/
pflags.go
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/
pflags.go
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//
// Copyright 2021 The Sigstore Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package app
import (
"encoding/base64"
"fmt"
"log"
"strconv"
"strings"
"time"
"github.com/sigstore/rekor/pkg/pki"
"github.com/sigstore/rekor/pkg/sharding"
"github.com/sigstore/rekor/pkg/util"
"github.com/spf13/pflag"
validator "github.com/go-playground/validator/v10"
)
type FlagType string
const (
uuidFlag FlagType = "uuid"
shaFlag FlagType = "sha"
emailFlag FlagType = "email"
operatorFlag FlagType = "operator"
logIndexFlag FlagType = "logIndex"
pkiFormatFlag FlagType = "pkiFormat"
typeFlag FlagType = "type"
fileFlag FlagType = "file"
urlFlag FlagType = "url"
fileOrURLFlag FlagType = "fileOrURL"
multiFileOrURLFlag FlagType = "multiFileOrURL"
oidFlag FlagType = "oid"
formatFlag FlagType = "format"
timeoutFlag FlagType = "timeout"
base64Flag FlagType = "base64"
)
type newPFlagValueFunc func() pflag.Value
var pflagValueFuncMap map[FlagType]newPFlagValueFunc
// TODO: unit tests for all of this
func initializePFlagMap() {
pflagValueFuncMap = map[FlagType]newPFlagValueFunc{
uuidFlag: func() pflag.Value {
// this validates a UUID with or without a prepended TreeID;
// the UUID corresponds to the merkle leaf hash of entries,
// which is represented by a 64 character hexadecimal string
return valueFactory(uuidFlag, validateID, "")
},
shaFlag: func() pflag.Value {
// this validates a valid sha256 checksum which is optionally prefixed with 'sha256:'
return valueFactory(shaFlag, validateSHAValue, "")
},
operatorFlag: func() pflag.Value {
// this validates a valid operator name
return valueFactory(shaFlag, validateString("oneof=and or"), "")
},
emailFlag: func() pflag.Value {
// this validates an email address
return valueFactory(emailFlag, validateString("required,email"), "")
},
logIndexFlag: func() pflag.Value {
// this checks for a valid integer >= 0
return valueFactory(logIndexFlag, validateLogIndex, "")
},
pkiFormatFlag: func() pflag.Value {
// this ensures a PKI implementation exists for the requested format
return valueFactory(pkiFormatFlag, validateString(fmt.Sprintf("required,oneof=%v", strings.Join(pki.SupportedFormats(), " "))), "pgp")
},
typeFlag: func() pflag.Value {
// this ensures the type of the log entry matches a type supported in the CLI
return valueFactory(typeFlag, validateTypeFlag, "rekord")
},
fileFlag: func() pflag.Value {
// this validates that the file exists and can be opened by the current uid
return valueFactory(fileFlag, validateString("required,file"), "")
},
urlFlag: func() pflag.Value {
// this validates that the string is a valid http/https URL
return valueFactory(urlFlag, validateString("required,url,startswith=http|startswith=https"), "")
},
fileOrURLFlag: func() pflag.Value {
// applies logic of fileFlag OR urlFlag validators from above
return valueFactory(fileOrURLFlag, validateFileOrURL, "")
},
multiFileOrURLFlag: func() pflag.Value {
// applies logic of fileFlag OR urlFlag validators from above for multi file and URL
return multiValueFactory(multiFileOrURLFlag, validateFileOrURL, []string{})
},
oidFlag: func() pflag.Value {
// this validates for an OID, which is a sequence of positive integers separated by periods
return valueFactory(oidFlag, validateOID, "")
},
formatFlag: func() pflag.Value {
// this validates the output format requested
return valueFactory(formatFlag, validateString("required,oneof=json default"), "")
},
timeoutFlag: func() pflag.Value {
// this validates the timeout is >= 0
return valueFactory(formatFlag, validateTimeout, "")
},
base64Flag: func() pflag.Value {
// This validates the string is in base64 format
return valueFactory(base64Flag, validateBase64, "")
},
}
}
// NewFlagValue creates a new pflag.Value for the specified type with the specified default value.
// If a default value is not desired, pass "" for defaultVal.
func NewFlagValue(flagType FlagType, defaultVal string) pflag.Value {
valFunc := pflagValueFuncMap[flagType]
val := valFunc()
if defaultVal != "" {
if err := val.Set(defaultVal); err != nil {
log.Fatal(fmt.Errorf("initializing flag: %w", err))
}
}
return val
}
type validationFunc func(string) error
func valueFactory(flagType FlagType, v validationFunc, defaultVal string) pflag.Value {
return &baseValue{
flagType: flagType,
validationFunc: v,
value: defaultVal,
}
}
func multiValueFactory(flagType FlagType, v validationFunc, defaultVal []string) pflag.Value {
return &multiBaseValue{
flagType: flagType,
validationFunc: v,
value: defaultVal,
}
}
// multiBaseValue implements pflag.Value
type multiBaseValue struct {
flagType FlagType
value []string
validationFunc validationFunc
}
func (b *multiBaseValue) String() string {
return strings.Join(b.value, ",")
}
// Type returns the type of this Value
func (b multiBaseValue) Type() string {
return string(b.flagType)
}
func (b *multiBaseValue) Set(value string) error {
if err := b.validationFunc(value); err != nil {
return err
}
b.value = append(b.value, value)
return nil
}
// baseValue implements pflag.Value
type baseValue struct {
flagType FlagType
value string
validationFunc validationFunc
}
// Type returns the type of this Value
func (b baseValue) Type() string {
return string(b.flagType)
}
// String returns the string representation of this Value
func (b baseValue) String() string {
return b.value
}
// Set validates the provided string against the appropriate validation rule
// for b.flagType; if the string validates, it is stored in the Value and nil is returned.
// Otherwise the validation error is returned but the state of the Value is not changed.
func (b *baseValue) Set(s string) error {
if err := b.validationFunc(s); err != nil {
return err
}
b.value = s
return nil
}
// isURL returns true if the supplied value is a valid URL and false otherwise
func isURL(v string) bool {
valGen := pflagValueFuncMap[urlFlag]
return valGen().Set(v) == nil
}
// validateSHAValue ensures that the supplied string matches the following formats:
// [sha256:]<64 hexadecimal characters>
// [sha1:]<40 hexadecimal characters>
// where [sha256:] and [sha1:] are optional
func validateSHAValue(v string) error {
err := util.ValidateSHA1Value(v)
if err == nil {
return nil
}
if err := util.ValidateSHA256Value(v); err != nil {
return fmt.Errorf("error parsing %v flag: %w", shaFlag, err)
}
return nil
}
// validateFileOrURL ensures the provided string is either a valid file path that can be opened or a valid URL
func validateFileOrURL(v string) error {
valGen := pflagValueFuncMap[fileFlag]
if valGen().Set(v) == nil {
return nil
}
valGen = pflagValueFuncMap[urlFlag]
return valGen().Set(v)
}
// validateID ensures the ID is either an EntryID (TreeID + UUID) or a UUID
func validateID(v string) error {
if len(v) != sharding.EntryIDHexStringLen && len(v) != sharding.UUIDHexStringLen {
return fmt.Errorf("ID len error, expected %v (EntryID) or %v (UUID) but got len %v for ID %v", sharding.EntryIDHexStringLen, sharding.UUIDHexStringLen, len(v), v)
}
if err := validateString("required,hexadecimal")(v); err != nil {
return fmt.Errorf("invalid uuid: %v", v)
}
return nil
}
// validateLogIndex ensures that the supplied string is a valid log index (integer >= 0)
func validateLogIndex(v string) error {
i, err := strconv.Atoi(v)
if err != nil {
return err
}
l := struct {
Index int `validate:"gte=0"`
}{i}
return useValidator(logIndexFlag, l)
}
// validateOID ensures that the supplied string is a valid ASN.1 object identifier
func validateOID(v string) error {
o := struct {
Oid []string `validate:"dive,numeric"`
}{strings.Split(v, ".")}
return useValidator(oidFlag, o)
}
// validateTimeout ensures that the supplied string is a valid time.Duration value >= 0
func validateTimeout(v string) error {
duration, err := time.ParseDuration(v)
if err != nil {
return err
}
d := struct {
Duration time.Duration `validate:"min=0"`
}{duration}
return useValidator(timeoutFlag, d)
}
// validateBase64 ensures that the supplied string is valid base64 encoded data
func validateBase64(v string) error {
_, err := base64.StdEncoding.DecodeString(v)
return err
}
// validateTypeFlag ensures that the string is in the format type(\.version)? and
// that one of the types requested is implemented
func validateTypeFlag(v string) error {
_, _, err := ParseTypeFlag(v)
return err
}
// validateString returns a function that validates an input string against the specified tag,
// as defined in the format supported by go-playground/validator
func validateString(tag string) validationFunc {
return func(v string) error {
validator := validator.New()
return validator.Var(v, tag)
}
}
// useValidator performs struct level validation on s as defined in the struct's tags using
// the go-playground/validator library
func useValidator(flagType FlagType, s interface{}) error {
validate := validator.New()
if err := validate.Struct(s); err != nil {
return fmt.Errorf("error parsing %v flag: %w", flagType, err)
}
return nil
}