jitterbug/wire.h

#ifndef _JITTERBUG__WIRE_H
#define _JITTERBUG__WIRE_H

#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>


#define DBUS_PROTOCOL_VERSION 1

#define DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER 1
#define DBUS_REQUEST_NAME_REPLY_IN_QUEUE 2
#define DBUS_REQUEST_NAME_REPLY_EXISTS 3
#define DBUS_REQUEST_NAME_REPLY_ALREADY_OWNER 4

#define DBUS_FLAG_NO_REPLY_EXPECTED 0x1
#define DBUS_FLAG_NO_AUTO_START 0x1
#define DBUS_FLAG_ALLOW_INTERACTIVE_AUTHORIZATION 0x1

enum {
    DBUS_HEADER_FIELD_INVALID = 0,
    DBUS_HEADER_FIELD_PATH,
    DBUS_HEADER_FIELD_INTERFACE,
    DBUS_HEADER_FIELD_MEMBER,
    DBUS_HEADER_FIELD_ERROR_NAME,
    DBUS_HEADER_FIELD_REPLY_SERIAL,
    DBUS_HEADER_FIELD_DESTINATION,
    DBUS_HEADER_FIELD_SENDER,
    DBUS_HEADER_FIELD_SIGNATURE,
    DBUS_HEADER_FIELD_UNIX_FDS,
};

enum {
    DBUS_MESSAGE_INVALID = 0,
    DBUS_MESSAGE_METHOD_CALL,
    DBUS_MESSAGE_METHOD_RETURN,
    DBUS_MESSAGE_ERROR,
    DBUS_MESSAGE_SIGNAL,
};

typedef struct wire_context {
    uint32_t byte_cursor;
    uint8_t *data;
    size_t data_len;
} wire_context_t;

// SPEC: https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-messages
typedef struct wire_message_field {
    bool present;
    union {
        char *str;
        uint32_t u32;
    } t;
} wire_message_field_t;
#define WIRE_MESSAGE_MAX_HEADER_FIELDS 9
typedef struct wire_message {
    uint8_t endianness, type, flags, protocol_version;
    uint32_t body_length, serial, header_fields_length;
    uint8_t header_fields_count;
    wire_message_field_t fields[WIRE_MESSAGE_MAX_HEADER_FIELDS]; /* cannot have more than 9 header fields */
} wire_message_t;
typedef struct wire_message_body_string {
    uint16_t index;
    char *str;
} wire_message_body_string_t;

#define _WIRE_DECL_BYTE_TYPE(M_mnemonic, M_type) \
    M_type *wire_get_##M_mnemonic(wire_context_t *c); \
    M_type *wire_set_##M_mnemonic(wire_context_t *c, M_type val); \

#define _WIRE_DECL_TYPE(M_mnemonic, M_type, M_alignment) \
    M_type *wire_get_##M_mnemonic(wire_context_t *c); \
    M_type *wire_set_##M_mnemonic(wire_context_t *c, M_type val); \

#define _WIRE_DEF_BYTE_TYPE(M_mnemonic, M_type) \
    M_type *wire_get_##M_mnemonic(wire_context_t *restrict c) { \
        if (unlikely(c->byte_cursor + 1 >= c->data_len)) return NULL; \
        M_type *value = (M_type*)&c->data[c->byte_cursor++]; \
        return value; \
    } \
    M_type *wire_set_##M_mnemonic(wire_context_t *restrict c, M_type val) { \
        if (unlikely(c->byte_cursor + 1 >= c->data_len)) return NULL; \
        M_type *dest = (M_type*)&c->data[c->byte_cursor++]; \
        *dest = val; \
        return dest; \
    } \

#define _WIRE_DEF_TYPE(M_mnemonic, M_type, M_alignment) \
    M_type *wire_get_##M_mnemonic(wire_context_t *restrict c) { \
        if (unlikely(!wire_align(c, M_alignment))) return NULL; \
        uint32_t new_cursor = c->byte_cursor + sizeof(M_type); \
        if (unlikely(new_cursor >= c->data_len)) return NULL; \
        M_type *value = (M_type*)&c->data[c->byte_cursor]; \
        c->byte_cursor = new_cursor; \
        return value; \
    } \
    M_type *wire_set_##M_mnemonic(wire_context_t *restrict c, M_type val) { \
        if (unlikely(!wire_write_align(c, M_alignment))) return NULL; \
        uint32_t new_cursor = c->byte_cursor + sizeof(M_type); \
        if (unlikely(new_cursor >= c->data_len)) return NULL; \
        M_type *dest = (M_type*)&c->data[c->byte_cursor]; \
        *dest = val; \
        c->byte_cursor = new_cursor; \
        return dest; \
    } \

bool wire_align(wire_context_t *c, uint32_t alignment);
bool wire_write_align(wire_context_t *c, uint32_t alignment);

// SPEC: https://dbus.freedesktop.org/doc/dbus-specification.html#id-1.4.6
_WIRE_DECL_BYTE_TYPE(i8, int8_t)
_WIRE_DECL_BYTE_TYPE(u8, uint8_t)
_WIRE_DECL_TYPE(i16, int16_t, 2)
_WIRE_DECL_TYPE(u16, uint16_t, 2)
_WIRE_DECL_TYPE(i32, int32_t, 4)
_WIRE_DECL_TYPE(u32, uint32_t, 4)
_WIRE_DECL_TYPE(boolean, uint32_t, 4)


char *wire_get_string_impl(wire_context_t *c, bool as_signature);
char *wire_set_string_impl(wire_context_t *c, const char *str, bool as_signature);
char *wire_get_string_check(wire_context_t *c, int min_length, int max_length);
int wire_parse_message(wire_context_t *c, wire_message_t *msg);
int wire_compose_reply(wire_context_t *c, wire_message_t *msg, const char *signature, uint32_t **out_body_length);
int wire_compose_error(wire_context_t *c, wire_message_t *msg, const char *error_name);
int wire_compose_unicast_reply(wire_context_t *c, wire_context_t *msg_c, wire_message_t *msg, char *sender_unique_name);
int wire_compose_signal(wire_context_t *c, wire_message_t *out_msg, const char *signature, const char *member, uint32_t **out_body_length);
int wire_collect_strings(wire_context_t *c, wire_message_t *msg, wire_message_body_string_t *strings, int strings_count);

static inline char *wire_get_signature(wire_context_t *c) {
    return wire_get_string_impl(c, true);
}

static inline char *wire_set_signature(wire_context_t *c, const char *str) {
    return wire_set_string_impl(c, str, true);
}

static inline char *wire_get_string(wire_context_t *c) {
    return wire_get_string_impl(c, false);
}

static inline char *wire_set_string(wire_context_t *c, const char *str) {
    return wire_set_string_impl(c, str, false);
}

// maximum name length is 255
static inline char *wire_get_name_string(wire_context_t *c) {
    return wire_get_string_check(c, 1, 255);
}


#endif // _JITTERBUG__WIRE_H