silentbob/silentbob-1.4/gclib/src/dns_low.cxx

   1 /*
   2  * (c) Oleg Puchinin 2006
   3  * graycardinalster@gmail.com
   4  *
   5  */
   6
   7 #include <gclib.h>
   8 #include <dns.h>
   9 #include <gclib_c.h>
  10
  11 extern int dns_last_id;
  12
  13 char * __name2dns (char *name, int *len)
  14 {
  15         char * d_buf;
  16         char * ptr;
  17         DList * list;
  18         __dlist_entry_t * one;
  19
  20         list = new DList;
  21         Dsplit (name, ".", list);
  22         d_buf = CNEW (char, 70);
  23         ptr = d_buf;
  24
  25         one = list->get_head ();
  26         while (one) {
  27                 buf_W8 (&ptr, strlen (one->data));
  28                 buf_WS (&ptr, one->data);
  29                 one = one->next;
  30         }
  31
  32         buf_W8 (&ptr, 0);
  33         delete list;
  34         if (len)
  35                 *len = ptr - d_buf;
  36         return d_buf;
  37 }
  38
  39 inline char * __ddup (char * ptr, unsigned char ch)
  40 {
  41         char *S = CNEW (char, ch+2);
  42         memcpy (S, ptr, ch);
  43         S[ch] = '.';
  44         S[ch+1] = '\0';
  45         return S;
  46 }
  47
  48 char * __dns_rd_chunk (DPBuf * p, char ** ptr, char * done)
  49 {
  50         char * ret;
  51         unsigned char ch;
  52
  53         if (! p->check (*ptr, 1))
  54                 return NULL;
  55
  56         ch = buf_R8 (ptr);
  57         if (! ch) {
  58                 *done = -1;
  59                 return NULL;
  60         }
  61
  62         if (ch & 0xc0) {
  63                 ret = NULL;
  64                 --(*ptr);
  65         } else {
  66                 if (! p->check (*ptr, ch))
  67                         return NULL;
  68                 ret = __ddup (*ptr, ch);
  69                 (*ptr) += ch;
  70         }
  71
  72         return ret;
  73 }
  74
  75 char * __dns_resp_domain (DPBuf * p, char * domain, char **domain_end)
  76 {
  77         unsigned char ch;
  78         uint16_t offset;
  79         char * ptr;
  80         char buf[128];
  81         char *S;
  82         char done = 0;
  83         bool d_try = true;
  84         int n = 20;
  85
  86         if (! p || ! domain)
  87                 return NULL;
  88
  89         buf[0] = 0;
  90         memset (buf, 0, 128);
  91         ptr = domain;
  92
  93 drd_try:
  94         while (true) {
  95                 S = __dns_rd_chunk (p, &ptr, &done);
  96                 if (done || ! S)
  97                         break;
  98
  99                 strcat (buf, S);
 100                 DROP (S);
 101         }
 102
 103         if ((domain_end != NULL) & d_try)
 104                 *domain_end = ptr;
 105
 106         if (! done) {
 107                 if (! p->check (ptr, 2))
 108                         return NULL;
 109
 110                 if (! --n)
 111                         return NULL;
 112
 113                 ch = buf_R8 (&ptr);
 114                 offset = (ch &= ~0xc0) << 8;
 115                 offset += buf_R8 (&ptr);
 116                 d_try = false;
 117                 ptr = &p->begin[offset];
 118                 goto drd_try;
 119         }
 120
 121         if (domain_end && ! d_try)
 122                 *domain_end += 2;
 123
 124         chop (buf);
 125         if (strlen (buf) > 0)
 126                 return strdup (buf);
 127         else
 128                 return NULL;
 129 }
 130
 131 char * make_dns_pkt (uint16_t id, uint16_t flags, uint16_t d_type,
 132                 uint16_t d_class, char * domain, int *len)
 133 {
 134         char * pkt;
 135         char * ptr;
 136         char * dns_name;
 137         int dns_len;
 138         struct dns_header hdr;
 139
 140         pkt = CNEW (char, 512);
 141         ptr = pkt;
 142         memset (&hdr, 0, sizeof (struct dns_header));
 143         hdr.id = htons (id);
 144         hdr.flags = htons (flags);
 145         hdr.nr = htons (1);
 146         buf_Wstruct (&ptr, &hdr);
 147
 148         dns_name = __name2dns (domain, &dns_len);
 149         memcpy (ptr, dns_name, dns_len);
 150         DROP (dns_name);
 151         ptr += dns_len;
 152
 153         buf_W16 (&ptr, htons (d_type)); // "A"
 154         buf_W16 (&ptr, htons (d_class)); // Internet
 155
 156         if (len)
 157                 *len = ptr-pkt;
 158
 159         return pkt;
 160 }
 161
 162 DList * dns_resp_split (dns_header *hdr, char *pkt, int len)
 163 {
 164         dns_header *query_hdr;
 165         dns_rheader *res_hdr = NULL;
 166         dns_reply *reply = NULL;
 167         char * d_end;
 168         char * d_name;
 169         uint16_t dr_type;
 170         uint16_t dr_class;
 171         DPBuf * p = NULL;
 172         char * ptr;
 173         DList * ret;
 174
 175         p = new DPBuf (pkt, len);
 176         query_hdr = (dns_header *) p->rd (pkt, sizeof (dns_header));
 177         if (! p->ok)
 178                 goto drs_out;
 179
 180         if (query_hdr->id != hdr->id)
 181                 goto drs_out;
 182
 183         ptr = &p->begin[sizeof (dns_header)];
 184         d_name = __dns_resp_domain (p, ptr, &d_end);
 185         if (d_name == NULL)
 186                 goto drs_out;
 187
 188         DROP (d_name);
 189         ptr = d_end;
 190
 191         if (! p->check (ptr, 4))
 192                 goto drs_out;
 193
 194         dr_type = htons (buf_R16 (&ptr));
 195         dr_class = htons (buf_R16 (&ptr));
 196
 197         reply = NULL;
 198         ret = new DList;
 199
 200         while (true) {
 201                 reply = CNEW (dns_reply, 1);
 202                 memset (reply, 0, sizeof (dns_reply));
 203
 204                 reply->domain = __dns_resp_domain (p, ptr, &d_end);
 205                 if (! reply->domain)
 206                         break;
 207
 208                 ptr = d_end;
 209                 res_hdr = NULL;
 210
 211                 if (! p->check (ptr, sizeof (struct dns_rheader)))
 212                         break;
 213
 214                 res_hdr = buf_Rstruct (&ptr, dns_rheader);
 215                 reply->TTL = htonl (res_hdr->TTL);
 216                 reply->data_len = htons (res_hdr->len);
 217                 reply->dr_type = htons (res_hdr->dr_type);
 218                 reply->dr_class = htons (res_hdr->dr_class);
 219                 if (! p->check (ptr, reply->data_len))
 220                         goto drs_out;
 221
 222                 reply->pkt_data_ptr = ptr;
 223                 reply->data = buf_RD (&ptr, reply->data_len);
 224                 ret->add_tail (LPCHAR (reply));
 225         }
 226
 227         delete p;
 228         return ret;
 229
 230 drs_out:
 231         if (reply) {
 232                 DROP (reply->domain);
 233                 DROP (reply);
 234                 DROP (reply->data);
 235         }
 236
 237         DROP (res_hdr);
 238         delete p;
 239         return NULL;
 240
 241 }
 242
 243 void dns_resp_clean (DList * list)
 244 {
 245         __dlist_entry_t *one;
 246         dns_reply * reply;
 247
 248         if (! list)
 249                 return;
 250
 251         while ((one = list->get_head ()) && one) {
 252                 reply = (dns_reply *) one->data;
 253                 DROP (reply->domain);
 254                 DROP (reply->data);
 255                 DROP (reply);
 256                 list->rm (one);
 257         }
 258         delete list;
 259 }
 260
 261 dns_reply * dns_scan (DList *list, uint16_t dr_type, uint16_t dr_class)
 262 {
 263         __dlist_entry_t * one;
 264         dns_reply *Ret = NULL;
 265         dns_reply *reply = NULL;
 266
 267         if (! list)
 268                 return NULL;
 269
 270         one = list->get_head ();
 271         if (! one)
 272                 return NULL;
 273
 274         while (one) {
 275                 reply = (dns_reply *) one->data;
 276                 if (reply->dr_type == dr_type && reply->dr_class == dr_class) {
 277                         Ret = reply;
 278                         break;
 279                 }
 280                 one = one->next;
 281         }
 282
 283         return Ret;
 284 }
 285