forked from coredns/policy
/
casbin.go
157 lines (141 loc) · 3.32 KB
/
casbin.go
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package casbin
import (
"context"
"errors"
"fmt"
casbin2 "github.com/casbin/casbin/v2"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/plugin/metadata"
"github.com/coredns/coredns/request"
"github.com/coredns/policy/plugin/firewall/policy"
"github.com/coredns/policy/plugin/pkg/rqdata"
"github.com/miekg/dns"
"reflect"
"strings"
)
type casbin struct {
engines map[string]*engine
next plugin.Handler
}
type engine struct {
modelPath string
policyPath string
enforcer *casbin2.Enforcer
fields []string
actionIndex int
mapping *rqdata.Mapping
}
func newCasbin() *casbin {
return &casbin{
engines: make(map[string]*engine),
}
}
func newEngine(m *rqdata.Mapping) *engine {
return &engine{
mapping: m,
}
}
func (c *casbin) Name() string {
return "casbin"
}
func (c *casbin) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
return plugin.NextOrFailure(c.Name(), c.next, ctx, w, r)
}
func (c *casbin) Engine(name string) policy.Engine {
return c.engines[name]
}
func (e *engine) BuildQueryData(ctx context.Context, state request.Request) (interface{}, error) {
return e.buildData(ctx, state, make(map[string]string)), nil
}
func (e *engine) BuildReplyData(ctx context.Context, state request.Request, queryData interface{}) (interface{}, error) {
return e.buildData(ctx, state, queryData.(map[string]string)), nil
}
func (e *engine) buildData(ctx context.Context, state request.Request, data map[string]string) map[string]string {
extractor := rqdata.NewExtractor(state, e.mapping)
for _, f := range e.fields {
if _, ok := data[f]; ok {
continue
}
var (
v string
ok bool
)
if e.mapping.ValidField(f) {
v, ok = extractor.Value(f)
if !ok {
continue
}
} else {
mdf := metadata.ValueFunc(ctx, f)
v := mdf()
if v == "" {
continue
}
}
if len(v) > 0 && v[0] == '[' && strings.HasSuffix(f, "_ip") {
v = v[1 : len(v)-1]
}
data[f] = v
}
return data
}
func (e *engine) getFields() {
m := e.enforcer.GetModel()
fields := make([]string, 0)
ast := m["r"]["r"]
for _, token := range ast.Tokens {
field := strings.TrimPrefix(token, "r_")
fields = append(fields, field)
}
e.fields = fields
}
func (e *engine) getActionIndex() error {
m := e.enforcer.GetModel()
index := -1
key := "p_action"
for i, k := range m["p"]["p"].Tokens {
if k == key {
index = i
}
}
if index == -1 {
return errors.New("could not get action column")
}
e.actionIndex = index
return nil
}
func (e *engine) BuildRule(args []string) (policy.Rule, error) {
return e, nil
}
func (e *engine) Evaluate(data interface{}) (int, error) {
pdata, ok := data.(map[string]string)
if !ok {
return 0, fmt.Errorf("input should be map[string]string instead of %v", reflect.TypeOf(data))
}
params := make([]interface{}, 0, len(pdata))
for _, v := range pdata {
params = append(params, v)
}
ok, p, err := e.enforcer.EnforceEx(params...)
if err != nil {
return 0, err
}
if len(p) == 0 {
return policy.TypeNone, nil
}
if ok {
switch p[e.actionIndex] {
case "allow":
return policy.TypeAllow, nil
case "refuse":
return policy.TypeRefuse, nil
case "block":
return policy.TypeBlock, nil
case "drop":
return policy.TypeDrop, nil
default:
return 0, fmt.Errorf("unknown action: '%s'", p[3])
}
}
return policy.TypeNone, nil
}