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package snowflake_client
import (
"bytes"
"errors"
"io"
"log"
"math/rand"
"net/http"
"net/url"
"time"
)
// httpRendezvous is a RendezvousMethod that communicates with the .../client
// route of the broker over HTTP or HTTPS, with optional domain fronting.
type httpRendezvous struct {
brokerURL *url.URL
fronts []string // Optional front domain to replace url.Host in requests.
transport http.RoundTripper // Used to make all requests.
}
// newHTTPRendezvous creates a new httpRendezvous that contacts the broker at
// the given URL, with an optional front domain. transport is the
// http.RoundTripper used to make all requests.
func newHTTPRendezvous(broker string, fronts []string, transport http.RoundTripper) (*httpRendezvous, error) {
brokerURL, err := url.Parse(broker)
if err != nil {
return nil, err
}
return &httpRendezvous{
brokerURL: brokerURL,
fronts: fronts,
transport: transport,
}, nil
}
func (r *httpRendezvous) Exchange(encPollReq []byte) ([]byte, error) {
log.Println("Negotiating via HTTP rendezvous...")
log.Println("Target URL: ", r.brokerURL.Host)
// Suffix the path with the broker's client registration handler.
reqURL := r.brokerURL.ResolveReference(&url.URL{Path: "client"})
req, err := http.NewRequest("POST", reqURL.String(), bytes.NewReader(encPollReq))
if err != nil {
return nil, err
}
if len(r.fronts) != 0 {
// Do domain fronting. Replace the domain in the URL's with a randomly
// selected front, and store the original domain the HTTP Host header.
rand.Seed(time.Now().UnixNano())
front := r.fronts[rand.Intn(len(r.fronts))]
log.Println("Front URL: ", front)
req.Host = req.URL.Host
req.URL.Host = front
}
resp, err := r.transport.RoundTrip(req)
if err != nil {
return nil, err
}
defer resp.Body.Close()
log.Printf("HTTP rendezvous response: %s", resp.Status)
if resp.StatusCode != http.StatusOK {
return nil, errors.New(brokerErrorUnexpected)
}
return limitedRead(resp.Body, readLimit)
}
func limitedRead(r io.Reader, limit int64) ([]byte, error) {
p, err := io.ReadAll(&io.LimitedReader{R: r, N: limit + 1})
if err != nil {
return p, err
} else if int64(len(p)) == limit+1 {
return p[0:limit], io.ErrUnexpectedEOF
}
return p, err
}
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