I am trying to set up a downchannel to the AVS endpoint (avs-alexa-na.amazon.com) from an embed device with mbedtls as the ssl lib. It has been working the past week (handshake is ok and I can set up the TLS session and do http2 GET/POST), but since yesterday I am getting tls handshake failures (i.e EOF from the other end. More like AVS endpoint does not reply). Hence, I am a bit clueless on what's happening on the other side or did something changed.
Any idea how to debug this? I've switched wifi networks, so it's probably not wifi problem. Note that I can use the same mbedtls lib to get acces token from the auth2 server which also requires TLS.
I've attached some output for reference.
fyi, some set up code for the downchannel.
const char *alpn_list; memset( (void * ) alpn_list, 0, sizeof( alpn_list ) ); alpn_list = "h2"; alpn_list = "http/1.1"; alpn_list = NULL;
... /* restrict cypher suites */ int cypher; memset((void *) cypher, 0, sizeof(cypher)); cypher = MBEDTLS_TLS_DHE_RSA_WITH_AES_128_GCM_SHA256; cypher = MBEDTLS_TLS_DHE_RSA_WITH_AES_256_GCM_SHA384; cypher = (int) NULL;