RFC8910/RFC8908 per device API URL

[pparent76]

Hello,

I'm opening a new issue concerning RFC8910/RFC8908 . From what I read:

If the API server needs information about the client identity that is not otherwise visible to it, the URI provided to the client during provisioning SHOULD be distinct per client. Thus, depending on how the Captive Portal system is configured, the URI will be unique for each client host and between sessions for the same client host.

RFC8910/RFC8908

The problem is that currently it seems that Coova-Chilli does not allow to give any specific paramters to the API url, that are specific to the client. From what I read

  if (_options.captiveportalapi_uri) {
    o[pos++] = DHCP_OPTION_CAPTIVE_PORTAL_URI;
    o[pos++] = strlen(_options.captiveportalapi_uri);
    memcpy(&o[pos], _options.captiveportalapi_uri, strlen(_options.captiveportalapi_uri));
    pos += strlen(_options.captiveportalapi_uri);
    if (_options.debug)
      syslog(LOG_DEBUG, "%s(%d): DHCP Captive Portal API URI %s\n", __FUNCTION__, __LINE__, _options.captiveportalapi_uri);
  }

https://github.com/coova/coova-chilli/blob/master/src/dhcp.c

The problem with that is that no distant API could work correctly without any information to identify the client. It would be good to have the possibility to customize the url of the API, with the mac of the client and/or a random ID, and possibly specify as well the nasid of the Coova-chilli instance, and possibly other infos.

[pparent76]

For example the following patch allow to concatenate the client mac to the API url, and therefore a remote API connected to the Radius can reply correctly depending on the client session (authenticated or not, and session time):

diff --git a/src/dhcp.c b/src/dhcp.c
index c044040..9506ca4 100644
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -3208,12 +3208,30 @@ static int dhcp_accept_opt(struct dhcp_conn_t *conn, uint8_t *o, int pos) {
 #endif
 
   if (_options.captiveportalapi_uri) {
-    o[pos++] = DHCP_OPTION_CAPTIVE_PORTAL_URI;
-    o[pos++] = strlen(_options.captiveportalapi_uri);
-    memcpy(&o[pos], _options.captiveportalapi_uri, strlen(_options.captiveportalapi_uri));
-    pos += strlen(_options.captiveportalapi_uri);
-    if (_options.debug)
-      syslog(LOG_DEBUG, "%s(%d): DHCP Captive Portal API URI %s\n", __FUNCTION__, __LINE__, _options.captiveportalapi_uri);
+      char mac_str[18];
+
+      snprintf(mac_str, sizeof(mac_str),
+              "%02x-%02x-%02x-%02x-%02x-%02x",
+              conn->hismac[0], conn->hismac[1], conn->hismac[2],
+              conn->hismac[3], conn->hismac[4], conn->hismac[5]);
+
+      size_t uri_len = strlen(_options.captiveportalapi_uri);
+      size_t mac_len = strlen(mac_str);
+
+      o[pos++] = DHCP_OPTION_CAPTIVE_PORTAL_URI;
+      o[pos++] = uri_len + mac_len;
+
+      memcpy(&o[pos], _options.captiveportalapi_uri, uri_len);
+      pos += uri_len;
+
+      memcpy(&o[pos], mac_str, mac_len);
+      pos += mac_len;
+
+      if (_options.debug)
+          syslog(LOG_DEBUG,
+                "%s(%d): DHCP Captive Portal API URI %s%s\n",
+                __FUNCTION__, __LINE__,
+                _options.captiveportalapi_uri, mac_str);
   }
 
   o[pos++] = DHCP_OPTION_END;