ooni-probe-cli/internal/cmd/oohelperd/dns.go
Simone Basso bb6563f363
refactor: move TH structs and definitions to model (#894)
This commit moves the TH structs and definitions to model. We don't want
oohelperd to depend on web_connectivity@v0.4.

Part of https://github.com/ooni/probe/issues/2240
2022-08-28 20:20:12 +02:00

92 lines
2.4 KiB
Go

package main
//
// DNS measurements
//
import (
"context"
"sync"
"time"
"github.com/ooni/probe-cli/v3/internal/model"
"github.com/ooni/probe-cli/v3/internal/netxlite"
"github.com/ooni/probe-cli/v3/internal/tracex"
)
// newfailure is a convenience shortcut to save typing
var newfailure = tracex.NewFailure
// ctrlDNSResult is the result of the DNS check performed by
// the Web Connectivity test helper.
type ctrlDNSResult = model.THDNSResult
// dnsConfig configures the DNS check.
type dnsConfig struct {
// Domain is the MANDATORY domain to resolve.
Domain string
// NewResolver is the MANDATORY factory to create a new resolver.
NewResolver func() model.Resolver
// Out is the channel where we publish the results.
Out chan ctrlDNSResult
// Wg allows to synchronize with the parent.
Wg *sync.WaitGroup
}
// dnsDo performs the DNS check.
func dnsDo(ctx context.Context, config *dnsConfig) {
const timeout = 4 * time.Second
ctx, cancel := context.WithTimeout(ctx, timeout)
defer cancel()
defer config.Wg.Done()
reso := config.NewResolver()
defer reso.CloseIdleConnections()
addrs, err := reso.LookupHost(ctx, config.Domain)
if addrs == nil {
addrs = []string{} // fix: the old test helper did that
}
failure := dnsMapFailure(newfailure(err))
config.Out <- ctrlDNSResult{
Failure: failure,
Addrs: addrs,
ASNs: []int64{}, // unused by the TH and not serialized
}
}
// dnsMapFailure attempts to map netxlite failures to the strings
// used by the original OONI test helper.
//
// See https://github.com/ooni/backend/blob/6ec4fda5b18/oonib/testhelpers/http_helpers.py#L430
func dnsMapFailure(failure *string) *string {
switch failure {
case nil:
return nil
default:
switch *failure {
case netxlite.FailureDNSNXDOMAINError:
// We have a name for this string because dnsanalysis.go is
// already checking for this specific error string.
s := model.THDNSNameError
return &s
case netxlite.FailureDNSNoAnswer:
// In this case the legacy TH would produce an empty
// reply that is not attached to any error.
//
// See https://github.com/ooni/probe/issues/1707#issuecomment-944322725
return nil
case netxlite.FailureDNSNonRecoverableFailure,
netxlite.FailureDNSRefusedError,
netxlite.FailureDNSServerMisbehaving,
netxlite.FailureDNSTemporaryFailure:
s := "dns_server_failure"
return &s
default:
s := "unknown_error"
return &s
}
}
}