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 bool blobmsg_check_attr(const struct blob_attr *attr, bool name)
  19 {
  20         const struct blobmsg_hdr *hdr;
  21
  22         if (blob_len(attr) < sizeof(struct blobmsg_hdr))
  23                 return false;
  24
  25         hdr = (void *) attr->data;
  26         if (!hdr->namelen && name)
  27                 return false;
  28
  29         if (hdr->namelen > blob_len(attr))
  30                 return false;
  31
  32         if (hdr->name[hdr->namelen] != 0)
  33                 return false;
  34
  35         return true;
  36 }
  37
  38 int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
  39                   struct blob_attr **tb, void *data, int len)
  40 {
  41         struct blobmsg_hdr *hdr;
  42         struct blob_attr *attr;
  43         uint8_t *pslen;
  44         int i;
  45
  46         memset(tb, 0, policy_len * sizeof(*tb));
  47         pslen = alloca(policy_len);
  48         for (i = 0; i < policy_len; i++) {
  49                 if (!policy[i].name)
  50                         continue;
  51
  52                 pslen[i] = strlen(policy[i].name);
  53         }
  54
  55         __blob_for_each_attr(attr, data, len) {
  56                 hdr = blob_data(attr);
  57                 for (i = 0; i < policy_len; i++) {
  58                         if (!policy[i].name)
  59                                 continue;
  60
  61                         if (policy[i].type != BLOBMSG_TYPE_UNSPEC &&
  62                             blob_id(attr) != policy[i].type)
  63                                 continue;
  64
  65                         if (hdr->namelen != pslen[i])
  66                                 continue;
  67
  68                         if (!blobmsg_check_attr(attr, true))
  69                                 return -1;
  70
  71                         if (tb[i])
  72                                 return -1;
  73
  74                         if (strcmp(policy[i].name, (char *) hdr->name) != 0)
  75                                 continue;
  76
  77                         tb[i] = attr;
  78                 }
  79         }
  80
  81         return 0;
  82 }
  83
  84
  85 static struct blob_attr *
  86 blobmsg_new(struct blob_buf *buf, int type, const char *name, int payload_len, void **data)
  87 {
  88         struct blob_attr *attr;
  89         struct blobmsg_hdr *hdr;
  90         int attrlen, namelen;
  91
  92         if (blob_id(buf->head) == BLOBMSG_TYPE_ARRAY && !name) {
  93                 attr = blob_new(buf, type, payload_len);
  94                 *data = blob_data(attr);
  95                 return attr;
  96         }
  97
  98         if (blob_id(buf->head) != BLOBMSG_TYPE_TABLE || !name)
  99                 return NULL;
 100
 101         namelen = strlen(name);
 102         attrlen = blobmsg_hdrlen(namelen) + payload_len;
 103         attr = blob_new(buf, type, attrlen);
 104         if (!attr)
 105                 return NULL;
 106
 107         hdr = blob_data(attr);
 108         hdr->namelen = namelen;
 109         strcpy((char *) hdr->name, (const char *)name);
 110         *data = blobmsg_data(attr);
 111
 112         return attr;
 113 }
 114
 115 static inline int
 116 attr_to_offset(struct blob_buf *buf, struct blob_attr *attr)
 117 {
 118         return (char *)attr - (char *) buf->buf;
 119 }
 120
 121
 122 void *
 123 blobmsg_open_nested(struct blob_buf *buf, const char *name, bool array)
 124 {
 125         struct blob_attr *head = buf->head;
 126         int type = array ? BLOBMSG_TYPE_ARRAY : BLOBMSG_TYPE_TABLE;
 127         unsigned long offset = attr_to_offset(buf, buf->head);
 128         void *data;
 129
 130         if (blob_id(head) == BLOBMSG_TYPE_ARRAY && !name)
 131                 return blob_nest_start(buf, type);
 132
 133         if (blob_id(head) == BLOBMSG_TYPE_TABLE && name) {
 134                 head = blobmsg_new(buf, type, name, 0, &data);
 135                 blob_set_raw_len(buf->head, blob_pad_len(buf->head) - blobmsg_hdrlen(strlen(name)));
 136                 buf->head = head;
 137                 return (void *)offset;
 138         }
 139
 140         return NULL;
 141 }
 142
 143 int
 144 blobmsg_add_field(struct blob_buf *buf, int type, const char *name,
 145                   const void *data, int len)
 146 {
 147         struct blob_attr *attr;
 148         void *data_dest;
 149
 150         if (type == BLOBMSG_TYPE_ARRAY ||
 151             type == BLOBMSG_TYPE_TABLE)
 152                 return -1;
 153
 154         attr = blobmsg_new(buf, type, name, len, &data_dest);
 155         if (!attr)
 156                 return -1;
 157
 158         if (len > 0)
 159                 memcpy(data_dest, data, len);
 160
 161         return 0;
 162 }