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package policy
import (
"errors"
"fmt"
"net"
"net/http"
"regexp"
"strings"
"github.com/TecharoHQ/anubis/internal"
"github.com/yl2chen/cidranger"
)
var (
ErrMisconfiguration = errors.New("[unexpected] policy: administrator misconfiguration")
)
type Checker interface {
Check(*http.Request) (bool, error)
Hash() string
}
type CheckerList []Checker
func (cl CheckerList) Check(r *http.Request) (bool, error) {
for _, c := range cl {
ok, err := c.Check(r)
if err != nil {
return ok, err
}
if ok {
return ok, nil
}
}
return false, nil
}
func (cl CheckerList) Hash() string {
var sb strings.Builder
for _, c := range cl {
fmt.Fprintln(&sb, c.Hash())
}
return internal.SHA256sum(sb.String())
}
type RemoteAddrChecker struct {
ranger cidranger.Ranger
hash string
}
func NewRemoteAddrChecker(cidrs []string) (Checker, error) {
ranger := cidranger.NewPCTrieRanger()
var sb strings.Builder
for _, cidr := range cidrs {
_, rng, err := net.ParseCIDR(cidr)
if err != nil {
return nil, fmt.Errorf("%w: range %s not parsing: %w", ErrMisconfiguration, cidr, err)
}
ranger.Insert(cidranger.NewBasicRangerEntry(*rng))
fmt.Fprintln(&sb, cidr)
}
return &RemoteAddrChecker{
ranger: ranger,
hash: internal.SHA256sum(sb.String()),
}, nil
}
func (rac *RemoteAddrChecker) Check(r *http.Request) (bool, error) {
host := r.Header.Get("X-Real-Ip")
if host == "" {
return false, fmt.Errorf("%w: header X-Real-Ip is not set", ErrMisconfiguration)
}
addr := net.ParseIP(host)
if addr == nil {
return false, fmt.Errorf("%w: %s is not an IP address", ErrMisconfiguration, host)
}
ok, err := rac.ranger.Contains(addr)
if err != nil {
return false, err
}
if ok {
return true, nil
}
return false, nil
}
func (rac *RemoteAddrChecker) Hash() string {
return rac.hash
}
type HeaderMatchesChecker struct {
header string
regexp *regexp.Regexp
hash string
}
func NewUserAgentChecker(rexStr string) (Checker, error) {
return NewHeaderMatchesChecker("User-Agent", rexStr)
}
func NewHeaderMatchesChecker(header, rexStr string) (Checker, error) {
rex, err := regexp.Compile(strings.TrimSpace(rexStr))
if err != nil {
return nil, fmt.Errorf("%w: regex %s failed parse: %w", ErrMisconfiguration, rexStr, err)
}
return &HeaderMatchesChecker{strings.TrimSpace(header), rex, internal.SHA256sum(header + ": " + rexStr)}, nil
}
func (hmc *HeaderMatchesChecker) Check(r *http.Request) (bool, error) {
if hmc.regexp.MatchString(r.Header.Get(hmc.header)) {
return true, nil
}
return false, nil
}
func (hmc *HeaderMatchesChecker) Hash() string {
return hmc.hash
}
type PathChecker struct {
regexp *regexp.Regexp
hash string
}
func NewPathChecker(rexStr string) (Checker, error) {
rex, err := regexp.Compile(strings.TrimSpace(rexStr))
if err != nil {
return nil, fmt.Errorf("%w: regex %s failed parse: %w", ErrMisconfiguration, rexStr, err)
}
return &PathChecker{rex, internal.SHA256sum(rexStr)}, nil
}
func (pc *PathChecker) Check(r *http.Request) (bool, error) {
if pc.regexp.MatchString(r.URL.Path) {
return true, nil
}
return false, nil
}
func (pc *PathChecker) Hash() string {
return pc.hash
}
func NewHeaderExistsChecker(key string) Checker {
return headerExistsChecker{strings.TrimSpace(key)}
}
type headerExistsChecker struct {
header string
}
func (hec headerExistsChecker) Check(r *http.Request) (bool, error) {
if r.Header.Get(hec.header) != "" {
return true, nil
}
return false, nil
}
func (hec headerExistsChecker) Hash() string {
return internal.SHA256sum(hec.header)
}
func NewHeadersChecker(headermap map[string]string) (Checker, error) {
var result CheckerList
var errs []error
for key, rexStr := range headermap {
if rexStr == ".*" {
result = append(result, headerExistsChecker{strings.TrimSpace(key)})
continue
}
rex, err := regexp.Compile(strings.TrimSpace(rexStr))
if err != nil {
errs = append(errs, fmt.Errorf("while compiling header %s regex %s: %w", key, rexStr, err))
continue
}
result = append(result, &HeaderMatchesChecker{key, rex, internal.SHA256sum(key + ": " + rexStr)})
}
if len(errs) != 0 {
return nil, errors.Join(errs...)
}
return result, nil
}
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