commit c58adc797656ecf0c4d544f0c67704406c909968
author Kazuho Oku <kazuhooku@gmail.com> Mon Nov 28 10:29:51 2022 +0900
committer Kazuho Oku <kazuhooku@gmail.com> Mon Nov 28 11:06:26 2022 +0900
tree b68cc12c77e4c2e609259d78ed8211276c4aa8e7
parent 761cc0341ec284774cd78772efb1dded7ebe5269

do not use ECH even when config is provided, unless server name is a DNS name

lib/picotls.c

diff --git a/lib/picotls.c b/lib/picotls.c
index 5134802..16f5cf1 100644
--- a/lib/picotls.c
+++ b/lib/picotls.c
@@ -2234,7 +2234,7 @@
 
     if (properties != NULL) {
         /* try to use ECH (ignore broken ECHConfigList; it is delivered insecurely) */
-        if (!is_second_flight && tls->ctx->ech.ciphers != NULL && tls->ctx->ech.kems != NULL &&
+        if (!is_second_flight && sni_name != NULL && tls->ctx->ech.ciphers != NULL && tls->ctx->ech.kems != NULL &&
             properties->client.ech.configs.len != 0) {
             struct st_decoded_ech_config_t decoded;
             decode_ech_config_list(tls->ctx, &decoded, properties->client.ech.configs);

t/picotls.c

diff --git a/t/picotls.c b/t/picotls.c
index 6612455..4277350 100644
--- a/t/picotls.c
+++ b/t/picotls.c
@@ -700,8 +700,10 @@
         ptls_set_server_name(client, "test.example.com", 0);
     }
 
-    if (can_ech(ctx, 0))
+    if (can_ech(ctx, 0)) {
+        ptls_set_server_name(client, "test.example.com", 0);
         client_hs_prop.client.ech.configs = ptls_iovec_init(ECH_CONFIG_LIST, sizeof(ECH_CONFIG_LIST) - 1);
+    }
 
     static ptls_on_extension_t cb = {on_extension_cb};
     ctx_peer->on_extension = &cb;
@@ -1275,6 +1277,7 @@
         }};
 
     client = ptls_new(ctx, 0);
+    ptls_set_server_name(client, "test.example.com", 0);
     server = ptls_new(ctx_peer, 1);
     ptls_buffer_init(&cbuf, "", 0);
     ptls_buffer_init(&sbuf, "", 0);