decode_short_ids: move to common.

We want to use it in devtools/decodemsg.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

common/Makefile

@@ -12,6 +12,7 @@ COMMON_SRC_NOGEN :=				\
 	common/cryptomsg.c			\
 	common/daemon.c				\
 	common/daemon_conn.c			\
+	common/decode_short_channel_ids.c	\
 	common/derive_basepoints.c		\
 	common/dev_disconnect.c			\
 	common/features.c			\

common/decode_short_channel_ids.c

@@ -0,0 +1,62 @@
+#include <common/decode_short_channel_ids.h>
+#include <common/utils.h>
+#include <wire/wire.h>
+#include <zlib.h>
+
+static u8 *unzlib(const tal_t *ctx, const u8 *encoded, size_t len)
+{
+	/* http://www.zlib.net/zlib_tech.html gives 1032:1 as worst-case,
+	 * which is 67632120 bytes for us.  But they're not encoding zeroes,
+	 * and each scid must be unique.  So 1MB is far more reasonable. */
+	unsigned long unclen = 1024*1024;
+	int zerr;
+	u8 *unc = tal_arr(ctx, u8, unclen);
+
+	zerr = uncompress(unc, &unclen, encoded, len);
+	if (zerr != Z_OK)
+		return tal_free(unc);
+
+	/* Truncate and return. */
+	tal_resize(&unc, unclen);
+	return unc;
+}
+
+struct short_channel_id *decode_short_ids(const tal_t *ctx, const u8 *encoded)
+{
+	struct short_channel_id *scids;
+	size_t max = tal_len(encoded), n;
+	enum scid_encode_types type;
+
+	/* BOLT #7:
+	 *
+	 * The receiver:
+	 *   - if the first byte of `encoded_short_ids` is not a known encoding
+	 *     type:
+	 *     - MAY fail the connection
+	 *   - if `encoded_short_ids` does not decode into a whole number of
+	 *     `short_channel_id`:
+	 *     - MAY fail the connection
+	 */
+	type = fromwire_u8(&encoded, &max);
+	switch (type) {
+	case SHORTIDS_ZLIB:
+		encoded = unzlib(tmpctx, encoded, max);
+		if (!encoded)
+			return NULL;
+		max = tal_len(encoded);
+		/* fall thru */
+	case SHORTIDS_UNCOMPRESSED:
+		n = 0;
+		scids = tal_arr(ctx, struct short_channel_id, n);
+		while (max) {
+			tal_resize(&scids, n+1);
+			fromwire_short_channel_id(&encoded, &max, &scids[n++]);
+		}
+
+		/* encoded is set to NULL if we ran over */
+		if (!encoded)
+			return tal_free(scids);
+		return scids;
+	}
+	return NULL;
+}

common/decode_short_channel_ids.h

@@ -0,0 +1,20 @@
+#ifndef LIGHTNING_COMMON_DECODE_SHORT_CHANNEL_IDS_H
+#define LIGHTNING_COMMON_DECODE_SHORT_CHANNEL_IDS_H
+#include "config.h"
+#include <ccan/short_types/short_types.h>
+#include <ccan/tal/tal.h>
+
+/* BOLT #7:
+ *
+ * Encoding types:
+ * * `0`: uncompressed array of `short_channel_id` types, in ascending order.
+ * * `1`: array of `short_channel_id` types, in ascending order, compressed with
+ *        zlib<sup>[1](#reference-1)</sup>
+ */
+enum scid_encode_types {
+	SHORTIDS_UNCOMPRESSED = 0,
+	SHORTIDS_ZLIB = 1
+};
+
+struct short_channel_id *decode_short_ids(const tal_t *ctx, const u8 *encoded);
+#endif /* LIGHTNING_COMMON_DECODE_SHORT_CHANNEL_IDS_H */

gossipd/Makefile

@@ -48,6 +48,7 @@ GOSSIPD_COMMON_OBJS :=				\
 	common/cryptomsg.o			\
 	common/daemon.o				\
 	common/daemon_conn.o			\
+	common/decode_short_channel_ids.o	\
 	common/dev_disconnect.o			\
 	common/features.o			\
 	common/gen_status_wire.o		\

gossipd/gossip.c

@@ -19,6 +19,7 @@
 #include <common/bech32_util.h>
 #include <common/cryptomsg.h>
 #include <common/daemon_conn.h>
+#include <common/decode_short_channel_ids.h>
 #include <common/features.h>
 #include <common/ping.h>
 #include <common/pseudorand.h>
@@ -65,18 +66,6 @@
 #define INITIAL_WAIT_SECONDS	1
 #define MAX_WAIT_SECONDS	300
 
-/* BOLT #7:
- *
- * Encoding types:
- * * `0`: uncompressed array of `short_channel_id` types, in ascending order.
- * * `1`: array of `short_channel_id` types, in ascending order, compressed with
- *        zlib<sup>[1](#reference-1)</sup>
- */
-enum scid_encode_types {
-	SHORTIDS_UNCOMPRESSED = 0,
-	SHORTIDS_ZLIB = 1
-};
-
 /* We put everything in this struct (redundantly) to pass it to timer cb */
 struct important_peerid {
 	struct daemon *daemon;
@@ -880,67 +869,6 @@ static u8 *handle_gossip_msg(struct daemon *daemon, const u8 *msg,
 	return NULL;
 }
 
-static u8 *unzlib(const tal_t *ctx, const u8 *encoded, size_t len)
-{
-	/* http://www.zlib.net/zlib_tech.html gives 1032:1 as worst-case,
-	 * which is 67632120 bytes for us.  But they're not encoding zeroes,
-	 * and each scid must be unique.  So 1MB is far more reasonable. */
-	unsigned long unclen = 1024*1024;
-	int zerr;
-	u8 *unc = tal_arr(ctx, u8, unclen);
-
-	zerr = uncompress(unc, &unclen, encoded, len);
-	if (zerr != Z_OK) {
-		status_trace("unzlib: error %i", zerr);
-		return tal_free(unc);
-	}
-
-	/* Truncate and return. */
-	tal_resize(&unc, unclen);
-	return unc;
-}
-
-static struct short_channel_id *decode_short_ids(const tal_t *ctx,
-						 const u8 *encoded)
-{
-	struct short_channel_id *scids;
-	size_t max = tal_len(encoded), n;
-	enum scid_encode_types type;
-
-	/* BOLT #7:
-	 *
-	 * The receiver:
-	 *   - if the first byte of `encoded_short_ids` is not a known encoding
-	 *     type:
-	 *     - MAY fail the connection
-	 *   - if `encoded_short_ids` does not decode into a whole number of
-	 *     `short_channel_id`:
-	 *     - MAY fail the connection
-	 */
-	type = fromwire_u8(&encoded, &max);
-	switch (type) {
-	case SHORTIDS_ZLIB:
-		encoded = unzlib(tmpctx, encoded, max);
-		if (!encoded)
-			return NULL;
-		max = tal_len(encoded);
-		/* fall thru */
-	case SHORTIDS_UNCOMPRESSED:
-		n = 0;
-		scids = tal_arr(ctx, struct short_channel_id, n);
-		while (max) {
-			tal_resize(&scids, n+1);
-			fromwire_short_channel_id(&encoded, &max, &scids[n++]);
-		}
-
-		/* encoded is set to NULL if we ran over */
-		if (!encoded)
-			return tal_free(scids);
-		return scids;
-	}
-	return NULL;
-}
-
 static void handle_query_short_channel_ids(struct peer *peer, u8 *msg)
 {
 	struct routing_state *rstate = peer->daemon->rstate;