Because basic match is made of multiple keywords and parsed and handle
differently
example:
$ tc filter add dev $eth_dev_name ingress priority 20000 protocol ipv4
basic match '(cmp(u8 at 9 layer network eq 6) or cmp(u8 at 9 layer network eq
17)) and ipset(sg-test-ipv4 src)' action pass
and if jsonw_string used then it will double-quote every string passed and
prints something like this:
"ematch": "("cmp(u8 at 9 layer 1 eq 6,")","OR "cmp(u8 at 9 layer 1 eq
17,")",") ","AND "ipset(sg-test-ipv4 src,")",
instead of like this:
"ematch": "(cmp(u8 at 9 layer 1 eq 6)OR cmp(u8 at 9 layer 1 eq 17)) AND
ipset(sg-test-ipv4 src)”,
Hope I explained it right.
> On Oct 29, 2020, at 7:16 PM, Stephen Hemminger <step...@networkplumber.org>
> wrote:
>
> On Thu, 29 Oct 2020 21:20:55 +0000
> "Sharma, Puneet" <pusha...@akamai.com> wrote:
>
>> I did provide an example to better explain what patch is doing.
>>
>> Sorry for long paste.
>>
>> So, with current implementation output of command:
>> $ tc -s -d -j filter show dev <eth_name> ingress
>>
>> would contain:
>> [{
>> "protocol": "ip",
>> "pref": 20000,
>> "kind": "basic",
>> "chain": 0
>> },{
>> "protocol": "ip",
>> "pref": 20000,
>> "kind": "basic",
>> "chain": 0,
>> "options": {handle 0x1
>> (
>> cmp(u8 at 9 layer 1 eq 6)
>> OR cmp(u8 at 9 layer 1 eq 17)
>> ) AND ipset(sg-test-ipv4 src)
>>
>> "actions": [{
>> "order": 1,
>> "kind": "gact",
>> "control_action": {
>> "type": "pass"
>> },
>> "prob": {
>> "random_type": "none",
>> "control_action": {
>> "type": "pass"
>> },
>> "val": 0
>> },
>> "index": 1,
>> "ref": 1,
>> "bind": 1,
>> "installed": 2633,
>> "last_used": 2633,
>> "stats": {
>> "bytes": 0,
>> "packets": 0,
>> "drops": 0,
>> "overlimits": 0,
>> "requeues": 0,
>> "backlog": 0,
>> "qlen": 0
>> }
>> }]
>> }
>> }
>> ]
>>
>> Clearly this is an invalid JSON. Look at “options"
>>
>>
>> With patch it would look like:
>> [{
>> "protocol": "ip",
>> "pref": 20000,
>> "kind": "basic",
>> "chain": 0
>> },{
>> "protocol": "ip",
>> "pref": 20000,
>> "kind": "basic",
>> "chain": 0,
>> "options": {
>> "handle": 1,
>> "ematch": "(cmp(u8 at 9 layer 1 eq 6)OR cmp(u8 at 9 layer 1 eq
>> 17)) AND ipset(sg-test-ipv4 src)",
>> "actions": [{
>> "order": 1,
>> "kind": "gact",
>> "control_action": {
>> "type": "pass"
>> },
>> "prob": {
>> "random_type": "none",
>> "control_action": {
>> "type": "pass"
>> },
>> "val": 0
>> },
>> "index": 1,
>> "ref": 1,
>> "bind": 1,
>> "installed": 297829723,
>> "last_used": 297829723,
>> "stats": {
>> "bytes": 0,
>> "packets": 0,
>> "drops": 0,
>> "overlimits": 0,
>> "requeues": 0,
>> "backlog": 0,
>> "qlen": 0
>> }
>> }]
>> }
>> }
>> ]
>>
>> Now it’s handling the “handle” and “ematch” inside “options" depending on
>> context.
>>
>> Hope it’s more clear now.
>>
>> Thanks,
>> ~Puneet.
>>
>>> On Oct 29, 2020, at 4:17 PM, Stephen Hemminger <step...@networkplumber.org>
>>> wrote:
>>>
>>> On Wed, 28 Oct 2020 14:35:54 -0400
>>> Puneet Sharma <pusha...@akamai.com> wrote:
>>>
>>>> Currently, json for basic rules output does not produce correct json
>>>> syntax. The following fixes were done to correct it for extended
>>>> matches for use with "basic" filters.
>>>>
>>>> tc/f_basic.c: replace fprintf with print_uint to support json output.
>>>> fixing this prints "handle" tag correctly in json output.
>>>>
>>>> tc/m_ematch.c: replace various fprintf with correct print.
>>>> add new "ematch" tag for json output which represents
>>>> "tc filter add ... basic match '()'" string. Added print_raw_string
>>>> to print raw string instead of key value for json.
>>>>
>>>> lib/json_writer.c: add jsonw_raw_string to print raw text in json.
>>>>
>>>> lib/json_print.c: add print_color_raw_string to print string
>>>> depending on context.
>>>>
>>>> example:
>>>> $ tc -s -d -j filter show dev <eth_name> ingress
>>>> Before:
>>>> ...
>>>> "options": {handle 0x2
>>>> (
>>>> cmp(u8 at 9 layer 1 eq 6)
>>>> OR cmp(u8 at 9 layer 1 eq 17)
>>>> ) AND ipset(test-ipv4 src)
>>>>
>>>> "actions": [{
>>>> ...
>>>>
>>>> After:
>>>> [{
>>>> ...
>>>> "options": {
>>>> "handle": 1,
>>>> "ematch": "(cmp(u8 at 9 layer 1 eq 6)OR cmp(u8 at 9 layer 1 eq 17)) AND
>>>> ipset(test-ipv4 src)",
>>>> ...
>>>> ]
>>>>
>>>> Signed-off-by: Puneet Sharma <pusha...@akamai.com>
>>>> ---
>>>
>>> What is the point of introducing raw string?
>>> The JSON standard says that string fields must use proper escapes.
>>>
>>> Please don't emit invalid JSON. It will break consumption by other
>>> libraries.
>>
>
>
> I agree that the existing output is wrong. But your patch introduces
>
> +void jsonw_raw_string(json_writer_t *self, const char *value);
>
> Why?
>
> You should just use jsonw_string() which already handles things like special
> characters in the string. In theory, there could be quotes or other characters
> in the ematch string.
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