b[size:] } } // DefaultReader is a sentinel type, embedded in the default // [crypto/rand.Reader], used to recognize it when passed to // APIs that accept a rand io.Reader. type DefaultReader interface{ defaultReader() } // ReadWithReader uses Reader to fill b with cryptographically secure random // bytes. It is intended for use in APIs that expose a rand io.Reader. // // If Reader is not the default Reader from crypto/rand, // [randutil.MaybeReadByte] and [fips140.RecordNonApproved] are called....

)

func getDefaultOpts(header http.Header, copySource bool, metadata map[string]string) (opts ObjectOptions, err error) {
	var clientKey [32]byte
	var sse encrypt.ServerSide

	opts = ObjectOptions{UserDefined: metadata}
	if v, ok := header[xhttp.MinIOSourceProxyRequest]; ok {
		opts.ProxyHeaderSet = true
		opts.ProxyRequest = strings.Join(v, "") == "true"
	}
	if _, ok := header[xhttp.MinIOSourceReplicationRequest]; ok {

      headers.name(-1)
    }
    assertThat(headers.name(0)).isEqualTo("a")
    assertThat(headers.name(1)).isEqualTo("c")
    assertFailsWith<IndexOutOfBoundsException> {
      headers.name(2)
    }
  }

  @Test fun valueIndexesAreStrict() {
    val headers = headersOf("a", "b", "c", "d")
    assertFailsWith<IndexOutOfBoundsException> {
      headers.value(-1)
    }
    assertThat(headers.value(0)).isEqualTo("b")

Symmetrically, interceptors can rewrite response headers and transform the response body. This is generally more dangerous than rewriting request headers because it may violate the webserver's expectations!

If you're in a tricky situation and prepared to deal with the consequences, rewriting response headers is a powerful way to work around problems. For example, you can fix a server's misconfigured `Cache-Control` response header to enable better response caching:

    peer.acceptFrame() // ACK
    peer.acceptFrame() // SYN_STREAM
    peer.sendFrame().headers(false, 3, headerEntries("a", "android"))
    val expectedRequestHeaders =
      listOf(
        Header(Header.TARGET_METHOD, "GET"),
        Header(Header.TARGET_SCHEME, "https"),
        Header(Header.TARGET_AUTHORITY, "squareup.com"),
        Header(Header.TARGET_PATH, "/cached"),
      )

}

// Return canonical headers.
func canonicalizedAmzHeadersV2(headers http.Header) string {
	var keys []string
	keyval := make(map[string]string, len(headers))
	for key := range headers {
		lkey := strings.ToLower(key)
		if !strings.HasPrefix(lkey, "x-amz-") {
			continue
		}
		keys = append(keys, lkey)
		keyval[lkey] = strings.Join(headers[key], ",")
	}
	sort.Strings(keys)

    val derReader = DerReader(buffer)

    derReader.read("test") { header ->
      assertThat(header.tag).isEqualTo(2L)
      assertThat(header.tagClass).isEqualTo(DerHeader.TAG_CLASS_CONTEXT_SPECIFIC)
      assertThat(header.length).isEqualTo(7L)

      derReader.read("test") { header ->
        assertThat(header.tag).isEqualTo(3L)
        assertThat(header.tagClass).isEqualTo(DerHeader.TAG_CLASS_APPLICATION)

	}
	extractedSignedHeaders := make(http.Header)
	for _, header := range signedHeaders {
		// `host` will not be found in the headers, can be found in r.Host.
		// but its always necessary that the list of signed headers containing host in it.
		val, ok := reqHeaders[http.CanonicalHeaderKey(header)]
		if !ok {
			// try to set headers from Query String
			val, ok = reqQueries[header]
		}
		if ok {

        .header("User-Agent", "OkHttp Headers.java")
        .addHeader("Accept", "application/json; q=0.5")
        .addHeader("Accept", "application/vnd.github.v3+json")
        .build()

    client.newCall(request).execute().use { response ->
      if (!response.isSuccessful) throw IOException("Unexpected code $response")

      println("Server: ${response.header("Server")}")

    * But it needs authentication for that specific endpoint.
    * So, to authenticate with our API, it sends a header `Authorization` with a value of `Bearer ` plus the token.
    * If the token contains `foobar`, the content of the `Authorization` header would be: `Bearer foobar`.

## **FastAPI**'s `OAuth2PasswordBearer` { #fastapis-oauth2passwordbearer }