104 lines
2.4 KiB
Go
104 lines
2.4 KiB
Go
package logging
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import (
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"fmt"
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"log"
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"net"
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"net/http"
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"strconv"
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"strings"
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"time"
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)
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// ---------- Access logging ----------
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// statusRecorder captures the status code and body size for the access log.
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type statusRecorder struct {
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http.ResponseWriter
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status int
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bytes int
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}
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func (r *statusRecorder) WriteHeader(code int) {
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if r.status == 0 {
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r.status = code
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}
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r.ResponseWriter.WriteHeader(code)
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}
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func (r *statusRecorder) Write(b []byte) (int, error) {
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if r.status == 0 {
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r.status = http.StatusOK
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}
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n, err := r.ResponseWriter.Write(b)
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r.bytes += n
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return n, err
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}
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// logField escapes a value for a quoted log field the way nginx does
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// (quotes, backslashes and control characters become \xHH) and uses "-"
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// for empty values.
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func logField(s string) string {
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if s == "" {
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return "-"
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}
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var b strings.Builder
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for i := 0; i < len(s); i++ {
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c := s[i]
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if c == '"' || c == '\\' || c < 0x20 || c == 0x7f {
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fmt.Fprintf(&b, "\\x%02X", c)
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} else {
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b.WriteByte(c)
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}
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}
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return b.String()
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}
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// clientKey attempts to produce a client host name as a key identifier to split
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// requests in the log between sources. Could be extended to also check
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// Forwarded-For or other proxy headers
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func clientKey(req *http.Request) string {
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host, _, err := net.SplitHostPort(req.RemoteAddr)
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if err != nil {
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return req.RemoteAddr
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}
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return host
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}
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// AccessLog wraps next, writing a line to logger for each request in the
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// Apache/nginx Common Log Format, or the Combined Log Format (which adds the
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// referer and user agent) if combined is true.
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func AccessLog(logger *log.Logger, combined bool, next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
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start := time.Now()
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rec := &statusRecorder{ResponseWriter: w}
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next.ServeHTTP(rec, req)
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if rec.status == 0 {
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rec.status = http.StatusOK
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}
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user := "-"
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if u, _, ok := req.BasicAuth(); ok && u != "" {
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user = logField(u)
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}
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size := "-" // CLF uses "-" for an empty body
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if rec.bytes > 0 {
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size = strconv.Itoa(rec.bytes)
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}
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line := fmt.Sprintf(`%s - %s [%s] "%s" %d %s`,
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clientKey(req),
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user,
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start.Format("02/Jan/2006:15:04:05 -0700"),
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logField(req.Method+" "+req.RequestURI+" "+req.Proto),
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rec.status,
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size,
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)
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if combined {
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line += fmt.Sprintf(
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` "%s" "%s"`, logField(req.Referer()), logField(req.UserAgent()),
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)
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}
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logger.Println(line)
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})
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}
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