1 files changed, 72 insertions, 0 deletions
diff --git a/lib9p/include/lib9p/9p.h b/lib9p/include/lib9p/9p.h
new file mode 100644
index 0000000..a55f08f
--- /dev/null
+++ b/lib9p/include/lib9p/9p.h
@@ -0,0 +1,72 @@
+/* lib9p/9p.h - Base 9P protocol definitions for both clients and servers
+ *
+ * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-Licence-Identifier: AGPL-3.0-or-later
+ */
+
+#ifndef _LIB9P_9P_H_
+#define _LIB9P_9P_H_
+
+#include <lib9p/linux-errno.h>
+#include <lib9p/_types.h>
+
+#define LIB9P_NOTAG ((uint16_t)~0U)
+#define LIB9P_NOFID ((uint32_t)~0U)
+
+struct lib9p_ctx;
+enum lib9p_version      lib9p_ctx_version(lib9p_ctx *);
+uint32_t                lib9p_ctx_max_msg_size(lib9p_ctx *);
+
+/** Write an static error into ctx, return -1.  */
+int lib9p_error(struct lib9p_ctx *ctx, uint32_t linux_errno, char const *msg);
+/** Write a printf-style error into ctx, return -1.  */
+int lib9p_errorf(struct lib9p_ctx *ctx, uint32_t linux_errno, char const *fmt, ...);
+
+/**
+ * Return how much space the message at net_bytes will take when
+ * unmarshaled.  This number may be larger than net_bytes due to (1)
+ * struct padding, (2) nul-terminator byes for strings.
+ *
+ * Emits an error (return -1, set ctx->err_num and ctx->err_msg) if
+ * either the message type is unknown, or if net_bytes is too short
+ * for that message type, or if an invalid string (invalid UTF-8,
+ * contains a nul-byte) is encountered.
+ *
+ * @param net_bytes : the complete request, starting with the "size[4]"
+ *
+ * @return required size, or -1 on error
+ */
+ssize_t lib9p_unmarshal_size(struct lib9p_ctx *ctx, uint8_t *net_bytes);
+
+/**
+ * Unmarshal the 9P message `net_bytes` into the C struct `ret_body`.
+ *
+ * Emits an error (return 0, set ctx->err_num and ctx->err_msg) if a
+ * string contains invalid UTF-8 or a nul-byte.
+ *
+ * @param ctx : negotiated protocol parameters, where to record errors
+ * @param net_bytes : the complete message, starting with the "size[4]"
+ *
+ * @return ret_typ : the mesage type
+ * @return ret_tag : the message-ID tag
+ * @return ret_body : the message body, must be at least lib9p_unmarshal_size() bytes
+ * @return the message type, or -1 on error
+ */
+bool lib9p_unmarshal(struct lib9p_ctx *ctx, uint8_t *net_bytes,
+                     enum lib9p_msg_typ *ret_typ, uint16_t *ret_tag, void *ret_body);
+
+/**
+ * Marshal a `struct lib9p_msg_{typ}` structure into a byte-array.  
+ *
+ * @param ctx : negotiated protocol parameters, where to record errors
+ * @param typ : the message type
+ * @param tag : the message-ID tag
+ * @param msg : the message to encode
+ *
+ * @return ret_bytes : the buffer to encode to, must be at be at least lib9p_ctx_max_msg_size(ctx) bytes
+ * @return whether there was an error (false=success, true=error)
+ */
+bool lib9p_marshal(struct lib9p_ctx *ctx, uint8_t typ, uint16_t tag, void *body,
+                   uint8_t *ret_bytes);
+
+#endif _LIB9P_9P_H_