[PATCH] wg show: Add json output

[Matthew Oliver]

This patch adds a new option to `wg show` called json. When
specified it'll output the WG interface in json output.

It works with both given an interface or all.

  # wg show wg1 json
  [
    {
      "interface": "wg1",
      "public_key": "Yh0kKjoqnJsxbCsTkQ/3uncEhdqa+EtJXCYcVzMdugs=",
      "private_key": "MKVTz8NCXL0uaE77MJfgIWSSy1AfqSmLFRx16oxmrmk=",
      "port": "51831",
      "fwmark": null,
      "peers": [
         {
           "peer": "GzY59HlXkCkfXl9uSkEFTHzOtBsxQFKu3KWGFH5P9Qc=",
           "preshared_key": null,
           "endpoint": "172.16.3.104:51834",
           "allowed_ips": [
             "10.0.3.0/24", "224.0.0.0/8", "172.16.0.0/16"
           ],
           "latest_handshake": 1581909869,
           "transfer": {
            "received": 3949216,
            "sent": 4531428
           },
           "persistent_keepalive": 30
         }
      ]
    }
  ]

Note however, that this will print out the private key.

Signed-off-by: Matthew Oliver <matt at oliver.net.au>
---
 src/show.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 72 insertions(+), 3 deletions(-)

diff --git a/src/show.c b/src/show.c
index e772339..f8c7543 100644
--- a/src/show.c
+++ b/src/show.c
@@ -202,7 +202,62 @@ static char *bytes(uint64_t b)
 static const char *COMMAND_NAME;
 static void show_usage(void)
 {
-	fprintf(stderr, "Usage: %s %s { <interface> | all | interfaces } [public-key | private-key | listen-port | fwmark | peers | preshared-keys | endpoints | allowed-ips | latest-handshakes | transfer | persistent-keepalive | dump]\n", PROG_NAME, COMMAND_NAME);
+	fprintf(stderr, "Usage: %s %s { <interface> | all | interfaces } [public-key | private-key | listen-port | fwmark | peers | preshared-keys | endpoints | allowed-ips | latest-handshakes | transfer | persistent-keepalive | dump | json]\n", PROG_NAME, COMMAND_NAME);
+}
+
+static void json_print(struct wgdevice *device)
+{
+	struct wgpeer *peer;
+	struct wgallowedip *allowedip;
+	terminal_printf(TERMINAL_RESET);
+	terminal_printf("  {\n");
+	terminal_printf("    \"interface\": \"%s\",\n", device->name);
+	terminal_printf("    \"public_key\": \"%s\",\n", key(device->public_key));
+	terminal_printf("    \"private_key\": \"%s\",\n", key(device->private_key));
+	terminal_printf("    \"port\": \"%d\",\n", device->listen_port);
+	if (device->fwmark)
+		terminal_printf("    \"fwmark\": \"0x%x\",\n", device->fwmark);
+	else
+		terminal_printf("    \"fwmark\": null,\n");
+	terminal_printf("    \"peers\": [\n");
+	sort_peers(device);
+	for_each_wgpeer(device, peer) {
+		terminal_printf("       {\n");
+		terminal_printf("         \"peer\": \"%s\",\n", key(peer->public_key));
+		if (peer->flags & WGPEER_HAS_PRESHARED_KEY)
+			terminal_printf("         \"preshared_key\": \"%s\",\n", key(peer->preshared_key));
+		else
+			terminal_printf("         \"preshared_key\": null,\n");
+		if (peer->endpoint.addr.sa_family == AF_INET || peer->endpoint.addr.sa_family == AF_INET6)
+			terminal_printf("         \"endpoint\": \"%s\",\n", endpoint(&peer->endpoint.addr));
+		else
+			terminal_printf("         \"endpoint\": null,\n");
+		terminal_printf("         \"allowed_ips\": [\n");
+		if (peer->first_allowedip) {
+			terminal_printf("           ");
+			for_each_wgallowedip(peer, allowedip)
+				terminal_printf("\"%s/%u\"%s", ip(allowedip), allowedip->cidr, allowedip->next_allowedip ? ", " : "\n");
+		}
+		terminal_printf("         ],\n");
+		if (peer->last_handshake_time.tv_sec)
+			terminal_printf("         \"latest_handshake\": %ld,\n", peer->last_handshake_time.tv_sec);
+		else
+			terminal_printf("         \"latest_handshake\": null,\n");
+		terminal_printf("         \"transfer\": {\n");
+		terminal_printf("          \"received\": %ld,\n", peer->rx_bytes);
+		terminal_printf("          \"sent\": %ld\n", peer->tx_bytes);
+		terminal_printf("         },\n");
+		if (peer->persistent_keepalive_interval)
+			terminal_printf("         \"persistent_keepalive\": %d\n", peer->persistent_keepalive_interval);
+		else
+			terminal_printf("         \"persistent_keepalive\": null\n");
+		if (peer->next_peer)
+			terminal_printf("       },\n");
+		else
+			terminal_printf("       }\n");
+	}
+	terminal_printf("    ]\n");
+	terminal_printf("  }");
 }
 
 static void pretty_print(struct wgdevice *device)
@@ -396,6 +451,8 @@ int show_main(int argc, char *argv[])
 		}
 		ret = !!*interfaces;
 		interface = interfaces;
+		if (argc == 3 && !strcmp(argv[2], "json"))
+			terminal_printf("[\n");
 		for (size_t len = 0; (len = strlen(interface)); interface += len + 1) {
 			struct wgdevice *device = NULL;
 
@@ -404,7 +461,13 @@ int show_main(int argc, char *argv[])
 				continue;
 			}
 			if (argc == 3) {
-				if (!ugly_print(device, argv[2], true)) {
+				if (!strcmp(argv[2], "json")) {
+					json_print(device);
+					if (strlen(interface + len + 1))
+						terminal_printf(",\n");
+					else
+						terminal_printf("\n");
+				} else if (!ugly_print(device, argv[2], true)) {
 					ret = 1;
 					free_wgdevice(device);
 					break;
@@ -417,6 +480,8 @@ int show_main(int argc, char *argv[])
 			free_wgdevice(device);
 			ret = 0;
 		}
+		if (argc == 3 && !strcmp(argv[2], "json"))
+			terminal_printf("]\n");
 		free(interfaces);
 	} else if (!strcmp(argv[1], "interfaces")) {
 		char *interfaces, *interface;
@@ -444,7 +509,11 @@ int show_main(int argc, char *argv[])
 			return 1;
 		}
 		if (argc == 3) {
-			if (!ugly_print(device, argv[2], false))
+			if (!strcmp(argv[2], "json")) {
+				terminal_printf("[\n");
+				json_print(device);
+				terminal_printf("\n]\n");
+			} else if (!ugly_print(device, argv[2], false))
 				ret = 1;
 		} else
 			pretty_print(device);
-- 
2.22.0