First commit

node_modules/@ldapjs/dn/lib/utils/parse-string/read-attribute-value.js

@@ -0,0 +1,165 @@
+'use strict'
+
+const readHexString = require('./read-hex-string')
+const readEscapeSequence = require('./read-escape-sequence')
+
+/**
+ * @typedef {object} ReadAttributeValueResult
+ * @property {number} endPos The position in the buffer that marks the end of
+ * the value.
+ * @property {string | import('@ldapjs/asn1').BerReader} value
+ */
+
+/**
+ * Read an attribute value string from a given {@link Buffer} and return it.
+ * If the value is an encoded octet string, it will be decoded and returned
+ * as a {@link Buffer}.
+ *
+ * @param {Buffer} searchBuffer
+ * @param {number} startPos
+ *
+ * @returns {ReadAttributeValueResult}
+ *
+ * @throws When there is a syntax error in the attribute value string.
+ */
+module.exports = function readAttributeValue ({ searchBuffer, startPos }) {
+  let pos = startPos
+
+  while (pos < searchBuffer.byteLength && searchBuffer[pos] === 0x20) {
+    // Skip over any leading whitespace before the '='.
+    pos += 1
+  }
+
+  if (pos >= searchBuffer.byteLength || searchBuffer[pos] !== 0x3d) {
+    throw Error('attribute value does not start with equals sign')
+  }
+
+  // Advance past the equals sign.
+  pos += 1
+  while (pos <= searchBuffer.byteLength && searchBuffer[pos] === 0x20) {
+    // Advance past any leading whitespace.
+    pos += 1
+  }
+
+  if (pos >= searchBuffer.byteLength) {
+    return { endPos: pos, value: '' }
+  }
+
+  if (searchBuffer[pos] === 0x23) {
+    const result = readHexString({ searchBuffer, startPos: pos + 1 })
+    pos = result.endPos
+    return { endPos: pos, value: result.berReader }
+  }
+
+  const readValueResult = readValueString({ searchBuffer, startPos: pos })
+  pos = readValueResult.endPos
+  return {
+    endPos: pos,
+    value: readValueResult.value.toString('utf8').trim()
+  }
+}
+
+/**
+ * @typedef {object} ReadValueStringResult
+ * @property {number} endPos
+ * @property {Buffer} value
+ * @private
+ */
+
+/**
+ * Read a series of bytes from the buffer as a plain string.
+ *
+ * @param {Buffer} searchBuffer
+ * @param {number} startPos
+ *
+ * @returns {ReadValueStringResult}
+ *
+ * @throws When the attribute value is malformed.
+ *
+ * @private
+ */
+function readValueString ({ searchBuffer, startPos }) {
+  let pos = startPos
+  let inQuotes = false
+  let endQuotePresent = false
+
+  const bytes = []
+  while (pos <= searchBuffer.byteLength) {
+    const char = searchBuffer[pos]
+
+    if (pos === searchBuffer.byteLength) {
+      if (inQuotes === true && endQuotePresent === false) {
+        throw Error('missing ending double quote for attribute value')
+      }
+      break
+    }
+
+    if (char === 0x22) {
+      // Handle the double quote (") character.
+      // RFC 2253 §4 allows for attribute values to be wrapped in double
+      // quotes in order to allow certain characters to be unescaped.
+      // We are not enforcing escaping of characters in this parser, so we only
+      // need to recognize that the quotes are present. Our RDN string encoder
+      // will escape characters as necessary.
+      if (inQuotes === true) {
+        pos += 1
+        endQuotePresent = true
+
+        // We should be at the end of the value.
+        while (pos < searchBuffer.byteLength) {
+          const nextChar = searchBuffer[pos]
+          if (isEndChar(nextChar) === true) {
+            break
+          }
+          if (nextChar !== 0x20) {
+            throw Error('significant rdn character found outside of quotes at position ' + pos)
+          }
+          pos += 1
+        }
+
+        break
+      }
+
+      if (pos !== startPos) {
+        throw Error('unexpected quote (") in rdn string at position ' + pos)
+      }
+      inQuotes = true
+      pos += 1
+      continue
+    }
+
+    if (isEndChar(char) === true && inQuotes === false) {
+      break
+    }
+
+    if (char === 0x5c) {
+      // We have encountered the start of an escape sequence.
+      const seqResult = readEscapeSequence({
+        searchBuffer,
+        startPos: pos
+      })
+      pos = seqResult.endPos
+      Array.prototype.push.apply(bytes, seqResult.parsed)
+      continue
+    }
+
+    bytes.push(char)
+    pos += 1
+  }
+
+  return {
+    endPos: pos,
+    value: Buffer.from(bytes)
+  }
+}
+
+function isEndChar (c) {
+  switch (c) {
+    case 0x2b: // +
+    case 0x2c: // ,
+    case 0x3b: // ; -- Allowed by RFC 2253 §4 in place of a comma.
+      return true
+    default:
+      return false
+  }
+}