MEDIUM: httpclient: disable SSL when the ca-file couldn't be loaded

Emit a warning when the ca-file couldn't be loaded for the httpclient,
and disable the SSL of the httpclient.

We must never be in a case where the verify is disabled without any
configuration, so better disable the SSL completely.

Move the check on the scheme above the initialization of the applet so
we could abort before initializing the appctx.
diff --git a/src/http_client.c b/src/http_client.c
index 668489a..52255be 100644
--- a/src/http_client.c
+++ b/src/http_client.c
@@ -465,6 +465,7 @@
 	struct sockaddr_storage ss_url;
 	struct sockaddr_storage* ss_dst;
 	struct split_url out;
+	enum obj_type *target = NULL;
 
 	/* if the client was started and not ended, an applet is already
 	 * running, we shouldn't try anything */
@@ -492,6 +493,26 @@
 		goto out_free_appctx;
 	}
 
+	/* choose the SSL server or not */
+	switch (out.scheme) {
+		case SCH_HTTP:
+			target = &httpclient_srv_raw->obj_type;
+			break;
+		case SCH_HTTPS:
+#ifdef USE_OPENSSL
+			if (httpclient_srv_ssl) {
+				target = &httpclient_srv_ssl->obj_type;
+			} else {
+				ha_alert("httpclient: SSL was disabled (wrong verify/ca-file)!\n");
+				goto out_free_sess;
+			}
+#else
+			ha_alert("httpclient: OpenSSL is not available %s:%d.\n", __FUNCTION__, __LINE__);
+			goto out_free_sess;
+#endif
+			break;
+	}
+
 	/* if httpclient_set_dst() was used, sets the alternative address */
 	if (hc->dst)
 		ss_dst = hc->dst;
@@ -508,28 +529,11 @@
 	}
 	s = DISGUISE(cs_strm(cs));
 
+	s->target = target;
 	/* set the "timeout server" */
 	s->req.wto = hc->timeout_server;
 	s->res.rto = hc->timeout_server;
 
-	/* choose the SSL server or not */
-	switch (out.scheme) {
-		case SCH_HTTP:
-			s->target = &httpclient_srv_raw->obj_type;
-			break;
-		case SCH_HTTPS:
-#ifdef USE_OPENSSL
-			s->target = &httpclient_srv_ssl->obj_type;
-#else
-			ha_alert("httpclient: OpenSSL is not available %s:%d.\n", __FUNCTION__, __LINE__);
-			LIST_DELETE(&s->list);
-			pool_free(pool_head_stream, s);
-			cs_free(cs);
-			goto out_free_addr;
-#endif
-			break;
-	}
-
 	s->csb->dst = addr;
 	s->csb->flags |= CS_FL_NOLINGER;
 	s->flags |= SF_ASSIGNED|SF_ADDR_SET;
@@ -1046,11 +1050,15 @@
 		goto err;
 
 	httpclient_srv_ssl->ssl_ctx.verify = httpclient_ssl_verify;
-
+	/* if the verify is required, try to load the system CA */
 	if (httpclient_ssl_verify == SSL_SOCK_VERIFY_REQUIRED) {
 		httpclient_srv_ssl->ssl_ctx.ca_file = strdup("@system-ca");
-		if (!ssl_store_load_locations_file(httpclient_srv_ssl->ssl_ctx.ca_file, 1, CAFILE_CERT))
-			goto err;
+		if (!ssl_store_load_locations_file(httpclient_srv_ssl->ssl_ctx.ca_file, 1, CAFILE_CERT)) {
+			ha_warning("httpclient: cannot initialize SSL verify with 'ca-file \"%s\"'. Disabling SSL.\n", httpclient_srv_ssl->ssl_ctx.ca_file);
+			ha_free(&httpclient_srv_ssl->ssl_ctx.ca_file);
+			srv_drop(httpclient_srv_ssl);
+			httpclient_srv_ssl = NULL;
+		}
 	}
 
 #endif
@@ -1064,8 +1072,10 @@
 	httpclient_proxy->srv = httpclient_srv_raw;
 
 #ifdef USE_OPENSSL
-	httpclient_srv_ssl->next = httpclient_proxy->srv;
-	httpclient_proxy->srv = httpclient_srv_ssl;
+	if (httpclient_srv_ssl) {
+		httpclient_srv_ssl->next = httpclient_proxy->srv;
+		httpclient_proxy->srv = httpclient_srv_ssl;
+	}
 #endif
 
 
@@ -1120,7 +1130,7 @@
 	}
 
 #ifdef USE_OPENSSL
-	{
+	if (httpclient_srv_ssl) {
 		int err_code = 0;
 
 		/* init the SNI expression */