87 lines
1.8 KiB
Go
87 lines
1.8 KiB
Go
package api
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import (
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"context"
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"reflect"
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"golang.org/x/xerrors"
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)
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type permKey int
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var permCtxKey permKey
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const (
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// When changing these, update docs/API.md too
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PermRead = "read" // default
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PermWrite = "write"
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PermSign = "sign" // Use wallet keys for signing
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PermAdmin = "admin" // Manage permissions
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)
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var AllPermissions = []string{PermRead, PermWrite, PermSign, PermAdmin}
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var defaultPerms = []string{PermRead}
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func WithPerm(ctx context.Context, perms []string) context.Context {
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return context.WithValue(ctx, permCtxKey, perms)
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}
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func Permissioned(a API) API {
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var out Struct
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rint := reflect.ValueOf(&out.Internal).Elem()
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ra := reflect.ValueOf(a)
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for f := 0; f < rint.NumField(); f++ {
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field := rint.Type().Field(f)
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requiredPerm := field.Tag.Get("perm")
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if requiredPerm == "" {
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panic("missing 'perm' tag on " + field.Name)
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}
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// Validate perm tag
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ok := false
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for _, perm := range AllPermissions {
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if requiredPerm == perm {
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ok = true
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break
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}
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}
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if !ok {
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panic("unknown 'perm' tag on " + field.Name)
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}
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fn := ra.MethodByName(field.Name)
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rint.Field(f).Set(reflect.MakeFunc(field.Type, func(args []reflect.Value) (results []reflect.Value) {
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ctx := args[0].Interface().(context.Context)
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callerPerms, ok := ctx.Value(permCtxKey).([]string)
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if !ok {
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callerPerms = defaultPerms
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}
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for _, callerPerm := range callerPerms {
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if callerPerm == requiredPerm {
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return fn.Call(args)
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}
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}
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err := xerrors.Errorf("missing permission to invoke '%s' (need '%s')", field.Name, requiredPerm)
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rerr := reflect.ValueOf(&err).Elem()
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if field.Type.NumOut() == 2 {
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return []reflect.Value{
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reflect.Zero(field.Type.Out(0)),
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rerr,
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}
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} else {
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return []reflect.Value{rerr}
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}
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}))
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}
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return &out
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}
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