fix: make sure we can parse integers from JSON (ooni#1435)

This commit ensures we can parse integer values provided using OONI Run
v2 descriptors into actual integers.

Values are originally parsed as float64, so we need to add a specific
conversion case for that scenario.

Diff extracted from: ooni#1423

Closes ooni/probe#2645

internal/cmd/miniooni/oonirun.go

@@ -53,6 +53,8 @@ func ooniRunMain(ctx context.Context,
 			logger.Warnf("oonirun: parsing OONI Run v2 descriptor failed: %s", err.Error())
 			continue
 		}
+		logger.Infof("oonirun: running '%s'", descr.Name)
+		logger.Infof("oonirun: link authored by '%s'", descr.Author)
 		if err := oonirun.V2MeasureDescriptor(ctx, cfg, &descr); err != nil {
 			logger.Warnf("oonirun: running link failed: %s", err.Error())
 			continue

internal/registry/factory.go

@@ -7,6 +7,7 @@ package registry
 import (
 	"errors"
 	"fmt"
+	"math"
 	"os"
 	"reflect"
 	"strconv"
@@ -107,6 +108,12 @@ func (b *Factory) setOptionBool(field reflect.Value, value any) error {
 	}
 }
 
+// With JSON we're limited by the 52 bits in the mantissa
+const (
+	jsonMaxInteger = 1<<53 - 1
+	jsonMinInteger = -1<<53 + 1
+)
+
 // setOptionInt sets an int option
 func (b *Factory) setOptionInt(field reflect.Value, value any) error {
 	switch v := value.(type) {
@@ -132,6 +139,18 @@ func (b *Factory) setOptionInt(field reflect.Value, value any) error {
 		}
 		field.SetInt(number)
 		return nil
+	case float64:
+		if math.IsNaN(v) || math.IsInf(v, 0) {
+			return fmt.Errorf("%w from: %v", ErrCannotSetIntegerOption, value)
+		}
+		if math.Trunc(v) != v {
+			return fmt.Errorf("%w from: %v", ErrCannotSetIntegerOption, value)
+		}
+		if v > jsonMaxInteger || v < jsonMinInteger {
+			return fmt.Errorf("%w from: %v", ErrCannotSetIntegerOption, value)
+		}
+		field.SetInt(int64(v))
+		return nil
 	default:
 		return fmt.Errorf("%w from a value of type %T", ErrCannotSetIntegerOption, value)
 	}

internal/registry/factory_test.go

@@ -3,6 +3,7 @@ package registry
 import (
 	"errors"
 	"fmt"
+	"math"
 	"os"
 	"testing"
 
@@ -251,6 +252,48 @@ func TestExperimentBuilderSetOptionAny(t *testing.T) {
 		FieldValue:    make(chan any),
 		ExpectErr:     ErrCannotSetIntegerOption,
 		ExpectConfig:  &fakeExperimentConfig{},
+	}, {
+		TestCaseName:  "[int] for NaN",
+		InitialConfig: &fakeExperimentConfig{},
+		FieldName:     "Value",
+		FieldValue:    math.NaN(),
+		ExpectErr:     ErrCannotSetIntegerOption,
+		ExpectConfig:  &fakeExperimentConfig{},
+	}, {
+		TestCaseName:  "[int] for +Inf",
+		InitialConfig: &fakeExperimentConfig{},
+		FieldName:     "Value",
+		FieldValue:    math.Inf(1),
+		ExpectErr:     ErrCannotSetIntegerOption,
+		ExpectConfig:  &fakeExperimentConfig{},
+	}, {
+		TestCaseName:  "[int] for -Inf",
+		InitialConfig: &fakeExperimentConfig{},
+		FieldName:     "Value",
+		FieldValue:    math.Inf(-1),
+		ExpectErr:     ErrCannotSetIntegerOption,
+		ExpectConfig:  &fakeExperimentConfig{},
+	}, {
+		TestCaseName:  "[int] for too large value",
+		InitialConfig: &fakeExperimentConfig{},
+		FieldName:     "Value",
+		FieldValue:    float64(jsonMaxInteger + 1),
+		ExpectErr:     ErrCannotSetIntegerOption,
+		ExpectConfig:  &fakeExperimentConfig{},
+	}, {
+		TestCaseName:  "[int] for too small value",
+		InitialConfig: &fakeExperimentConfig{},
+		FieldName:     "Value",
+		FieldValue:    float64(jsonMinInteger - 1),
+		ExpectErr:     ErrCannotSetIntegerOption,
+		ExpectConfig:  &fakeExperimentConfig{},
+	}, {
+		TestCaseName:  "[int] for float64 with nonzero fractional value",
+		InitialConfig: &fakeExperimentConfig{},
+		FieldName:     "Value",
+		FieldValue:    1.11,
+		ExpectErr:     ErrCannotSetIntegerOption,
+		ExpectConfig:  &fakeExperimentConfig{},
 	}, {
 		TestCaseName:  "[string] for serialized bool value while setting a string value",
 		InitialConfig: &fakeExperimentConfig{},