feat(oonirun): implement OONIRun v1 (#843)

This diff adds support for running OONIRun v1 links.

Run with `miniooni` using:

```
./miniooni -i LINK oonirun
```

Part of https://github.com/ooni/probe/issues/2184

internal/oonirun/v1.go

@@ -0,0 +1,90 @@
+package oonirun
+
+//
+// OONI Run v1 implementation
+//
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net/url"
+)
+
+var (
+	// ErrInvalidV1URLScheme indicates a v1 OONI Run URL has an invalid scheme.
+	ErrInvalidV1URLScheme = errors.New("oonirun: invalid v1 URL scheme")
+
+	// ErrInvalidV1URLHost indicates a v1 OONI Run URL has an invalid host.
+	ErrInvalidV1URLHost = errors.New("oonirun: invalid v1 URL host")
+
+	// ErrInvalidV1URLPath indicates a v1 OONI Run URL has an invalid path.
+	ErrInvalidV1URLPath = errors.New("oonirun: invalid v1 URL path")
+
+	// ErrInvalidV1URLQueryArgument indicates a v1 OONI Run URL query argument is invalid.
+	ErrInvalidV1URLQueryArgument = errors.New("oonirun: invalid v1 URL query argument")
+)
+
+// v1Arguments contains arguments for a v1 OONI Run URL. These arguments are
+// always encoded inside of the "ta" field, which is optional.
+type v1Arguments struct {
+	URLs []string `json:"urls"`
+}
+
+// v1Measure performs a measurement using the given v1 OONI Run URL.
+func v1Measure(ctx context.Context, config *LinkConfig, URL string) error {
+	config.Session.Logger().Infof("oonirun/v1: running %s", URL)
+	pu, err := url.Parse(URL)
+	if err != nil {
+		return err
+	}
+	switch pu.Scheme {
+	case "https":
+		if pu.Host != "run.ooni.io" {
+			return ErrInvalidV1URLHost
+		}
+		if pu.Path != "/nettest" {
+			return ErrInvalidV1URLPath
+		}
+	case "ooni":
+		if pu.Host != "nettest" {
+			return ErrInvalidV1URLHost
+		}
+		if pu.Path != "" {
+			return ErrInvalidV1URLPath
+		}
+	default:
+		return ErrInvalidV1URLScheme
+	}
+	name := pu.Query().Get("tn")
+	if name == "" {
+		return ErrInvalidV1URLQueryArgument
+	}
+	var inputs []string
+	if ra := pu.Query().Get("ta"); ra != "" {
+		pa, err := url.QueryUnescape(ra)
+		if err != nil {
+			return err
+		}
+		var arguments v1Arguments
+		if err := json.Unmarshal([]byte(pa), &arguments); err != nil {
+			return err
+		}
+		inputs = arguments.URLs
+	}
+	// TODO(bassosimone): reject mv < 1.2.0
+	exp := &Experiment{
+		Annotations:    config.Annotations,
+		ExtraOptions:   nil, // no way to specify with v1 URLs
+		Inputs:         inputs,
+		InputFilePaths: nil,
+		MaxRuntime:     config.MaxRuntime,
+		Name:           name,
+		NoCollector:    config.NoCollector,
+		NoJSON:         config.NoJSON,
+		Random:         config.Random,
+		ReportFile:     config.ReportFile,
+		Session:        config.Session,
+	}
+	return exp.Run(ctx)
+}