Add a comment about final empty extension intolerance.
We reordered extensions some time ago to ensure a non-empty extension was last, but the comment was since lost (or I forgot to put one in in the first place). Add one now so we don't regress. Change-Id: I2f6e2c3777912eb2c522a54bbbee579ee37ee58a Reviewed-on: https://boringssl-review.googlesource.com/7570 Reviewed-by: David Benjamin <davidben@google.com>
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@ -2037,6 +2037,9 @@ static const struct tls_extension kExtensions[] = {
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ext_ec_point_parse_clienthello,
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ext_ec_point_add_serverhello,
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},
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/* The final extension must be non-empty. WebSphere Application Server 7.0 is
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* intolerant to the last extension being zero-length. See
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* https://crbug.com/363583. */
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{
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TLSEXT_TYPE_elliptic_curves,
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ext_ec_curves_init,
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@ -2123,9 +2126,10 @@ int ssl_add_clienthello_tlsext(SSL *ssl, CBB *out, size_t header_len) {
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* NB: because this code works out the length of all existing extensions
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* it MUST always appear last. */
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size_t padding_len = 0x200 - header_len;
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/* Extensions take at least four bytes to encode. Always include least
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/* Extensions take at least four bytes to encode. Always include at least
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* one byte of data if including the extension. WebSphere Application
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* Server 7.0 is intolerant to the last extension being zero-length. */
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* Server 7.0 is intolerant to the last extension being zero-length. See
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* https://crbug.com/363583. */
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if (padding_len >= 4 + 1) {
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padding_len -= 4;
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} else {
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