Add hostname support to pico network driver #1173

UncleGrumpy · 2024-05-29T02:37:28Z

Adds support for setting a unique default device hostname (as the ESP32 platform does), and setting per interface hostname in the interface configuration (honoring the dhcp_hostname key value).

closes #1094

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

bettio · 2024-06-30T15:46:16Z

@pguyot do you have any opinion about this?

pguyot · 2024-06-30T15:51:32Z

src/platforms/rp2040/src/lib/networkdriver.c

+        } else {
+            buf = interop_term_to_string(hostname_term, &ok);
+        }
+        if (!ok || IS_NULL_PTR(buf)) {


if ok is false, we still need to free buf.

(!ok || IS_NULL_PTR(buf)) might also be normalized to (UNLIKELY(!ok || buf != NULL)).

I fixed both comments.

pguyot · 2024-06-30T15:52:49Z

src/platforms/rp2040/src/lib/networkdriver.c

+            free(psk);
+            return BADARG_ATOM;
+        }
+        ap_hostname = malloc(strlen(buf) + 1);


I am very confused about when this is freed.

At the beginning of this section (line 483 new):
char *ap_hostname = driver_data->ap_hostname;

This is freed when the driver is terminated.

void network_driver_destroy(GlobalContext *global) { if (driver_data) { if (driver_data->hostname) { free(driver_data->hostname); } if (driver_data->ap_hostname) { free(driver_data->ap_hostname); ...

pguyot · 2024-06-30T15:53:50Z

src/platforms/rp2040/src/lib/networkdriver.c

+            free(psk);
+            return BADARG_ATOM;
+        }
+        hostname = malloc(strlen(buf) + 1);


I am confused about this allocation. When is it freed?

pguyot · 2024-06-30T15:55:56Z

src/platforms/rp2040/src/lib/networkdriver.c

@@ -705,6 +810,12 @@ void network_driver_init(GlobalContext *global)
 void network_driver_destroy(GlobalContext *global)
 {
    if (driver_data) {
+        if (driver_data->hostname) {


if is not required here AFAIK

The per interface hostname resides in driver_data until the driver terminates at which point it is freed, but I realize now I wrote this before I fully understood how the driver_destroy functions work. This code should be placed in network:stop/0 which this driver does not yet support.

In the Pico-SDK netif_set_hostname() is defined as:

#define netif_set_hostname(netif, name) do { if((netif) != NULL) { (netif)->hostname = name; }}while(0)

If the hostname is freed the interface hostname will immediately revert to PicoW, since NULL has the same effect as the hostname being unset.

In examples for Pico-SDK that set a hostname it is always hardcoded in a string in flash, so there is no additional memory consumed, but to have this set programmatically we don't have that luxury. Perhaps we could come up with an NVS like solution to store this kind of data?

Sorry for the confusion. I meant that:

if (ptr) { free(ptr); }

is equivalent to:

free(ptr);

as free accepts NULL.

pguyot · 2024-06-30T15:57:46Z

@pguyot do you have any opinion about this?

I was a little bit confused by the fact that DNS was involved in the conversation in #1094 and offline, but this PR is a welcome addition. We need to fix the memory management though.

pguyot · 2024-07-07T07:41:33Z

src/platforms/rp2040/src/lib/networkdriver.c

@@ -705,6 +810,12 @@ void network_driver_init(GlobalContext *global)
 void network_driver_destroy(GlobalContext *global)
 {
    if (driver_data) {
+        if (driver_data->hostname) {


Sorry for the confusion. I meant that:

if (ptr) { free(ptr); }

is equivalent to:

free(ptr);

as free accepts NULL.

pguyot · 2024-07-07T07:44:08Z

src/platforms/rp2040/src/lib/networkdriver.c

+            }
+            return BADARG_ATOM;
+        }
+        driver_data->ap_hostname = malloc(strlen(buf) + 1);


You could use strdup(3) which would do the computation of the length, the allocation and the copy in a single call. Alternatively, if it's not available in some SDKs (it's part of C89), you could save the length to avoid computing it twice.

pguyot · 2024-07-07T07:44:57Z

src/platforms/rp2040/src/lib/networkdriver.c

+            free(psk);
+            return BADARG_ATOM;
+        }
+        driver_data->hostname = malloc(strlen(buf) + 1);


You could use strdup(3) which would do the computation of the length, the allocation and the copy in a single call. Alternatively, if it's not available in some SDKs (it's part of C89), you could save the length to avoid computing it twice.

pguyot · 2024-07-07T07:46:39Z

src/platforms/rp2040/src/lib/networkdriver.c

+            free(ssid);
+            free(psk);
+            return OUT_OF_MEMORY_ATOM;
+        } else {


Let's be coherent with what is done on line 293 and remove else here.

pguyot · 2024-07-07T07:46:50Z

src/platforms/rp2040/src/lib/networkdriver.c

+            free(ssid);
+            free(psk);
+            return OUT_OF_MEMORY_ATOM;
+        } else {


Let's be coherent with what is done on line 293 and remove else here.

pguyot · 2024-07-07T07:47:31Z

src/platforms/rp2040/src/lib/networkdriver.c

+            free(ssid);
+            free(psk);
+            return OUT_OF_MEMORY_ATOM;
+        } else {


Let's be coherent with what is done on line 514 and remove else here.

pguyot · 2024-07-07T07:47:36Z

src/platforms/rp2040/src/lib/networkdriver.c

+            free(ssid);
+            free(psk);
+            return OUT_OF_MEMORY_ATOM;
+        } else {


Let's be coherent with what is done on line 514 and remove else here.

Fixes a leak in `get_default_device_name()`, if the driver if stopped the memory holding the device name is never free'd. This could be especially problematic if the driver is stopped and restarted multiple times, as may be the case with a battery powered device. Fixes a potential memory leak of `psk` used for the ap if the given `psk` is invalid due to not meeting the minimum size requirement. Signed-off-by: Winford <winford@object.stream>

Adds support for setting `dhcp_hostname` from `sta_config_options()` and/or `ap_config_options()`, or, if undefined, sets the hostname to the default device name of `atomvm-${DEVICE_MAC}`. Formerly all pico_w devices tried to register to an access point with the factory default `PicoW` hostname, which would make all subsequent pico devices to connect to an access point, after the first one, unreachable by hostname. Closes atomvm#1094 Signed-off-by: Winford <winford@object.stream>

UncleGrumpy requested a review from pguyot June 27, 2024 22:54

UncleGrumpy force-pushed the pico_hostname branch from 2cfae05 to cfec95d Compare June 27, 2024 23:09

pguyot reviewed Jun 30, 2024

View reviewed changes

UncleGrumpy force-pushed the pico_hostname branch from cfec95d to 7d3972b Compare July 3, 2024 03:50

pguyot reviewed Jul 7, 2024

View reviewed changes

UncleGrumpy added 2 commits August 18, 2024 17:26

UncleGrumpy force-pushed the pico_hostname branch from 7d3972b to 2e0e53f Compare August 19, 2024 15:36

UncleGrumpy requested a review from pguyot August 19, 2024 17:54

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Add hostname support to pico network driver #1173

Add hostname support to pico network driver #1173

UncleGrumpy commented May 29, 2024

bettio commented Jun 30, 2024

pguyot Jun 30, 2024

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Add hostname support to pico network driver #1173

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Add hostname support to pico network driver #1173

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UncleGrumpy commented May 29, 2024

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