json_object_object_get_ex returning the original object

[RudiSchloesser]

I'm using json-c to parse messages provided by a device driver.
It works perfect within most of all cases (thanks, great job), but I'm facing an issue, in case larger JSON messages are parsed:
The parser correctly parses the message (see Message).
Afterwards I'm extracting the "data" object and passing it to a
handler. In case of short messages, everything works as expected.
For the larger message, the handler gets the original message object instead of "data". Extracting "data" a 2nd time solves the problem, but that's, I think, not the proper way.

static int
handle_config(struct json_object *msg)
{
    struct json_object *data, *obj;

    printf("CONFIG:\n  %s\n\n\n", json_object_to_json_string_ext(msg, JSON_C_TO_STRING_SPACED));
    json_object_object_get_ex(msg, "data", &data);
    printf("CONFIG (Date):\n  %s\n\n\n", json_object_to_json_string_ext(data, JSON_C_TO_STRING_SPACED));
    return 0;
}

static int
handle_config(struct json_object *data)
{
    printf("Event:\n  %s\n\n\n", json_object_to_json_string_ext(data, JSON_C_TO_STRING_SPACED));
    return 0;
}

void 
handle_msg(const char *json)
{
    struct json_object *msg, *data;

    msg = json_tokener_parse(json);
    printf("  %s\n", json_object_to_json_string_ext(msg, JSON_C_TO_STRING_SPACED));    
    if (msg == NULL) {
        return;
    }
    json_object_object_get_ex(msg, "type", &obj);
    if (obj == NULL) {
        goto exit;
    }
    type = json_object_get_string(obj);
    json_object_object_get_ex(msg, "data", &data);
    if (strcmp(type, "CONFIG") == 0) {
        if (data) {
            handle_config(data);
        }
    } else if (strcmp(type, "EVENT") == 0) {
        if (data) {
            handle_event(data);
        }
    }
exit:
    json_object_put(msg);    
}

Message:
  { "type": "CONFIG", "ip": "10.0.0.42", "data": { "ip": "10.0.0.42", "type": "CONFIG", "data": { "manufacturer": "atecom GmbH", "model": "Eagle", "serial-no": "253.00.01.0001.0002.592BDE31", "hardware-version": "1.1", "firmware-version": "1.3", "hostname": "Eagle1", "services": [ { "name": "gbe2", "type": "Eagle:1000BaseX", "admin_status": 2, "status": 4, "ip": "192.168.2.1", "mask": "255.255.0.0", "typ": "1000Base-X", "mac": "00:50:66:00:20:0b" }, { "name": "gbe3", "type": "Eagle:1000BaseX", "admin_status": 2, "status": 4, "ip": "192.168.3.1", "mask": "255.255.0.0", "typ": "1000Base-X", "mac": "00:50:66:00:20:0c" }, { "name": "gbe1", "type": "Eagle:1000BaseT", "admin_status": 2, "status": 4, "ip": "192.168.1.1", "mask": "255.255.255.0", "typ": "1000Base-T", "mac": "00:50:66:00:20:0a", "parents": [ { "host": "Eagle1", "service": "gbe1.4" } ] }, { "name": "gbe0", "type": "Eagle:1000BaseT", "admin_status": 2, "status": 4, "ip": "192.168.0.1", "mask": "255.255.255.0", "typ": "1000Base-T", "mac": "00:50:66:00:20:09", "parents": [ { "host": "Eagle1", "service": "gbe0.4" } ] }, { "name": "gbe0.4", "type": "Eagle:VLAN", "admin_status": 2, "status": 4, "ip": "192.168.111.1", "mask": "255.255.255.0", "typ": "1000Base-T", "vlan_id": 4, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "gbe1.4", "type": "Eagle:VLAN", "admin_status": 2, "status": 4, "ip": "172.16.13.1", "mask": "255.255.255.0", "typ": "1000Base-T", "vlan_id": 4, "parents": [ { "host": "Eagle1", "service": "gbe1" } ] }, { "name": "Mds1-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.5", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds2-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.1", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds3-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.3", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds4-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.4", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds5-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.2", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "SW-Mds1", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds1-L1-RX" } ] }, { "name": "SW-Mds2", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds2-L1-RX" } ] }, { "name": "SW-Mds3", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds3-L1-RX" } ] }, { "name": "SW-Mds4", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds4-L1-RX" } ] }, { "name": "SW-Mds5", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds5-L1-RX" } ] }, { "name": "Mds1-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 1, "parents": [ { "host": "Eagle1", "service": "SW-Mds1" } ] }, { "name": "Mds2-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 2, "parents": [ { "host": "Eagle1", "service": "SW-Mds2" } ] }, { "name": "Mds3-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 3, "parents": [ { "host": "Eagle1", "service": "SW-Mds3" } ] }, { "name": "Mds4-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 4, "parents": [ { "host": "Eagle1", "service": "SW-Mds4" } ] }, { "name": "Mds5-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 5, "parents": [ { "host": "Eagle1", "service": "SW-Mds5" } ] } ] } } }


CONFIG:
  { "ip": "10.0.0.42", "type": "CONFIG", "data": { "manufacturer": "atecom GmbH", "model": "Eagle", "serial-no": "253.00.01.0001.0002.592BDE31", "hardware-version": "1.1", "firmware-version": "1.3", "hostname": "Eagle1", "services": [ { "name": "gbe2", "type": "Eagle:1000BaseX", "admin_status": 2, "status": 4, "ip": "192.168.2.1", "mask": "255.255.0.0", "typ": "1000Base-X", "mac": "00:50:66:00:20:0b" }, { "name": "gbe3", "type": "Eagle:1000BaseX", "admin_status": 2, "status": 4, "ip": "192.168.3.1", "mask": "255.255.0.0", "typ": "1000Base-X", "mac": "00:50:66:00:20:0c" }, { "name": "gbe1", "type": "Eagle:1000BaseT", "admin_status": 2, "status": 4, "ip": "192.168.1.1", "mask": "255.255.255.0", "typ": "1000Base-T", "mac": "00:50:66:00:20:0a", "parents": [ { "host": "Eagle1", "service": "gbe1.4" } ] }, { "name": "gbe0", "type": "Eagle:1000BaseT", "admin_status": 2, "status": 4, "ip": "192.168.0.1", "mask": "255.255.255.0", "typ": "1000Base-T", "mac": "00:50:66:00:20:09", "parents": [ { "host": "Eagle1", "service": "gbe0.4" } ] }, { "name": "gbe0.4", "type": "Eagle:VLAN", "admin_status": 2, "status": 4, "ip": "192.168.111.1", "mask": "255.255.255.0", "typ": "1000Base-T", "vlan_id": 4, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "gbe1.4", "type": "Eagle:VLAN", "admin_status": 2, "status": 4, "ip": "172.16.13.1", "mask": "255.255.255.0", "typ": "1000Base-T", "vlan_id": 4, "parents": [ { "host": "Eagle1", "service": "gbe1" } ] }, { "name": "Mds1-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.5", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds2-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.1", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds3-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.3", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds4-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.4", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds5-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.2", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "SW-Mds1", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds1-L1-RX" } ] }, { "name": "SW-Mds2", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds2-L1-RX" } ] }, { "name": "SW-Mds3", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds3-L1-RX" } ] }, { "name": "SW-Mds4", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds4-L1-RX" } ] }, { "name": "SW-Mds5", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds5-L1-RX" } ] }, { "name": "Mds1-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 1, "parents": [ { "host": "Eagle1", "service": "SW-Mds1" } ] }, { "name": "Mds2-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 2, "parents": [ { "host": "Eagle1", "service": "SW-Mds2" } ] }, { "name": "Mds3-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 3, "parents": [ { "host": "Eagle1", "service": "SW-Mds3" } ] }, { "name": "Mds4-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 4, "parents": [ { "host": "Eagle1", "service": "SW-Mds4" } ] }, { "name": "Mds5-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 5, "parents": [ { "host": "Eagle1", "service": "SW-Mds5" } ] } ] } }


CONFIG (Date)
  { "manufacturer": "atecom GmbH", "model": "Eagle", "serial-no": "253.00.01.0001.0002.592BDE31", "hardware-version": "1.1", "firmware-version": "1.3", "hostname": "Eagle1", "services": [ { "name": "gbe2", "type": "Eagle:1000BaseX", "admin_status": 2, "status": 4, "ip": "192.168.2.1", "mask": "255.255.0.0", "typ": "1000Base-X", "mac": "00:50:66:00:20:0b" }, { "name": "gbe3", "type": "Eagle:1000BaseX", "admin_status": 2, "status": 4, "ip": "192.168.3.1", "mask": "255.255.0.0", "typ": "1000Base-X", "mac": "00:50:66:00:20:0c" }, { "name": "gbe1", "type": "Eagle:1000BaseT", "admin_status": 2, "status": 4, "ip": "192.168.1.1", "mask": "255.255.255.0", "typ": "1000Base-T", "mac": "00:50:66:00:20:0a", "parents": [ { "host": "Eagle1", "service": "gbe1.4" } ] }, { "name": "gbe0", "type": "Eagle:1000BaseT", "admin_status": 2, "status": 4, "ip": "192.168.0.1", "mask": "255.255.255.0", "typ": "1000Base-T", "mac": "00:50:66:00:20:09", "parents": [ { "host": "Eagle1", "service": "gbe0.4" } ] }, { "name": "gbe0.4", "type": "Eagle:VLAN", "admin_status": 2, "status": 4, "ip": "192.168.111.1", "mask": "255.255.255.0", "typ": "1000Base-T", "vlan_id": 4, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "gbe1.4", "type": "Eagle:VLAN", "admin_status": 2, "status": 4, "ip": "172.16.13.1", "mask": "255.255.255.0", "typ": "1000Base-T", "vlan_id": 4, "parents": [ { "host": "Eagle1", "service": "gbe1" } ] }, { "name": "Mds1-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.5", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds2-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.1", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds3-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.3", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds4-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.4", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "Mds5-L1-RX", "type": "Eagle:IPv4RX", "admin_status": 2, "status": 2, "itf": "gbe0", "dst_ip": "239.232.0.2", "dst_port": 5000, "src_ip": "0.0.0.0", "src_port": 0, "parents": [ { "host": "Eagle1", "service": "gbe0" } ] }, { "name": "SW-Mds1", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds1-L1-RX" } ] }, { "name": "SW-Mds2", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds2-L1-RX" } ] }, { "name": "SW-Mds3", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds3-L1-RX" } ] }, { "name": "SW-Mds4", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds4-L1-RX" } ] }, { "name": "SW-Mds5", "type": "Eagle:MPEGSwitch", "admin_status": 2, "status": 2, "parents": [ { "host": "Eagle1", "service": "Mds5-L1-RX" } ] }, { "name": "Mds1-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 1, "parents": [ { "host": "Eagle1", "service": "SW-Mds1" } ] }, { "name": "Mds2-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 2, "parents": [ { "host": "Eagle1", "service": "SW-Mds2" } ] }, { "name": "Mds3-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 3, "parents": [ { "host": "Eagle1", "service": "SW-Mds3" } ] }, { "name": "Mds4-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 4, "parents": [ { "host": "Eagle1", "service": "SW-Mds4" } ] }, { "name": "Mds5-ASIOUT", "type": "Eagle:ASIOutput", "admin_status": 2, "status": 2, "chn": 5, "parents": [ { "host": "Eagle1", "service": "SW-Mds5" } ] } ] }

Message:
  { "type": "EVENT", "ip": "10.0.0.42", "data": { "resource": "Eagle1", "event": "alert", "text": "FAN-1 failure", "severity": "Major", "dt": "2020-01-06 10:27:29.942" } }

EVENT:
  { "resource": "Eagle1", "event": "alert", "text": "FAN-1 failure", "severity": "Major", "dt": "2020-01-06 10:27:29.942" }

[dota17]

I don't understand your question well. In case of short messages, the short string will be stored in char array[32], For the larger message（long string/Nested object）, the json-object will store the address (*ptr/*c_object ) of string/nested object.

[ploxiln]

Look carefully at your original "CONFIG" message. Printing it out with indenting helps:

{
  "type": "CONFIG",
  "ip": "10.0.0.42",
  "data": {
    "ip": "10.0.0.42",
    "type": "CONFIG",
    "data": {
      "manufacturer": "atecom GmbH",
      "model": "Eagle",
      "serial-no": "253.00.01.0001.0002.592BDE31",
      "hardware-version": "1.1",
      "firmware-version": "1.3",
      "hostname": "Eagle1",
      "services": [
        {
          "name": "gbe2",
...

it is the original message that is double-nested, json_object_object_get_ex() works consistently and correctly, it's just a strange message structure.

[RudiSchloesser]

Dear Pierce,
many thanks for looking into it and giving me the hint. My mistake.
Thanks again

[ploxiln]

you wrote "clusterId:" for the key to get, but it should be "clusterId"

[hawicz]

@sohail-shareef, this is not a message forum, please don't hijack issues (especially other people's), and instead ask your questions at https://groups.google.com/g/json-c