1 files changed, 27 insertions, 14 deletions

diff --git a/src/lib/libssl/ssl_clnt.c b/src/lib/libssl/ssl_clnt.c
index 65939141a2..f46b66c372 100644
--- a/src/lib/libssl/ssl_clnt.c
+++ b/src/lib/libssl/ssl_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_clnt.c,v 1.8 2017/03/04 16:15:02 jsing Exp $ */
+/* $OpenBSD: ssl_clnt.c,v 1.9 2017/03/05 14:24:12 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -2619,27 +2619,40 @@ err:
 int
 ssl3_send_next_proto(SSL *s)
 {
-        unsigned int     len, padding_len;
-        unsigned char   *d, *p;
+        CBB cbb, nextproto, npn, padding;
+        size_t pad_len;
+        uint8_t *pad;
 
-        if (s->internal->state == SSL3_ST_CW_NEXT_PROTO_A) {
-                d = p = ssl3_handshake_msg_start(s, SSL3_MT_NEXT_PROTO);
+        memset(&cbb, 0, sizeof(cbb));
 
-                len = s->internal->next_proto_negotiated_len;
-                padding_len = 32 - ((len + 2) % 32);
-                *(p++) = len;
-                memcpy(p, s->internal->next_proto_negotiated, len);
-                p += len;
-                *(p++) = padding_len;
-                memset(p, 0, padding_len);
-                p += padding_len;
+        if (s->internal->state == SSL3_ST_CW_NEXT_PROTO_A) {
+                pad_len = 32 - ((s->internal->next_proto_negotiated_len + 2) % 32);
 
-                ssl3_handshake_msg_finish(s, p - d);
+                if (!ssl3_handshake_msg_start_cbb(s, &cbb, &nextproto,
+                    SSL3_MT_NEXT_PROTO))
+                        goto err;
+                if (!CBB_add_u8_length_prefixed(&nextproto, &npn))
+                        goto err;
+                if (!CBB_add_bytes(&npn, s->internal->next_proto_negotiated,
+                    s->internal->next_proto_negotiated_len))
+                        goto err;
+                if (!CBB_add_u8_length_prefixed(&nextproto, &padding))
+                        goto err;
+                if (!CBB_add_space(&padding, &pad, pad_len))
+                        goto err;
+                memset(pad, 0, pad_len);
+                if (!ssl3_handshake_msg_finish_cbb(s, &cbb))
+                        goto err;
 
                 s->internal->state = SSL3_ST_CW_NEXT_PROTO_B;
         }
 
         return (ssl3_handshake_write(s));
+
+ err:
+        CBB_cleanup(&cbb);
+
+        return (-1);
 }
 
 /*