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         buf->buflen += ((minlen / 256) + 1) * 256;
  22         buf->buf = realloc(buf->buf, buf->buflen);
  23         return !!buf->buf;
  24 }
  25
  26 static void
  27 blob_init(struct blob_attr *attr, int id, unsigned int len)
  28 {
  29         len &= BLOB_ATTR_LEN_MASK;
  30         len |= (id << BLOB_ATTR_ID_SHIFT) & BLOB_ATTR_ID_MASK;
  31         attr->id_len = cpu_to_be32(len);
  32 }
  33
  34 static inline struct blob_attr *
  35 offset_to_attr(struct blob_buf *buf, int offset)
  36 {
  37         void *ptr = (char *)buf->buf + offset;
  38         return ptr;
  39 }
  40
  41 static inline int
  42 attr_to_offset(struct blob_buf *buf, struct blob_attr *attr)
  43 {
  44         return (char *)attr - (char *) buf->buf;
  45 }
  46
  47 static struct blob_attr *
  48 blob_add(struct blob_buf *buf, struct blob_attr *pos, int id, int payload)
  49 {
  50         int offset = attr_to_offset(buf, pos);
  51         int required = (offset + sizeof(struct blob_attr) + payload) - buf->buflen;
  52         struct blob_attr *attr;
  53
  54         if (required > 0) {
  55                 int offset_head = attr_to_offset(buf, buf->head);
  56
  57                 if (!buf->grow || !buf->grow(buf, required))
  58                         return NULL;
  59
  60                 buf->head = offset_to_attr(buf, offset_head);
  61                 attr = offset_to_attr(buf, offset);
  62         } else {
  63                 attr = pos;
  64         }
  65
  66         blob_init(attr, id, payload + sizeof(struct blob_attr));
  67         return attr;
  68 }
  69
  70 int
  71 blob_buf_init(struct blob_buf *buf, int id)
  72 {
  73         if (!buf->grow)
  74                 buf->grow = blob_buffer_grow;
  75
  76         buf->head = buf->buf;
  77         if (blob_add(buf, buf->buf, id, 0) == NULL)
  78                 return -ENOMEM;
  79
  80         return 0;
  81 }
  82
  83 void
  84 blob_buf_free(struct blob_buf *buf)
  85 {
  86         free(buf->buf);
  87         buf->buf = NULL;
  88         buf->buflen = 0;
  89 }
  90
  91 struct blob_attr *
  92 blob_new(struct blob_buf *buf, int id, int payload)
  93 {
  94         struct blob_attr *attr;
  95
  96         attr = blob_add(buf, blob_next(buf->head), id, payload);
  97         if (!attr)
  98                 return NULL;
  99
 100         blob_set_raw_len(buf->head, blob_pad_len(buf->head) + blob_pad_len(attr));
 101         return attr;
 102 }
 103
 104 struct blob_attr *
 105 blob_put(struct blob_buf *buf, int id, const void *ptr, int len)
 106 {
 107         struct blob_attr *attr;
 108
 109         attr = blob_new(buf, id, len);
 110         if (!attr)
 111                 return NULL;
 112
 113         if (ptr)
 114                 memcpy(blob_data(attr), ptr, len);
 115         return attr;
 116 }
 117
 118 void *
 119 blob_nest_start(struct blob_buf *buf, int id)
 120 {
 121         unsigned long offset = attr_to_offset(buf, buf->head);
 122         buf->head = blob_new(buf, id, 0);
 123         return (void *) offset;
 124 }
 125
 126 void
 127 blob_nest_end(struct blob_buf *buf, void *cookie)
 128 {
 129         struct blob_attr *attr = offset_to_attr(buf, (unsigned long) cookie);
 130         blob_set_raw_len(attr, blob_pad_len(attr) + blob_len(buf->head));
 131         buf->head = attr;
 132 }
 133
 134 static const int blob_type_minlen[BLOB_ATTR_LAST] = {
 135         [BLOB_ATTR_STRING] = 1,
 136         [BLOB_ATTR_INT8] = sizeof(uint8_t),
 137         [BLOB_ATTR_INT16] = sizeof(uint16_t),
 138         [BLOB_ATTR_INT32] = sizeof(uint32_t),
 139         [BLOB_ATTR_INT64] = sizeof(uint64_t),
 140 };
 141
 142 bool
 143 blob_check_type(const void *ptr, int len, int type)
 144 {
 145         const char *data = ptr;
 146
 147         if (type >= BLOB_ATTR_LAST)
 148                 return false;
 149
 150         if (type >= BLOB_ATTR_INT8 && type <= BLOB_ATTR_INT64) {
 151                 if (len != blob_type_minlen[type])
 152                         return false;
 153         } else {
 154                 if (len < blob_type_minlen[type])
 155                         return false;
 156         }
 157
 158         if (type == BLOB_ATTR_STRING && data[len - 1] != 0)
 159                 return false;
 160
 161         return true;
 162 }
 163
 164 int
 165 blob_parse(struct blob_attr *attr, struct blob_attr **data, const struct blob_attr_info *info, int max)
 166 {
 167         struct blob_attr *pos;
 168         int found = 0;
 169         int rem;
 170
 171         memset(data, 0, sizeof(struct blob_attr *) * max);
 172         blob_for_each_attr(pos, attr, rem) {
 173                 int id = blob_id(pos);
 174                 int len = blob_len(pos);
 175
 176                 if (id >= max)
 177                         continue;
 178
 179                 if (info) {
 180                         int type = info[id].type;
 181
 182                         if (type < BLOB_ATTR_LAST) {
 183                                 if (!blob_check_type(blob_data(pos), len, type))
 184                                         continue;
 185                         }
 186
 187                         if (info[id].minlen && len < info[id].minlen)
 188                                 continue;
 189
 190                         if (info[id].maxlen && len > info[id].maxlen)
 191                                 continue;
 192
 193                         if (info[id].validate && !info[id].validate(&info[id], attr))
 194                                 continue;
 195                 }
 196
 197                 if (!data[id])
 198                         found++;
 199
 200                 data[id] = pos;
 201         }
 202         return found;
 203 }