70 lines
1.8 KiB
Go
70 lines
1.8 KiB
Go
package auth
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import (
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"errors"
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"net/http"
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)
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// Permission represents a permission granted to a user.
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//
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// The nil permission represents any authenticated user.
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type Permission func(user *AuthUser, r *http.Request) (ok Grant, err error)
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// Grant represents an object that either grants or denies access for a certain permission
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type Grant interface {
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isGranted()
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// Granted returns a boolean indicating if permission to the resource in question
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// has been granted
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Granted() bool
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// Denied returns a string containing an error message to display to the user when permission is denied.
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// When Granted() returns true, the behaviour is undefined.
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Denied() string
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}
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// Bool2Grant returns a new grant that returns granted for the given boolean, and message as the denied message.
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func Bool2Grant(granted bool, message string) Grant {
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if granted {
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return grantAllow{}
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}
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return grantDeny(message)
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}
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type grantAllow struct{}
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func (grantAllow) isGranted() {}
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func (grantAllow) Granted() bool { return true }
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func (grantAllow) Denied() string { return "" }
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type grantDeny string
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func (grantDeny) isGranted() {}
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func (g grantDeny) Granted() bool { return false }
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func (g grantDeny) Denied() string {
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if g == "" {
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return "Forbidden"
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}
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return string(g)
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}
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var errPermissionPanic = errors.New("permission: panic()")
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// Permit checks if the given user has this permission.
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func (perm Permission) Permit(user *AuthUser, r *http.Request) (ok Grant, err error) {
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// if there is no permission, then we just check if there is some user
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if perm == nil {
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return Bool2Grant(user != nil, ""), nil
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}
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// recover any panic()ed permission call
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// to prevent the handler from panic()ing
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defer func() {
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if p := recover(); p != nil {
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ok = Bool2Grant(false, "unknown error")
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err = errPermissionPanic
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}
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}()
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return perm(user, r)
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}
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