lightning/gossipd/gossip_store.c

#include "gossip_store.h"

#include <ccan/endian/endian.h>
#include <ccan/read_write_all/read_write_all.h>
#include <common/status.h>
#include <common/utils.h>
#include <errno.h>
#include <fcntl.h>
#include <gossipd/gen_gossip_wire.h>
#include <unistd.h>
#include <wire/gen_peer_wire.h>
#include <wire/wire.h>

#define GOSSIP_STORE_FILENAME "gossip_store"
static u8 gossip_store_version = 0x01;

struct gossip_store {
	int fd;
	off_t write_pos;
	u8 version;
};

static void gossip_store_destroy(struct gossip_store *gs)
{
	close(gs->fd);
}

struct gossip_store *gossip_store_new(const tal_t *ctx)
{
	struct gossip_store *gs = tal(ctx, struct gossip_store);
	gs->fd = open(GOSSIP_STORE_FILENAME, O_RDWR|O_APPEND|O_CREAT, 0600);
	gs->write_pos = lseek(gs->fd, 0, SEEK_END);

	/* Try to read the version, write it if this is a new file, or truncate
	 * if the version doesn't match */
	if (pread(gs->fd, &gs->version, sizeof(gs->version), 0) != 1 ||
	    gs->version != gossip_store_version) {
		status_trace("Truncating gossip_store, either it was empty or "
			     "the version was not supported.");
		gs->version = gossip_store_version;
		gs->write_pos = 1;
		pwrite(gs->fd, &gossip_store_version, sizeof(gossip_store_version), 0);
		ftruncate(gs->fd, gs->write_pos);
	}

	tal_add_destructor(gs, gossip_store_destroy);

	return gs;
}
/**
 * Write an incoming message to the `gossip_store`
 *
 * @param gs  The gossip_store to write to
 * @param msg The message to write
 * @return The newly created and initialized `gossip_store`
 */
static void gossip_store_append(struct gossip_store *gs, const u8 *msg)
{
	u32 msglen = tal_len(msg);
	beint32_t belen = cpu_to_be32(msglen);

	if (pwrite(gs->fd, &belen, sizeof(belen), gs->write_pos) != sizeof(belen) ||
	    pwrite(gs->fd, msg, msglen, gs->write_pos + sizeof(belen)) != msglen) {
		return;
	} else
		gs->write_pos += sizeof(belen) + msglen;
}

void gossip_store_add_channel_announcement(struct gossip_store *gs, const u8 *gossip_msg, u64 satoshis)
{
	u8 *msg = towire_gossip_store_channel_announcement(NULL, gossip_msg, satoshis);
	gossip_store_append(gs, msg);
	tal_free(msg);
}

void gossip_store_add_channel_update(struct gossip_store *gs,
				     const u8 *gossip_msg)
{
	u8 *msg = towire_gossip_store_channel_update(NULL, gossip_msg);
	gossip_store_append(gs, msg);
	tal_free(msg);
}

void gossip_store_add_node_announcement(struct gossip_store *gs,
					const u8 *gossip_msg)
{
	u8 *msg = towire_gossip_store_node_announcement(NULL, gossip_msg);
	gossip_store_append(gs, msg);
	tal_free(msg);
}

void gossip_store_add_channel_delete(struct gossip_store *gs,
				     const struct short_channel_id *scid)
{
	u8 *msg = towire_gossip_store_channel_delete(NULL, scid);
	gossip_store_append(gs, msg);
	tal_free(msg);
}

void gossip_store_load(struct routing_state *rstate, struct gossip_store *gs)
{
	beint32_t belen;
	u32 msglen;
	u8 *msg, *gossip_msg;
	u64 satoshis;
	struct short_channel_id scid;
	/* We set/check version byte on creation */
	off_t known_good = 1;
	const char *bad;

	lseek(gs->fd, known_good, SEEK_SET);
	while (read(gs->fd, &belen, sizeof(belen)) == sizeof(belen)) {
		msglen = be32_to_cpu(belen);
		msg = tal_arr(gs, u8, msglen);

		if (read(gs->fd, msg, msglen) != msglen) {
			status_unusual("gossip_store: truncated file?");
			goto truncate_nomsg;
		}

		if (fromwire_gossip_store_channel_announcement(msg, msg,
							       &gossip_msg,
							       &satoshis)) {
			if (!routing_add_channel_announcement(rstate,
							      gossip_msg,
							      satoshis)) {
				bad = "Bad channel_announcement";
				goto truncate;
			}
		} else if (fromwire_gossip_store_channel_update(msg, msg,
								&gossip_msg)) {
			if (!routing_add_channel_update(rstate, gossip_msg)) {
				bad = "Bad channel_update";
				goto truncate;
			}
		} else if (fromwire_gossip_store_node_announcement(msg, msg,
								   &gossip_msg)) {
			if (!routing_add_node_announcement(rstate, gossip_msg)) {
				bad = "Bad node_announcement";
				goto truncate;
			}
		} else if (fromwire_gossip_store_channel_delete(msg, &scid)) {
			struct chan *c = get_channel(rstate, &scid);
			if (!c) {
				bad = "Bad channel_delete";
				goto truncate;
			}
			tal_free(c);
		} else {
			bad = "Unknown message";
			goto truncate;
		}
		known_good += sizeof(belen) + msglen;
		tal_free(msg);
	}
	return;

truncate:
	status_unusual("gossip_store: %s (%s) truncating to %"PRIu64,
		       bad, tal_hex(msg, msg), (u64)known_good);
truncate_nomsg:
	if (ftruncate(gs->fd, known_good) != 0)
		status_failed(STATUS_FAIL_INTERNAL_ERROR,
			      "Truncating store: %s", strerror(errno));
}