tools/generate-wire.py: wirestring type for handing strings.

A convenient alias for char *, though we don't allow control characters
so our logs can't be fooled with embedded \n.

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

tools/generate-wire.py

@@ -33,6 +33,7 @@ varlen_structs = [
     'failed_htlc',
     'utxo',
     'bitcoin_tx',
+    'wirestring',
 ]
 
 class FieldType(object):

wire/fromwire.c

@@ -206,6 +206,27 @@ void fromwire_pad(const u8 **cursor, size_t *max, size_t num)
 	fromwire(cursor, max, NULL, num);
 }
 
+/*
+ * Don't allow control chars except spaces: we only use this for stuff
+ * from subdaemons, who shouldn't do that.
+ */
+char *fromwire_wirestring(const tal_t *ctx, const u8 **cursor, size_t *max)
+{
+	size_t i;
+
+	for (i = 0; i < *max; i++) {
+		if ((*cursor)[i] == '\0') {
+			char *str = tal_arr(ctx, char, i + 1);
+			fromwire(cursor, max, str, i + 1);
+			return str;
+		}
+		if ((*cursor)[i] < ' ')
+			break;
+	}
+	fromwire_fail(cursor, max);
+	return NULL;
+}
+
 REGISTER_TYPE_TO_STRING(short_channel_id, short_channel_id_to_str);
 REGISTER_TYPE_TO_HEXSTR(channel_id);
 

wire/towire.c

@@ -151,6 +151,11 @@ void towire_pad(u8 **pptr, size_t num)
 	memset(*pptr + oldsize, 0, num);
 }
 
+void towire_wirestring(u8 **pptr, const char *str)
+{
+	towire(pptr, str, strlen(str) + 1);
+}
+
 void towire_bitcoin_tx(u8 **pptr, const struct bitcoin_tx *tx)
 {
 	tal_t *tmpctx = tal_tmpctx(NULL);

wire/wire.h

@@ -21,6 +21,9 @@ struct bitcoin_txid;
 struct preimage;
 struct ripemd160;
 
+/* Makes generate-wire.py work */
+typedef char wirestring;
+
 void derive_channel_id(struct channel_id *channel_id,
 		       struct bitcoin_txid *txid, u16 txout);
 
@@ -55,6 +58,7 @@ void towire_bool(u8 **pptr, bool v);
 void towire_u8_array(u8 **pptr, const u8 *arr, size_t num);
 
 void towire_bitcoin_tx(u8 **pptr, const struct bitcoin_tx *tx);
+void towire_wirestring(u8 **pptr, const char *str);
 
 const u8 *fromwire(const u8 **cursor, size_t *max, void *copy, size_t n);
 u8 fromwire_u8(const u8 **cursor, size_t *max);
@@ -86,6 +90,7 @@ void fromwire_ripemd160(const u8 **cursor, size_t *max, struct ripemd160 *ripemd
 void fromwire_pad(const u8 **cursor, size_t *max, size_t num);
 
 void fromwire_u8_array(const u8 **cursor, size_t *max, u8 *arr, size_t num);
+char *fromwire_wirestring(const tal_t *ctx, const u8 **cursor, size_t *max);
 
 struct bitcoin_tx *fromwire_bitcoin_tx(const tal_t *ctx,
 				       const u8 **cursor, size_t *max);