Useful http debugging file. Replaces http.DefaultTransport with a logger of all http traffic.

debug.go

package main

import (
        "fmt"
        "io"
        "net/http"
        "net/http/httputil"
        "os"
)

func init() {
        http.DefaultTransport = wrapRoundTripper(http.DefaultTransport, os.Stdout)
}

func wrapRoundTripper(in http.RoundTripper, log io.Writer) http.RoundTripper {
        return &loggingRoundTripper{inner: in, logger: log}
}

type loggingRoundTripper struct {
        inner  http.RoundTripper
        logger io.Writer
}

func (d *loggingRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
        d.dumpRequest(req)
        res, err := d.inner.RoundTrip(req)
        d.dumpResponse(res)
        return res, err
}

func (d *loggingRoundTripper) dumpRequest(r *http.Request) {
        dump, err := httputil.DumpRequestOut(r, true)
        if err != nil {
                fmt.Fprintf(d.logger, "\n\tERROR dumping: %v\n", err)
        }
        d.dump("REQUEST", dump)
}

func (d *loggingRoundTripper) dumpResponse(r *http.Response) {
        dump, err := httputil.DumpResponse(r, true)
        if err != nil {
                fmt.Fprintf(d.logger, "\n\tERROR dumping: %v\n", err)
        }
        d.dump("RESPONSE", dump)
}

func (d *loggingRoundTripper) dump(label string, dump []byte) {
        fmt.Fprintf(d.logger, "\n------------------------------------------------------------\n")
        defer fmt.Fprintf(d.logger, "\n------------------------------------------------------------\n")

        fmt.Fprintf(d.logger, "%s:\n--\n%s", label, string(dump))
}