okhttp3.internal.http.HttpDate.kt Maven / Gradle / Ivy

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/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * 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.
 */
package okhttp3.internal.http

import okhttp3.internal.Util.UTC
import java.text.DateFormat
import java.text.ParsePosition
import java.text.SimpleDateFormat
import java.util.Locale
import java.util.Date

/**
 * Best-effort parser for HTTP dates.
 */
object HttpDate {
  /** The last four-digit year: "Fri, 31 Dec 9999 23:59:59 GMT".  */
  const val MAX_DATE = 253402300799999L

  /**
   * Most websites serve cookies in the blessed format. Eagerly create the parser to ensure such
   * cookies are on the fast path.
   */
  private val STANDARD_DATE_FORMAT = object : ThreadLocal() {
    override fun initialValue(): DateFormat {
      // Date format specified by RFC 7231 section 7.1.1.1.
      return SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss 'GMT'", Locale.US).apply {
        isLenient = false
        timeZone = UTC
      }
    }
  }

  /** If we fail to parse a date in a non-standard format, try each of these formats in sequence.  */
  private val BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS = arrayOf(
      // HTTP formats required by RFC2616 but with any timezone.
      "EEE, dd MMM yyyy HH:mm:ss zzz", // RFC 822, updated by RFC 1123 with any TZ
      "EEEE, dd-MMM-yy HH:mm:ss zzz", // RFC 850, obsoleted by RFC 1036 with any TZ.
      "EEE MMM d HH:mm:ss yyyy", // ANSI C's asctime() format
      // Alternative formats.
      "EEE, dd-MMM-yyyy HH:mm:ss z",
      "EEE, dd-MMM-yyyy HH-mm-ss z",
      "EEE, dd MMM yy HH:mm:ss z",
      "EEE dd-MMM-yyyy HH:mm:ss z",
      "EEE dd MMM yyyy HH:mm:ss z",
      "EEE dd-MMM-yyyy HH-mm-ss z",
      "EEE dd-MMM-yy HH:mm:ss z",
      "EEE dd MMM yy HH:mm:ss z",
      "EEE,dd-MMM-yy HH:mm:ss z",
      "EEE,dd-MMM-yyyy HH:mm:ss z",
      "EEE, dd-MM-yyyy HH:mm:ss z",

      /* RI bug 6641315 claims a cookie of this format was once served by www.yahoo.com */
      "EEE MMM d yyyy HH:mm:ss z"
  )

  private val BROWSER_COMPATIBLE_DATE_FORMATS = arrayOfNulls(BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS.size)

  /** Returns the date for [value]. Returns null if the value couldn't be parsed.  */
  @JvmStatic
  fun parse(value: String): Date? {
    if (value.isEmpty()) {
      return null
    }

    val position = ParsePosition(0)
    var result = STANDARD_DATE_FORMAT.get().parse(value, position)
    if (position.index == value.length) {
      // STANDARD_DATE_FORMAT must match exactly; all text must be consumed, e.g. no ignored
      // non-standard trailing "+01:00". Those cases are covered below.
      return result
    }
    synchronized(BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS) {
      for (i in 0 until BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS.size) {
        var format: DateFormat? = BROWSER_COMPATIBLE_DATE_FORMATS[i]
        if (format == null) {
          format = SimpleDateFormat(BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS[i], Locale.US).apply {
            // Set the timezone to use when interpreting formats that don't have a timezone. GMT is
            // specified by RFC 7231.
            timeZone = UTC
          }
          BROWSER_COMPATIBLE_DATE_FORMATS[i] = format
        }
        position.index = 0
        result = format.parse(value, position)
        if (position.index != 0) {
          // Something was parsed. It's possible the entire string was not consumed but we ignore
          // that. If any of the BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS ended in "'GMT'" we'd have
          // to also check that position.getIndex() == value.length() otherwise parsing might have
          // terminated early, ignoring things like "+01:00". Leaving this as != 0 means that any
          // trailing junk is ignored.
          return result
        }
      }
    }
    return null
  }

  /** Returns the string for [value].  */
  @JvmStatic
  fun format(value: Date): String {
    return STANDARD_DATE_FORMAT.get().format(value)
  }
}