Merge branch 'lukeshu/9p-misc'

1 files changed, 178 insertions, 0 deletions

diff --git a/lib9p/tables.c b/lib9p/tables.c
new file mode 100644
index 0000000..36fe3b3
--- /dev/null
+++ b/lib9p/tables.c
@@ -0,0 +1,178 @@
+/* lib9p/tables.c - Access tables of version and message information
+ *
+ * Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+#include <string.h>
+
+#include <libmisc/endian.h>
+#include <libmisc/log.h> /* for const_byte_str() */
+
+#include "tables.h"
+
+/* bounds checks **************************************************************/
+
+static inline void assert_ver(enum lib9p_version ver) {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wtype-limits"
+	assert(0 <= ver && ver < LIB9P_VER_NUM);
+#pragma GCC diagnostic pop
+}
+
+static inline void assert_typ(enum lib9p_msg_type typ) {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wtype-limits"
+	assert(0 <= typ && typ < 0xFF);
+#pragma GCC diagnostic pop
+}
+
+/* simple lookups *************************************************************/
+
+const char *lib9p_version_str(enum lib9p_version ver) {
+	assert_ver(ver);
+	return _lib9p_table_ver[ver].name;
+}
+
+uint32_t lib9p_version_min_msg_size(enum lib9p_version ver) {
+	assert_ver(ver);
+	return _lib9p_table_ver[ver].min_msg_size;
+}
+
+const char *lib9p_msgtype_str(enum lib9p_version ver, enum lib9p_msg_type typ) {
+	assert_ver(ver);
+	assert_typ(typ);
+	return _lib9p_table_msg[ver][typ].name ?: const_byte_str(typ);
+}
+
+/* main message functions *****************************************************/
+
+static
+ssize_t _lib9p_validate(uint8_t                          xxx_low_typ_bit,
+                        const char                      *xxx_errmsg,
+                        const struct _lib9p_recv_tentry  xxx_table[LIB9P_VER_NUM][0x80],
+                        struct lib9p_ctx *ctx, uint8_t *net_bytes) {
+	assert_ver(ctx->version);
+	/* Inspect the first 5 bytes ourselves.  */
+	uint32_t net_size = uint32le_decode(net_bytes);
+	if (net_size < 5)
+		return lib9p_error(ctx, LINUX_EBADMSG, "message is impossibly short");
+	uint8_t typ = net_bytes[4];
+	if (typ % 2 != xxx_low_typ_bit)
+		return lib9p_errorf(ctx, LINUX_EOPNOTSUPP, "%s: message_type=%s", xxx_errmsg,
+		                    lib9p_msgtype_str(ctx->version, typ));
+	struct _lib9p_recv_tentry tentry = xxx_table[ctx->version][typ/2];
+	if (!tentry.validate)
+		return lib9p_errorf(ctx, LINUX_EOPNOTSUPP, "unknown message type: %s (protocol_version=%s)",
+		                    lib9p_msgtype_str(ctx->version, typ), lib9p_version_str(ctx->version));
+
+	/* Now use the message-type-specific tentry to process the whole thing.  */
+	return tentry.validate(ctx, net_size, net_bytes);
+}
+
+ssize_t lib9p_Tmsg_validate(struct lib9p_ctx *ctx, uint8_t *net_bytes) {
+	return _lib9p_validate(0, "expected a T-message but got an R-message", _lib9p_table_Tmsg_recv,
+	                       ctx, net_bytes);
+}
+
+ssize_t lib9p_Rmsg_validate(struct lib9p_ctx *ctx, uint8_t *net_bytes) {
+	return _lib9p_validate(1, "expected an R-message but got a T-message", _lib9p_table_Rmsg_recv,
+	                       ctx, net_bytes);
+}
+
+static
+void _lib9p_unmarshal(const struct _lib9p_recv_tentry xxx_table[LIB9P_VER_NUM][0x80],
+                      struct lib9p_ctx *ctx, uint8_t *net_bytes,
+                      enum lib9p_msg_type *ret_typ, void *ret_body) {
+	assert_ver(ctx->version);
+	enum lib9p_msg_type typ = net_bytes[4];
+	*ret_typ = typ;
+	struct _lib9p_recv_tentry tentry = xxx_table[ctx->version][typ/2];
+
+	tentry.unmarshal(ctx, net_bytes, ret_body);
+}
+
+void lib9p_Tmsg_unmarshal(struct lib9p_ctx *ctx, uint8_t *net_bytes,
+                          enum lib9p_msg_type *ret_typ, void *ret_body) {
+	_lib9p_unmarshal(_lib9p_table_Tmsg_recv,
+	                 ctx, net_bytes, ret_typ, ret_body);
+}
+
+void lib9p_Rmsg_unmarshal(struct lib9p_ctx *ctx, uint8_t *net_bytes,
+                          enum lib9p_msg_type *ret_typ, void *ret_body) {
+	_lib9p_unmarshal(_lib9p_table_Rmsg_recv,
+	                 ctx, net_bytes, ret_typ, ret_body);
+}
+
+static
+bool _lib9p_marshal(const struct _lib9p_send_tentry xxx_table[LIB9P_VER_NUM][0x80],
+                    struct lib9p_ctx *ctx, enum lib9p_msg_type typ, void *body,
+                    size_t *ret_iov_cnt, struct iovec *ret_iov, uint8_t *ret_copied) {
+	assert_ver(ctx->version);
+	assert_typ(typ);
+	struct _marshal_ret ret = {
+		.net_iov_cnt     = 1,
+		.net_iov         = ret_iov,
+		.net_copied_size = 0,
+		.net_copied      = ret_copied,
+	};
+
+	struct _lib9p_send_tentry tentry = xxx_table[ctx->version][typ/2];
+	bool ret_erred = tentry.marshal(ctx, body, &ret);
+	if (ret_iov[ret.net_iov_cnt-1].iov_len == 0)
+		ret.net_iov_cnt--;
+	*ret_iov_cnt = ret.net_iov_cnt;
+	return ret_erred;
+}
+
+bool lib9p_Tmsg_marshal(struct lib9p_ctx *ctx, enum lib9p_msg_type typ, void *body,
+                        struct lib9p_Tmsg_send_buf *ret) {
+	assert(typ % 2 == 0);
+	memset(ret, 0, sizeof(*ret));
+	return _lib9p_marshal(_lib9p_table_Tmsg_send,
+	                      ctx, typ, body,
+	                      &ret->iov_cnt, ret->iov, ret->copied);
+}
+
+bool lib9p_Rmsg_marshal(struct lib9p_ctx *ctx, enum lib9p_msg_type typ, void *body,
+                        struct lib9p_Rmsg_send_buf *ret) {
+	assert(typ % 2 == 1);
+	memset(ret, 0, sizeof(*ret));
+	return _lib9p_marshal(_lib9p_table_Rmsg_send,
+	                      ctx, typ, body,
+	                      &ret->iov_cnt, ret->iov, ret->copied);
+}
+
+/* `struct lib9p_stat` helpers ************************************************/
+
+bool lib9p_stat_validate(struct lib9p_ctx *ctx, uint32_t net_size, uint8_t *net_bytes,
+                         uint32_t *ret_net_size, ssize_t *ret_host_size) {
+	ssize_t host_size = _lib9p_stat_validate(ctx, net_size, net_bytes, ret_net_size);
+	if (host_size < 0)
+		return true;
+	if (ret_host_size)
+		*ret_host_size = host_size;
+	return false;
+}
+
+void lib9p_stat_unmarshal(struct lib9p_ctx *ctx, uint8_t *net_bytes,
+                          struct lib9p_stat *ret) {
+	_lib9p_stat_unmarshal(ctx, net_bytes, ret);
+}
+
+uint32_t lib9p_stat_marshal(struct lib9p_ctx *ctx, uint32_t max_net_size, struct lib9p_stat *obj,
+                            uint8_t *ret_bytes) {
+	struct lib9p_ctx _ctx = *ctx;
+	_ctx.max_msg_size = max_net_size;
+
+	struct iovec iov = {0};
+	struct _marshal_ret ret = {
+		.net_iov_cnt     = 1,
+		.net_iov         = &iov,
+		.net_copied_size = 0,
+		.net_copied      = ret_bytes,
+	};
+	if (_lib9p_stat_marshal(&_ctx, obj, &ret))
+		return 0;
+	return ret.net_iov[0].iov_len;
+}