cloudfoundry/dea_ng

package directoryserver

import (
    "encoding/json"
    "errors"
    "fmt"
    "io"
    "net/http"
)

type DeaClient struct {
    Host string
    Port uint16
}

var (
    ErrUnreachable = errors.New("DEA is unreachable")
    ErrNotOK       = errors.New("DEA did not respond with 200 status")
    ErrInvalidJson = errors.New("DEA responded with invalid JSON")
)

// LookupPath makes a request to a DEA on behalf of the specified request.
// On errors, it writes the error to the specified response writer and returns
// one of the defined errors to the caller.
// On success, it returns the path extracted from the DEA response.
func (x *DeaClient) LookupPath(w http.ResponseWriter, r *http.Request) (string, error) {
    y := fmt.Sprintf("http://%s:%d%s", x.Host, x.Port, r.URL.String())

    log.Infof("Sending HTTP request to DEA: %s", y)

    res, err := http.Get(y)
    if err != nil {
        http.Error(w, ErrUnreachable.Error(), http.StatusInternalServerError)
        return "", ErrUnreachable
    }

    defer res.Body.Close()

    if res.StatusCode != 200 {
        // Forward DEA response
        for h, i := range res.Header {
            w.Header().Del(h)
            for _, j := range i {
                w.Header().Add(h, j)
            }
        }

        w.WriteHeader(res.StatusCode)
        io.Copy(w, res.Body)
        return "", ErrNotOK
    }

    d := json.NewDecoder(res.Body)
    m := make(map[string]interface{})
    err = d.Decode(&m)
    if err != nil {
        http.Error(w, ErrInvalidJson.Error(), http.StatusInternalServerError)
        return "", ErrInvalidJson
    }

    p, ok := m["instance_path"].(string)
    if !ok {
        http.Error(w, ErrInvalidJson.Error(), http.StatusInternalServerError)
        return "", ErrInvalidJson
    }

    return p, nil
}