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ctx.go
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ctx.go
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/*
* Copyright 2021 Comcast Cable Communications Management, LLC
*
* 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.
*
* SPDX-License-Identifier: Apache-2.0
*/
package dsl
import (
"context"
"fmt"
"log"
"regexp"
"strings"
"time"
"github.com/Comcast/plax/subst"
)
var (
// DefaultLogger is the default logger.
DefaultLogger Logger = &GoLogger{}
// DefaultLogLevel is the default log level.
//
// ToDo: Use an enum.
DefaultLogLevel = "info"
)
// Ctx includes a context.Context, logging specifications, and some
// directories for various file inclusions.
type Ctx struct {
context.Context
Logger
IncludeDirs []string
Dir string
LogLevel string
// Redact, if true, will redact substrings that match
// Redactions in logging output.
Redact bool
Redactions map[string]*regexp.Regexp
}
// NewCtx build a new dsl.Ctx
func NewCtx(ctx context.Context) *Ctx {
if ctx == nil {
ctx = context.Background()
}
// Make default redactions
redactions := make(map[string]*regexp.Regexp)
// If the context was a dsl.Ctx then use the redactions from the original context
if dslCtx, ok := ctx.(*Ctx); ok {
redactions = dslCtx.Redactions
}
return &Ctx{
Context: ctx,
Logger: DefaultLogger,
LogLevel: DefaultLogLevel,
IncludeDirs: make([]string, 0, 1),
Dir: ".",
Redactions: redactions,
}
}
// WithCancel builds a new dsl.Ctx with a cancel function.
func (c *Ctx) WithCancel() (*Ctx, func()) {
ctx, cancel := context.WithCancel(c.Context)
return &Ctx{
Context: ctx,
Logger: DefaultLogger,
LogLevel: c.LogLevel,
IncludeDirs: c.IncludeDirs,
Dir: c.Dir,
Redact: c.Redact,
Redactions: c.Redactions, // not copying
}, cancel
}
// WithTimeout builds a new dsl.Ctx with a timeout function.
func (c *Ctx) WithTimeout(d time.Duration) (*Ctx, func()) {
ctx, cancel := context.WithTimeout(c.Context, d)
return &Ctx{
Context: ctx,
Logger: DefaultLogger,
LogLevel: c.LogLevel,
IncludeDirs: c.IncludeDirs,
Dir: c.Dir,
Redact: c.Redact,
Redactions: c.Redactions, // not copying
}, cancel
}
// SetLogLevel sets the dsl.Ctx LogLevel.
func (c *Ctx) SetLogLevel(level string) error {
canonical := strings.ToLower(level)
// No strings.TrimSpace.
switch canonical {
case "info", "debug", "none":
default:
return fmt.Errorf("Ctx.LogLevel '%s' isn't 'info', 'debug', or 'none'", canonical)
}
c.LogLevel = canonical
return nil
}
// AddRedaction compiles the given string as a regular expression and
// installs that regexp as a desired redaction in logging output.
func (c *Ctx) AddRedaction(pat string) error {
r, err := regexp.Compile(pat)
if err != nil {
return err
}
c.Redactions[pat] = r
return nil
}
// WantsRedaction reports whether the parameter's value should be
// redacted.
//
// Currently if a parameter starts with "X_" after ignoring special
// characters, then the parameter's value should be redacted.
func WantsRedaction(p string) bool {
return strings.HasPrefix(strings.Trim(p, "?!*"), "X_")
}
// bindingRedactions adds redaction patterns for values of binding
// variables that start with X_.
func (ctx *Ctx) BindingsRedactions(bs Bindings) error {
for p, v := range bs {
if WantsRedaction(p) {
var s string
switch vv := v.(type) {
case string:
s = vv
case interface{}:
bs, err := subst.JSONMarshal(vv)
if err != nil {
return err
}
s = string(bs)
}
pat := regexp.QuoteMeta(s)
if err := ctx.AddRedaction(pat); err != nil {
return err
}
}
}
return nil
}
// Redact might replace part of s with <redacted> depending on the
// given Regexp.
//
// If the Regexp has no groups, all substrings that match the Regexp
// are redacted.
//
// For each named group with a name starting with "redact", that group
// is redacted (for all matches).
//
// If there are groups but none has a name starting with "redact",
// then the first matching (non-captured) group is redacted.
func Redact(r *regexp.Regexp, s string) string {
replacement := "<redacted>"
if r.NumSubexp() == 0 {
return r.ReplaceAllString(s, replacement)
}
var acc string
for {
match := r.FindStringSubmatchIndex(s)
if match == nil {
acc += s
break
}
var (
redacted = false
names = r.SubexpNames()
last = match[1]
start, end int
)
for i, name := range names {
// First one is anonymous everything group.
if strings.HasPrefix(name, "redact") {
redacted = true
start, end = match[2*i], match[2*i+1]
break
}
}
if !redacted {
// The first group will be redacted.
start, end = match[2], match[3]
}
acc += s[0:start] + replacement + s[end:last]
s = s[last:]
}
return acc
}
// Redactf calls c.Printf with any requested redactions with c.Redact
// is true.
func (c *Ctx) Redactf(format string, args ...interface{}) {
s := fmt.Sprintf(format, args...)
if c.Redact {
for _, r := range c.Redactions {
s = Redact(r, s)
}
}
c.Printf("%s", s)
}
// Indf emits a log line starting with a '|' when ctx.LogLevel isn't 'none'.
func (c *Ctx) Indf(format string, args ...interface{}) {
switch c.LogLevel {
case "none", "NONE":
default:
c.Redactf("| "+format, args...)
}
}
// Inddf emits a log line starting with a '|' when ctx.LogLevel is 'debug';
//
// The second 'd' is for "debug".
func (c *Ctx) Inddf(format string, args ...interface{}) {
switch c.LogLevel {
case "debug", "DEBUG":
c.Redactf("| "+format, args...)
}
}
// Warnf emits a log with a '!' prefix.
func (c *Ctx) Warnf(format string, args ...interface{}) {
c.Redactf("! "+format, args...)
}
// Logf emits a log line starting with a '>' when ctx.LogLevel isn't 'none'.
func (c *Ctx) Logf(format string, args ...interface{}) {
switch c.LogLevel {
case "none", "NONE":
default:
c.Redactf("> "+format, args...)
}
}
// Logdf emits a log line starting with a '>' when ctx.LogLevel is 'debug';
//
// The second 'd' is for "debug".
func (c *Ctx) Logdf(format string, args ...interface{}) {
switch c.LogLevel {
case "debug", "DEBUG":
c.Redactf("> "+format, args...)
}
}
// Logger is an interface that allows for pluggable loggers.
//
// Used in the Plax Lambda.
type Logger interface {
Printf(format string, args ...interface{})
}
// GoLogger is just basic Go logging.
type GoLogger struct {
}
// Printf logs
func (l *GoLogger) Printf(format string, args ...interface{}) {
log.Printf(format, args...)
}