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refs.go
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refs.go
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package config
import (
"errors"
"fmt"
"net/url"
"os"
"path/filepath"
"strconv"
"strings"
"unicode/utf8"
"github.com/dafanshu/benthos/v3/lib/util/text"
"gopkg.in/yaml.v3"
)
//------------------------------------------------------------------------------
// ReadWithJSONPointers takes a config file path, reads the contents, performs a
// generic parse, resolves any JSON Pointers, marshals the result back into
// bytes and returns it so that it can be unmarshalled into a typed structure.
func ReadWithJSONPointers(path string, replaceEnvs bool) ([]byte, error) {
b, _, err := ReadWithJSONPointersLinted(path, replaceEnvs)
return b, err
}
// ReadWithJSONPointersLinted takes a config file path, reads the contents,
// performs a generic parse, resolves any JSON Pointers, marshals the result
// back into bytes and returns it so that it can be unmarshalled into a typed
// structure.
//
// If any non-fatal errors occur lints are returned along with the result.
func ReadWithJSONPointersLinted(path string, replaceEnvs bool) (configBytes []byte, lints []string, err error) {
configBytes, err = os.ReadFile(path)
if err != nil {
return nil, nil, err
}
if !utf8.Valid(configBytes) {
lints = append(lints, "Detected invalid utf-8 encoding in config, this may result in interpolation functions not working as expected")
}
if replaceEnvs {
configBytes = text.ReplaceEnvVariables(configBytes)
}
var gen interface{}
if err := yaml.Unmarshal(configBytes, &gen); err != nil {
return nil, lints, err
}
refFound, err := refWalk(path, 0, gen, gen)
if err != nil {
return nil, lints, err
}
if !refFound {
return configBytes, lints, nil
}
if configBytes, err = yaml.Marshal(gen); err != nil {
return nil, lints, fmt.Errorf("failed to marshal ref evaluated structure: %v", err)
}
return configBytes, lints, nil
}
//------------------------------------------------------------------------------
// JSONPointer parses a JSON pointer path (https://tools.ietf.org/html/rfc6901)
// and either returns an interface{} containing the result or an error if the
// referenced item could not be found.
func JSONPointer(path string, object interface{}) (interface{}, error) {
if len(path) < 1 {
return nil, errors.New("failed to resolve JSON pointer: path must not be empty")
}
if path[0] != '/' {
return nil, errors.New("failed to resolve JSON pointer: path must begin with '/'")
}
hierarchy := strings.Split(path, "/")[1:]
for i, v := range hierarchy {
v = strings.ReplaceAll(v, "~1", "/")
v = strings.ReplaceAll(v, "~0", "~")
hierarchy[i] = v
}
for target := 0; target < len(hierarchy); target++ {
pathSeg := hierarchy[target]
switch typedObject := object.(type) {
case map[string]interface{}:
var ok bool
if object, ok = typedObject[pathSeg]; !ok {
return nil, fmt.Errorf("failed to resolve JSON pointer: index '%v' value '%v' was not found", target, pathSeg)
}
case map[interface{}]interface{}:
var ok bool
if object, ok = typedObject[pathSeg]; !ok {
return nil, fmt.Errorf("failed to resolve JSON pointer: index '%v' value '%v' was not found", target, pathSeg)
}
case []interface{}:
index, err := strconv.Atoi(pathSeg)
if err != nil {
return nil, fmt.Errorf("failed to resolve JSON pointer: could not parse index '%v' value '%v' into array index: %v", target, pathSeg, err)
}
if len(typedObject) <= index {
return nil, fmt.Errorf("failed to resolve JSON pointer: index '%v' value '%v' exceeded target array size of '%v'", target, pathSeg, len(typedObject))
}
object = typedObject[index]
default:
return nil, fmt.Errorf("failed to resolve JSON pointer: index '%v' field '%v' was not found", target, pathSeg)
}
}
return object, nil
}
//------------------------------------------------------------------------------
// ErrExceededRefLimit is returned when a configuration hierarchy results in
// nested references beyond a hard coded limit. This is intended to prevent
// looped references from blocking the service.
var ErrExceededRefLimit = errors.New("exceeded limit of nested references")
var refLimit = 1000
func getRefVal(obj interface{}) interface{} {
switch x := obj.(type) {
case map[interface{}]interface{}:
for k, v := range x {
if k == "$ref" {
return v
}
}
case map[string]interface{}:
for k, v := range x {
if k == "$ref" {
return v
}
}
}
return nil
}
func expandRefVal(path string, level int, root, v interface{}) (interface{}, error) {
if level == refLimit {
return nil, ErrExceededRefLimit
}
s, ok := v.(string)
if !ok {
return nil, fmt.Errorf("config '%v' contained non-string $ref value '%v' (%T)", path, v, v)
}
u, err := url.Parse(s)
if err != nil {
return nil, fmt.Errorf("failed to parse $ref value '%v' in config '%v' as URI: %v", s, path, err)
}
if u.Scheme != "" && u.Scheme != "file" {
return nil, fmt.Errorf("config '%v' contained non-path $ref value '%v'", path, v)
}
if u.Path == "" && u.Fragment == "" {
return nil, fmt.Errorf("failed to resolve $ref value '%v' in config '%v': reference URI must contain at least a path or fragment", s, path)
}
var nextObj interface{}
if len(u.Path) > 0 {
rPath := u.Path
if !filepath.IsAbs(rPath) {
rPath = filepath.Join(filepath.Dir(path), rPath)
}
configBytes, err := os.ReadFile(rPath)
if err != nil {
return nil, fmt.Errorf("failed to read relative $ref path '%v' in config '%v': %v", rPath, path, err)
}
configBytes = text.ReplaceEnvVariables(configBytes)
var gen interface{}
if err := yaml.Unmarshal(configBytes, &gen); err != nil {
return nil, err
}
root = gen
nextObj = gen
path = rPath
}
if len(u.Fragment) > 0 {
if nextObj, err = JSONPointer(u.Fragment, root); err != nil {
return nil, fmt.Errorf("failed to resolve $ref fragment '%v' in config '%v': %v", u.Fragment, path, err)
}
}
if rVal := getRefVal(nextObj); rVal != nil {
return expandRefVal(path, level+1, root, rVal)
}
if _, err = refWalk(path, level+1, root, nextObj); err != nil {
return nil, err
}
return nextObj, nil
}
func refWalk(path string, level int, root, obj interface{}) (refFound bool, err error) {
switch x := obj.(type) {
case map[string]interface{}:
for k, v := range x {
if rv := getRefVal(v); rv != nil {
if x[k], err = expandRefVal(path, level, root, rv); err != nil {
return
}
refFound = true
} else {
var rFound bool
if rFound, err = refWalk(path, level, root, v); err != nil {
return
} else if rFound {
refFound = true
}
}
}
case map[interface{}]interface{}:
for k, v := range x {
if rv := getRefVal(v); rv != nil {
if x[k], err = expandRefVal(path, level, root, rv); err != nil {
return
}
refFound = true
} else {
var rFound bool
if rFound, err = refWalk(path, level, root, v); err != nil {
return
} else if rFound {
refFound = true
}
}
}
case []interface{}:
for i, v := range x {
if rv := getRefVal(v); rv != nil {
if x[i], err = expandRefVal(path, level, root, rv); err != nil {
return
}
refFound = true
} else {
var rFound bool
if rFound, err = refWalk(path, level, root, v); err != nil {
return
} else if rFound {
refFound = true
}
}
}
}
return
}
//------------------------------------------------------------------------------