blob.c

   1 /*
   2  * blob - library for generating/parsing tagged binary data
   3  *
   4  * Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU Lesser General Public License version 2.1
   8  * as published by the Free Software Foundation
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  */
  15
  16 #include "blob.h"
  17
  18 static bool
  19 blob_buffer_grow(struct blob_buf *buf, int minlen)
  20 {
  21         int delta = ((minlen / 256) + 1) * 256;
  22         buf->buflen += delta;
  23         buf->buf = realloc(buf->buf, buf->buflen);
  24         if (buf->buf)
  25                 memset(buf->buf + buf->buflen - delta, 0, delta);
  26         return !!buf->buf;
  27 }
  28
  29 static void
  30 blob_init(struct blob_attr *attr, int id, unsigned int len)
  31 {
  32         len &= BLOB_ATTR_LEN_MASK;
  33         len |= (id << BLOB_ATTR_ID_SHIFT) & BLOB_ATTR_ID_MASK;
  34         attr->id_len = cpu_to_be32(len);
  35 }
  36
  37 static inline struct blob_attr *
  38 offset_to_attr(struct blob_buf *buf, int offset)
  39 {
  40         void *ptr = (char *)buf->buf + offset;
  41         return ptr;
  42 }
  43
  44 static inline int
  45 attr_to_offset(struct blob_buf *buf, struct blob_attr *attr)
  46 {
  47         return (char *)attr - (char *) buf->buf;
  48 }
  49
  50 static struct blob_attr *
  51 blob_add(struct blob_buf *buf, struct blob_attr *pos, int id, int payload)
  52 {
  53         int offset = attr_to_offset(buf, pos);
  54         int required = (offset + sizeof(struct blob_attr) + payload) - buf->buflen;
  55         struct blob_attr *attr;
  56
  57         if (required > 0) {
  58                 int offset_head = attr_to_offset(buf, buf->head);
  59
  60                 if (!buf->grow || !buf->grow(buf, required))
  61                         return NULL;
  62
  63                 buf->head = offset_to_attr(buf, offset_head);
  64                 attr = offset_to_attr(buf, offset);
  65         } else {
  66                 attr = pos;
  67         }
  68
  69         blob_init(attr, id, payload + sizeof(struct blob_attr));
  70         return attr;
  71 }
  72
  73 int
  74 blob_buf_init(struct blob_buf *buf, int id)
  75 {
  76         if (!buf->grow)
  77                 buf->grow = blob_buffer_grow;
  78
  79         buf->head = buf->buf;
  80         if (blob_add(buf, buf->buf, id, 0) == NULL)
  81                 return -ENOMEM;
  82
  83         return 0;
  84 }
  85
  86 void
  87 blob_buf_free(struct blob_buf *buf)
  88 {
  89         free(buf->buf);
  90         buf->buf = NULL;
  91         buf->buflen = 0;
  92 }
  93
  94 static void
  95 blob_fill_pad(struct blob_attr *attr)
  96 {
  97         char *buf = (char *) attr;
  98         int len = blob_pad_len(attr);
  99         int delta = len - blob_raw_len(attr);
 100
 101         if (delta > 0)
 102                 memset(buf + len - delta, 0, delta);
 103 }
 104
 105 void
 106 blob_set_raw_len(struct blob_attr *attr, unsigned int len)
 107 {
 108         int id = blob_id(attr);
 109         len &= BLOB_ATTR_LEN_MASK;
 110         len |= (id << BLOB_ATTR_ID_SHIFT) & BLOB_ATTR_ID_MASK;
 111         attr->id_len = cpu_to_be32(len);
 112         blob_fill_pad(attr);
 113 }
 114
 115 struct blob_attr *
 116 blob_new(struct blob_buf *buf, int id, int payload)
 117 {
 118         struct blob_attr *attr;
 119
 120         attr = blob_add(buf, blob_next(buf->head), id, payload);
 121         if (!attr)
 122                 return NULL;
 123
 124         blob_set_raw_len(buf->head, blob_pad_len(buf->head) + blob_pad_len(attr));
 125         return attr;
 126 }
 127
 128 struct blob_attr *
 129 blob_put(struct blob_buf *buf, int id, const void *ptr, int len)
 130 {
 131         struct blob_attr *attr;
 132
 133         attr = blob_new(buf, id, len);
 134         if (!attr)
 135                 return NULL;
 136
 137         if (ptr)
 138                 memcpy(blob_data(attr), ptr, len);
 139         return attr;
 140 }
 141
 142 void *
 143 blob_nest_start(struct blob_buf *buf, int id)
 144 {
 145         unsigned long offset = attr_to_offset(buf, buf->head);
 146         buf->head = blob_new(buf, id, 0);
 147         return (void *) offset;
 148 }
 149
 150 void
 151 blob_nest_end(struct blob_buf *buf, void *cookie)
 152 {
 153         struct blob_attr *attr = offset_to_attr(buf, (unsigned long) cookie);
 154         blob_set_raw_len(attr, blob_pad_len(attr) + blob_len(buf->head));
 155         buf->head = attr;
 156 }
 157
 158 static const int blob_type_minlen[BLOB_ATTR_LAST] = {
 159         [BLOB_ATTR_STRING] = 1,
 160         [BLOB_ATTR_INT8] = sizeof(uint8_t),
 161         [BLOB_ATTR_INT16] = sizeof(uint16_t),
 162         [BLOB_ATTR_INT32] = sizeof(uint32_t),
 163         [BLOB_ATTR_INT64] = sizeof(uint64_t),
 164 };
 165
 166 bool
 167 blob_check_type(const void *ptr, int len, int type)
 168 {
 169         const char *data = ptr;
 170
 171         if (type >= BLOB_ATTR_LAST)
 172                 return false;
 173
 174         if (type >= BLOB_ATTR_INT8 && type <= BLOB_ATTR_INT64) {
 175                 if (len != blob_type_minlen[type])
 176                         return false;
 177         } else {
 178                 if (len < blob_type_minlen[type])
 179                         return false;
 180         }
 181
 182         if (type == BLOB_ATTR_STRING && data[len - 1] != 0)
 183                 return false;
 184
 185         return true;
 186 }
 187
 188 int
 189 blob_parse(struct blob_attr *attr, struct blob_attr **data, const struct blob_attr_info *info, int max)
 190 {
 191         struct blob_attr *pos;
 192         int found = 0;
 193         int rem;
 194
 195         memset(data, 0, sizeof(struct blob_attr *) * max);
 196         blob_for_each_attr(pos, attr, rem) {
 197                 int id = blob_id(pos);
 198                 int len = blob_len(pos);
 199
 200                 if (id >= max)
 201                         continue;
 202
 203                 if (info) {
 204                         int type = info[id].type;
 205
 206                         if (type < BLOB_ATTR_LAST) {
 207                                 if (!blob_check_type(blob_data(pos), len, type))
 208                                         continue;
 209                         }
 210
 211                         if (info[id].minlen && len < info[id].minlen)
 212                                 continue;
 213
 214                         if (info[id].maxlen && len > info[id].maxlen)
 215                                 continue;
 216
 217                         if (info[id].validate && !info[id].validate(&info[id], attr))
 218                                 continue;
 219                 }
 220
 221                 if (!data[id])
 222                         found++;
 223
 224                 data[id] = pos;
 225         }
 226         return found;
 227 }
 228
 229 bool
 230 blob_attr_equal(const struct blob_attr *a1, const struct blob_attr *a2)
 231 {
 232         if (!a1 && !a2)
 233                 return true;
 234
 235         if (!a1 || !a2)
 236                 return false;
 237
 238         if (blob_pad_len(a1) != blob_pad_len(a2))
 239                 return false;
 240
 241         return !memcmp(a1, a2, blob_pad_len(a1));
 242 }