paymod: Consolidate parsing RPC results in libplugin

We handle these in a number of different ways, and regularly get the parsing
and logic for optional fields wrong, so let's consolidate them here.

plugins/libplugin.c

@@ -1266,3 +1266,192 @@ void plugin_main(char *argv[],
 
 	tal_free(plugin);
 }
+
+static struct listpeers_channel *json_to_listpeers_channel(const tal_t *ctx,
+							   const char *buffer,
+							   const jsmntok_t *tok)
+{
+	struct listpeers_channel *chan;
+	const jsmntok_t *privtok = json_get_member(buffer, tok, "private"),
+			*statetok = json_get_member(buffer, tok, "state"),
+			*ftxidtok =
+			    json_get_member(buffer, tok, "funding_txid"),
+			*scidtok =
+			    json_get_member(buffer, tok, "short_channel_id"),
+			*dirtok = json_get_member(buffer, tok, "direction"),
+			*tmsattok =
+			    json_get_member(buffer, tok, "total_msat"),
+			*smsattok =
+			    json_get_member(buffer, tok, "spendable_msat");
+
+	if (privtok == NULL || privtok->type != JSMN_PRIMITIVE ||
+	    statetok == NULL || statetok->type != JSMN_STRING ||
+	    ftxidtok == NULL || ftxidtok->type != JSMN_STRING ||
+	    (scidtok != NULL && scidtok->type != JSMN_STRING) ||
+	    (dirtok != NULL && dirtok->type != JSMN_PRIMITIVE) ||
+	    tmsattok == NULL || tmsattok->type != JSMN_STRING ||
+	    smsattok == NULL || smsattok->type != JSMN_STRING)
+		return NULL;
+
+	chan = tal(ctx, struct listpeers_channel);
+
+	json_to_bool(buffer, privtok, &chan->private);
+	chan->state = json_strdup(chan, buffer, statetok);
+	json_to_txid(buffer, ftxidtok, &chan->funding_txid);
+	if (scidtok != NULL) {
+		assert(dirtok != NULL);
+		chan->scid = tal(chan, struct short_channel_id);
+		chan->direction = tal(chan, int);
+		json_to_short_channel_id(buffer, scidtok, chan->scid);
+		json_to_int(buffer, dirtok, chan->direction);
+	}else {
+		assert(dirtok == NULL);
+		chan->scid = NULL;
+		chan->direction = NULL;
+	}
+
+	json_to_msat(buffer, tmsattok, &chan->total_msat);
+	json_to_msat(buffer, smsattok, &chan->spendable_msat);
+
+	return chan;
+}
+
+static struct listpeers_peer *json_to_listpeers_peer(const tal_t *ctx,
+						  const char *buffer,
+						  const jsmntok_t *tok)
+{
+	struct listpeers_peer *res;
+	size_t i;
+	const jsmntok_t *iter;
+	const jsmntok_t *idtok = json_get_member(buffer, tok, "id"),
+			*conntok = json_get_member(buffer, tok, "connected"),
+			*netaddrtok = json_get_member(buffer, tok, "netaddr"),
+			*channelstok = json_get_member(buffer, tok, "channels");
+
+	/* Preliminary sanity checks. */
+	if (idtok == NULL || idtok->type != JSMN_STRING || conntok == NULL ||
+	    conntok->type != JSMN_PRIMITIVE ||
+	    (netaddrtok != NULL && netaddrtok->type != JSMN_ARRAY) ||
+	    channelstok == NULL || channelstok->type != JSMN_ARRAY)
+		return NULL;
+
+	res = tal(ctx, struct listpeers_peer);
+	json_to_node_id(buffer, idtok, &res->id);
+	json_to_bool(buffer, conntok, &res->connected);
+
+	res->netaddr = tal_arr(res, const char *, 0);
+	if (netaddrtok != NULL) {
+		json_for_each_arr(i, iter, netaddrtok) {
+			tal_arr_expand(&res->netaddr,
+				       json_strdup(res, buffer, iter));
+		}
+	}
+
+	res->channels = tal_arr(res, struct listpeers_channel *, 0);
+	json_for_each_arr(i, iter, channelstok) {
+		struct listpeers_channel *chan = json_to_listpeers_channel(res, buffer, iter);
+		assert(chan != NULL);
+		tal_arr_expand(&res->channels, chan);
+	}
+
+	return res;
+}
+
+struct listpeers_result *json_to_listpeers_result(const tal_t *ctx,
+							  const char *buffer,
+							  const jsmntok_t *toks)
+{
+	size_t i;
+	const jsmntok_t *iter;
+	struct listpeers_result *res;
+	const jsmntok_t *peerstok = json_get_member(buffer, toks, "peers");
+
+	if (peerstok == NULL || peerstok->type != JSMN_ARRAY)
+		return NULL;
+
+	res = tal(ctx, struct listpeers_result);
+	res->peers = tal_arr(res, struct listpeers_peer *, 0);
+
+	json_for_each_obj(i, iter, peerstok) {
+		struct listpeers_peer *p =
+		    json_to_listpeers_peer(res, buffer, iter);
+		if (p == NULL)
+			return tal_free(res);
+		tal_arr_expand(&res->peers, p);
+	}
+	return res;
+}
+
+struct createonion_response *json_to_createonion_response(const tal_t *ctx,
+							  const char *buffer,
+							  const jsmntok_t *toks)
+{
+	size_t i;
+	struct createonion_response *resp;
+	const jsmntok_t *oniontok = json_get_member(buffer, toks, "onion");
+	const jsmntok_t *secretstok = json_get_member(buffer, toks, "shared_secrets");
+	const jsmntok_t *cursectok;
+
+	if (oniontok == NULL || secretstok == NULL)
+		return NULL;
+
+	resp = tal(ctx, struct createonion_response);
+
+	if (oniontok->type != JSMN_STRING)
+		goto fail;
+
+	resp->onion = json_tok_bin_from_hex(resp, buffer, oniontok);
+	resp->shared_secrets = tal_arr(resp, struct secret, secretstok->size);
+
+	json_for_each_arr(i, cursectok, secretstok) {
+		if (cursectok->type != JSMN_STRING)
+			goto fail;
+		json_to_secret(buffer, cursectok, &resp->shared_secrets[i]);
+	}
+	return resp;
+
+fail:
+	return tal_free(resp);
+}
+
+static bool json_to_route_hop_inplace(struct route_hop *dst, const char *buffer,
+				      const jsmntok_t *toks)
+{
+	const jsmntok_t *idtok = json_get_member(buffer, toks, "id");
+	const jsmntok_t *channeltok = json_get_member(buffer, toks, "channel");
+	const jsmntok_t *directiontok = json_get_member(buffer, toks, "direction");
+	const jsmntok_t *amounttok = json_get_member(buffer, toks, "amount_msat");
+	const jsmntok_t *delaytok = json_get_member(buffer, toks, "delay");
+	const jsmntok_t *styletok = json_get_member(buffer, toks, "style");
+
+	if (idtok == NULL || channeltok == NULL || directiontok == NULL ||
+	    amounttok == NULL || delaytok == NULL || styletok == NULL)
+		return false;
+
+	json_to_node_id(buffer, idtok, &dst->nodeid);
+	json_to_short_channel_id(buffer, channeltok, &dst->channel_id);
+	json_to_int(buffer, directiontok, &dst->direction);
+	json_to_msat(buffer, amounttok, &dst->amount);
+	json_to_number(buffer, delaytok, &dst->delay);
+	dst->style = json_tok_streq(buffer, styletok, "legacy")
+			 ? ROUTE_HOP_LEGACY
+			 : ROUTE_HOP_TLV;
+	return true;
+}
+
+struct route_hop *json_to_route(const tal_t *ctx, const char *buffer,
+				const jsmntok_t *toks)
+{
+	size_t num = toks->size, i;
+	struct route_hop *hops;
+	const jsmntok_t *rtok;
+	if (toks->type != JSMN_ARRAY)
+		return NULL;
+
+	hops = tal_arr(ctx, struct route_hop, num);
+	json_for_each_arr(i, rtok, toks) {
+		if (!json_to_route_hop_inplace(&hops[i], buffer, rtok))
+			return tal_free(hops);
+	}
+	return hops;
+}