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>

lib/policy/policy.go

@@ -0,0 +1,122 @@
+package policy
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"regexp"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"github.com/yl2chen/cidranger"
+
+	"github.com/TecharoHQ/anubis/lib/policy/config"
+)
+
+var (
+	PolicyApplications = promauto.NewCounterVec(prometheus.CounterOpts{
+		Name: "anubis_policy_results",
+		Help: "The results of each policy rule",
+	}, []string{"rule", "action"})
+)
+
+type ParsedConfig struct {
+	orig config.Config
+
+	Bots              []Bot
+	DNSBL             bool
+	DefaultDifficulty int
+}
+
+func NewParsedConfig(orig config.Config) *ParsedConfig {
+	return &ParsedConfig{
+		orig: orig,
+	}
+}
+
+func ParseConfig(fin io.Reader, fname string, defaultDifficulty int) (*ParsedConfig, error) {
+	var c config.Config
+	if err := json.NewDecoder(fin).Decode(&c); err != nil {
+		return nil, fmt.Errorf("can't parse policy config JSON %s: %w", fname, err)
+	}
+
+	if err := c.Valid(); err != nil {
+		return nil, err
+	}
+
+	var err error
+
+	result := NewParsedConfig(c)
+	result.DefaultDifficulty = defaultDifficulty
+
+	for _, b := range c.Bots {
+		if berr := b.Valid(); berr != nil {
+			err = errors.Join(err, berr)
+			continue
+		}
+
+		var botParseErr error
+		parsedBot := Bot{
+			Name:   b.Name,
+			Action: b.Action,
+		}
+
+		if b.RemoteAddr != nil && len(b.RemoteAddr) > 0 {
+			parsedBot.Ranger = cidranger.NewPCTrieRanger()
+
+			for _, cidr := range b.RemoteAddr {
+				_, rng, err := net.ParseCIDR(cidr)
+				if err != nil {
+					return nil, fmt.Errorf("[unexpected] range %s not parsing: %w", cidr, err)
+				}
+
+				parsedBot.Ranger.Insert(cidranger.NewBasicRangerEntry(*rng))
+			}
+		}
+
+		if b.UserAgentRegex != nil {
+			userAgent, err := regexp.Compile(*b.UserAgentRegex)
+			if err != nil {
+				botParseErr = errors.Join(botParseErr, fmt.Errorf("while compiling user agent regexp: %w", err))
+				continue
+			} else {
+				parsedBot.UserAgent = userAgent
+			}
+		}
+
+		if b.PathRegex != nil {
+			path, err := regexp.Compile(*b.PathRegex)
+			if err != nil {
+				botParseErr = errors.Join(botParseErr, fmt.Errorf("while compiling path regexp: %w", err))
+				continue
+			} else {
+				parsedBot.Path = path
+			}
+		}
+
+		if b.Challenge == nil {
+			parsedBot.Challenge = &config.ChallengeRules{
+				Difficulty: defaultDifficulty,
+				ReportAs:   defaultDifficulty,
+				Algorithm:  config.AlgorithmFast,
+			}
+		} else {
+			parsedBot.Challenge = b.Challenge
+			if parsedBot.Challenge.Algorithm == config.AlgorithmUnknown {
+				parsedBot.Challenge.Algorithm = config.AlgorithmFast
+			}
+		}
+
+		result.Bots = append(result.Bots, parsedBot)
+	}
+
+	if err != nil {
+		return nil, fmt.Errorf("errors validating policy config JSON %s: %w", fname, err)
+	}
+
+	result.DNSBL = c.DNSBL
+
+	return result, nil
+}