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dns: handle EAI_NONAME as fatal

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This causes the blocking dns lookup to treat EAI_NONAME as immediately
fatal, this is usually caused by an assertive NXDOMAIN from the DNS server
or similar.

Not being able to reach the server should continue to retry.

In order to make the problem visible, it reports the situation using
CLIENT_CONNECTION_ERROR, even though it is still inside the outer client
creation call.
This commit is contained in:
Andy Green 2021-06-28 05:06:38 +01:00
parent 9e5acc05e4
commit eeea000ced
2 changed files with 31 additions and 6 deletions
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18
lib/core-net/client/connect2.c
View file

@ -124,6 +124,10 @@ lws_getaddrinfo46(struct lws *wsi, const char *ads, struct addrinfo **result)
}
#endif
#if !defined(LWS_WITH_SYS_ASYNC_DNS) && defined(EAI_NONAME)
static const char * const dns_nxdomain = "DNS NXDOMAIN";
#endif
struct lws *
lws_client_connect_2_dnsreq(struct lws *wsi)
{
@ -344,6 +348,20 @@ solo:
* blocking dns resolution
*/
n = lws_getaddrinfo46(wsi, ads, &result);
#if defined(EAI_NONAME)
if (n == EAI_NONAME) {
/*
* The DNS server responded with NXDOMAIN... even
* though this is still in the client creation call,
* we need to make a CCE, otherwise there won't be
* any user indication of what went wrong
*/
wsi->client_suppress_CONNECTION_ERROR = 0;
lws_inform_client_conn_fail(wsi, (void *)dns_nxdomain,
sizeof(dns_nxdomain));
goto failed1;
}
#endif
}
#else
/* this is either FAILED, CONTINUING, or already called connect_4 */

19
lib/secure-streams/secure-streams.c
View file

@ -804,13 +804,20 @@ _lws_ss_client_connect(lws_ss_handle_t *h, int is_retry, void *conn_if_sspc_onw)
* having to go around the event loop
*/
r = lws_ss_event_helper(h, LWSSSCS_UNREACHABLE);
if (r)
return r;
if (h->prev_ss_state != LWSSSCS_UNREACHABLE &&
h->prev_ss_state != LWSSSCS_ALL_RETRIES_FAILED) {
/*
* blocking DNS failure can get to unreachable via
* CCE, and unreachable can get to ALL_RETRIES_FAILED
*/
r = lws_ss_event_helper(h, LWSSSCS_UNREACHABLE);
if (r)
return r;
r = lws_ss_backoff(h);
if (r)
return r;
r = lws_ss_backoff(h);
if (r)
return r;
}
return LWSSSSRET_TX_DONT_SEND;
}