[PATCH iproute2(-next) 1/1] ip: fix ip route show json output for multipath nexthops

[PATCH iproute2(-next) 1/1] ip: fix ip route show json output for multipath nexthops

[Julien Fortin]

From: Julien Fortin <julien@cumulusnetworks.com>

print_rta_multipath doesn't support JSON output:

{
    "dst":"27.0.0.13",
    "protocol":"bgp",
    "metric":20,
    "flags":[],
    "gateway":"169.254.0.1"dev uplink-1 weight 1 ,
    "flags":["onlink"],
    "gateway":"169.254.0.1"dev uplink-2 weight 1 ,
    "flags":["onlink"]
},

since RTA_MULTIPATH has nested objects we should print them
in a json array.

With the path we have the following output:

{
    "flags": [],
    "dst": "36.0.0.13",
    "protocol": "bgp",
    "metric": 20,
    "nexthops": [
        {
	    "weight": 1,
	    "flags": [
	        "onlink"
	    ],
	    "gateway": "169.254.0.1",
	    "dev": "uplink-1"
        },
	{
	    "weight": 1,
	    "flags": [
	        "onlink"
            ],
	    "gateway": "169.254.0.1",
	    "dev": "uplink-2"
        }
    ]
}

Fixes: 663c3cb23103f4 ("iproute: implement JSON and color output")

Signed-off-by: Julien Fortin <julien@cumulusnetworks.com>
---
 ip/iproute.c | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/ip/iproute.c b/ip/iproute.c
index a4533851..5d5f1551 100644
--- a/ip/iproute.c
+++ b/ip/iproute.c
@@ -649,23 +649,27 @@ static void print_rta_multipath(FILE *fp, const struct rtmsg *r,
 	int len = RTA_PAYLOAD(rta);
 	int first = 1;
 
+	open_json_array(PRINT_JSON, "nexthops");
+
 	while (len >= sizeof(*nh)) {
 		struct rtattr *tb[RTA_MAX + 1];
 
 		if (nh->rtnh_len > len)
 			break;
 
+		open_json_object(NULL);
+
 		if (!is_json_context()) {
 			if ((r->rtm_flags & RTM_F_CLONED) &&
 			    r->rtm_type == RTN_MULTICAST) {
 				if (first) {
-					fprintf(fp, "Oifs: ");
+					print_string(PRINT_FP, NULL, "Oifs: ", NULL);
 					first = 0;
 				} else {
-					fprintf(fp, " ");
+					print_string(PRINT_FP, NULL, " ", NULL);
 				}
 			} else
-				fprintf(fp, "%s\tnexthop ", _SL_);
+				print_string(PRINT_FP, NULL, "%s\tnexthop ", _SL_);
 		}
 
 		if (nh->rtnh_len > sizeof(*nh)) {
@@ -689,22 +693,30 @@ static void print_rta_multipath(FILE *fp, const struct rtmsg *r,
 
 		if ((r->rtm_flags & RTM_F_CLONED) &&
 		    r->rtm_type == RTN_MULTICAST) {
-			fprintf(fp, "%s", ll_index_to_name(nh->rtnh_ifindex));
+			print_string(PRINT_ANY, "dev",
+				     "%s", ll_index_to_name(nh->rtnh_ifindex));
+
 			if (nh->rtnh_hops != 1)
-				fprintf(fp, "(ttl>%d)", nh->rtnh_hops);
-			fprintf(fp, " ");
+				print_int(PRINT_ANY, "ttl", "(ttl>%d)", nh->rtnh_hops);
+
+			print_string(PRINT_FP, NULL, " ", NULL);
 		} else {
-			fprintf(fp, "dev %s ", ll_index_to_name(nh->rtnh_ifindex));
+			print_string(PRINT_ANY, "dev",
+				     "dev %s ", ll_index_to_name(nh->rtnh_ifindex));
+
 			if (r->rtm_family != AF_MPLS)
-				fprintf(fp, "weight %d ",
-					nh->rtnh_hops+1);
+				print_int(PRINT_ANY, "weight",
+					  "weight %d ", nh->rtnh_hops + 1);
 		}
 
 		print_rt_flags(fp, nh->rtnh_flags);
 
 		len -= NLMSG_ALIGN(nh->rtnh_len);
 		nh = RTNH_NEXT(nh);
+
+		close_json_object();
 	}
+	close_json_array(PRINT_JSON, NULL);
 }
 
 int print_route(struct nlmsghdr *n, void *arg)
-- 
2.23.0

Re: [PATCH iproute2(-next) 1/1] ip: fix ip route show json output for multipath nexthops

[David Ahern]

On 9/24/19 4:32 PM, Julien Fortin wrote:
> diff --git a/ip/iproute.c b/ip/iproute.c
> index a4533851..5d5f1551 100644
> --- a/ip/iproute.c
> +++ b/ip/iproute.c
> @@ -649,23 +649,27 @@ static void print_rta_multipath(FILE *fp, const struct rtmsg *r,
>  	int len = RTA_PAYLOAD(rta);
>  	int first = 1;
>  
> +	open_json_array(PRINT_JSON, "nexthops");
> +
>  	while (len >= sizeof(*nh)) {
>  		struct rtattr *tb[RTA_MAX + 1];
>  
>  		if (nh->rtnh_len > len)
>  			break;
>  
> +		open_json_object(NULL);
> +
>  		if (!is_json_context()) {

With the fprintf removed in favor of print_string(PRINT_FP), you should
be able to remove this is_json_context() check and remove a level of
indentation for this section.

>  			if ((r->rtm_flags & RTM_F_CLONED) &&
>  			    r->rtm_type == RTN_MULTICAST) {
>  				if (first) {
> -					fprintf(fp, "Oifs: ");
> +					print_string(PRINT_FP, NULL, "Oifs: ", NULL);
>  					first = 0;
>  				} else {
> -					fprintf(fp, " ");
> +					print_string(PRINT_FP, NULL, " ", NULL);
>  				}
>  			} else
> -				fprintf(fp, "%s\tnexthop ", _SL_);
> +				print_string(PRINT_FP, NULL, "%s\tnexthop ", _SL_);
>  		}
>  
>  		if (nh->rtnh_len > sizeof(*nh)) {