1 files changed, 148 insertions, 1 deletions

diff --git a/src/lib/libssl/ssl_tlsext.c b/src/lib/libssl/ssl_tlsext.c
index 60daff6f8d..405882c0e9 100644
--- a/src/lib/libssl/ssl_tlsext.c
+++ b/src/lib/libssl/ssl_tlsext.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.c,v 1.10 2017/08/23 15:39:38 doug Exp $ */
+/* $OpenBSD: ssl_tlsext.c,v 1.11 2017/08/26 20:23:46 doug Exp $ */
 /*
  * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
@@ -23,6 +23,144 @@
 #include "bytestring.h"
 #include "ssl_tlsext.h"
 
+/*
+ * Supported Application-Layer Protocol Negotiation - RFC 7301
+ */
+
+int
+tlsext_alpn_clienthello_needs(SSL *s)
+{
+        /* ALPN protos have been specified and this is the initial handshake */
+        return s->internal->alpn_client_proto_list != NULL &&
+            S3I(s)->tmp.finish_md_len == 0;
+}
+
+int
+tlsext_alpn_clienthello_build(SSL *s, CBB *cbb)
+{
+        CBB protolist;
+
+        if (!CBB_add_u16_length_prefixed(cbb, &protolist))
+                return 0;
+
+        if (!CBB_add_bytes(&protolist, s->internal->alpn_client_proto_list,
+            s->internal->alpn_client_proto_list_len))
+                return 0;
+
+        if (!CBB_flush(cbb))
+                return 0;
+
+        return 1;
+}
+
+int
+tlsext_alpn_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+        CBS proto_name_list, alpn;
+        const unsigned char *selected;
+        unsigned char selected_len;
+        int r;
+
+        if (s->ctx->internal->alpn_select_cb == NULL)
+                return 1;
+
+        if (!CBS_get_u16_length_prefixed(cbs, &alpn))
+                goto err;
+        if (CBS_len(&alpn) < 2)
+                goto err;
+        if (CBS_len(cbs) != 0)
+                goto err;
+
+        CBS_dup(&alpn, &proto_name_list);
+        while (CBS_len(&proto_name_list) > 0) {
+                CBS proto_name;
+
+                if (!CBS_get_u8_length_prefixed(&proto_name_list, &proto_name))
+                        goto err;
+                if (CBS_len(&proto_name) == 0)
+                        goto err;
+        }
+
+        r = s->ctx->internal->alpn_select_cb(s, &selected, &selected_len,
+            CBS_data(&alpn), CBS_len(&alpn),
+            s->ctx->internal->alpn_select_cb_arg);
+        if (r == SSL_TLSEXT_ERR_OK) {
+                free(S3I(s)->alpn_selected);
+                if ((S3I(s)->alpn_selected = malloc(selected_len)) == NULL) {
+                        *alert = SSL_AD_INTERNAL_ERROR;
+                        return 0;
+                }
+                memcpy(S3I(s)->alpn_selected, selected, selected_len);
+                S3I(s)->alpn_selected_len = selected_len;
+        }
+
+        return 1;
+
+ err:
+        *alert = SSL_AD_DECODE_ERROR;
+        return 0;
+}
+
+int
+tlsext_alpn_serverhello_needs(SSL *s)
+{
+        return S3I(s)->alpn_selected != NULL;
+}
+
+int
+tlsext_alpn_serverhello_build(SSL *s, CBB *cbb)
+{
+        CBB list, selected;
+
+        if (!CBB_add_u16_length_prefixed(cbb, &list))
+                return 0;
+
+        if (!CBB_add_u8_length_prefixed(&list, &selected))
+                return 0;
+
+        if (!CBB_add_bytes(&selected, S3I(s)->alpn_selected,
+            S3I(s)->alpn_selected_len))
+                return 0;
+
+        if (!CBB_flush(cbb))
+                return 0;
+
+        return 1;
+}
+
+int
+tlsext_alpn_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+        CBS list, proto;
+
+        if (s->internal->alpn_client_proto_list == NULL) {
+                *alert = TLS1_AD_UNSUPPORTED_EXTENSION;
+                return 0;
+        }
+
+        if (!CBS_get_u16_length_prefixed(cbs, &list))
+                goto err;
+        if (CBS_len(cbs) != 0)
+                goto err;
+
+        if (!CBS_get_u8_length_prefixed(&list, &proto))
+                goto err;
+
+        if (CBS_len(&list) != 0)
+                goto err;
+        if (CBS_len(&proto) == 0)
+                goto err;
+
+        if (!CBS_stow(&proto, &(S3I(s)->alpn_selected),
+            &(S3I(s)->alpn_selected_len)))
+                goto err;
+
+        return 1;
+
+ err:
+        *alert = TLS1_AD_DECODE_ERROR;
+        return 0;
+}
 
 /*
  * Supported Elliptic Curves - RFC 4492 section 5.1.1
@@ -919,6 +1057,15 @@ static struct tls_extension tls_extensions[] = {
                 .serverhello_build = tlsext_sigalgs_serverhello_build,
                 .serverhello_parse = tlsext_sigalgs_serverhello_parse,
         },
+        {
+                .type = TLSEXT_TYPE_application_layer_protocol_negotiation,
+                .clienthello_needs = tlsext_alpn_clienthello_needs,
+                .clienthello_build = tlsext_alpn_clienthello_build,
+                .clienthello_parse = tlsext_alpn_clienthello_parse,
+                .serverhello_needs = tlsext_alpn_serverhello_needs,
+                .serverhello_build = tlsext_alpn_serverhello_build,
+                .serverhello_parse = tlsext_alpn_serverhello_parse,
+        },
 };
 
 #define N_TLS_EXTENSIONS (sizeof(tls_extensions) / sizeof(*tls_extensions))