crypto_sync: synchronous routines for inter-peer crypto.

This is used by the opening daemon, for example.

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

lightningd/crypto_sync.c

@@ -0,0 +1,34 @@
+#include <ccan/read_write_all/read_write_all.h>
+#include <lightningd/crypto_sync.h>
+#include <lightningd/cryptomsg.h>
+#include <wire/wire_sync.h>
+
+bool sync_crypto_write(struct crypto_state *cs, int fd, const void *msg)
+{
+	u8 *enc = cryptomsg_encrypt_msg(msg, cs, msg);
+	bool ret;
+
+	ret = wire_sync_write(fd, enc);
+	tal_free(enc);
+	return ret;
+}
+
+u8 *sync_crypto_read(const tal_t *ctx, struct crypto_state *cs, int fd)
+{
+	u8 hdr[18], *enc, *dec;
+	u16 len;
+
+	if (!read_all(fd, hdr, sizeof(hdr)))
+		return NULL;
+
+	if (!cryptomsg_decrypt_header(cs, hdr, &len))
+		return NULL;
+
+	enc = tal_arr(ctx, u8, len);
+	if (!read_all(fd, enc, len))
+		return tal_free(enc);
+
+	dec = cryptomsg_decrypt_body(ctx, cs, enc);
+	tal_free(enc);
+	return dec;
+}