fix(netxlite): hotfix for Android EAI_NODATA

The problem is explained in ooni/probe#2029.

I am also working on a more comprehensive fix for this
issue in #698.

This diff WILL NOT need forwardporting. It's just meant as
an hotfix for the release/3.14 branch and it's not such that
I'd be happy keeping it in release/3.15+.

go.mod

@@ -50,11 +50,11 @@ require (
 	github.com/ziutek/mymysql v1.5.4 // indirect
 	gitlab.com/yawning/obfs4.git v0.0.0-20210511220700-e330d1b7024b
 	gitlab.com/yawning/utls.git v0.0.12-1
-	golang.org/x/crypto v0.0.0-20220112180741-5e0467b6c7ce
+	golang.org/x/crypto v0.0.0-20220112180741-5e0467b6c7ce // indirect
 	golang.org/x/net v0.0.0-20220114011407-0dd24b26b47d
-	golang.org/x/sys v0.0.0-20220114195835-da31bd327af9
+	golang.org/x/sys v0.0.0-20220222200937-f2425489ef4c
 	golang.org/x/term v0.0.0-20210927222741-03fcf44c2211 // indirect
-	golang.org/x/tools v0.1.8 // indirect
+	golang.org/x/tools v0.1.9 // indirect
 	gopkg.in/mgo.v2 v2.0.0-20190816093944-a6b53ec6cb22 // indirect
 	upper.io/db.v3 v3.8.0+incompatible
 )

go.sum

@@ -973,8 +973,8 @@ golang.org/x/sys v0.0.0-20210915083310-ed5796bab164/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20211019181941-9d821ace8654/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20211103235746-7861aae1554b/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220114195835-da31bd327af9 h1:XfKQ4OlFl8okEOr5UvAqFRVj8pY/4yfcXrddB8qAbU0=
-golang.org/x/sys v0.0.0-20220114195835-da31bd327af9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220222200937-f2425489ef4c h1:sSIdNI2Dd6vGv47bKc/xArpfxVmEz2+3j0E6I484xC4=
+golang.org/x/sys v0.0.0-20220222200937-f2425489ef4c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210503060354-a79de5458b56/go.mod h1:tfny5GFUkzUvx4ps4ajbZsCe5lw1metzhBm9T3x7oIY=
@@ -1016,8 +1016,8 @@ golang.org/x/tools v0.0.0-20201224043029-2b0845dc783e/go.mod h1:emZCQorbCU4vsT4f
 golang.org/x/tools v0.1.0/go.mod h1:xkSsbof2nBLbhDlRMhhhyNLN/zl3eTqcnHD5viDpcZ0=
 golang.org/x/tools v0.1.1/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
 golang.org/x/tools v0.1.6-0.20210726203631-07bc1bf47fb2/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
-golang.org/x/tools v0.1.8 h1:P1HhGGuLW4aAclzjtmJdf0mJOjVUZUzOTqkAkWL+l6w=
-golang.org/x/tools v0.1.8/go.mod h1:nABZi5QlRsZVlzPpHl034qft6wpY4eDcsTt5AaioBiU=
+golang.org/x/tools v0.1.9 h1:j9KsMiaP1c3B0OTQGth0/k+miLGTgLsAFUCrF2vLcF8=
+golang.org/x/tools v0.1.9/go.mod h1:nABZi5QlRsZVlzPpHl034qft6wpY4eDcsTt5AaioBiU=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

internal/netxlite/classify.go

@@ -5,6 +5,7 @@ import (
 	"crypto/x509"
 	"errors"
 	"fmt"
+	"runtime"
 	"strings"
 
 	"github.com/lucas-clemente/quic-go"
@@ -64,6 +65,14 @@ func classifyGenericError(err error) string {
 	return scrubber.Scrub(formatted) // scrub IP addresses in the error
 }
 
+// This suffix is returned on (some?) Android devices where getaddrinfo seems
+// to return EAI_NODATA instead of EAI_NONAME for NXDOMAIN conditions. We handle
+// this specific string to correctly route the error as an hotfix for just the
+// release/3.14 branch, while a more comprehensive fix will land in release/3.15.
+//
+// See https://github.com/ooni/probe/issues/2029.
+const dnsAndroidEAINODATASuffix = "No address associated with hostname"
+
 // classifyWithStringSuffix is a subset of ClassifyGenericError that
 // performs classification by looking at error suffixes. This function
 // will return an empty string if it cannot classify the error.
@@ -87,6 +96,17 @@ func classifyWithStringSuffix(err error) string {
 	if strings.HasSuffix(s, "TLS handshake timeout") {
 		return FailureGenericTimeoutError
 	}
+	if runtime.GOOS == "android" && strings.HasSuffix(s, dnsAndroidEAINODATASuffix) {
+		// Because this is a release hotfix, here we're going to apply
+		// the simplest fix and just consider EAI_NODATA to be same
+		// as NXDOMAIN, even though this is probably not the most correct
+		// mapping to apply. We're not going to merge this diff into
+		// master, thus it's okay to have this simplistic fix here while
+		// we work on a more comprehensive solution.
+		//
+		// See https://github.com/ooni/probe/issues/2029.
+		return FailureDNSNXDOMAINError
+	}
 	if strings.HasSuffix(s, DNSNoSuchHostSuffix) {
 		// This is dns_lookup_error in MK but such error is used as a
 		// generic "hey, the lookup failed" error. Instead, this error