/
templating.go
359 lines (299 loc) · 8.56 KB
/
templating.go
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package identity
import (
"encoding/json"
"errors"
"fmt"
"strconv"
"strings"
"time"
"github.com/hashicorp/errwrap"
"github.com/hashicorp/vault/helper/namespace"
)
var (
ErrUnbalancedTemplatingCharacter = errors.New("unbalanced templating characters")
ErrNoEntityAttachedToToken = errors.New("string contains entity template directives but no entity was provided")
ErrNoGroupsAttachedToToken = errors.New("string contains groups template directives but no groups were provided")
ErrTemplateValueNotFound = errors.New("no value could be found for one of the template directives")
)
const (
ACLTemplating = iota // must be the first value for backwards compatibility
JSONTemplating
)
type PopulateStringInput struct {
String string
ValidityCheckOnly bool
Entity *Entity
Groups []*Group
Namespace *namespace.Namespace
Mode int // processing mode, ACLTemplate or JSONTemplating
Now time.Time // optional, defaults to current time
templateHandler templateHandlerFunc
groupIDs []string
groupNames []string
}
// templateHandlerFunc allows generating string outputs based on data type, and
// different handlers can be used based on mode. For example in ACL mode, strings
// are emitted verbatim, but they're wrapped in double quotes for JSON mode. And
// some structures, like slices, might be rendered in one mode but prohibited in
// another.
type templateHandlerFunc func(interface{}, ...string) (string, error)
// aclTemplateHandler processes known parameter data types when operating
// in ACL mode.
func aclTemplateHandler(v interface{}, keys ...string) (string, error) {
switch t := v.(type) {
case string:
if t == "" {
return "", ErrTemplateValueNotFound
}
return t, nil
case []string:
return "", ErrTemplateValueNotFound
case map[string]string:
if len(keys) > 0 {
val, ok := t[keys[0]]
if ok {
return val, nil
}
}
return "", ErrTemplateValueNotFound
}
return "", fmt.Errorf("unknown type: %T", v)
}
// jsonTemplateHandler processes known parameter data types when operating
// in JSON mode.
func jsonTemplateHandler(v interface{}, keys ...string) (string, error) {
jsonMarshaller := func(v interface{}) (string, error) {
enc, err := json.Marshal(v)
if err != nil {
return "", err
}
return string(enc), nil
}
switch t := v.(type) {
case string:
return strconv.Quote(t), nil
case []string:
return jsonMarshaller(t)
case map[string]string:
if len(keys) > 0 {
return strconv.Quote(t[keys[0]]), nil
}
if t == nil {
return "{}", nil
}
return jsonMarshaller(t)
}
return "", fmt.Errorf("unknown type: %T", v)
}
func PopulateString(p PopulateStringInput) (bool, string, error) {
if p.String == "" {
return false, "", nil
}
// preprocess groups
for _, g := range p.Groups {
p.groupNames = append(p.groupNames, g.Name)
p.groupIDs = append(p.groupIDs, g.ID)
}
// set up mode-specific handler
switch p.Mode {
case ACLTemplating:
p.templateHandler = aclTemplateHandler
case JSONTemplating:
p.templateHandler = jsonTemplateHandler
default:
return false, "", fmt.Errorf("unknown mode %q", p.Mode)
}
var subst bool
splitStr := strings.Split(p.String, "{{")
if len(splitStr) >= 1 {
if strings.Contains(splitStr[0], "}}") {
return false, "", ErrUnbalancedTemplatingCharacter
}
if len(splitStr) == 1 {
return false, p.String, nil
}
}
var b strings.Builder
if !p.ValidityCheckOnly {
b.Grow(2 * len(p.String))
}
for i, str := range splitStr {
if i == 0 {
if !p.ValidityCheckOnly {
b.WriteString(str)
}
continue
}
splitPiece := strings.Split(str, "}}")
switch len(splitPiece) {
case 2:
subst = true
if !p.ValidityCheckOnly {
tmplStr, err := performTemplating(strings.TrimSpace(splitPiece[0]), &p)
if err != nil {
return false, "", err
}
b.WriteString(tmplStr)
b.WriteString(splitPiece[1])
}
default:
return false, "", ErrUnbalancedTemplatingCharacter
}
}
return subst, b.String(), nil
}
func performTemplating(input string, p *PopulateStringInput) (string, error) {
performAliasTemplating := func(trimmed string, alias *Alias) (string, error) {
switch {
case trimmed == "id":
return p.templateHandler(alias.ID)
case trimmed == "name":
return p.templateHandler(alias.Name)
case trimmed == "metadata":
return p.templateHandler(alias.Metadata)
case strings.HasPrefix(trimmed, "metadata."):
split := strings.SplitN(trimmed, ".", 2)
return p.templateHandler(alias.Metadata, split[1])
}
return "", ErrTemplateValueNotFound
}
performEntityTemplating := func(trimmed string) (string, error) {
switch {
case trimmed == "id":
return p.templateHandler(p.Entity.ID)
case trimmed == "name":
return p.templateHandler(p.Entity.Name)
case trimmed == "metadata":
return p.templateHandler(p.Entity.Metadata)
case strings.HasPrefix(trimmed, "metadata."):
split := strings.SplitN(trimmed, ".", 2)
return p.templateHandler(p.Entity.Metadata, split[1])
case trimmed == "groups.names":
return p.templateHandler(p.groupNames)
case trimmed == "groups.ids":
return p.templateHandler(p.groupIDs)
case strings.HasPrefix(trimmed, "aliases."):
split := strings.SplitN(strings.TrimPrefix(trimmed, "aliases."), ".", 2)
if len(split) != 2 {
return "", errors.New("invalid alias selector")
}
var alias *Alias
for _, a := range p.Entity.Aliases {
if split[0] == a.MountAccessor {
alias = a
break
}
}
if alias == nil {
if p.Mode == ACLTemplating {
return "", errors.New("alias not found")
}
// An empty alias is sufficient for generating defaults
alias = &Alias{Metadata: make(map[string]string)}
}
return performAliasTemplating(split[1], alias)
}
return "", ErrTemplateValueNotFound
}
performGroupsTemplating := func(trimmed string) (string, error) {
var ids bool
selectorSplit := strings.SplitN(trimmed, ".", 2)
switch {
case len(selectorSplit) != 2:
return "", errors.New("invalid groups selector")
case selectorSplit[0] == "ids":
ids = true
case selectorSplit[0] == "names":
default:
return "", errors.New("invalid groups selector")
}
trimmed = selectorSplit[1]
accessorSplit := strings.SplitN(trimmed, ".", 2)
if len(accessorSplit) != 2 {
return "", errors.New("invalid groups accessor")
}
var found *Group
for _, group := range p.Groups {
var compare string
if ids {
compare = group.ID
} else {
if p.Namespace != nil && group.NamespaceID == p.Namespace.ID {
compare = group.Name
} else {
continue
}
}
if compare == accessorSplit[0] {
found = group
break
}
}
if found == nil {
return "", fmt.Errorf("entity is not a member of group %q", accessorSplit[0])
}
trimmed = accessorSplit[1]
switch {
case trimmed == "id":
return found.ID, nil
case trimmed == "name":
if found.Name == "" {
return "", ErrTemplateValueNotFound
}
return found.Name, nil
case strings.HasPrefix(trimmed, "metadata."):
val, ok := found.Metadata[strings.TrimPrefix(trimmed, "metadata.")]
if !ok {
return "", ErrTemplateValueNotFound
}
return val, nil
}
return "", ErrTemplateValueNotFound
}
performTimeTemplating := func(trimmed string) (string, error) {
now := p.Now
if now.IsZero() {
now = time.Now()
}
opsSplit := strings.SplitN(trimmed, ".", 3)
if opsSplit[0] != "now" {
return "", fmt.Errorf("invalid time selector %q", opsSplit[0])
}
result := now
switch len(opsSplit) {
case 1:
// return current time
case 2:
return "", errors.New("missing time operand")
case 3:
duration, err := time.ParseDuration(opsSplit[2])
if err != nil {
return "", errwrap.Wrapf("invalid duration: {{err}}", err)
}
switch opsSplit[1] {
case "plus":
result = result.Add(duration)
case "minus":
result = result.Add(-duration)
default:
return "", fmt.Errorf("invalid time operator %q", opsSplit[1])
}
}
return strconv.FormatInt(result.Unix(), 10), nil
}
switch {
case strings.HasPrefix(input, "identity.entity."):
if p.Entity == nil {
return "", ErrNoEntityAttachedToToken
}
return performEntityTemplating(strings.TrimPrefix(input, "identity.entity."))
case strings.HasPrefix(input, "identity.groups."):
if len(p.Groups) == 0 {
return "", ErrNoGroupsAttachedToToken
}
return performGroupsTemplating(strings.TrimPrefix(input, "identity.groups."))
case strings.HasPrefix(input, "time."):
return performTimeTemplating(strings.TrimPrefix(input, "time."))
}
return "", ErrTemplateValueNotFound
}