d45e58c14f
Part of https://github.com/ooni/ooni.org/issues/361 Co-authored-by: Arturo Filastò <arturo@openobservatory.org>
135 lines
4.0 KiB
Go
135 lines
4.0 KiB
Go
// -=-=- StartHere -=-=-
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//
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// # Chapter VII: HTTPSSvc DNS queries
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//
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// The program we see here is _really_ similar to the one we
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// discussed in the previous chapter. The main difference
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// is the following: now we also issue HTTPSSvc DNS queries
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// to discover HTTP/3 endpoints. (Because HTTPSSvc is
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// still a draft and is mostly implemented by Cloudflare
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// at this point, we are going to use as the example
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// input URL a Cloudflare URL.)
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//
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// (This file is auto-generated. Do not edit it directly! To apply
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// changes you need to modify `./internal/tutorial/measurex/chapter08/main.go`.)
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//
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// ## main.go
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//
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// The beginning of the program is pretty much the same. We
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// have just amended our `measurement` type to contain multiple
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// `DNSMeasurement` results.
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//
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// ```Go
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package main
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import (
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"context"
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"encoding/json"
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"flag"
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"fmt"
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"net/url"
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"time"
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"github.com/ooni/probe-cli/v3/internal/measurex"
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"github.com/ooni/probe-cli/v3/internal/runtimex"
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)
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type measurement struct {
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DNS []*measurex.DNSMeasurement
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Endpoints []*measurex.HTTPEndpointMeasurement
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}
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func print(v interface{}) {
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data, err := json.Marshal(v)
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runtimex.PanicOnError(err, "json.Marshal failed")
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fmt.Printf("%s\n", string(data))
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}
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func main() {
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URL := flag.String("url", "https://blog.cloudflare.com/", "URL to fetch")
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address := flag.String("address", "8.8.4.4:53", "DNS-over-UDP server address")
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timeout := flag.Duration("timeout", 60*time.Second, "timeout to use")
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flag.Parse()
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ctx, cancel := context.WithTimeout(context.Background(), *timeout)
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defer cancel()
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parsed, err := url.Parse(*URL)
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runtimex.PanicOnError(err, "url.Parse failed")
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mx := measurex.NewMeasurerWithDefaultSettings()
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m := &measurement{}
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// ```
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// ### Call LookupHTTPSSvc
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//
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// Here we perform the `LookupHostUDP` we performed in the
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// previous chapter and then we call `LookupHTTPSvcUDP`.
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//
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// ```Go
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m.DNS = append(m.DNS, mx.LookupHostUDP(ctx, parsed.Hostname(), *address))
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m.DNS = append(m.DNS, mx.LookupHTTPSSvcUDP(ctx, parsed.Hostname(), *address))
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// ```
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//
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// The `LookupHTTPSSvcUDP` function has the same signature
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// of `LookupHostUDP` _but_ it behaves differently. Rather than
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// querying for `A` and `AAAA`, it performs an `HTTPS` DNS
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// lookup. This query returns:
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//
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// 1. a list of ALPNs for the domain;
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//
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// 2. a list of IPv4 addresses;
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//
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// 3. a list of IPv6 addresses.
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//
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// ### Build an []HTTPEndpoint and run serial measurements
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//
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// Here we call `AllHTTPEndpointsForURL` like we did in the
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// previous chapter. However, note that we pass to it the
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// whole content of `m.DNS`, which now contains not only the
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// A/AAAA lookups results but also the HTTPS lookup results.
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//
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// The `AllHTTPEndpointsForURL` function will recognize that
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// we also have HTTPS lookups and, if the "h3" ALPN is
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// present, will _also_ build HTTP/3 endpoints using "quic"
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// as the `HTTPEndpoint.Network`.
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//
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// ```Go
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headers := measurex.NewHTTPRequestHeaderForMeasuring()
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httpEndpoints, err := measurex.AllHTTPEndpointsForURL(parsed, headers, m.DNS...)
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runtimex.PanicOnError(err, "cannot get all the HTTP endpoints")
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// ```
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//
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// This is it. The rest of the program is exactly the same.
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//
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// ```Go
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for _, epnt := range httpEndpoints {
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m.Endpoints = append(m.Endpoints, mx.HTTPEndpointGetWithoutCookies(ctx, epnt))
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}
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print(m)
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}
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// ```
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//
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// ## Running the example program
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//
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// Let us perform a vanilla run first:
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//
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// ```bash
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// go run -race ./internal/tutorial/measurex/chapter08
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// ```
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//
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// Please, check the JSON output. Do you recognize the fields
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// we have described in previous chapters? You should see
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// that, compared to previous chapters, now we're also testing
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// QUIC/HTTP3 endpoints.
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//
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// Can you provoke common errors such as DNS resolution
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// errors, TCP connect errors, TLS handshake errors, and
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// HTTP round trip errors? What is a good way to cause
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// timeout and SNI mismatch errors for QUIC?
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//
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// ## Conclusion
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//
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// We have seen how to extend fetching all the HTTPS
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// endpoints to include the QUIC/HTTP3 endpoints discovered
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// using HTTPSSvc.
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//
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// -=-=- StopHere -=-=-
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