143 lines
3.3 KiB
Go
143 lines
3.3 KiB
Go
// +build darwin dragonfly freebsd linux netbsd openbsd solaris
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package logging
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import (
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"fmt"
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"log"
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"log/syslog"
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"strconv"
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)
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// Errors related to parsing priority
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var (
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ErrPriorityNoStart = fmt.Errorf("No start char found for priority")
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ErrPriorityEmpty = fmt.Errorf("Priority field empty")
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ErrPriorityNoEnd = fmt.Errorf("No end char found for priority")
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ErrPriorityTooShort = fmt.Errorf("Priority field too short")
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ErrPriorityTooLong = fmt.Errorf("Priority field too long")
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ErrPriorityNonDigit = fmt.Errorf("Non digit found in priority")
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)
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// Priority header and ending characters
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const (
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PRI_PART_START = '<'
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PRI_PART_END = '>'
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)
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// SyslogMessage represents a log line received
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type SyslogMessage struct {
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Message []byte
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Severity syslog.Priority
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}
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// Priority holds all the priority bits in a syslog log line
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type Priority struct {
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Pri int
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Facility syslog.Priority
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Severity syslog.Priority
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}
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// DockerLogParser parses a line of log message that the docker daemon ships
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type DockerLogParser struct {
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logger *log.Logger
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}
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// NewDockerLogParser creates a new DockerLogParser
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func NewDockerLogParser(logger *log.Logger) *DockerLogParser {
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return &DockerLogParser{logger: logger}
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}
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// Parse parses a syslog log line
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func (d *DockerLogParser) Parse(line []byte) *SyslogMessage {
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pri, _, _ := d.parsePriority(line)
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msgIdx := d.logContentIndex(line)
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// Create a copy of the line so that subsequent Scans do not override the
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// message
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lineCopy := make([]byte, len(line[msgIdx:]))
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copy(lineCopy, line[msgIdx:])
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return &SyslogMessage{
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Severity: pri.Severity,
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Message: lineCopy,
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}
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}
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// logContentIndex finds out the index of the start index of the content in a
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// syslog line
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func (d *DockerLogParser) logContentIndex(line []byte) int {
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cursor := 0
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numSpace := 0
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for i := 0; i < len(line); i++ {
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if line[i] == ' ' {
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numSpace += 1
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if numSpace == 1 {
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cursor = i
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break
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}
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}
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}
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for i := cursor; i < len(line); i++ {
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if line[i] == ':' {
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cursor = i
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break
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}
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}
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return cursor + 1
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}
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// parsePriority parses the priority in a syslog message
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func (d *DockerLogParser) parsePriority(line []byte) (Priority, int, error) {
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cursor := 0
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pri := d.newPriority(0)
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if len(line) <= 0 {
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return pri, cursor, ErrPriorityEmpty
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}
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if line[cursor] != PRI_PART_START {
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return pri, cursor, ErrPriorityNoStart
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}
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i := 1
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priDigit := 0
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for i < len(line) {
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if i >= 5 {
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return pri, cursor, ErrPriorityTooLong
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}
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c := line[i]
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if c == PRI_PART_END {
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if i == 1 {
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return pri, cursor, ErrPriorityTooShort
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}
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cursor = i + 1
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return d.newPriority(priDigit), cursor, nil
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}
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if d.isDigit(c) {
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v, e := strconv.Atoi(string(c))
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if e != nil {
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return pri, cursor, e
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}
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priDigit = (priDigit * 10) + v
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} else {
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return pri, cursor, ErrPriorityNonDigit
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}
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i++
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}
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return pri, cursor, ErrPriorityNoEnd
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}
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// isDigit checks if a byte is a numeric char
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func (d *DockerLogParser) isDigit(c byte) bool {
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return c >= '0' && c <= '9'
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}
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// newPriority creates a new default priority
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func (d *DockerLogParser) newPriority(p int) Priority {
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// The Priority value is calculated by first multiplying the Facility
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// number by 8 and then adding the numerical value of the Severity.
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return Priority{
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Pri: p,
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Facility: syslog.Priority(p / 8),
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Severity: syslog.Priority(p % 8),
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}
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}
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