libhsmd: Add scaffolding to start separating hsmd from io logic

hsmd/Makefile

@@ -1,7 +1,9 @@
 #! /usr/bin/make
 
 HSMD_SRC := hsmd/hsmd.c	\
-	hsmd/hsmd_wiregen.c
+	hsmd/hsmd_wiregen.c \
+	hsmd/libhsmd.c
+
 HSMD_HEADERS := hsmd/hsmd_wiregen.h
 HSMD_OBJS := $(HSMD_SRC:.c=.o)
 

hsmd/hsmd.c

@@ -43,6 +43,7 @@
 #include <hsmd/capabilities.h>
 /*~ _wiregen files are autogenerated by tools/generate-wire.py */
 #include <hsmd/hsmd_wiregen.h>
+#include <hsmd/libhsmd.h>
 #include <inttypes.h>
 #include <secp256k1_ecdh.h>
 #include <secp256k1_schnorrsig.h>
@@ -61,29 +62,20 @@
  * stream from lightningd. */
 #define REQ_FD 3
 
-/*~ Nobody will ever find it here!  hsm_secret is our root secret, the bip32
- * tree and bolt12 payer_id keys are derived from that, and cached here. */
-static struct {
-	struct secret hsm_secret;
-	struct ext_key bip32;
-	secp256k1_keypair bolt12;
-} secretstuff;
-
-/* Have we initialized the secretstuff? */
-static bool initialized = false;
-
 /* Version codes for BIP32 extended keys in libwally-core.
  * It's not suitable to add this struct into client struct,
  * so set it static.*/
-static struct  bip32_key_version  bip32_key_version;
+extern struct  bip32_key_version  bip32_key_version;
 
 #if DEVELOPER
 /* If they specify --dev-force-privkey it ends up in here. */
-static struct privkey *dev_force_privkey;
+extern struct privkey *dev_force_privkey;
 /* If they specify --dev-force-bip32-seed it ends up in here. */
-static struct secret *dev_force_bip32_seed;
+extern struct secret *dev_force_bip32_seed;
 #endif
 
+extern bool initialized;
+
 /*~ We keep track of clients, but there's not much to keep. */
 struct client {
 	/* The ccan/io async io connection for this client: it closes, we die. */
@@ -110,6 +102,9 @@ struct client {
 
 	/* Params to apply to all transactions for this client */
 	const struct chainparams *chainparams;
+
+	/* Client context to pass over to libhsmd for its calls. */
+	struct hsmd_client *hsmd_client;
 };
 
 /*~ We keep a map of nonzero dbid -> clients, mainly for leak detection.
@@ -266,6 +261,7 @@ static struct client *new_client(const tal_t *ctx,
 	if (dbid == 0) {
 		assert(num_dbid_zero_clients < ARRAY_SIZE(dbid_zero_clients));
 		dbid_zero_clients[num_dbid_zero_clients++] = c;
+		c->hsmd_client = hsmd_client_new_main(c, c->capabilities, c);
 	} else {
 		struct client *old_client = uintmap_get(&clients, dbid);
 
@@ -277,6 +273,8 @@ static struct client *new_client(const tal_t *ctx,
 			status_failed(STATUS_FAIL_INTERNAL_ERROR,
 				      "Failed inserting dbid %"PRIu64, dbid);
 		tal_add_destructor(c, destroy_client);
+		c->hsmd_client =
+		    hsmd_client_new_peer(c, c->capabilities, dbid, id, c);
 	}
 
 	return c;

hsmd/libhsmd.c

@@ -0,0 +1,46 @@
+#include <hsmd/capabilities.h>
+#include <hsmd/libhsmd.h>
+
+/* Version codes for BIP32 extended keys in libwally-core.
+ * It's not suitable to add this struct into client struct,
+ * so set it static.*/
+struct  bip32_key_version  bip32_key_version;
+
+#if DEVELOPER
+/* If they specify --dev-force-privkey it ends up in here. */
+struct privkey *dev_force_privkey;
+/* If they specify --dev-force-bip32-seed it ends up in here. */
+struct secret *dev_force_bip32_seed;
+#endif
+
+/* Have we initialized the secretstuff? */
+bool initialized = false;
+
+struct hsmd_client *hsmd_client_new_main(const tal_t *ctx, u64 capabilities,
+					 void *extra)
+{
+	struct hsmd_client *c = tal(ctx, struct hsmd_client);
+	c->dbid = 0;
+	c->capabilities = capabilities;
+	c->extra = extra;
+	return c;
+}
+
+struct hsmd_client *hsmd_client_new_peer(const tal_t *ctx, u64 capabilities,
+					 u64 dbid,
+					 const struct node_id *peer_id,
+					 void *extra)
+{
+	struct hsmd_client *c = tal(ctx, struct hsmd_client);
+	c->dbid = dbid;
+	c->capabilities = capabilities;
+	c->id = *peer_id;
+	c->extra = extra;
+	return c;
+}
+
+u8 *hsmd_handle_client_message(const tal_t *ctx, struct hsmd_client *client,
+			       const u8 *msg)
+{
+	return NULL;
+}

hsmd/libhsmd.h

@@ -0,0 +1,73 @@
+#ifndef LIGHTNING_HSMD_LIBHSMD_H
+#define LIGHTNING_HSMD_LIBHSMD_H
+
+#include <bitcoin/privkey.h>
+#include <ccan/short_types/short_types.h>
+#include <ccan/tal/tal.h>
+#include <common/node_id.h>
+#include <common/status_levels.h>
+#include <hsmd/hsmd_wiregen.h>
+#include <secp256k1_ecdh.h>
+#include <secp256k1_schnorrsig.h>
+#include <sodium.h>
+#include <wally_bip32.h>
+
+/*~ A struct that holds some context about the origin of an
+ * incoming request. It can either be a main daemon client, which is
+ * not associated with a peer or channel, or a peer client, which does
+ * have an association. */
+struct hsmd_client {
+	/*~ Useful for logging, but also used to derive the per-channel seed. */
+	struct node_id id;
+
+	/*~ This is a unique value handed to us from lightningd, used for
+	 * per-channel seed generation (a single id may have multiple channels
+	 * over time).
+	 *
+	 * It's actually zero for the initial lightningd client connection and
+	 * the ones for gossipd and connectd, which don't have channels
+	 * associated. */
+	u64 dbid;
+
+	/* What is this client allowed to ask for? */
+	u64 capabilities;
+
+	/* Params to apply to all transactions for this client */
+	const struct chainparams *chainparams;
+
+	/* A pointer to extra context that is to be passed around with
+	 * the request. Used in `hsmd` to determine which connection
+	 * originated the request. It is passed to the `hsmd_status_*`
+	 * functions to allow reporting errors to the client. */
+	void *extra;
+};
+
+struct hsmd_client *hsmd_client_new_main(const tal_t *ctx, u64 capabilities,
+					 void *extra);
+
+struct hsmd_client *hsmd_client_new_peer(const tal_t *ctx, u64 capabilities,
+					 u64 dbid,
+					 const struct node_id *peer_id,
+					 void *extra);
+
+/* Handle an incoming request with the provided context. Upon
+ * successful processing we return a response message that is
+ * allocated off of `ctx`. Failures return a `NULL` pointer, and the
+ * failure details were passed to `hsmd_failed`. */
+u8 *hsmd_handle_client_message(const tal_t *ctx, struct hsmd_client *client,
+			       const u8 *msg);
+
+/* The following declarations are here only temporarily while we migrate logic from hsmd.c to libhsmd.c */
+
+/*~ Nobody will ever find it here!  hsm_secret is our root secret, the bip32
+ * tree and bolt12 payer_id keys are derived from that, and cached here. */
+/* TODO: Move into the libhsmd.c file as soon as hsmd.c doesn't need
+ * it anymore. */
+struct {
+	struct secret hsm_secret;
+	struct ext_key bip32;
+	secp256k1_keypair bolt12;
+} secretstuff;
+
+/* end of temporary global declarations. The above will be removed once we complete the migration. */
+#endif /* LIGHTNING_HSMD_LIBHSMD_H */