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 struct blob_attr *
  95 blob_new(struct blob_buf *buf, int id, int payload)
  96 {
  97         struct blob_attr *attr;
  98
  99         attr = blob_add(buf, blob_next(buf->head), id, payload);
 100         if (!attr)
 101                 return NULL;
 102
 103         blob_set_raw_len(buf->head, blob_pad_len(buf->head) + blob_pad_len(attr));
 104         return attr;
 105 }
 106
 107 struct blob_attr *
 108 blob_put(struct blob_buf *buf, int id, const void *ptr, int len)
 109 {
 110         struct blob_attr *attr;
 111
 112         attr = blob_new(buf, id, len);
 113         if (!attr)
 114                 return NULL;
 115
 116         if (ptr)
 117                 memcpy(blob_data(attr), ptr, len);
 118         return attr;
 119 }
 120
 121 void *
 122 blob_nest_start(struct blob_buf *buf, int id)
 123 {
 124         unsigned long offset = attr_to_offset(buf, buf->head);
 125         buf->head = blob_new(buf, id, 0);
 126         return (void *) offset;
 127 }
 128
 129 void
 130 blob_nest_end(struct blob_buf *buf, void *cookie)
 131 {
 132         struct blob_attr *attr = offset_to_attr(buf, (unsigned long) cookie);
 133         blob_set_raw_len(attr, blob_pad_len(attr) + blob_len(buf->head));
 134         buf->head = attr;
 135 }
 136
 137 static const int blob_type_minlen[BLOB_ATTR_LAST] = {
 138         [BLOB_ATTR_STRING] = 1,
 139         [BLOB_ATTR_INT8] = sizeof(uint8_t),
 140         [BLOB_ATTR_INT16] = sizeof(uint16_t),
 141         [BLOB_ATTR_INT32] = sizeof(uint32_t),
 142         [BLOB_ATTR_INT64] = sizeof(uint64_t),
 143 };
 144
 145 bool
 146 blob_check_type(const void *ptr, int len, int type)
 147 {
 148         const char *data = ptr;
 149
 150         if (type >= BLOB_ATTR_LAST)
 151                 return false;
 152
 153         if (type >= BLOB_ATTR_INT8 && type <= BLOB_ATTR_INT64) {
 154                 if (len != blob_type_minlen[type])
 155                         return false;
 156         } else {
 157                 if (len < blob_type_minlen[type])
 158                         return false;
 159         }
 160
 161         if (type == BLOB_ATTR_STRING && data[len - 1] != 0)
 162                 return false;
 163
 164         return true;
 165 }
 166
 167 int
 168 blob_parse(struct blob_attr *attr, struct blob_attr **data, const struct blob_attr_info *info, int max)
 169 {
 170         struct blob_attr *pos;
 171         int found = 0;
 172         int rem;
 173
 174         memset(data, 0, sizeof(struct blob_attr *) * max);
 175         blob_for_each_attr(pos, attr, rem) {
 176                 int id = blob_id(pos);
 177                 int len = blob_len(pos);
 178
 179                 if (id >= max)
 180                         continue;
 181
 182                 if (info) {
 183                         int type = info[id].type;
 184
 185                         if (type < BLOB_ATTR_LAST) {
 186                                 if (!blob_check_type(blob_data(pos), len, type))
 187                                         continue;
 188                         }
 189
 190                         if (info[id].minlen && len < info[id].minlen)
 191                                 continue;
 192
 193                         if (info[id].maxlen && len > info[id].maxlen)
 194                                 continue;
 195
 196                         if (info[id].validate && !info[id].validate(&info[id], attr))
 197                                 continue;
 198                 }
 199
 200                 if (!data[id])
 201                         found++;
 202
 203                 data[id] = pos;
 204         }
 205         return found;
 206 }
 207
 208 bool
 209 blob_attr_equal(const struct blob_attr *a1, const struct blob_attr *a2)
 210 {
 211         if (!a1 && !a2)
 212                 return true;
 213
 214         if (!a1 || !a2)
 215                 return false;
 216
 217         if (blob_pad_len(a1) != blob_pad_len(a2))
 218                 return false;
 219
 220         return !memcmp(a1, a2, blob_pad_len(a1));
 221 }