Refactor and split out things into cmd and lib (#77)

* Refactor anubis to split business logic into a lib, and cmd to just be direct usage.

* Post-rebase fixes.

* Update changelog, remove unnecessary one.

* lib: refactor this

This is mostly based on my personal preferences for how Go code should
be laid out. I'm not sold on the package name "lib" (I'd call it anubis
but that would stutter), but people are probably gonna import it as
libanubis so it's likely fine.

Packages have been "flattened" to centralize implementation with area of
concern. This goes against the Java-esque style that many people like,
but I think this helps make things simple.

Most notably: the dnsbl client (which is a hack) is an internal package
until it's made more generic. Then it can be made external.

I also fixed the logic such that `go generate` works and rebased on
main.

* internal/test: run tests iff npx exists and DONT_USE_NETWORK is not set

Signed-off-by: Xe Iaso <me@xeiaso.net>

* internal/test: install deps

Signed-off-by: Xe Iaso <me@xeiaso.net>

* .github/workflows: verbose go tests?

Signed-off-by: Xe Iaso <me@xeiaso.net>

* internal/test: sleep 2

Signed-off-by: Xe Iaso <me@xeiaso.net>

* internal/test: nix this test so CI works

Signed-off-by: Xe Iaso <me@xeiaso.net>

* internal/test: warmup per browser?

Signed-off-by: Xe Iaso <me@xeiaso.net>

* internal/test: disable for now :(

Signed-off-by: Xe Iaso <me@xeiaso.net>

* lib/anubis: do not apply bot rules if address check fails

Closes #83

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>
Co-authored-by: Xe Iaso <me@xeiaso.net>

3 files changed, 210 insertions, 0 deletions

diff --git a/internal/dnsbl/dnsbl.go b/internal/dnsbl/dnsbl.go
new file mode 100644
index 0000000..60edd5c
--- /dev/null
+++ b/internal/dnsbl/dnsbl.go
@@ -0,0 +1,95 @@
+package dnsbl
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"strings"
+)
+
+//go:generate go tool golang.org/x/tools/cmd/stringer -type=DroneBLResponse
+
+type DroneBLResponse byte
+
+const (
+	AllGood               DroneBLResponse = 0
+	IRCDrone              DroneBLResponse = 3
+	Bottler               DroneBLResponse = 5
+	UnknownSpambotOrDrone DroneBLResponse = 6
+	DDOSDrone             DroneBLResponse = 7
+	SOCKSProxy            DroneBLResponse = 8
+	HTTPProxy             DroneBLResponse = 9
+	ProxyChain            DroneBLResponse = 10
+	OpenProxy             DroneBLResponse = 11
+	OpenDNSResolver       DroneBLResponse = 12
+	BruteForceAttackers   DroneBLResponse = 13
+	OpenWingateProxy      DroneBLResponse = 14
+	CompromisedRouter     DroneBLResponse = 15
+	AutoRootingWorms      DroneBLResponse = 16
+	AutoDetectedBotIP     DroneBLResponse = 17
+	Unknown               DroneBLResponse = 255
+)
+
+func Reverse(ip net.IP) string {
+	if ip.To4() != nil {
+		return reverse4(ip)
+	}
+
+	return reverse6(ip)
+}
+
+func reverse4(ip net.IP) string {
+	splitAddress := strings.Split(ip.String(), ".")
+
+	// swap first and last octet
+	splitAddress[0], splitAddress[3] = splitAddress[3], splitAddress[0]
+	// swap middle octets
+	splitAddress[1], splitAddress[2] = splitAddress[2], splitAddress[1]
+
+	return strings.Join(splitAddress, ".")
+}
+
+func reverse6(ip net.IP) string {
+	ipBytes := []byte(ip)
+	var sb strings.Builder
+
+	for i := len(ipBytes) - 1; i >= 0; i-- {
+		// Split the byte into two nibbles
+		highNibble := ipBytes[i] >> 4
+		lowNibble := ipBytes[i] & 0x0F
+
+		// Append the nibbles in reversed order
+		sb.WriteString(fmt.Sprintf("%x.%x.", lowNibble, highNibble))
+	}
+
+	return sb.String()[:len(sb.String())-1]
+}
+
+func Lookup(ipStr string) (DroneBLResponse, error) {
+	ip := net.ParseIP(ipStr)
+	if ip == nil {
+		return Unknown, errors.New("dnsbl: input is not an IP address")
+	}
+
+	revIP := Reverse(ip) + ".dnsbl.dronebl.org"
+
+	ips, err := net.LookupIP(revIP)
+	if err != nil {
+		var dnserr *net.DNSError
+		if errors.As(err, &dnserr) {
+			if dnserr.IsNotFound {
+				return AllGood, nil
+			}
+		}
+
+		return Unknown, err
+	}
+
+	if len(ips) != 0 {
+		for _, ip := range ips {
+			return DroneBLResponse(ip.To4()[3]), nil
+		}
+	}
+
+	return UnknownSpambotOrDrone, nil
+}
diff --git a/internal/dnsbl/dnsbl_test.go b/internal/dnsbl/dnsbl_test.go
new file mode 100644
index 0000000..ccadd64
--- /dev/null
+++ b/internal/dnsbl/dnsbl_test.go
@@ -0,0 +1,61 @@
+package dnsbl
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"testing"
+)
+
+func TestReverse4(t *testing.T) {
+	cases := []struct {
+		inp, out string
+	}{
+		{"1.2.3.4", "4.3.2.1"},
+	}
+
+	for _, cs := range cases {
+		t.Run(fmt.Sprintf("%s->%s", cs.inp, cs.out), func(t *testing.T) {
+			out := reverse4(net.ParseIP(cs.inp))
+
+			if out != cs.out {
+				t.Errorf("wanted %s\ngot:   %s", cs.out, out)
+			}
+		})
+	}
+}
+
+func TestReverse6(t *testing.T) {
+	cases := []struct {
+		inp, out string
+	}{
+		{
+			inp: "1234:5678:9ABC:DEF0:1234:5678:9ABC:DEF0",
+			out: "0.f.e.d.c.b.a.9.8.7.6.5.4.3.2.1.0.f.e.d.c.b.a.9.8.7.6.5.4.3.2.1",
+		},
+	}
+
+	for _, cs := range cases {
+		t.Run(fmt.Sprintf("%s->%s", cs.inp, cs.out), func(t *testing.T) {
+			out := reverse6(net.ParseIP(cs.inp))
+
+			if out != cs.out {
+				t.Errorf("wanted %s, got: %s", cs.out, out)
+			}
+		})
+	}
+}
+
+func TestLookup(t *testing.T) {
+	if os.Getenv("DONT_USE_NETWORK") != "" {
+		t.Skip("test requires network egress")
+		return
+	}
+
+	resp, err := Lookup("27.65.243.194")
+	if err != nil {
+		t.Fatalf("it broked: %v", err)
+	}
+
+	t.Logf("response: %d", resp)
+}
diff --git a/internal/dnsbl/droneblresponse_string.go b/internal/dnsbl/droneblresponse_string.go
new file mode 100644
index 0000000..5104dda
--- /dev/null
+++ b/internal/dnsbl/droneblresponse_string.go
@@ -0,0 +1,54 @@
+// Code generated by "stringer -type=DroneBLResponse"; DO NOT EDIT.
+
+package dnsbl
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[AllGood-0]
+	_ = x[IRCDrone-3]
+	_ = x[Bottler-5]
+	_ = x[UnknownSpambotOrDrone-6]
+	_ = x[DDOSDrone-7]
+	_ = x[SOCKSProxy-8]
+	_ = x[HTTPProxy-9]
+	_ = x[ProxyChain-10]
+	_ = x[OpenProxy-11]
+	_ = x[OpenDNSResolver-12]
+	_ = x[BruteForceAttackers-13]
+	_ = x[OpenWingateProxy-14]
+	_ = x[CompromisedRouter-15]
+	_ = x[AutoRootingWorms-16]
+	_ = x[AutoDetectedBotIP-17]
+	_ = x[Unknown-255]
+}
+
+const (
+	_DroneBLResponse_name_0 = "AllGood"
+	_DroneBLResponse_name_1 = "IRCDrone"
+	_DroneBLResponse_name_2 = "BottlerUnknownSpambotOrDroneDDOSDroneSOCKSProxyHTTPProxyProxyChainOpenProxyOpenDNSResolverBruteForceAttackersOpenWingateProxyCompromisedRouterAutoRootingWormsAutoDetectedBotIP"
+	_DroneBLResponse_name_3 = "Unknown"
+)
+
+var (
+	_DroneBLResponse_index_2 = [...]uint8{0, 7, 28, 37, 47, 56, 66, 75, 90, 109, 125, 142, 158, 175}
+)
+
+func (i DroneBLResponse) String() string {
+	switch {
+	case i == 0:
+		return _DroneBLResponse_name_0
+	case i == 3:
+		return _DroneBLResponse_name_1
+	case 5 <= i && i <= 17:
+		i -= 5
+		return _DroneBLResponse_name_2[_DroneBLResponse_index_2[i]:_DroneBLResponse_index_2[i+1]]
+	case i == 255:
+		return _DroneBLResponse_name_3
+	default:
+		return "DroneBLResponse(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+}