blob.c

   1 /*
   2  * blob - library for generating/parsing tagged binary data
   3  *
   4  * Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include "blob.h"
  20
  21 static bool
  22 blob_buffer_grow(struct blob_buf *buf, int minlen)
  23 {
  24         int delta = ((minlen / 256) + 1) * 256;
  25         buf->buflen += delta;
  26         buf->buf = realloc(buf->buf, buf->buflen);
  27         if (buf->buf)
  28                 memset(buf->buf + buf->buflen - delta, 0, delta);
  29         return !!buf->buf;
  30 }
  31
  32 static void
  33 blob_init(struct blob_attr *attr, int id, unsigned int len)
  34 {
  35         len &= BLOB_ATTR_LEN_MASK;
  36         len |= (id << BLOB_ATTR_ID_SHIFT) & BLOB_ATTR_ID_MASK;
  37         attr->id_len = cpu_to_be32(len);
  38 }
  39
  40 static inline struct blob_attr *
  41 offset_to_attr(struct blob_buf *buf, int offset)
  42 {
  43         void *ptr = (char *)buf->buf + offset;
  44         return ptr;
  45 }
  46
  47 static inline int
  48 attr_to_offset(struct blob_buf *buf, struct blob_attr *attr)
  49 {
  50         return (char *)attr - (char *) buf->buf;
  51 }
  52
  53 void
  54 blob_buf_grow(struct blob_buf *buf, int required)
  55 {
  56         int offset_head = attr_to_offset(buf, buf->head);
  57
  58         if (!buf->grow || !buf->grow(buf, required))
  59                 return;
  60
  61         buf->head = offset_to_attr(buf, offset_head);
  62 }
  63
  64 static struct blob_attr *
  65 blob_add(struct blob_buf *buf, struct blob_attr *pos, int id, int payload)
  66 {
  67         int offset = attr_to_offset(buf, pos);
  68         int required = (offset + sizeof(struct blob_attr) + payload) - buf->buflen;
  69         struct blob_attr *attr;
  70
  71         if (required > 0) {
  72                 blob_buf_grow(buf, required);
  73                 attr = offset_to_attr(buf, offset);
  74         } else {
  75                 attr = pos;
  76         }
  77
  78         blob_init(attr, id, payload + sizeof(struct blob_attr));
  79         blob_fill_pad(attr);
  80         return attr;
  81 }
  82
  83 int
  84 blob_buf_init(struct blob_buf *buf, int id)
  85 {
  86         if (!buf->grow)
  87                 buf->grow = blob_buffer_grow;
  88
  89         buf->head = buf->buf;
  90         if (blob_add(buf, buf->buf, id, 0) == NULL)
  91                 return -ENOMEM;
  92
  93         return 0;
  94 }
  95
  96 void
  97 blob_buf_free(struct blob_buf *buf)
  98 {
  99         free(buf->buf);
 100         buf->buf = NULL;
 101         buf->buflen = 0;
 102 }
 103
 104 void
 105 blob_fill_pad(struct blob_attr *attr)
 106 {
 107         char *buf = (char *) attr;
 108         int len = blob_pad_len(attr);
 109         int delta = len - blob_raw_len(attr);
 110
 111         if (delta > 0)
 112                 memset(buf + len - delta, 0, delta);
 113 }
 114
 115 void
 116 blob_set_raw_len(struct blob_attr *attr, unsigned int len)
 117 {
 118         int id = blob_id(attr);
 119         len &= BLOB_ATTR_LEN_MASK;
 120         len |= (id << BLOB_ATTR_ID_SHIFT) & BLOB_ATTR_ID_MASK;
 121         attr->id_len = cpu_to_be32(len);
 122 }
 123
 124 struct blob_attr *
 125 blob_new(struct blob_buf *buf, int id, int payload)
 126 {
 127         struct blob_attr *attr;
 128
 129         attr = blob_add(buf, blob_next(buf->head), id, payload);
 130         if (!attr)
 131                 return NULL;
 132
 133         blob_set_raw_len(buf->head, blob_pad_len(buf->head) + blob_pad_len(attr));
 134         return attr;
 135 }
 136
 137 struct blob_attr *
 138 blob_put(struct blob_buf *buf, int id, const void *ptr, int len)
 139 {
 140         struct blob_attr *attr;
 141
 142         attr = blob_new(buf, id, len);
 143         if (!attr)
 144                 return NULL;
 145
 146         if (ptr)
 147                 memcpy(blob_data(attr), ptr, len);
 148         return attr;
 149 }
 150
 151 void *
 152 blob_nest_start(struct blob_buf *buf, int id)
 153 {
 154         unsigned long offset = attr_to_offset(buf, buf->head);
 155         buf->head = blob_new(buf, id, 0);
 156         return (void *) offset;
 157 }
 158
 159 void
 160 blob_nest_end(struct blob_buf *buf, void *cookie)
 161 {
 162         struct blob_attr *attr = offset_to_attr(buf, (unsigned long) cookie);
 163         blob_set_raw_len(attr, blob_pad_len(attr) + blob_len(buf->head));
 164         buf->head = attr;
 165 }
 166
 167 static const int blob_type_minlen[BLOB_ATTR_LAST] = {
 168         [BLOB_ATTR_STRING] = 1,
 169         [BLOB_ATTR_INT8] = sizeof(uint8_t),
 170         [BLOB_ATTR_INT16] = sizeof(uint16_t),
 171         [BLOB_ATTR_INT32] = sizeof(uint32_t),
 172         [BLOB_ATTR_INT64] = sizeof(uint64_t),
 173 };
 174
 175 bool
 176 blob_check_type(const void *ptr, int len, int type)
 177 {
 178         const char *data = ptr;
 179
 180         if (type >= BLOB_ATTR_LAST)
 181                 return false;
 182
 183         if (type >= BLOB_ATTR_INT8 && type <= BLOB_ATTR_INT64) {
 184                 if (len != blob_type_minlen[type])
 185                         return false;
 186         } else {
 187                 if (len < blob_type_minlen[type])
 188                         return false;
 189         }
 190
 191         if (type == BLOB_ATTR_STRING && data[len - 1] != 0)
 192                 return false;
 193
 194         return true;
 195 }
 196
 197 int
 198 blob_parse(struct blob_attr *attr, struct blob_attr **data, const struct blob_attr_info *info, int max)
 199 {
 200         struct blob_attr *pos;
 201         int found = 0;
 202         int rem;
 203
 204         memset(data, 0, sizeof(struct blob_attr *) * max);
 205         blob_for_each_attr(pos, attr, rem) {
 206                 int id = blob_id(pos);
 207                 int len = blob_len(pos);
 208
 209                 if (id >= max)
 210                         continue;
 211
 212                 if (info) {
 213                         int type = info[id].type;
 214
 215                         if (type < BLOB_ATTR_LAST) {
 216                                 if (!blob_check_type(blob_data(pos), len, type))
 217                                         continue;
 218                         }
 219
 220                         if (info[id].minlen && len < info[id].minlen)
 221                                 continue;
 222
 223                         if (info[id].maxlen && len > info[id].maxlen)
 224                                 continue;
 225
 226                         if (info[id].validate && !info[id].validate(&info[id], attr))
 227                                 continue;
 228                 }
 229
 230                 if (!data[id])
 231                         found++;
 232
 233                 data[id] = pos;
 234         }
 235         return found;
 236 }
 237
 238 bool
 239 blob_attr_equal(const struct blob_attr *a1, const struct blob_attr *a2)
 240 {
 241         if (!a1 && !a2)
 242                 return true;
 243
 244         if (!a1 || !a2)
 245                 return false;
 246
 247         if (blob_pad_len(a1) != blob_pad_len(a2))
 248                 return false;
 249
 250         return !memcmp(a1, a2, blob_pad_len(a1));
 251 }
 252
 253 struct blob_attr *
 254 blob_memdup(struct blob_attr *attr)
 255 {
 256         struct blob_attr *ret;
 257         int size = blob_pad_len(attr);
 258
 259         ret = malloc(size);
 260         if (!ret)
 261                 return NULL;
 262
 263         memcpy(ret, attr, size);
 264         return ret;
 265 }