[lwip-users] SMTP client with altcp+mbedtls

[Kosma Moczek]

Hello,

I'm trying to get the SMTP client working over TLS. I've got the following working:

- lwip 2.1.3 working (http, dhcp, etc.)

- mbedtls added to the project and compiling without problems

- email sending works when TLS is disabled

- I can create a config with altcp_tls_create_config_client()

What doesn't work is: 

After smtp.c calls altcp_connect(pcb, &addr, smtp_server_port, smtp_tcp_connected) and the connection to the server is established, the smtp_tcp_connected callback is fired but altcp_mbedtls_lower_connected is not, so there is no ClientHello sent and the connection stalls (SSL is not negotiated, and SMTP client is waiting for a hello from the server). The comment on that function is not encouraging:

/** Connected callback from lower connection (i.e. TCP).
 * Not really implemented/tested yet...
 */
static err_t
altcp_mbedtls_lower_connected(void *arg, struct altcp_pcb *inner_conn, err_t err)

I've traced the code and stepped through it multiple times and I am really lost in all the altcp layering, and can't figure out why the "mbedtls connected" callback isn't firing. Does anyone have a clue what could be wrong? Has anyone ever gotten the altcp mbedtls to work?

--

Kosma Moczek

Electronics Engineer

 

R&D Department

ul. Stargardzka 10

54-156 Wrocław
Poland

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gsm: +48 785 870 777

 

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