net: lib: downloader: limit number of redirects

Limit the number of redirects before downloader fails the download.

Co-authored-by: Seppo Takalo <seppo.takalo@nordicsemi.no>
Signed-off-by: Eivind Jølsgard <eivind.jolsgard@nordicsemi.no>

include/net/downloader.h

@@ -56,6 +56,7 @@ enum downloader_evt_id {
 	 * - -EAFNOSUPPORT: Unsupported address family (IPv4/IPv6).
 	 * - -EHOSTUNREACH: Failed to resolve the target address.
 	 * - -EMSGSIZE: TLS packet is larger than the nRF91 Modem can handle.
+	 * - -EMLINK: Maximum number of redirects reached.
 	 *
 	 * In case of @c ECONNRESET errors, returning zero from the callback will let the
 	 * library attempt to reconnect to the server and download the last fragment again.
@@ -196,6 +197,11 @@ struct downloader_host_cfg {
 	 * This string is used in case you are requesting a proxied file from a CoAP server.
 	 */
 	const char *proxy_uri;
+	/**
+	 * Maximum number of HTTP redirects.
+	 * Use 0 to set the value of CONFIG_DOWNLOADER_MAX_REDIRECTS.
+	 */
+	uint8_t redirects_max;
 };
 
 /**

subsys/net/lib/downloader/Kconfig

@@ -26,6 +26,13 @@ config DOWNLOADER_MAX_FILENAME_SIZE
 	range 8 2048
 	default 255
 
+config DOWNLOADER_MAX_REDIRECTS
+	int "Number of redirects before download is aborted"
+	range 0 255
+	default 10
+	help
+	   The maximum number of redirects can be overwritten in the host config.
+
 config DOWNLOADER_SHELL
 	bool "Download client shell"
 	depends on SHELL

subsys/net/lib/downloader/src/downloader.c

@@ -463,6 +463,10 @@ static int downloader_start(struct downloader *dl, const struct downloader_host_
 	dl->buf_offset = 0;
 	dl->complete = false;
 
+	if (dl->host_cfg.redirects_max == 0) {
+		dl->host_cfg.redirects_max = CONFIG_DOWNLOADER_MAX_REDIRECTS;
+	}
+
 	dl->transport = NULL;
 	STRUCT_SECTION_FOREACH(dl_transport_entry, entry)
 	{

subsys/net/lib/downloader/src/transports/http.c

@@ -99,6 +99,8 @@ struct transport_params_http {
 
 	/** Request new data */
 	bool new_data_req;
+	/** Redirect retries */
+	uint8_t redirects;
 };
 
 BUILD_ASSERT(CONFIG_DOWNLOADER_TRANSPORT_PARAMS_SIZE >= sizeof(struct transport_params_http));
@@ -293,6 +295,13 @@ static int http_header_parse(struct downloader *dl, size_t buf_len)
 					return -EBADMSG;
 				}
 
+				http->redirects++;
+
+				if (http->redirects > dl->host_cfg.redirects_max) {
+					LOG_ERR("Maximum redirections reached, aborting");
+					return -EMLINK;
+				}
+
 				return -ECONNRESET;
 			}
 		}

tests/subsys/net/lib/downloader/CMakeLists.txt

@@ -44,4 +44,5 @@ target_compile_options(app
   -DCONFIG_COAP_INIT_ACK_TIMEOUT_MS=100
   -DCONFIG_COAP_BACKOFF_PERCENT=5
   -DCONFIG_COAP_BLOCK_SIZE=5
+  -DCONFIG_DOWNLOADER_MAX_REDIRECTS=1
 )

tests/subsys/net/lib/downloader/src/main.c

@@ -959,7 +959,8 @@ static ssize_t z_impl_zsock_recvfrom_http_redirect_and_close(
 		return 0;
 	}
 
-	return 0;
+	memcpy(buf, HTTP_HDR_REDIRECT, strlen(HTTP_HDR_REDIRECT));
+	return strlen(HTTP_HDR_REDIRECT);
 }
 
 int z_impl_zsock_socket_http_then_https(int family, int type, int proto)
@@ -1395,6 +1396,32 @@ void test_downloader_get_https_partial_content_partial_2nd_header(void)
 	dl_wait_for_event(DOWNLOADER_EVT_DEINITIALIZED, K_SECONDS(1));
 }
 
+void test_downloader_https_unlimited_redirect(void)
+{
+	int err;
+	struct downloader_evt evt;
+
+	err = downloader_init(&dl, &dl_cfg);
+	TEST_ASSERT_EQUAL(0, err);
+
+	zsock_getaddrinfo_fake.custom_fake = zsock_getaddrinfo_server_ok;
+	zsock_freeaddrinfo_fake.custom_fake = zsock_freeaddrinfo_server_ipv6;
+	z_impl_zsock_socket_fake.custom_fake = z_impl_zsock_socket_https_ipv6_ok;
+	z_impl_zsock_connect_fake.custom_fake = z_impl_zsock_connect_ipv6_ok;
+	z_impl_zsock_setsockopt_fake.custom_fake = z_impl_zsock_setsockopt_https_ok;
+	z_impl_zsock_sendto_fake.custom_fake = z_impl_zsock_sendto_ok;
+	z_impl_zsock_recvfrom_fake.custom_fake = z_impl_zsock_recvfrom_http_redirect_and_close;
+
+
+	err = downloader_get(&dl, &dl_host_conf_w_sec_tags, HTTPS_URL, 0);
+	TEST_ASSERT_EQUAL(0, err);
+
+	evt = dl_wait_for_event(DOWNLOADER_EVT_ERROR, K_SECONDS(3));
+
+	downloader_deinit(&dl);
+	dl_wait_for_event(DOWNLOADER_EVT_DEINITIALIZED, K_SECONDS(1));
+}
+
 void test_downloader_get_http_connect_enetunreach(void)
 {
 	int err;