Check for invalid ALPN inputs in SSL_(CTX_)set_alpn_protos.
See also 86a90dc749af91f8a7b8da6628c9ffca2bae3009 from upstream. This
differs from upstream's which treats {NULL, 2} as a valid way to spell
the empty list. (I think this is a mistake and have asked them about
it.)
Upstream's CL also, for them, newly makes the empty list disable ALPN,
when previously they'd disable it but misread it as a malloc failure.
For us, we'd already fixed the misreading due to our switch to
bssl::Array and bssl::Span, but the documentation was odd. This CL
preserves that behavior, but updates the documentation and writes a
test.
Update-Note: SSL_CTX_set_alpn_protos and SSL_set_alpn_protos will now
reject invalud inputs. Previously, they would accept them, but silently
send an invalid ALPN extension which the server would almost certainly
error on.
Change-Id: Id5830b2d8c3a5cee4712878fe92ee350c4914367
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/46804
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/internal.h b/ssl/internal.h
index 7a3979b..e1585c3 100644
--- a/ssl/internal.h
+++ b/ssl/internal.h
@@ -2052,6 +2052,9 @@
SSL_HANDSHAKE *hs, Array<uint8_t> *out,
enum ssl_cert_verify_context_t cert_verify_context);
+// ssl_is_valid_alpn_list returns whether |in| is a valid ALPN protocol list.
+bool ssl_is_valid_alpn_list(Span<const uint8_t> in);
+
// ssl_is_alpn_protocol_allowed returns whether |protocol| is a valid server
// selection for |hs->ssl|'s client preferences.
bool ssl_is_alpn_protocol_allowed(const SSL_HANDSHAKE *hs,
