '"', ']':
t[j] = '\\'
t[j+1] = c
j += 2
default:
t[j] = s[i]
j++
}
}
return string(t)
}
func isPrintableUsASCII(s string) bool {
for _, ch := range s {
if ch < 33 || ch > 126 {
return false
}
}
return true
}
func isValidSdName(s string) bool {
if !allowLongSdNames && len(s) > 32 {
return false
}
for _, ch := range s {
if ch < 33 || ch > 126 {
return false
}
if ch == '=' || ch == ']' || ch == '"' {
return false
}
}
return true
}
func (m Message) assertValid() error {
// HOSTNAME = NILVALUE / 1*255PRINTUSASCII
if !isPrintableUsASCII(m.Hostname) {
return invalidValue("Hostname", m.Hostname)
}
if len(m.Hostname) > 255 {
return invalidValue("Hostname", m.Hostname)
}
// APP-NAME = NILVALUE / 1*48PRINTUSASCII
if !isPrintableUsASCII(m.AppName) {
return invalidValue("AppName", m.AppName)
}
if len(m.AppName) > 48 {
return invalidValue("AppName", m.AppName)
}
// PROCID = NILVALUE / 1*128PRINTUSASCII
if !isPrintableUsASCII(m.ProcessID) {
return invalidValue("ProcessID", m.ProcessID)
}
if len(m.ProcessID) > 128 {
return invalidValue("ProcessID", m.ProcessID)
}
// MSGID = NILVALUE / 1*32PRINTUSASCII
if !isPrintableUsASCII(m.MessageID) {
return invalidValue("MessageID", m.MessageID)
}
if len(m.MessageID) > 32 {
return invalidValue("MessageID", m.MessageID)
}
for _, sdElement := range m.StructuredData {
if !isValidSdName(sdElement.ID) {
return invalidValue("StructuredData/ID", sdElement.ID)
}
for _, sdParam := range sdElement.Parameters {
if !isValidSdName(sdParam.Name) {
return invalidValue("StructuredData/Name", sdParam.Name)
}
if !utf8.ValidString(sdParam.Value) {
return invalidValue("StructuredData/Value", sdParam.Value)
}
}
}
return nil
}
// MarshalBinary marshals the message to a byte slice, or returns an error
func (m Message) MarshalBinary() ([]byte, error) {
if err := m.assertValid(); err != nil {
return nil, err
}
b := bytes.NewBuffer(nil)
fmt.Fprintf(b, "<%d>1 %s %s %s %s %s ",
m.Priority,
m.Timestamp.Format(RFC5424TimeOffsetNum),
nilify(m.Hostname),
nilify(m.AppName),
nilify(m.ProcessID),
nilify(m.MessageID))
if len(m.StructuredData) == 0 {
fmt.Fprint(b, "-")
}
for _, sdElement := range m.StructuredData {
fmt.Fprintf(b, "[%s", sdElement.ID)
for _, sdParam := range sdElement.Parameters {
fmt.Fprintf(b, " %s=\"%s\"", sdParam.Name,
escapeSDParam(sdParam.Value))
}
fmt.Fprintf(b, "]")
}
if len(m.Message) > 0 {
fmt.Fprint(b, " ")
b.Write(m.Message)
}
return b.Bytes(), nil
}