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List:       netfilter
Subject:    Re: [PATCH 2/5 nft] json: osf: add version json support
From:       Fernando Fernandez Mancera <ffmancera () riseup ! net>
Date:       2019-03-06 12:51:24
Message-ID: 0a3c02e9-0fbd-6537-7ac7-e41f8ee1884e () riseup ! net
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Hello,

I have added support for json to the version option but it would be nice
if you could take a look to it. I have followed the pattern of other
similar implementations. Thanks.

On 3/6/19 1:45 PM, Fernando Fernandez Mancera wrote:
> Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
> ---
>  doc/libnftables-json.adoc |  7 +++++-
>  src/json.c                | 13 +++++++++++
>  src/parser_json.c         | 48 ++++++++++++++++++++++++++++++++++++++-
>  3 files changed, 66 insertions(+), 2 deletions(-)
> 
> diff --git a/doc/libnftables-json.adoc b/doc/libnftables-json.adoc
> index dbe5ac3..6981c69 100644
> --- a/doc/libnftables-json.adoc
> +++ b/doc/libnftables-json.adoc
> @@ -1302,11 +1302,16 @@ Construct a reference to packet's socket.
>  ____
>  *{ "osf": {
>  	"key":* 'OSF_KEY'*,
> -	"ttl":* 'OSF_TTL'
> +	"ttl":* 'OSF_TTL'*,
> +	"flags":* 'OSF_FLAGS'
>  *}}*
>  
>  'OSF_KEY' := *"name"*
>  'OSF_TTL' := *"loose"* | *"skip"*
> +
> +'OSF_FLAGS' := 'OSF_FLAG' | *[* 'OSF_FLAG_LIST' *]*
> +'OSF_FLAG_LIST' := 'OSF_FLAG' [*,* 'OSF_FLAG_LIST' ]
> +'OSF_FLAG' := *"version"*
>  ____
>  
>  Perform OS fingerprinting. This expression is typically used in the LHS of a *match*
> diff --git a/src/json.c b/src/json.c
> index 276a3c0..a46188d 100644
> --- a/src/json.c
> +++ b/src/json.c
> @@ -865,6 +865,7 @@ json_t *socket_expr_json(const struct expr *expr, struct output_ctx *octx)
>  json_t *osf_expr_json(const struct expr *expr, struct output_ctx *octx)
>  {
>  	json_t *root = json_pack("{s:s}", "key", "name");
> +	const char *osf_flags[] = { "version" }
>  
>  	switch (expr->osf.ttl) {
>  	case 1:
> @@ -875,6 +876,18 @@ json_t *osf_expr_json(const struct expr *expr, struct output_ctx *octx)
>  		break;
>  	}
>  
> +	if (expr->osf.flags) {
> +		json_t *tmp = json_array();
> +		unsigned int i;
> +
> +		for (i = 0; i < array_size(osf_flags); i++) {
> +			if (osf.flags & (1 << i)) {
> +				json_array_append_new(tmp, json_string(osf_flags[i]));
> +			}
> +		}
> +		json_object_set_new(root, "flags", tmp);
> +	}
> +
>  	return json_pack("{s:o}", "osf", root);
>  }
>  
> diff --git a/src/parser_json.c b/src/parser_json.c
> index 7b190bc..ae197f0 100644
> --- a/src/parser_json.c
> +++ b/src/parser_json.c
> @@ -377,10 +377,26 @@ static struct expr *json_parse_meta_expr(struct json_ctx *ctx,
>  	return meta_expr_alloc(int_loc, key);
>  }
>  
> +static int osf_flag_parse(const char *name, int *flagval)
> +{
> +	const char *osf_flags[] = { "version" };
> +	unsigned int i;
> +
> +	for (i = 0; i < array_size(osf_flags); i++) {
> +		if (!strcmp(name, osf_flags[i])) {
> +			*flagval |= (1 << i);
> +			return 0;
> +		}
> +	}
> +	return 1;
> +}
> +
>  static struct expr *json_parse_osf_expr(struct json_ctx *ctx,
>  					const char *type, json_t *root)
>  {
> +	json_t *flags, *value;
>  	const char *key, *ttl;
> +	uint8_t flagval = 0;
>  	uint8_t ttlval = 0;
>  
>  	if (json_unpack_err(ctx, root, "{s:s}", "key", &key))
> @@ -397,8 +413,38 @@ static struct expr *json_parse_osf_expr(struct json_ctx *ctx,
>  		}
>  	}
>  
> +	if (!json_unpack(root, "{s:o}", "flags", &flags)) {
> +		const char *flag;
> +
> +		if (json_is_string(flags)) {
> +			flag = json_string_value(flags);
> +
> +			if (osf_flag_parse(flag, &flagval)) {
> +				json_error(ctx, "Invalidad osf flag '%s'.", flag);
> +				return NULL;
> +			}
> +
> +		} else if (!json_is_array) {
> +			json_error(ctx, "Unexpected object type in osf flags tuple.");
> +			return NULL;
> +		}
> +
> +		json_array_foreach(flags, index, value) {
> +			if (!json_is_string(value)) {
> +				json_error(ctx, "Unexpected object type in osf flags array at index %zd.", index);
> +				return NULL;
> +			}
> +			flag = json_string_value(value);
> +
> +			if (osf_flag_parse(flag, &flagval)) {
> +				json_error(ctx, "Invalid osf flag '%s'.", flag);
> +				return NULL;
> +			}
> +		}
> +	}
> +
>  	if (!strcmp(key, "name"))
> -		return osf_expr_alloc(int_loc, ttlval);
> +		return osf_expr_alloc(int_loc, ttlval, flagval);
>  
>  	json_error(ctx, "Invalid osf key value.");
>  	return NULL;
> 
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