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plugin.go
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plugin.go
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package lessor
import (
"context"
"errors"
"fmt"
caddy "github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
"github.com/caddyserver/caddy/v2/modules/caddyhttp"
"github.com/coreos/go-oidc/v3/oidc"
"github.com/golang-jwt/jwt/v5"
"go.uber.org/zap"
"net/http"
"strings"
"github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile"
)
type Middleware struct {
Issuer string
provider *oidc.Provider
logger *zap.Logger
}
// CaddyModule returns the Caddy module information.
func (m *Middleware) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "http.handlers.lessor",
New: func() caddy.Module { return new(Middleware) },
}
}
func init() {
caddy.RegisterModule(&Middleware{})
httpcaddyfile.RegisterHandlerDirective("lessor", parseCaddyfile)
}
// Provision implements caddy.Provisioner.
func (m *Middleware) Provision(ctx caddy.Context) error {
m.logger = ctx.Logger() // g.logger is a *zap.Logger
provider, err := oidc.NewProvider(ctx, m.Issuer)
if err != nil {
m.logger.Error("error provisioning issuer", zap.String("issuer", m.Issuer), zap.Error(err))
return fmt.Errorf("erorr provisioning issuer '%s': %w", m.Issuer, err)
// handle error
}
m.provider = provider
return nil
}
// Validate implements caddy.Validator.
func (m *Middleware) Validate() error {
return nil
}
// ServeHTTP implements caddyhttp.MiddlewareHandler.
func (m *Middleware) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
err := m.injectScopeHeader(r)
if err != nil {
return err
}
return next.ServeHTTP(w, r)
}
// UnmarshalCaddyfile sets up Lessor from Caddyfile tokens. Syntax:
// UnmarshalCaddyfile sets up the DNS provider from Caddyfile tokens. Syntax:
//
// lessor [<issuer_url>] {
// issuer <issuer_url>
// }
func (m *Middleware) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
for d.Next() {
if d.NextArg() {
m.Issuer = d.Val()
}
if d.NextArg() {
return d.ArgErr()
}
for nesting := d.Nesting(); d.NextBlock(nesting); {
switch d.Val() {
case "issuer":
if m.Issuer != "" {
return d.Err("Issuer already set")
}
m.Issuer = d.Val()
if d.NextArg() {
return d.ArgErr()
}
default:
return d.Errf("unrecognized subdirective '%s'", d.Val())
}
}
}
return nil
}
func (m *Middleware) injectScopeHeader(r *http.Request) error {
// Extract tenants and inject them into X-Scope-OrgID header
tokenString := r.Header.Get("X-Id-Token")
if len(tokenString) == 0 { // Skip
return nil
}
verifier := m.provider.Verifier(&oidc.Config{
SkipClientIDCheck: true,
})
_, err := verifier.Verify(context.Background(), tokenString)
if err != nil {
m.logger.Error("failed to validate token", zap.Error(err), zap.Int("len", len(tokenString)))
return fmt.Errorf("token verification failed: %w", err)
}
type DexClaims struct {
LogReaders []string `json:"tenant:logreaders,omitempty"`
jwt.RegisteredClaims
}
token, err := jwt.ParseWithClaims(tokenString, &DexClaims{}, func(token *jwt.Token) (interface{}, error) {
return []byte(""), jwt.ErrTokenUnverifiable // We already verified
})
if !errors.Is(err, jwt.ErrTokenUnverifiable) {
m.logger.Error("token parsing error", zap.Error(err))
return fmt.Errorf("token parsing error: %w", err)
}
// Verified
claims, ok := token.Claims.(*DexClaims)
if !ok {
m.logger.Error("invalid claims detected", zap.Error(err))
return fmt.Errorf("invalid claims detected: %w", err)
}
if len(claims.LogReaders) > 0 {
tenants := strings.Join(claims.LogReaders, "|")
m.logger.Info("setting X-Scope-OrgID to tenants found in claim", zap.String("tenants", tenants))
r.Header.Set("X-Scope-OrgID", tenants)
} else {
m.logger.Info("setting X-Scope-OrgID to fallback fake tenant")
r.Header.Set("X-Scope-OrgID", "fake") // Default to fake
}
return nil
}
// parseCaddyfile unmarshals tokens from h into a new Middleware.
func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
m := &Middleware{}
err := m.UnmarshalCaddyfile(h.Dispenser)
return m, err
}
// Interface guards
var (
_ caddy.Provisioner = (*Middleware)(nil)
_ caddy.Validator = (*Middleware)(nil)
_ caddyhttp.MiddlewareHandler = (*Middleware)(nil)
_ caddyfile.Unmarshaler = (*Middleware)(nil)
)