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1const {2  URL_MATCHER,3  TYPE_URL,4  TYPE_REGEX,5  TYPE_PATH,6} = require('./matchers')7 8/**9 * creates a string of asterisks,10 * this forces a minimum asterisk for security purposes11 */12const asterisk = (length = 0) => {13  length = typeof length === 'string' ? length.length : length14  if (length < 8) {15    return '*'.repeat(8)16  }17  return '*'.repeat(length)18}19 20/**21 * escapes all special regex chars22 * @see https://stackoverflow.com/a/931075223 * @see https://github.com/tc39/proposal-regex-escaping24 */25const escapeRegExp = (text) => {26  return text.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, `\\$&`)27}28 29/**30 * provieds a regex "or" of the url versions of a string31 */32const urlEncodeRegexGroup = (value) => {33  const decoded = decodeURIComponent(value)34  const encoded = encodeURIComponent(value)35  const union = [...new Set([encoded, decoded, value])].map(escapeRegExp).join('|')36  return union37}38 39/**40 * a tagged template literal that returns a regex ensures all variables are excaped41 */42const urlEncodeRegexTag = (strings, ...values) => {43  let pattern = ''44  for (let i = 0; i < values.length; i++) {45    pattern += strings[i] + `(${urlEncodeRegexGroup(values[i])})`46  }47  pattern += strings[strings.length - 1]48  return new RegExp(pattern)49}50 51/**52 * creates a matcher for redacting url hostname53 */54const redactUrlHostnameMatcher = ({ hostname, replacement } = {}) => ({55  type: TYPE_URL,56  predicate: ({ url }) => url.hostname === hostname,57  pattern: ({ url }) => {58    return urlEncodeRegexTag`(^${url.protocol}//${url.username}:.+@)?${url.hostname}`59  },60  replacement: `$1${replacement || asterisk()}`,61})62 63/**64 * creates a matcher for redacting url search / query parameter values65 */66const redactUrlSearchParamsMatcher = ({ param, replacement } = {}) => ({67  type: TYPE_URL,68  predicate: ({ url }) => url.searchParams.has(param),69  pattern: ({ url }) => urlEncodeRegexTag`(${param}=)${url.searchParams.get(param)}`,70  replacement: `$1${replacement || asterisk()}`,71})72 73/** creates a matcher for redacting the url password */74const redactUrlPasswordMatcher = ({ replacement } = {}) => ({75  type: TYPE_URL,76  predicate: ({ url }) => url.password,77  pattern: ({ url }) => urlEncodeRegexTag`(^${url.protocol}//${url.username}:)${url.password}`,78  replacement: `$1${replacement || asterisk()}`,79})80 81const redactUrlReplacement = (...matchers) => (subValue) => {82  try {83    const url = new URL(subValue)84    return redactMatchers(...matchers)(subValue, { url })85  } catch (err) {86    return subValue87  }88}89 90/**91 * creates a matcher / submatcher for urls, this function allows you to first92 * collect all urls within a larger string and then pass those urls to a93 * submatcher94 *95 * @example96 * console.log("this will first match all urls, then pass those urls to the password patcher")97 * redactMatchers(redactUrlMatcher(redactUrlPasswordMatcher()))98 *99 * @example100 * console.log(101 *   "this will assume you are passing in a string that is a url, and will redact the password"102 * )103 * redactMatchers(redactUrlPasswordMatcher())104 *105 */106const redactUrlMatcher = (...matchers) => {107  return {108    ...URL_MATCHER,109    replacement: redactUrlReplacement(...matchers),110  }111}112 113const matcherFunctions = {114  [TYPE_REGEX]: (matcher) => (value) => {115    if (typeof value === 'string') {116      value = value.replace(matcher.pattern, matcher.replacement)117    }118    return value119  },120  [TYPE_URL]: (matcher) => (value, ctx) => {121    if (typeof value === 'string') {122      try {123        const url = ctx?.url || new URL(value)124        const { predicate, pattern } = matcher125        const predicateValue = predicate({ url })126        if (predicateValue) {127          value = value.replace(pattern({ url }), matcher.replacement)128        }129      } catch (_e) {130        return value131      }132    }133    return value134  },135  [TYPE_PATH]: (matcher) => (value, ctx) => {136    const rawPath = ctx?.path137    const path = rawPath.join('.').toLowerCase()138    const { predicate, replacement } = matcher139    const replace = typeof replacement === 'function' ? replacement : () => replacement140    const shouldRun = predicate({ rawPath, path })141    if (shouldRun) {142      value = replace(value, { rawPath, path })143    }144    return value145  },146}147 148/** converts a matcher to a function */149const redactMatcher = (matcher) => {150  return matcherFunctions[matcher.type](matcher)151}152 153/** converts a series of matchers to a function */154const redactMatchers = (...matchers) => (value, ctx) => {155  const flatMatchers = matchers.flat()156  return flatMatchers.reduce((result, matcher) => {157    const fn = (typeof matcher === 'function') ? matcher : redactMatcher(matcher)158    return fn(result, ctx)159  }, value)160}161 162/**163 * replacement handler, keeping $1 (if it exists) and replacing the164 * rest of the string with asterisks, maintaining string length165 */166const redactDynamicReplacement = () => (value, start) => {167  if (typeof start === 'number') {168    return asterisk(value)169  }170  return start + asterisk(value.substring(start.length).length)171}172 173/**174 * replacement handler, keeping $1 (if it exists) and replacing the175 * rest of the string with a fixed number of asterisks176 */177const redactFixedReplacement = (length) => (_value, start) => {178  if (typeof start === 'number') {179    return asterisk(length)180  }181  return start + asterisk(length)182}183 184const redactUrlPassword = (value, replacement) => {185  return redactMatchers(redactUrlPasswordMatcher({ replacement }))(value)186}187 188module.exports = {189  asterisk,190  escapeRegExp,191  urlEncodeRegexGroup,192  urlEncodeRegexTag,193  redactUrlHostnameMatcher,194  redactUrlSearchParamsMatcher,195  redactUrlPasswordMatcher,196  redactUrlMatcher,197  redactUrlReplacement,198  redactDynamicReplacement,199  redactFixedReplacement,200  redactMatchers,201  redactUrlPassword,202}203