server.go

package harhar

import (
    "bytes"
    "io"
    "log"
    "net/http"
    "time"
)

// ServeHTTP implements http.Handler (aka a Server-side recorder)
func (c *Recorder) ServeHTTP(w http.ResponseWriter, req *http.Request) {
    c.mu.Lock()
    defer c.mu.Unlock()

    var err error
    ent := Entry{}
    ent.Request, err = makeRequest(req)
    if err != nil {
        log.Println("unable to record HAR for request ", req.URL.String())
    }

    responseWrapper := &HARResponseWriter{}

    startTime := time.Now()
    c.Handler.ServeHTTP(responseWrapper, req)
    ent.Time = float64(time.Since(startTime).Milliseconds())
    ent.Start = startTime.Format(time.RFC3339Nano)
    ent.Timings.Send = -1
    ent.Timings.Receive = -1

    // copy headers
    for h, vals := range responseWrapper.header {
        for _, val := range vals {
            w.Header().Set(h, val)
        }
    }
    w.WriteHeader(responseWrapper.statusCode)
    w.Write(responseWrapper.body.Bytes())

    resp := responseWrapper.AsResponse(req)
    ent.Response, err = makeResponse(resp)
    if err != nil {
        log.Println("unable to record HAR for response ", req.URL.String())
    }
    c.HAR.Log.Entries = append(c.HAR.Log.Entries, ent)
}

type HARResponseWriter struct {
    body       bytes.Buffer
    statusCode int
    header     http.Header

    didWriteHeaders bool
}

func (w *HARResponseWriter) Header() http.Header {
    if w.header == nil {
        w.header = make(http.Header, 5)
    }
    return w.header
}

func (w *HARResponseWriter) Write(b []byte) (int, error) {
    if !w.didWriteHeaders {
        w.WriteHeader(http.StatusOK)
    }
    return w.body.Write(b)
}

func (w *HARResponseWriter) WriteHeader(statusCode int) {
    w.statusCode = statusCode
    w.didWriteHeaders = true
}

func (w *HARResponseWriter) AsResponse(req *http.Request) *http.Response {
    resp := &http.Response{
        StatusCode: w.statusCode,
        Proto:      req.Proto,
        Header:     w.header.Clone(),
        Body:       io.NopCloser(bytes.NewReader(w.body.Bytes())),
    }
    return resp
}