external/boringssl: Sync to 66e61c577d39e757bf491468f651461fa79fd5e1.

This includes the following changes:

https://boringssl.googlesource.com/boringssl/+log/c1571feb5faf5cce844354c63d0f3e842464bea3..66e61c577d39e757bf491468f651461fa79fd5e1

* Allow PKCS7_sign to work for signing kernel modules.
* Speed up constant-time base64 decoding.
* Unwind remnants of ASN1_TFLG_NDEF.
* acvptool: add CS3 support.
* Ignore SIGPIPE in the bssl tool.
* Add FIPS counters for AES-GCM in EVP_AEAD.
* Refresh fuzzer corpus for ECH draft-13.
* Fix the TLS fuzzers for ECH draft-13.
* Clarify that TLS sessions are not application sessions.
* Fix BN_prime_checks_for_validation to align with false-positive rate.
* Add maskHash to RSA_PSS_PARAMS for compat
* Remove ASN1_OP_I2D_* callbacks.
* Don't read it->funcs without checking it->itype.
* Reject missing required fields in i2d functions.
Update-Note: Structures with missing mandatory fields can no longer be
encoded. Note that, apart from the cases already handled by preceding
CLs, tasn_new.c will fill in non-NULL empty objects everywhere. The main
downstream impact I've seen of this particular change is in combination
with other bugs. Consider a caller that does:
* Reject -1 types in ASN1_TYPE and MSTRINGs when encoding.
Update-Note: A default-constructed object with a required ANY or
string-like CHOICE field cannot be encoded until the field is specified.
Note this affects i2d_X509: notBefore and notAfter are string-like
CHOICEs in OpenSSL.
* Correctly handle invalid ASN1_OBJECTs when encoding.
Update-Note: A default-constructed object with a required ASN1_OBJECT
field can no longer be encoded without initializing the ASN1_OBJECT.
Note this affects X509: the signature algorithm is an ASN1_OBJECT. Tests
that try to serialize an X509_new() must fill in all required fields.
(Production code is unlikely to be affected because the output was
unparsable anyway, while tests sometimes wouldn't notice.)
* Check for invalid CHOICE selectors in i2d functions.
Update-Note: An invalid CHOICE object (e.g. GENERAL_NAME) will now fail
when encoded, rather than be silently omitted. In particular, CHOICE
objects are default-initialized by tasn_new.c in an empty -1 state.
Structures containing a required CHOICE field can no longer be encoded
without filling in the CHOICE.
* Fix x509_name_ex_i2d error-handling.
* Correctly propagate errors in i2d functions.
Update-Note: Some error cases which were silently misinterpreted as
missing OPTIONAL elements will now cause encoding to fail.
* acvptool: add hmacDRBG support
* Check for __TRUSTY__ instead of TRUSTY.
* Update comment for ECH draft-13.
* Silence a GCC false positive warning.
* Switch to the new, simpler WHATWG URL formulation.
* Revert "Guard use of sdallocx with BORINGSSL_SDALLOCX"
* Fix calculation of draft-13 ECH confirmation signal.
* Update to draft-ietf-tls-esni-13.
* Reword SSL_get0_ech_name_override documentation.
* Remove SSL_set_verify_result.
* Make most of crypto/x509 opaque.
Update-Note: Patch cl/390055173 into the roll that includes this. This
unexports most of the X.509 structs, aligning with OpenSSL. Use the
accessor APIs instead.
* Remove V_ASN1_APP_CHOOSE.
Update-Note: V_ASN1_APP_CHOOSE is removed. I only found one use, which
has been fixed.
* Rewrite ASN1_PRINTABLE_type and add tests.
* Include SHA512-256 in EVP_get_digestbyname and EVP_MD_do_all.
* NUL is not printable.
Update-Note: ASN1_mbstring_ncopy will no longer allow PrintableString
for strings containing NUL.
* Make RSA_check_key more than 2x as fast.
* Benchmark RSA private key parsing.
* Work around yet another MSVC 2015 SFINAE bug.
* Avoid re-hashing the transcript multiple times.
* Make ssl_parse_extensions a little easier to use.
* Deduplicate our three ServerHello parsers.
* Merge in OpenSSL's X.509 corpus.
* Run X509_print in the certificate fuzzer.
* Fix some error-handling in i2v functions.
* Fix typo.
* OPENSSL_strndup should not return NULL given {NULL, 0}.
* Rewrite name constraints matching with CBS.
* Add some tests for name constraints.
* Fix i2v_GENERAL_NAME to not assume NUL terminated strings
* Do not rely on ASN1_STRING being NUL-terminated.
* Add a CBB_add_zeros helper.
* Linkify RFCs in documentation.
* Refer to RFCs consistently.
* runner: Test session IDs over 32 bytes.
* Process the TLS 1.3 cipher suite in one place.
* Guard use of sdallocx with BORINGSSL_SDALLOCX
* Bump minimum GCC version and note impending VS2015 deprecation.
* Add Span::first() and Span::last().
* Simplify built-in BIOs slightly.
* Fix some error returns from SSL_read and SSL_write.
* Fix negative ENUMERATED values in multi-strings.
* Add a test for ASN1_mbstring_copy and clean up.
* Remove ASN1_TFLG_SET_ORDER.
* Fix ASN1_STRING_print_ex with negative integers.
* Check i2d_ASN1_TYPE's return value in ASN1_STRING_print_ex.
* Document ASN.1 printing functions.
* Move some ASN1 printing functions to crypto/asn1.
* Move a_strex.c back to asn1, split X509_NAME bits out.
* Unwind io_ch abstraction in print functions.
* Implement ASN1_STRING_print_ex_fp, etc., with file BIOs.
* Remove OPENSSL_NO_FP_API ifdefs.
* Move X509_ALGOR to x509.h.
* Unexport BIT_STRING_BITNAME.
* Unexport ub_* constants.
Update-Note: Removed some unnamespaced constants.
* Always use an ASN1_STRING_TABLE global mask of UTF8String.
Update-Note: The global mask for ASN1_STRING_set_by_NID is now always
UTF-8. Callers that want another type should reconsider and, if UTF-8 is
still unsuitable, just pass the actual desired type into
ASN1_mbstring_copy, X509_NAME_ENTRY_set_data, etc
* Document ASN1_mbstring_copy.
* Update ghashv8-armx.pl from upstream.
* Align with upstream on 'close STDOUT' lines.
* Avoid double-expanding variables in CMake.
* Reject years outside 0000-9999 in ASN1_GENERALIZEDTIME_adj.
* Add some tests for time_t to ASN1_TIME conversions.
* Remove ASN1_STRING_FLAG_MSTRING.
Update-Note: ASN1_STRING_FLAG_MSTRING is no longer defined and
X509_time_adj_ex now behaves more predictably. Callers that actually
wanted to lock to a specific type should call ASN1_UTCTIME_adj or
ASN1_GENERALIZEDTIME_adj instead.
* Document another batch of functions.
* Clarify BIO_new_mum_buf's lifetime rules.
* generate_ech.cc: include needed headers
* Don't overread in poly_Rq_mul
* acvp: recognise another style of JSON.
* Revert "Revert "Revert "Disable check that X.509 extensions implies v3."""

Test: atest CtsLibcoreTestCases CtsLibcoreOkHttpTestCases
Change-Id: I4f2228ef815ded0599322186ab7bad49ab1bb5af

1 files changed, 266 insertions, 357 deletions

diff --git a/src/ssl/encrypted_client_hello.cc b/src/ssl/encrypted_client_hello.cc
index b70f66c1..64fee3d0 100644
--- a/src/ssl/encrypted_client_hello.cc
+++ b/src/ssl/encrypted_client_hello.cc
@@ -31,12 +31,6 @@
 #include "internal.h"
 
 
-#if defined(OPENSSL_MSAN)
-#define NO_SANITIZE_MEMORY __attribute__((no_sanitize("memory")))
-#else
-#define NO_SANITIZE_MEMORY
-#endif
-
 BSSL_NAMESPACE_BEGIN
 
 // ECH reuses the extension code point for the version number.
@@ -84,16 +78,71 @@ static bool ssl_client_hello_write_without_extensions(
   return true;
 }
 
+static bool is_valid_client_hello_inner(SSL *ssl, uint8_t *out_alert,
+                                        Span<const uint8_t> body) {
+  // See draft-ietf-tls-esni-13, section 7.1.
+  SSL_CLIENT_HELLO client_hello;
+  CBS extension;
+  if (!ssl_client_hello_init(ssl, &client_hello, body) ||
+      !ssl_client_hello_get_extension(&client_hello, &extension,
+                                      TLSEXT_TYPE_encrypted_client_hello) ||
+      CBS_len(&extension) != 1 ||  //
+      CBS_data(&extension)[0] != ECH_CLIENT_INNER ||
+      !ssl_client_hello_get_extension(&client_hello, &extension,
+                                      TLSEXT_TYPE_supported_versions)) {
+    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
+    OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_CLIENT_HELLO_INNER);
+    return false;
+  }
+  // Parse supported_versions and reject TLS versions prior to TLS 1.3. Older
+  // versions are incompatible with ECH.
+  CBS versions;
+  if (!CBS_get_u8_length_prefixed(&extension, &versions) ||
+      CBS_len(&extension) != 0 ||  //
+      CBS_len(&versions) == 0) {
+    *out_alert = SSL_AD_DECODE_ERROR;
+    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
+    return false;
+  }
+  while (CBS_len(&versions) != 0) {
+    uint16_t version;
+    if (!CBS_get_u16(&versions, &version)) {
+      *out_alert = SSL_AD_DECODE_ERROR;
+      OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
+      return false;
+    }
+    if (version == SSL3_VERSION || version == TLS1_VERSION ||
+        version == TLS1_1_VERSION || version == TLS1_2_VERSION ||
+        version == DTLS1_VERSION || version == DTLS1_2_VERSION) {
+      *out_alert = SSL_AD_ILLEGAL_PARAMETER;
+      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_CLIENT_HELLO_INNER);
+      return false;
+    }
+  }
+  return true;
+}
+
 bool ssl_decode_client_hello_inner(
     SSL *ssl, uint8_t *out_alert, Array<uint8_t> *out_client_hello_inner,
     Span<const uint8_t> encoded_client_hello_inner,
     const SSL_CLIENT_HELLO *client_hello_outer) {
   SSL_CLIENT_HELLO client_hello_inner;
-  if (!ssl_client_hello_init(ssl, &client_hello_inner,
-                             encoded_client_hello_inner)) {
+  CBS cbs = encoded_client_hello_inner;
+  if (!ssl_parse_client_hello_with_trailing_data(ssl, &cbs,
+                                                 &client_hello_inner)) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     return false;
   }
+  // The remaining data is padding.
+  uint8_t padding;
+  while (CBS_get_u8(&cbs, &padding)) {
+    if (padding != 0) {
+      OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
+      *out_alert = SSL_AD_ILLEGAL_PARAMETER;
+      return false;
+    }
+  }
+
   // TLS 1.3 ClientHellos must have extensions, and EncodedClientHelloInners use
   // ClientHelloOuter's session_id.
   if (client_hello_inner.extensions_len == 0 ||
@@ -106,120 +155,84 @@ bool ssl_decode_client_hello_inner(
 
   // Begin serializing a message containing the ClientHelloInner in |cbb|.
   ScopedCBB cbb;
-  CBB body, extensions;
+  CBB body, extensions_cbb;
   if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CLIENT_HELLO) ||
       !ssl_client_hello_write_without_extensions(&client_hello_inner, &body) ||
-      !CBB_add_u16_length_prefixed(&body, &extensions)) {
+      !CBB_add_u16_length_prefixed(&body, &extensions_cbb)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return false;
   }
 
-  // Sort the extensions in ClientHelloOuter, so ech_outer_extensions may be
-  // processed in O(n*log(n)) time, rather than O(n^2).
-  struct Extension {
-    uint16_t extension = 0;
-    Span<const uint8_t> body;
-    bool copied = false;
-  };
-
-  // MSan's libc interceptors do not handle |bsearch|. See b/182583130.
-  auto compare_extension = [](const void *a, const void *b)
-                               NO_SANITIZE_MEMORY -> int {
-    const Extension *extension_a = reinterpret_cast<const Extension *>(a);
-    const Extension *extension_b = reinterpret_cast<const Extension *>(b);
-    if (extension_a->extension < extension_b->extension) {
-      return -1;
-    } else if (extension_a->extension > extension_b->extension) {
-      return 1;
-    }
-    return 0;
-  };
-  GrowableArray<Extension> sorted_extensions;
-  CBS unsorted_extensions(MakeConstSpan(client_hello_outer->extensions,
-                                        client_hello_outer->extensions_len));
-  while (CBS_len(&unsorted_extensions) > 0) {
-    Extension extension;
-    CBS extension_body;
-    if (!CBS_get_u16(&unsorted_extensions, &extension.extension) ||
-        !CBS_get_u16_length_prefixed(&unsorted_extensions, &extension_body)) {
+  auto inner_extensions = MakeConstSpan(client_hello_inner.extensions,
+                                        client_hello_inner.extensions_len);
+  CBS ext_list_wrapper;
+  if (!ssl_client_hello_get_extension(&client_hello_inner, &ext_list_wrapper,
+                                      TLSEXT_TYPE_ech_outer_extensions)) {
+    // No ech_outer_extensions. Copy everything.
+    if (!CBB_add_bytes(&extensions_cbb, inner_extensions.data(),
+                       inner_extensions.size())) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
       return false;
     }
-    extension.body = extension_body;
-    if (!sorted_extensions.Push(extension)) {
-      return false;
-    }
-  }
-  qsort(sorted_extensions.data(), sorted_extensions.size(), sizeof(Extension),
-        compare_extension);
-
-  // Copy extensions from |client_hello_inner|, expanding ech_outer_extensions.
-  CBS inner_extensions(MakeConstSpan(client_hello_inner.extensions,
-                                     client_hello_inner.extensions_len));
-  while (CBS_len(&inner_extensions) > 0) {
-    uint16_t extension_id;
-    CBS extension_body;
-    if (!CBS_get_u16(&inner_extensions, &extension_id) ||
-        !CBS_get_u16_length_prefixed(&inner_extensions, &extension_body)) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
+  } else {
+    const size_t offset = CBS_data(&ext_list_wrapper) - inner_extensions.data();
+    auto inner_extensions_before =
+        inner_extensions.subspan(0, offset - 4 /* extension header */);
+    auto inner_extensions_after =
+        inner_extensions.subspan(offset + CBS_len(&ext_list_wrapper));
+    if (!CBB_add_bytes(&extensions_cbb, inner_extensions_before.data(),
+                       inner_extensions_before.size())) {
+      OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
       return false;
     }
-    if (extension_id != TLSEXT_TYPE_ech_outer_extensions) {
-      if (!CBB_add_u16(&extensions, extension_id) ||
-          !CBB_add_u16(&extensions, CBS_len(&extension_body)) ||
-          !CBB_add_bytes(&extensions, CBS_data(&extension_body),
-                         CBS_len(&extension_body))) {
-        OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-        return false;
-      }
-      continue;
-    }
 
-    // Replace ech_outer_extensions with the corresponding outer extensions.
-    CBS outer_extensions;
-    if (!CBS_get_u8_length_prefixed(&extension_body, &outer_extensions) ||
-        CBS_len(&extension_body) != 0) {
+    // Expand ech_outer_extensions. See draft-ietf-tls-esni-13, Appendix B.
+    CBS ext_list;
+    if (!CBS_get_u8_length_prefixed(&ext_list_wrapper, &ext_list) ||
+        CBS_len(&ext_list) == 0 || CBS_len(&ext_list_wrapper) != 0) {
       OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
       return false;
     }
-    while (CBS_len(&outer_extensions) > 0) {
-      uint16_t extension_needed;
-      if (!CBS_get_u16(&outer_extensions, &extension_needed)) {
-        OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-        return false;
-      }
-      if (extension_needed == TLSEXT_TYPE_encrypted_client_hello) {
-        *out_alert = SSL_AD_ILLEGAL_PARAMETER;
+    CBS outer_extensions;
+    CBS_init(&outer_extensions, client_hello_outer->extensions,
+             client_hello_outer->extensions_len);
+    while (CBS_len(&ext_list) != 0) {
+      // Find the next extension to copy.
+      uint16_t want;
+      if (!CBS_get_u16(&ext_list, &want)) {
         OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
         return false;
       }
-      // Find the referenced extension.
-      Extension key;
-      key.extension = extension_needed;
-      Extension *result = reinterpret_cast<Extension *>(
-          bsearch(&key, sorted_extensions.data(), sorted_extensions.size(),
-                  sizeof(Extension), compare_extension));
-      if (result == nullptr) {
-        *out_alert = SSL_AD_ILLEGAL_PARAMETER;
+      // Seek to |want| in |outer_extensions|. |ext_list| is required to match
+      // ClientHelloOuter in order.
+      uint16_t found;
+      CBS ext_body;
+      do {
+        if (CBS_len(&outer_extensions) == 0) {
+          *out_alert = SSL_AD_ILLEGAL_PARAMETER;
+          OPENSSL_PUT_ERROR(SSL, SSL_R_OUTER_EXTENSION_NOT_FOUND);
+          return false;
+        }
+        if (!CBS_get_u16(&outer_extensions, &found) ||
+            !CBS_get_u16_length_prefixed(&outer_extensions, &ext_body)) {
+          OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
+          return false;
+        }
+      } while (found != want);
+      // Copy the extension.
+      if (!CBB_add_u16(&extensions_cbb, found) ||
+          !CBB_add_u16(&extensions_cbb, CBS_len(&ext_body)) ||
+          !CBB_add_bytes(&extensions_cbb, CBS_data(&ext_body),
+                         CBS_len(&ext_body))) {
         OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
         return false;
       }
+    }
 
-      // Extensions may be referenced at most once, to bound the result size.
-      if (result->copied) {
-        *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-        OPENSSL_PUT_ERROR(SSL, SSL_R_DUPLICATE_EXTENSION);
-        return false;
-      }
-      result->copied = true;
-
-      if (!CBB_add_u16(&extensions, extension_needed) ||
-          !CBB_add_u16(&extensions, result->body.size()) ||
-          !CBB_add_bytes(&extensions, result->body.data(),
-                         result->body.size())) {
-        OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
-        return false;
-      }
+    if (!CBB_add_bytes(&extensions_cbb, inner_extensions_after.data(),
+                       inner_extensions_after.size())) {
+      OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
+      return false;
     }
   }
   if (!CBB_flush(&body)) {
@@ -227,46 +240,10 @@ bool ssl_decode_client_hello_inner(
     return false;
   }
 
-  // See https://github.com/tlswg/draft-ietf-tls-esni/pull/411
-  CBS extension;
-  if (!ssl_client_hello_init(ssl, &client_hello_inner,
-                             MakeConstSpan(CBB_data(&body), CBB_len(&body))) ||
-      !ssl_client_hello_get_extension(&client_hello_inner, &extension,
-                                      TLSEXT_TYPE_ech_is_inner) ||
-      CBS_len(&extension) != 0 ||
-      ssl_client_hello_get_extension(&client_hello_inner, &extension,
-                                     TLSEXT_TYPE_encrypted_client_hello) ||
-      !ssl_client_hello_get_extension(&client_hello_inner, &extension,
-                                      TLSEXT_TYPE_supported_versions)) {
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_CLIENT_HELLO_INNER);
-    return false;
-  }
-  // Parse supported_versions and reject TLS versions prior to TLS 1.3. Older
-  // versions are incompatible with ECH.
-  CBS versions;
-  if (!CBS_get_u8_length_prefixed(&extension, &versions) ||
-      CBS_len(&extension) != 0 ||  //
-      CBS_len(&versions) == 0) {
-    *out_alert = SSL_AD_DECODE_ERROR;
-    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
+  if (!is_valid_client_hello_inner(
+          ssl, out_alert, MakeConstSpan(CBB_data(&body), CBB_len(&body)))) {
     return false;
   }
-  while (CBS_len(&versions) != 0) {
-    uint16_t version;
-    if (!CBS_get_u16(&versions, &version)) {
-      *out_alert = SSL_AD_DECODE_ERROR;
-      OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-      return false;
-    }
-    if (version == SSL3_VERSION || version == TLS1_VERSION ||
-        version == TLS1_1_VERSION || version == TLS1_2_VERSION ||
-        version == DTLS1_VERSION || version == DTLS1_2_VERSION) {
-      *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_CLIENT_HELLO_INNER);
-      return false;
-    }
-  }
 
   if (!ssl->method->finish_message(ssl, cbb.get(), out_client_hello_inner)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
@@ -275,56 +252,31 @@ bool ssl_decode_client_hello_inner(
   return true;
 }
 
-bool ssl_client_hello_decrypt(
-    EVP_HPKE_CTX *hpke_ctx, Array<uint8_t> *out_encoded_client_hello_inner,
-    bool *out_is_decrypt_error, const SSL_CLIENT_HELLO *client_hello_outer,
-    uint16_t kdf_id, uint16_t aead_id, const uint8_t config_id,
-    Span<const uint8_t> enc, Span<const uint8_t> payload) {
+bool ssl_client_hello_decrypt(EVP_HPKE_CTX *hpke_ctx, Array<uint8_t> *out,
+                              bool *out_is_decrypt_error,
+                              const SSL_CLIENT_HELLO *client_hello_outer,
+                              Span<const uint8_t> payload) {
   *out_is_decrypt_error = false;
 
-  // Compute the ClientHello portion of the ClientHelloOuterAAD value. See
-  // draft-ietf-tls-esni-10, section 5.2.
-  ScopedCBB aad;
-  CBB enc_cbb, outer_hello_cbb, extensions_cbb;
-  if (!CBB_init(aad.get(), 256) ||
-      !CBB_add_u16(aad.get(), kdf_id) ||
-      !CBB_add_u16(aad.get(), aead_id) ||
-      !CBB_add_u8(aad.get(), config_id) ||
-      !CBB_add_u16_length_prefixed(aad.get(), &enc_cbb) ||
-      !CBB_add_bytes(&enc_cbb, enc.data(), enc.size()) ||
-      !CBB_add_u24_length_prefixed(aad.get(), &outer_hello_cbb) ||
-      !ssl_client_hello_write_without_extensions(client_hello_outer,
-                                                 &outer_hello_cbb) ||
-      !CBB_add_u16_length_prefixed(&outer_hello_cbb, &extensions_cbb)) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
+  // The ClientHelloOuterAAD is |client_hello_outer| with |payload| (which must
+  // point within |client_hello_outer->extensions|) replaced with zeros. See
+  // draft-ietf-tls-esni-13, section 5.2.
+  Array<uint8_t> aad;
+  if (!aad.CopyFrom(MakeConstSpan(client_hello_outer->client_hello,
+                                  client_hello_outer->client_hello_len))) {
     return false;
   }
 
-  CBS extensions(MakeConstSpan(client_hello_outer->extensions,
-                               client_hello_outer->extensions_len));
-  while (CBS_len(&extensions) > 0) {
-    uint16_t extension_id;
-    CBS extension_body;
-    if (!CBS_get_u16(&extensions, &extension_id) ||
-        !CBS_get_u16_length_prefixed(&extensions, &extension_body)) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-      return false;
-    }
-    if (extension_id == TLSEXT_TYPE_encrypted_client_hello) {
-      continue;
-    }
-    if (!CBB_add_u16(&extensions_cbb, extension_id) ||
-        !CBB_add_u16(&extensions_cbb, CBS_len(&extension_body)) ||
-        !CBB_add_bytes(&extensions_cbb, CBS_data(&extension_body),
-                       CBS_len(&extension_body))) {
-      OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
-      return false;
-    }
-  }
-  if (!CBB_flush(aad.get())) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
-    return false;
-  }
+  // We assert with |uintptr_t| because the comparison would be UB if they
+  // didn't alias.
+  assert(reinterpret_cast<uintptr_t>(client_hello_outer->extensions) <=
+         reinterpret_cast<uintptr_t>(payload.data()));
+  assert(reinterpret_cast<uintptr_t>(client_hello_outer->extensions +
+                                     client_hello_outer->extensions_len) >=
+         reinterpret_cast<uintptr_t>(payload.data() + payload.size()));
+  Span<uint8_t> payload_aad = MakeSpan(aad).subspan(
+      payload.data() - client_hello_outer->client_hello, payload.size());
+  OPENSSL_memset(payload_aad.data(), 0, payload_aad.size());
 
 #if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
   // In fuzzer mode, disable encryption to improve coverage. We reserve a short
@@ -336,124 +288,75 @@ bool ssl_client_hello_decrypt(
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED);
     return false;
   }
-  if (!out_encoded_client_hello_inner->CopyFrom(payload)) {
+  if (!out->CopyFrom(payload)) {
     return false;
   }
 #else
-  // Attempt to decrypt into |out_encoded_client_hello_inner|.
-  if (!out_encoded_client_hello_inner->Init(payload.size())) {
+  // Attempt to decrypt into |out|.
+  if (!out->Init(payload.size())) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return false;
   }
-  size_t encoded_client_hello_inner_len;
-  if (!EVP_HPKE_CTX_open(hpke_ctx, out_encoded_client_hello_inner->data(),
-                         &encoded_client_hello_inner_len,
-                         out_encoded_client_hello_inner->size(), payload.data(),
-                         payload.size(), CBB_data(aad.get()),
-                         CBB_len(aad.get()))) {
+  size_t len;
+  if (!EVP_HPKE_CTX_open(hpke_ctx, out->data(), &len, out->size(),
+                         payload.data(), payload.size(), aad.data(),
+                         aad.size())) {
     *out_is_decrypt_error = true;
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED);
     return false;
   }
-  out_encoded_client_hello_inner->Shrink(encoded_client_hello_inner_len);
+  out->Shrink(len);
 #endif
   return true;
 }
 
-static bool parse_ipv4_number(Span<const uint8_t> in, uint32_t *out) {
-  // See https://url.spec.whatwg.org/#ipv4-number-parser.
-  uint32_t base = 10;
-  if (in.size() >= 2 && in[0] == '0' && (in[1] == 'x' || in[1] == 'X')) {
-    in = in.subspan(2);
-    base = 16;
-  } else if (in.size() >= 1 && in[0] == '0') {
-    in = in.subspan(1);
-    base = 8;
-  }
-  *out = 0;
-  for (uint8_t c : in) {
-    uint32_t d;
-    if ('0' <= c && c <= '9') {
-      d = c - '0';
-    } else if ('a' <= c && c <= 'f') {
-      d = c - 'a' + 10;
-    } else if ('A' <= c && c <= 'F') {
-      d = c - 'A' + 10;
-    } else {
-      return false;
-    }
-    if (d >= base ||
-        *out > UINT32_MAX / base) {
-      return false;
-    }
-    *out *= base;
-    if (*out > UINT32_MAX - d) {
+static bool is_hex_component(Span<const uint8_t> in) {
+  if (in.size() < 2 || in[0] != '0' || (in[1] != 'x' && in[1] != 'X')) {
+    return false;
+  }
+  for (uint8_t b : in.subspan(2)) {
+    if (!('0' <= b && b <= '9') && !('a' <= b && b <= 'f') &&
+        !('A' <= b && b <= 'F')) {
       return false;
     }
-    *out += d;
   }
   return true;
 }
 
-static bool is_ipv4_address(Span<const uint8_t> in) {
-  // See https://url.spec.whatwg.org/#concept-ipv4-parser
-  uint32_t numbers[4];
-  size_t num_numbers = 0;
-  while (!in.empty()) {
-    if (num_numbers == 4) {
-      // Too many components.
-      return false;
-    }
-    // Find the next dot-separated component.
-    auto dot = std::find(in.begin(), in.end(), '.');
-    if (dot == in.begin()) {
-      // Empty components are not allowed.
-      return false;
-    }
-    Span<const uint8_t> component;
-    if (dot == in.end()) {
-      component = in;
-      in = Span<const uint8_t>();
-    } else {
-      component = in.subspan(0, dot - in.begin());
-      in = in.subspan(dot - in.begin() + 1);  // Skip the dot.
-    }
-    if (!parse_ipv4_number(component, &numbers[num_numbers])) {
-      return false;
-    }
-    num_numbers++;
-  }
-  if (num_numbers == 0) {
+static bool is_decimal_component(Span<const uint8_t> in) {
+  if (in.empty()) {
     return false;
   }
-  for (size_t i = 0; i < num_numbers - 1; i++) {
-    if (numbers[i] > 255) {
+  for (uint8_t b : in) {
+    if (!('0' <= b && b <= '9')) {
       return false;
     }
   }
-  return num_numbers == 1 ||
-         numbers[num_numbers - 1] < 1u << (8 * (5 - num_numbers));
+  return true;
 }
 
 bool ssl_is_valid_ech_public_name(Span<const uint8_t> public_name) {
-  // See draft-ietf-tls-esni-11, Section 4 and RFC5890, Section 2.3.1. The
+  // See draft-ietf-tls-esni-13, Section 4 and RFC 5890, Section 2.3.1. The
   // public name must be a dot-separated sequence of LDH labels and not begin or
   // end with a dot.
-  auto copy = public_name;
-  if (copy.empty()) {
+  auto remaining = public_name;
+  if (remaining.empty()) {
     return false;
   }
-  while (!copy.empty()) {
+  Span<const uint8_t> last;
+  while (!remaining.empty()) {
     // Find the next dot-separated component.
-    auto dot = std::find(copy.begin(), copy.end(), '.');
+    auto dot = std::find(remaining.begin(), remaining.end(), '.');
     Span<const uint8_t> component;
-    if (dot == copy.end()) {
-      component = copy;
-      copy = Span<const uint8_t>();
+    if (dot == remaining.end()) {
+      component = remaining;
+      last = component;
+      remaining = Span<const uint8_t>();
     } else {
-      component = copy.subspan(0, dot - copy.begin());
-      copy = copy.subspan(dot - copy.begin() + 1);  // Skip the dot.
-      if (copy.empty()) {
+      component = remaining.subspan(0, dot - remaining.begin());
+      // Skip the dot.
+      remaining = remaining.subspan(dot - remaining.begin() + 1);
+      if (remaining.empty()) {
         // Trailing dots are not allowed.
         return false;
       }
@@ -472,7 +375,15 @@ bool ssl_is_valid_ech_public_name(Span<const uint8_t> public_name) {
     }
   }
 
-  return !is_ipv4_address(public_name);
+  // The WHATWG URL parser additionally does not allow any DNS names that end in
+  // a numeric component. See:
+  // https://url.spec.whatwg.org/#concept-host-parser
+  // https://url.spec.whatwg.org/#ends-in-a-number-checker
+  //
+  // The WHATWG parser is formulated in terms of parsing decimal, octal, and
+  // hex, along with a separate ASCII digits check. The ASCII digits check
+  // subsumes the decimal and octal check, so we only need to check two cases.
+  return !is_hex_component(last) && !is_decimal_component(last);
 }
 
 static bool parse_ech_config(CBS *cbs, ECHConfig *out, bool *out_supported,
@@ -508,8 +419,8 @@ static bool parse_ech_config(CBS *cbs, ECHConfig *out, bool *out_supported,
       CBS_len(&public_key) == 0 ||
       !CBS_get_u16_length_prefixed(&contents, &cipher_suites) ||
       CBS_len(&cipher_suites) == 0 || CBS_len(&cipher_suites) % 4 != 0 ||
-      !CBS_get_u16(&contents, &out->maximum_name_length) ||
-      !CBS_get_u16_length_prefixed(&contents, &public_name) ||
+      !CBS_get_u8(&contents, &out->maximum_name_length) ||
+      !CBS_get_u8_length_prefixed(&contents, &public_name) ||
       CBS_len(&public_name) == 0 ||
       !CBS_get_u16_length_prefixed(&contents, &extensions) ||
       CBS_len(&contents) != 0) {
@@ -773,15 +684,6 @@ static size_t aead_overhead(const EVP_HPKE_AEAD *aead) {
 #endif
 }
 
-static size_t compute_extension_length(const EVP_HPKE_AEAD *aead,
-                                       size_t enc_len, size_t in_len) {
-  size_t ret = 4;      // HpkeSymmetricCipherSuite cipher_suite
-  ret++;               // uint8 config_id
-  ret += 2 + enc_len;  // opaque enc<1..2^16-1>
-  ret += 2 + in_len + aead_overhead(aead);  // opaque payload<1..2^16-1>
-  return ret;
-}
-
 // random_size returns a random value between |min| and |max|, inclusive.
 static size_t random_size(size_t min, size_t max) {
   assert(min < max);
@@ -814,38 +716,32 @@ static bool setup_ech_grease(SSL_HANDSHAKE *hs) {
   //   2+32+1+2   version, random, legacy_session_id, legacy_compression_methods
   //   2+4*2      cipher_suites (three TLS 1.3 ciphers, GREASE)
   //   2          extensions prefix
-  //   4          ech_is_inner
+  //   5          inner encrypted_client_hello
   //   4+1+2*2    supported_versions (TLS 1.3, GREASE)
   //   4+1+10*2   outer_extensions (key_share, sigalgs, sct, alpn,
   //              supported_groups, status_request, psk_key_exchange_modes,
   //              compress_certificate, GREASE x2)
   //
   // The server_name extension has an overhead of 9 bytes. For now, arbitrarily
-  // estimate maximum_name_length to be between 32 and 100 bytes.
-  //
-  // TODO(https://crbug.com/boringssl/275): If the padding scheme changes to
-  // also round the entire payload, adjust this to match. See
-  // https://github.com/tlswg/draft-ietf-tls-esni/issues/433
-  const size_t overhead = aead_overhead(aead);
-  const size_t in_len = random_size(128, 196);
-  const size_t extension_len =
-      compute_extension_length(aead, sizeof(enc), in_len);
+  // estimate maximum_name_length to be between 32 and 100 bytes. Then round up
+  // to a multiple of 32, to match draft-ietf-tls-esni-13, section 6.1.3.
+  const size_t payload_len =
+      32 * random_size(128 / 32, 224 / 32) + aead_overhead(aead);
   bssl::ScopedCBB cbb;
   CBB enc_cbb, payload_cbb;
   uint8_t *payload;
-  if (!CBB_init(cbb.get(), extension_len) ||
+  if (!CBB_init(cbb.get(), 256) ||
       !CBB_add_u16(cbb.get(), kdf_id) ||
       !CBB_add_u16(cbb.get(), EVP_HPKE_AEAD_id(aead)) ||
       !CBB_add_u8(cbb.get(), config_id) ||
       !CBB_add_u16_length_prefixed(cbb.get(), &enc_cbb) ||
       !CBB_add_bytes(&enc_cbb, enc, sizeof(enc)) ||
       !CBB_add_u16_length_prefixed(cbb.get(), &payload_cbb) ||
-      !CBB_add_space(&payload_cbb, &payload, in_len + overhead) ||
-      !RAND_bytes(payload, in_len + overhead) ||
-      !CBBFinishArray(cbb.get(), &hs->ech_client_bytes)) {
+      !CBB_add_space(&payload_cbb, &payload, payload_len) ||
+      !RAND_bytes(payload, payload_len) ||
+      !CBBFinishArray(cbb.get(), &hs->ech_client_outer)) {
     return false;
   }
-  assert(hs->ech_client_bytes.size() == extension_len);
   return true;
 }
 
@@ -856,22 +752,22 @@ bool ssl_encrypt_client_hello(SSL_HANDSHAKE *hs, Span<const uint8_t> enc) {
   }
 
   // Construct ClientHelloInner and EncodedClientHelloInner. See
-  // draft-ietf-tls-esni-10, sections 5.1 and 6.1.
-  bssl::ScopedCBB cbb, encoded;
+  // draft-ietf-tls-esni-13, sections 5.1 and 6.1.
+  ScopedCBB cbb, encoded_cbb;
   CBB body;
   bool needs_psk_binder;
-  bssl::Array<uint8_t> hello_inner;
+  Array<uint8_t> hello_inner;
   if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CLIENT_HELLO) ||
-      !CBB_init(encoded.get(), 256) ||
+      !CBB_init(encoded_cbb.get(), 256) ||
       !ssl_write_client_hello_without_extensions(hs, &body,
                                                  ssl_client_hello_inner,
                                                  /*empty_session_id=*/false) ||
-      !ssl_write_client_hello_without_extensions(hs, encoded.get(),
+      !ssl_write_client_hello_without_extensions(hs, encoded_cbb.get(),
                                                  ssl_client_hello_inner,
                                                  /*empty_session_id=*/true) ||
-      !ssl_add_clienthello_tlsext(hs, &body, encoded.get(), &needs_psk_binder,
-                                  ssl_client_hello_inner, CBB_len(&body),
-                                  /*omit_ech_len=*/0) ||
+      !ssl_add_clienthello_tlsext(hs, &body, encoded_cbb.get(),
+                                  &needs_psk_binder, ssl_client_hello_inner,
+                                  CBB_len(&body)) ||
       !ssl->method->finish_message(ssl, cbb.get(), &hello_inner)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return false;
@@ -884,13 +780,12 @@ bool ssl_encrypt_client_hello(SSL_HANDSHAKE *hs, Span<const uint8_t> enc) {
       return false;
     }
     // Also update the EncodedClientHelloInner.
-    if (CBB_len(encoded.get()) < binder_len) {
-      OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-      return false;
-    }
-    OPENSSL_memcpy(const_cast<uint8_t *>(CBB_data(encoded.get())) +
-                       CBB_len(encoded.get()) - binder_len,
-                   hello_inner.data() + hello_inner.size() - binder_len,
+    auto encoded_binder =
+        MakeSpan(const_cast<uint8_t *>(CBB_data(encoded_cbb.get())),
+                 CBB_len(encoded_cbb.get()))
+            .last(binder_len);
+    auto hello_inner_binder = MakeConstSpan(hello_inner).last(binder_len);
+    OPENSSL_memcpy(encoded_binder.data(), hello_inner_binder.data(),
                    binder_len);
   }
 
@@ -898,74 +793,82 @@ bool ssl_encrypt_client_hello(SSL_HANDSHAKE *hs, Span<const uint8_t> enc) {
     return false;
   }
 
-  // Construct ClientHelloOuterAAD. See draft-ietf-tls-esni-10, section 5.2.
-  // TODO(https://crbug.com/boringssl/275): This ends up constructing the
-  // ClientHelloOuter twice. Revisit this in the next draft, which uses a more
-  // forgiving construction.
+  // Pad the EncodedClientHelloInner. See draft-ietf-tls-esni-13, section 6.1.3.
+  size_t padding_len = 0;
+  size_t maximum_name_length = hs->selected_ech_config->maximum_name_length;
+  if (ssl->hostname) {
+    size_t hostname_len = strlen(ssl->hostname.get());
+    if (hostname_len <= maximum_name_length) {
+      padding_len = maximum_name_length - hostname_len;
+    }
+  } else {
+    // No SNI. Pad up to |maximum_name_length|, including server_name extension
+    // overhead.
+    padding_len = 9 + maximum_name_length;
+  }
+  // Pad the whole thing to a multiple of 32 bytes.
+  padding_len += 31 - ((CBB_len(encoded_cbb.get()) + padding_len - 1) % 32);
+  Array<uint8_t> encoded;
+  if (!CBB_add_zeros(encoded_cbb.get(), padding_len) ||
+      !CBBFinishArray(encoded_cbb.get(), &encoded)) {
+    return false;
+  }
+
+  // Encrypt |encoded|. See draft-ietf-tls-esni-13, section 6.1.1. First,
+  // assemble the extension with a placeholder value for ClientHelloOuterAAD.
+  // See draft-ietf-tls-esni-13, section 5.2.
   const EVP_HPKE_KDF *kdf = EVP_HPKE_CTX_kdf(hs->ech_hpke_ctx.get());
   const EVP_HPKE_AEAD *aead = EVP_HPKE_CTX_aead(hs->ech_hpke_ctx.get());
-  const size_t extension_len =
-      compute_extension_length(aead, enc.size(), CBB_len(encoded.get()));
+  size_t payload_len = encoded.size() + aead_overhead(aead);
+  CBB enc_cbb, payload_cbb;
+  if (!CBB_init(cbb.get(), 256) ||
+      !CBB_add_u16(cbb.get(), EVP_HPKE_KDF_id(kdf)) ||
+      !CBB_add_u16(cbb.get(), EVP_HPKE_AEAD_id(aead)) ||
+      !CBB_add_u8(cbb.get(), hs->selected_ech_config->config_id) ||
+      !CBB_add_u16_length_prefixed(cbb.get(), &enc_cbb) ||
+      !CBB_add_bytes(&enc_cbb, enc.data(), enc.size()) ||
+      !CBB_add_u16_length_prefixed(cbb.get(), &payload_cbb) ||
+      !CBB_add_zeros(&payload_cbb, payload_len) ||
+      !CBBFinishArray(cbb.get(), &hs->ech_client_outer)) {
+    return false;
+  }
+
+  // Construct ClientHelloOuterAAD.
+  // TODO(https://crbug.com/boringssl/275): This ends up constructing the
+  // ClientHelloOuter twice. Instead, reuse |aad| for the ClientHello, now that
+  // draft-12 made the length prefixes match.
   bssl::ScopedCBB aad;
-  CBB outer_hello;
-  CBB enc_cbb;
   if (!CBB_init(aad.get(), 256) ||
-      !CBB_add_u16(aad.get(), EVP_HPKE_KDF_id(kdf)) ||
-      !CBB_add_u16(aad.get(), EVP_HPKE_AEAD_id(aead)) ||
-      !CBB_add_u8(aad.get(), hs->selected_ech_config->config_id) ||
-      !CBB_add_u16_length_prefixed(aad.get(), &enc_cbb) ||
-      !CBB_add_bytes(&enc_cbb, enc.data(), enc.size()) ||
-      !CBB_add_u24_length_prefixed(aad.get(), &outer_hello) ||
-      !ssl_write_client_hello_without_extensions(hs, &outer_hello,
+      !ssl_write_client_hello_without_extensions(hs, aad.get(),
                                                  ssl_client_hello_outer,
                                                  /*empty_session_id=*/false) ||
-      !ssl_add_clienthello_tlsext(hs, &outer_hello, /*out_encoded=*/nullptr,
+      !ssl_add_clienthello_tlsext(hs, aad.get(), /*out_encoded=*/nullptr,
                                   &needs_psk_binder, ssl_client_hello_outer,
-                                  CBB_len(&outer_hello),
-                                  /*omit_ech_len=*/4 + extension_len) ||
-      !CBB_flush(aad.get())) {
+                                  CBB_len(aad.get()))) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return false;
   }
+
   // ClientHelloOuter may not require a PSK binder. Otherwise, we have a
   // circular dependency.
   assert(!needs_psk_binder);
 
-  CBB payload_cbb;
-  if (!CBB_init(cbb.get(), extension_len) ||
-      !CBB_add_u16(cbb.get(), EVP_HPKE_KDF_id(kdf)) ||
-      !CBB_add_u16(cbb.get(), EVP_HPKE_AEAD_id(aead)) ||
-      !CBB_add_u8(cbb.get(), hs->selected_ech_config->config_id) ||
-      !CBB_add_u16_length_prefixed(cbb.get(), &enc_cbb) ||
-      !CBB_add_bytes(&enc_cbb, enc.data(), enc.size()) ||
-      !CBB_add_u16_length_prefixed(cbb.get(), &payload_cbb)) {
-    return false;
-  }
+  // Replace the payload in |hs->ech_client_outer| with the encrypted value.
+  auto payload_span = MakeSpan(hs->ech_client_outer).last(payload_len);
 #if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
   // In fuzzer mode, the server expects a cleartext payload.
-  if (!CBB_add_bytes(&payload_cbb, CBB_data(encoded.get()),
-                     CBB_len(encoded.get()))) {
-    return false;
-  }
+  assert(payload_span.size() == encoded.size());
+  OPENSSL_memcpy(payload_span.data(), encoded.data(), encoded.size());
 #else
-  uint8_t *payload;
-  size_t payload_len =
-      CBB_len(encoded.get()) + EVP_AEAD_max_overhead(EVP_HPKE_AEAD_aead(aead));
-  if (!CBB_reserve(&payload_cbb, &payload, payload_len) ||
-      !EVP_HPKE_CTX_seal(hs->ech_hpke_ctx.get(), payload, &payload_len,
-                         payload_len, CBB_data(encoded.get()),
-                         CBB_len(encoded.get()), CBB_data(aad.get()),
+  if (!EVP_HPKE_CTX_seal(hs->ech_hpke_ctx.get(), payload_span.data(),
+                         &payload_len, payload_span.size(), encoded.data(),
+                         encoded.size(), CBB_data(aad.get()),
                          CBB_len(aad.get())) ||
-      !CBB_did_write(&payload_cbb, payload_len)) {
+      payload_len != payload_span.size()) {
     return false;
   }
 #endif // BORINGSSL_UNSAFE_FUZZER_MODE
-  if (!CBBFinishArray(cbb.get(), &hs->ech_client_bytes)) {
-    return false;
-  }
 
-  // The |aad| calculation relies on |extension_length| being correct.
-  assert(hs->ech_client_bytes.size() == extension_len);
   return true;
 }
 
@@ -1045,7 +948,13 @@ int SSL_marshal_ech_config(uint8_t **out, size_t *out_len, uint8_t config_id,
     return 0;
   }
 
-  // See draft-ietf-tls-esni-10, section 4.
+  // The maximum name length is encoded in one byte.
+  if (max_name_len > 0xff) {
+    OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_LENGTH);
+    return 0;
+  }
+
+  // See draft-ietf-tls-esni-13, section 4.
   ScopedCBB cbb;
   CBB contents, child;
   uint8_t *public_key;
@@ -1066,8 +975,8 @@ int SSL_marshal_ech_config(uint8_t **out, size_t *out_len, uint8_t config_id,
       !CBB_add_u16(&child, EVP_HPKE_AES_128_GCM) ||
       !CBB_add_u16(&child, EVP_HPKE_HKDF_SHA256) ||
       !CBB_add_u16(&child, EVP_HPKE_CHACHA20_POLY1305) ||
-      !CBB_add_u16(&contents, max_name_len) ||
-      !CBB_add_u16_length_prefixed(&contents, &child) ||
+      !CBB_add_u8(&contents, max_name_len) ||
+      !CBB_add_u8_length_prefixed(&contents, &child) ||
       !CBB_add_bytes(&child, public_name_u8.data(), public_name_u8.size()) ||
       // TODO(https://crbug.com/boringssl/275): Reserve some GREASE extensions
       // and include some.