blob.c

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/*
 * blob - library for generating/parsing tagged binary data
 *
 * Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
#include "blob.h"
 
static bool
blob_buffer_grow(struct blob_buf *buf, int minlen)
{
        struct blob_buf *new;
        int delta = ((minlen / 256) + 1) * 256;
        new = realloc(buf->buf, buf->buflen + delta);
        if (new) {
                buf->buf = new;
                memset(buf->buf + buf->buflen, 0, delta);
                buf->buflen += delta;
        }
        return !!new;
}
 
static void
blob_init(struct blob_attr *attr, int id, unsigned int len)
{
        len &= BLOB_ATTR_LEN_MASK;
        len |= (id << BLOB_ATTR_ID_SHIFT) & BLOB_ATTR_ID_MASK;
        attr->id_len = cpu_to_be32(len);
}
 
static inline struct blob_attr *
offset_to_attr(struct blob_buf *buf, int offset)
{
        void *ptr = (char *)buf->buf + offset - BLOB_COOKIE;
        return ptr;
}
 
static inline int
attr_to_offset(struct blob_buf *buf, struct blob_attr *attr)
{
        return (char *)attr - (char *) buf->buf + BLOB_COOKIE;
}
 
bool
blob_buf_grow(struct blob_buf *buf, int required)
{
        int offset_head = attr_to_offset(buf, buf->head);
 
        if ((buf->buflen + required) > BLOB_ATTR_LEN_MASK)
                return false;
        if (!buf->grow || !buf->grow(buf, required))
                return false;
 
        buf->head = offset_to_attr(buf, offset_head);
        return true;
}
 
static struct blob_attr *
blob_add(struct blob_buf *buf, struct blob_attr *pos, int id, int payload)
{
        int offset = attr_to_offset(buf, pos);
        int required = (offset - BLOB_COOKIE + sizeof(struct blob_attr) + payload) - buf->buflen;
        struct blob_attr *attr;
 
        if (required > 0) {
                if (!blob_buf_grow(buf, required))
                        return NULL;
                attr = offset_to_attr(buf, offset);
        } else {
                attr = pos;
        }
 
        blob_init(attr, id, payload + sizeof(struct blob_attr));
        blob_fill_pad(attr);
        return attr;
}
 
int
blob_buf_init(struct blob_buf *buf, int id)
{
        if (!buf->grow)
                buf->grow = blob_buffer_grow;
 
        buf->head = buf->buf;
        if (blob_add(buf, buf->buf, id, 0) == NULL)
                return -ENOMEM;
 
        return 0;
}
 
void
blob_buf_free(struct blob_buf *buf)
{
        free(buf->buf);
        buf->buf = NULL;
        buf->head = NULL;
        buf->buflen = 0;
}
 
void
blob_fill_pad(struct blob_attr *attr)
{
        char *buf = (char *) attr;
        int len = blob_pad_len(attr);
        int delta = len - blob_raw_len(attr);
 
        if (delta > 0)
                memset(buf + len - delta, 0, delta);
}
 
void
blob_set_raw_len(struct blob_attr *attr, unsigned int len)
{
        len &= BLOB_ATTR_LEN_MASK;
        attr->id_len &= ~cpu_to_be32(BLOB_ATTR_LEN_MASK);
        attr->id_len |= cpu_to_be32(len);
}
 
struct blob_attr *
blob_new(struct blob_buf *buf, int id, int payload)
{
        struct blob_attr *attr;
 
        attr = blob_add(buf, blob_next(buf->head), id, payload);
        if (!attr)
                return NULL;
 
        blob_set_raw_len(buf->head, blob_pad_len(buf->head) + blob_pad_len(attr));
        return attr;
}
 
struct blob_attr *
blob_put_raw(struct blob_buf *buf, const void *ptr, unsigned int len)
{
        struct blob_attr *attr;
 
        if (len < sizeof(struct blob_attr) || !ptr)
                return NULL;
 
        attr = blob_add(buf, blob_next(buf->head), 0, len - sizeof(struct blob_attr));
        if (!attr)
                return NULL;
        blob_set_raw_len(buf->head, blob_pad_len(buf->head) + len);
        memcpy(attr, ptr, len);
        return attr;
}
 
struct blob_attr *
blob_put(struct blob_buf *buf, int id, const void *ptr, unsigned int len)
{
        struct blob_attr *attr;
 
        attr = blob_new(buf, id, len);
        if (!attr)
                return NULL;
 
        if (ptr)
                memcpy(blob_data(attr), ptr, len);
        return attr;
}
 
void *
blob_nest_start(struct blob_buf *buf, int id)
{
        unsigned long offset = attr_to_offset(buf, buf->head);
        buf->head = blob_new(buf, id, 0);
        if (!buf->head)
                return NULL;
        return (void *) offset;
}
 
void
blob_nest_end(struct blob_buf *buf, void *cookie)
{
        struct blob_attr *attr = offset_to_attr(buf, (unsigned long) cookie);
        blob_set_raw_len(attr, blob_pad_len(attr) + blob_len(buf->head));
        buf->head = attr;
}
 
static const size_t blob_type_minlen[BLOB_ATTR_LAST] = {
        [BLOB_ATTR_STRING] = 1,
        [BLOB_ATTR_INT8] = sizeof(uint8_t),
        [BLOB_ATTR_INT16] = sizeof(uint16_t),
        [BLOB_ATTR_INT32] = sizeof(uint32_t),
        [BLOB_ATTR_INT64] = sizeof(uint64_t),
        [BLOB_ATTR_DOUBLE] = sizeof(double),
};
 
bool
blob_check_type(const void *ptr, unsigned int len, int type)
{
        const char *data = ptr;
 
        if (type >= BLOB_ATTR_LAST)
                return false;
 
        if (type >= BLOB_ATTR_INT8 && type <= BLOB_ATTR_INT64) {
                if (len != blob_type_minlen[type])
                        return false;
        } else {
                if (len < blob_type_minlen[type])
                        return false;
        }
 
        if (type == BLOB_ATTR_STRING && data[len - 1] != 0)
                return false;
 
        return true;
}
 
static int
blob_parse_attr(struct blob_attr *attr, size_t attr_len, struct blob_attr **data, const struct blob_attr_info *info, int max)
{
        int id;
        size_t len;
        int found = 0;
        size_t data_len;
 
        if (!attr || attr_len < sizeof(struct blob_attr))
                return 0;
 
        id = blob_id(attr);
        if (id >= max)
                return 0;
 
        len = blob_raw_len(attr);
        if (len > attr_len || len < sizeof(struct blob_attr))
                return 0;
 
        data_len = blob_len(attr);
        if (data_len > len)
                return 0;
 
        if (info) {
                int type = info[id].type;
 
                if (type < BLOB_ATTR_LAST) {
                        if (!blob_check_type(blob_data(attr), data_len, type))
                                return 0;
                }
 
                if (info[id].minlen && len < info[id].minlen)
                        return 0;
 
                if (info[id].maxlen && len > info[id].maxlen)
                        return 0;
 
                if (info[id].validate && !info[id].validate(&info[id], attr))
                        return 0;
        }
 
        if (!data[id])
                found++;
 
        data[id] = attr;
        return found;
}
 
int
blob_parse_untrusted(struct blob_attr *attr, size_t attr_len, struct blob_attr **data, const struct blob_attr_info *info, int max)
{
        struct blob_attr *pos;
        size_t len = 0;
        int found = 0;
        size_t rem;
 
        if (!attr || attr_len < sizeof(struct blob_attr))
                return 0;
 
        len = blob_raw_len(attr);
        if (attr_len < len)
                return 0;
 
        memset(data, 0, sizeof(struct blob_attr *) * max);
        blob_for_each_attr_len(pos, attr, len, rem) {
                found += blob_parse_attr(pos, rem, data, info, max);
        }
 
        return found;
}
 
/* use only on trusted input, otherwise consider blob_parse_untrusted */
int
blob_parse(struct blob_attr *attr, struct blob_attr **data, const struct blob_attr_info *info, int max)
{
        struct blob_attr *pos;
        int found = 0;
        size_t rem;
 
        memset(data, 0, sizeof(struct blob_attr *) * max);
        blob_for_each_attr(pos, attr, rem) {
                found += blob_parse_attr(pos, rem, data, info, max);
        }
 
        return found;
}
 
bool
blob_attr_equal(const struct blob_attr *a1, const struct blob_attr *a2)
{
        if (!a1 && !a2)
                return true;
 
        if (!a1 || !a2)
                return false;
 
        if (blob_pad_len(a1) != blob_pad_len(a2))
                return false;
 
        return !memcmp(a1, a2, blob_pad_len(a1));
}
 
struct blob_attr *
blob_memdup(struct blob_attr *attr)
{
        struct blob_attr *ret;
        int size = blob_pad_len(attr);
 
        ret = malloc(size);
        if (!ret)
                return NULL;
 
        memcpy(ret, attr, size);
        return ret;
}