blobmsg.c

   1 /*
   2  * blobmsg - library for generating/parsing structured blob messages
   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 "blobmsg.h"
  17
  18 static const int blob_type[__BLOBMSG_TYPE_LAST] = {
  19         [BLOBMSG_TYPE_INT8] = BLOB_ATTR_INT8,
  20         [BLOBMSG_TYPE_INT16] = BLOB_ATTR_INT16,
  21         [BLOBMSG_TYPE_INT32] = BLOB_ATTR_INT32,
  22         [BLOBMSG_TYPE_INT64] = BLOB_ATTR_INT64,
  23         [BLOBMSG_TYPE_STRING] = BLOB_ATTR_STRING,
  24 };
  25
  26 static uint16_t
  27 blobmsg_namelen(const struct blobmsg_hdr *hdr)
  28 {
  29         return be16_to_cpu(hdr->namelen);
  30 }
  31
  32 bool blobmsg_check_attr(const struct blob_attr *attr, bool name)
  33 {
  34         const struct blobmsg_hdr *hdr;
  35         const char *data;
  36         int id, len;
  37
  38         if (blob_len(attr) < sizeof(struct blobmsg_hdr))
  39                 return false;
  40
  41         hdr = (void *) attr->data;
  42         if (!hdr->namelen && name)
  43                 return false;
  44
  45         if (blobmsg_namelen(hdr) > blob_len(attr) - sizeof(struct blobmsg_hdr))
  46                 return false;
  47
  48         if (hdr->name[blobmsg_namelen(hdr)] != 0)
  49                 return false;
  50
  51         id = blob_id(attr);
  52         len = blobmsg_data_len(attr);
  53         data = blobmsg_data(attr);
  54
  55         if (!id || id > BLOBMSG_TYPE_LAST)
  56                 return false;
  57
  58         if (!blob_type[id])
  59                 return true;
  60
  61         return blob_check_type(data, len, blob_type[id]);
  62 }
  63
  64 int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
  65                   struct blob_attr **tb, void *data, int len)
  66 {
  67         struct blobmsg_hdr *hdr;
  68         struct blob_attr *attr;
  69         uint8_t *pslen;
  70         int i;
  71
  72         memset(tb, 0, policy_len * sizeof(*tb));
  73         pslen = alloca(policy_len);
  74         for (i = 0; i < policy_len; i++) {
  75                 if (!policy[i].name)
  76                         continue;
  77
  78                 pslen[i] = strlen(policy[i].name);
  79         }
  80
  81         __blob_for_each_attr(attr, data, len) {
  82                 hdr = blob_data(attr);
  83                 for (i = 0; i < policy_len; i++) {
  84                         if (!policy[i].name)
  85                                 continue;
  86
  87                         if (policy[i].type != BLOBMSG_TYPE_UNSPEC &&
  88                             blob_id(attr) != policy[i].type)
  89                                 continue;
  90
  91                         if (blobmsg_namelen(hdr) != pslen[i])
  92                                 continue;
  93
  94                         if (!blobmsg_check_attr(attr, true))
  95                                 return -1;
  96
  97                         if (tb[i])
  98                                 continue;
  99
 100                         if (strcmp(policy[i].name, (char *) hdr->name) != 0)
 101                                 continue;
 102
 103                         tb[i] = attr;
 104                 }
 105         }
 106
 107         return 0;
 108 }
 109
 110
 111 static struct blob_attr *
 112 blobmsg_new(struct blob_buf *buf, int type, const char *name, int payload_len, void **data)
 113 {
 114         struct blob_attr *attr;
 115         struct blobmsg_hdr *hdr;
 116         int attrlen, namelen;
 117         char *pad_start, *pad_end;
 118
 119         if (!name)
 120                 name = "";
 121
 122         namelen = strlen(name);
 123         attrlen = blobmsg_hdrlen(namelen) + payload_len;
 124         attr = blob_new(buf, type, attrlen);
 125         if (!attr)
 126                 return NULL;
 127
 128         hdr = blob_data(attr);
 129         hdr->namelen = cpu_to_be16(namelen);
 130         strcpy((char *) hdr->name, (const char *)name);
 131         pad_end = *data = blobmsg_data(attr);
 132         pad_start = (char *) &hdr->name[namelen];
 133         if (pad_start < pad_end)
 134                 memset(pad_start, 0, pad_end - pad_start);
 135
 136         return attr;
 137 }
 138
 139 static inline int
 140 attr_to_offset(struct blob_buf *buf, struct blob_attr *attr)
 141 {
 142         return (char *)attr - (char *) buf->buf;
 143 }
 144
 145
 146 void *
 147 blobmsg_open_nested(struct blob_buf *buf, const char *name, bool array)
 148 {
 149         struct blob_attr *head = buf->head;
 150         int type = array ? BLOBMSG_TYPE_ARRAY : BLOBMSG_TYPE_TABLE;
 151         unsigned long offset = attr_to_offset(buf, buf->head);
 152         void *data;
 153
 154         if (!name)
 155                 name = "";
 156
 157         head = blobmsg_new(buf, type, name, 0, &data);
 158         blob_set_raw_len(buf->head, blob_pad_len(buf->head) - blobmsg_hdrlen(strlen(name)));
 159         buf->head = head;
 160         return (void *)offset;
 161 }
 162
 163 void *
 164 blobmsg_alloc_string_buffer(struct blob_buf *buf, const char *name, int maxlen)
 165 {
 166         struct blob_attr *attr;
 167         void *data_dest;
 168
 169         attr = blobmsg_new(buf, BLOBMSG_TYPE_STRING, name, maxlen, &data_dest);
 170         if (!attr)
 171                 return NULL;
 172
 173         data_dest = blobmsg_data(attr);
 174         blob_set_raw_len(buf->head, blob_pad_len(buf->head) - blob_pad_len(attr));
 175         blob_set_raw_len(attr, blob_raw_len(attr) - maxlen);
 176
 177         return data_dest;
 178 }
 179
 180 void
 181 blobmsg_add_string_buffer(struct blob_buf *buf)
 182 {
 183         struct blob_attr *attr;
 184         int len, attrlen;
 185
 186         attr = blob_next(buf->head);
 187         len = strlen(blobmsg_data(attr)) + 1;
 188
 189         attrlen = blob_raw_len(attr) + len;
 190         blob_set_raw_len(attr, attrlen);
 191         blob_fill_pad(attr);
 192
 193         blob_set_raw_len(buf->head, blob_raw_len(buf->head) + blob_pad_len(attr));
 194 }
 195
 196 int
 197 blobmsg_add_field(struct blob_buf *buf, int type, const char *name,
 198                   const void *data, int len)
 199 {
 200         struct blob_attr *attr;
 201         void *data_dest;
 202
 203         attr = blobmsg_new(buf, type, name, len, &data_dest);
 204         if (!attr)
 205                 return -1;
 206
 207         if (len > 0)
 208                 memcpy(data_dest, data, len);
 209
 210         return 0;
 211 }