src/packet.c

   1 /* $Id$
   2  * UDP Gateway utility packet assembly and disassembly layer
   3  * Copyright (C) 2004 Jan Kratochvil <project-udpgate@jankratochvil.net>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; exactly version 2 of June 1991 is required
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17  */
  18
  19
  20 /* Protocol documentation:
  21  * 8 bytes: "UDPGate0" (55 44 50 47 61 74 65 30) = Packet identifier
  22  * Follows arbitrary number of elements in no particular order.
  23  * Structure of each such element:
  24  * 4 bytes: element identifier; network byte order
  25  *     bit 31 (0x80000000) means mandatory element:
  26  *         If the element is not recognized the packet must be dropped.
  27  *     bits 0..30 (0x7FFFFFFF) specify element id.
  28  * 4 bytes: element data length; network byte order
  29  * X bytes: element data; minimal data alignment is 1 byte (=no alignment)
  30  * Known elements; see: http://cvs.jankratochvil.net/viewcvs/udpgate/src/packet.h?rev=HEAD
  31  *     PROGRAM_VERSION: data=string (no zero terminator); currently "1.0"
  32  *         This element is currently ignored.
  33  *     CLIENT_INADDR: Client IPv4 address; network byte order; length=4B
  34  *     CLIENT_PORT: Client IPv4 port; network byte order; length=2B
  35  *     DATA_GUINT32: Session unique number; network byte order; length=4B
  36  *         Reply packet will copy this element intact.
  37  * Step 1:
  38  *     Client sends from port A (35545 here) to port 8201 (probe port) packet:
  39  *         PROGRAM_VERSION (of the client udpgate)
  40  *         CLIENT_PORT (chosen port; default is 9201)
  41  *         DATA_GUINT32 (chosen random number)
  42  *     Example:
  43  *         09:07:01.966123 127.0.0.1.35545 > 127.0.0.1.8201: udp 44 (DF)
  44  *            16=$0010: <UDP packet headers................> 55 44 50 47 |             UDPG
  45  *            32=$0020: 61 74 65 30 80 00 00 01  00 00 00 06 31 2E 30 63 | ate0........1.0c
  46  *            48=$0030: 76 73 80 00 00 03 00 00  00 02 1A 0A 80 00 00 04 | vs..............
  47  *            64=$0040: 00 00 00 04 99 E1 4B 04                          | ......K.
  48  * Step 2:
  49  *     Probe server replies from port B (currently always 8201) to the packet
  50  *             originating address CLIENT_INADDR and the received CLIENT_PORT:
  51  *         PROGRAM_VERSION (of the probe server)
  52  *         CLIENT_INADDR (detected from the originating packet address)
  53  *         DATA_GUINT32 (copied from the request packet)
  54  *     Example:
  55  *         09:07:01.970252 127.0.0.1.8201 > 127.0.0.1.6666: udp 46 (DF)
  56  *            16=$0010: <UDP packet headers................> 55 44 50 47 |             UDPG
  57  *            32=$0020: 61 74 65 30 80 00 00 01  00 00 00 06 31 2E 30 63 | ate0........1.0c
  58  *            48=$0030: 76 73 80 00 00 02 00 00  00 04 7F 00 00 01 80 00 | vs..............
  59  *            64=$0040: 00 04 00 00 00 04 99 E1  4B 04                   | ........K.
  60  * Step 3:
  61  *     Client must ignore probe replies with nonmatching DATA_GUINT32.
  62  *     Client will stop if no probe reply is received in PROBE_TIMEOUT_SEC.
  63  *     Client displays the received CLIENT_INADDR to the user.
  64  */
  65
  66
  67 #include "config.h"
  68
  69 #include <glib/gmessages.h>
  70 #include <glib/gstring.h>
  71 #include <glib/ghash.h>
  72 #include <netinet/in.h>
  73 #include <string.h>
  74 #include <glib/gslist.h>
  75
  76 #include "packet.h"
  77 #include "main.h"       /* for optarg_verbose */
  78
  79
  80 static void packet_assembly_guint32(GString *gstring,guint32 value_guint32)
  81 {
  82 guint32 value_guint32_htonl;
  83
  84         g_return_if_fail(gstring!=NULL);
  85
  86         value_guint32_htonl=htonl(value_guint32);
  87         g_assert(4==sizeof(value_guint32_htonl));
  88         g_string_append_len(gstring,(const gchar *)&value_guint32_htonl,sizeof(value_guint32_htonl));
  89 }
  90
  91 static void packet_assembly_guint16(GString *gstring,guint16 value_guint16)
  92 {
  93 guint16 value_guint16_htonl;
  94
  95         g_return_if_fail(gstring!=NULL);
  96
  97         value_guint16_htonl=htons(value_guint16);
  98         g_assert(2==sizeof(value_guint16_htonl));
  99         g_string_append_len(gstring,(const gchar *)&value_guint16_htonl,sizeof(value_guint16_htonl));
 100 }
 101
 102 static void packet_assembly_data_guint32(GString *gstring,guint32 value_guint32)
 103 {
 104         g_return_if_fail(gstring!=NULL);
 105
 106         g_assert(4==sizeof(value_guint32));
 107         packet_assembly_guint32(gstring,sizeof(value_guint32));
 108         packet_assembly_guint32(gstring,value_guint32);
 109 }
 110
 111 static void packet_assembly_data_guint16(GString *gstring,guint16 value_guint16)
 112 {
 113         g_return_if_fail(gstring!=NULL);
 114
 115         g_assert(2==sizeof(value_guint16));
 116         packet_assembly_guint32(gstring,sizeof(value_guint16));
 117         packet_assembly_guint16(gstring,value_guint16);
 118 }
 119
 120 static void packet_assembly_data_string(GString *gstring,const gchar *string)
 121 {
 122 size_t string_length;
 123 #ifndef G_DISABLE_ASSERT
 124 size_t gstring_length_orig;
 125 #endif  /* !G_DISABLE_ASSERT */
 126
 127         g_return_if_fail(gstring!=NULL);
 128         g_return_if_fail(string!=NULL);
 129
 130         string_length=strlen(string);
 131         packet_assembly_guint32(gstring,string_length);
 132 #ifndef G_DISABLE_ASSERT
 133         gstring_length_orig=gstring->len;
 134 #endif  /* !G_DISABLE_ASSERT */
 135         g_string_append(gstring,string);
 136 #ifndef G_DISABLE_ASSERT
 137         g_assert(gstring_length_orig+string_length==gstring->len);
 138 #endif  /* !G_DISABLE_ASSERT */
 139 }
 140
 141 static void packet_assembly_foreach(gpointer elem_type_gpointer,gpointer value,GString *gstring /* user_data */)        /* GHFunc */
 142 {
 143 guint32 elem_type_uint32;
 144
 145         g_return_if_fail(gstring!=NULL);
 146
 147         elem_type_uint32=GPOINTER_TO_UINT(elem_type_gpointer);
 148         packet_assembly_guint32(gstring,elem_type_uint32);
 149
 150         switch (elem_type_uint32) {
 151                 case PACKET_ELEM_TYPE_PROGRAM_VERSION:
 152                         packet_assembly_data_string(gstring,value);
 153                         if (optarg_verbose)
 154                                 g_message(_("Assembled PROGRAM_VERSION: %s"),(const char *)value);
 155                         break;
 156                 case PACKET_ELEM_TYPE_CLIENT_INADDR:
 157                         packet_assembly_data_guint32(gstring,GPOINTER_TO_UINT(value));
 158                         if (optarg_verbose)
 159                                 g_message(_("Assembled CLIENT_INADDR: %s"),HOSTIP_GUINT32_TO_STRING(GPOINTER_TO_UINT(value)));
 160                         break;
 161                 case PACKET_ELEM_TYPE_DATA_GUINT32:
 162                         packet_assembly_data_guint32(gstring,GPOINTER_TO_UINT(value));
 163                         if (optarg_verbose)
 164                                 g_message(_("Assembled DATA_GUINT32: 0x%08X"),(unsigned)GPOINTER_TO_UINT(value));
 165                         break;
 166                 case PACKET_ELEM_TYPE_CLIENT_PORT:
 167                         packet_assembly_data_guint16(gstring,GPOINTER_TO_UINT(value));
 168                         if (optarg_verbose)
 169                                 g_message(_("Assembled CLIENT_PORT: %d"),(int)GPOINTER_TO_UINT(value));
 170                         break;
 171                 default:
 172                         g_assert_not_reached();
 173                 }
 174 }
 175
 176 void *packet_assembly(size_t *packet_length_pointer,GHashTable *values)
 177 {
 178 GString *gstring;
 179
 180         g_return_val_if_fail(packet_length_pointer!=NULL,NULL);
 181         g_return_val_if_fail(values!=NULL,NULL);
 182
 183         if (optarg_verbose)
 184                 g_message(_("Assembling packet..."));
 185
 186         gstring=g_string_new(NULL);
 187
 188         g_string_append(gstring,PACKET_HEADER);
 189
 190         packet_assembly_foreach(GINT_TO_POINTER(PACKET_ELEM_TYPE_PROGRAM_VERSION),VERSION,gstring);
 191         g_hash_table_foreach(
 192                         values, /* hash_table */
 193                         (GHFunc)packet_assembly_foreach,        /* func */
 194                         gstring);       /* user_data */
 195
 196         if (optarg_verbose)
 197                 g_message(_("Packet assembly done."));
 198
 199         *packet_length_pointer=gstring->len;
 200         return g_string_free(gstring,
 201                         FALSE); /* free_segment */
 202 }
 203
 204 static gboolean packet_disassembly_guint32
 205                 (guint32 *elem_type_guint32_pointer,gconstpointer *packet_pointer,gconstpointer packet_end)
 206 {
 207         g_return_val_if_fail(elem_type_guint32_pointer!=NULL,FALSE);
 208         g_return_val_if_fail(packet_pointer!=NULL,FALSE);
 209         g_return_val_if_fail(packet_end!=NULL,FALSE);
 210         g_return_val_if_fail(*packet_pointer<=packet_end,FALSE);
 211
 212         if ((*packet_pointer)+sizeof(*elem_type_guint32_pointer)>packet_end)
 213                 return FALSE;
 214
 215         *elem_type_guint32_pointer=ntohl(*((guint32 *)*packet_pointer));
 216         (*packet_pointer)+=sizeof(*elem_type_guint32_pointer);
 217         return TRUE;
 218 }
 219
 220 static void packet_disassembly_value_destroy_func(gpointer data)        /* GDestroyNotify */
 221 {
 222
 223 }
 224
 225 /* map: (GHashTable *) -> (GSList *) */
 226 static GHashTable *packet_disassembly_destroy_registry;
 227
 228 static void packet_disassembly_destroy_key_destroy_func(GHashTable *hash) /* GDestroyNotify */
 229 {
 230         g_return_if_fail(hash!=NULL);
 231
 232         g_hash_table_destroy(hash);
 233 }
 234
 235 static void packet_disassembly_destroy_value_destroy_func(GSList *items)        /* GDestroyNotify */
 236 {
 237         /* 'items' may be NULL */
 238
 239         g_slist_foreach(
 240                         items,  /* list */
 241                         (GFunc)g_free,  /* func */
 242                         NULL);  /* user_data */
 243 }
 244
 245 static void packet_disassembly_destroy_registry_init(void)
 246 {
 247         if (!packet_disassembly_destroy_registry) {
 248                 packet_disassembly_destroy_registry=g_hash_table_new_full(
 249                         g_direct_hash,  /* hash_func */
 250                         g_direct_equal, /* key_equal_func */
 251                         (GDestroyNotify)packet_disassembly_destroy_key_destroy_func,    /* key_destroy_func */
 252                         (GDestroyNotify)packet_disassembly_destroy_value_destroy_func); /* value_destroy_func */
 253                 }
 254 }
 255
 256 void packet_disassembly_destroy(GHashTable *hash)
 257 {
 258 gboolean errgboolean;
 259
 260         g_return_if_fail(hash!=NULL);
 261
 262         packet_disassembly_destroy_registry_init();
 263
 264         errgboolean=g_hash_table_remove(packet_disassembly_destroy_registry,hash);
 265         g_assert(errgboolean==TRUE);
 266 }
 267
 268 static gboolean packet_disassembly_data_string
 269                 (gpointer *value_pointer,gconstpointer elem_data,guint32 elem_data_length_guint32,GSList **items_pointer)
 270 {
 271 gchar *string;
 272
 273         g_return_val_if_fail(value_pointer!=NULL,FALSE);
 274         g_return_val_if_fail(elem_data!=NULL,FALSE);
 275         g_return_val_if_fail(items_pointer!=NULL,FALSE);
 276
 277         udpgate_newn(string,elem_data_length_guint32+1);
 278         *items_pointer=g_slist_prepend(*items_pointer,string);
 279         memcpy(string,elem_data,elem_data_length_guint32);
 280         string[elem_data_length_guint32]='\0';
 281         *value_pointer=string;
 282
 283         return TRUE;
 284 }
 285
 286 static gboolean packet_disassembly_data_guint32
 287                 (gpointer *value_pointer,gconstpointer elem_data,guint32 elem_data_length_guint32,GSList **items_pointer)
 288 {
 289 guint32 value_guint32;
 290
 291         g_return_val_if_fail(value_pointer!=NULL,FALSE);
 292         g_return_val_if_fail(elem_data!=NULL,FALSE);
 293         g_return_val_if_fail(items_pointer!=NULL,FALSE);
 294
 295         g_assert(4==sizeof(value_guint32));
 296         if (elem_data_length_guint32!=sizeof(value_guint32))
 297                 return FALSE;
 298
 299         value_guint32=ntohl(*(guint32 *)elem_data);
 300         *value_pointer=GUINT_TO_POINTER(value_guint32);
 301
 302         return TRUE;
 303 }
 304
 305 static gboolean packet_disassembly_data_guint16
 306                 (gpointer *value_pointer,gconstpointer elem_data,guint32 elem_data_length_guint32,GSList **items_pointer)
 307 {
 308 guint16 value_guint16;
 309
 310         g_return_val_if_fail(value_pointer!=NULL,FALSE);
 311         g_return_val_if_fail(elem_data!=NULL,FALSE);
 312         g_return_val_if_fail(items_pointer!=NULL,FALSE);
 313
 314         g_assert(2==sizeof(value_guint16));
 315         if (elem_data_length_guint32!=sizeof(value_guint16))
 316                 return FALSE;
 317
 318         value_guint16=ntohs(*(guint16 *)elem_data);
 319         *value_pointer=GUINT_TO_POINTER((guint)value_guint16);
 320
 321         return TRUE;
 322 }
 323
 324 gboolean packet_recognized(gconstpointer packet,size_t packet_length)
 325 {
 326         if (strlen(PACKET_HEADER)>packet_length)
 327                 return FALSE;
 328         if (memcmp(packet,PACKET_HEADER,strlen(PACKET_HEADER)))
 329                 return FALSE;
 330         return TRUE;
 331 }
 332
 333 GHashTable *packet_disassembly(gconstpointer packet,size_t packet_length)
 334 {
 335 GHashTable *r;
 336 gconstpointer packet_end;
 337 GSList *items;
 338
 339         g_return_val_if_fail(packet!=NULL,NULL);
 340
 341         if (optarg_verbose)
 342                 g_message(_("Decoding packet..."));
 343
 344         r=g_hash_table_new_full(
 345                         g_direct_hash,  /* hash_func */
 346                         g_direct_equal, /* key_equal_func */
 347                         NULL,   /* key_destroy_func */
 348                         packet_disassembly_value_destroy_func); /* value_destroy_func */
 349         packet_end=packet+packet_length;
 350
 351         if (packet+strlen(PACKET_HEADER)>packet_end) {
 352 err_g_hash_table_destroy_r:
 353                 g_hash_table_destroy(r);
 354                 return NULL;
 355                 }
 356         if (memcmp(packet,PACKET_HEADER,strlen(PACKET_HEADER)))
 357                 goto err_g_hash_table_destroy_r;
 358         packet+=strlen(PACKET_HEADER);
 359
 360         items=NULL;
 361         while (packet<packet_end) {
 362 guint32 elem_type_guint32;
 363 guint32 elem_data_length_guint32;
 364 gconstpointer elem_data;
 365 gpointer value;
 366
 367                 if (!packet_disassembly_guint32(&elem_type_guint32,&packet,packet_end)) {
 368 err_packet_disassembly_destroy_value_destroy_func_items:
 369                         /* 'items' are not yet registered in 'packet_disassembly_destroy_registry' */
 370                         packet_disassembly_destroy_value_destroy_func(items);
 371                         goto err_g_hash_table_destroy_r;
 372                         }
 373                 if (!packet_disassembly_guint32(&elem_data_length_guint32,&packet,packet_end))
 374                         goto err_packet_disassembly_destroy_value_destroy_func_items;
 375                 elem_data=packet;
 376                 packet+=elem_data_length_guint32;
 377
 378                 switch (elem_type_guint32) {
 379                 case PACKET_ELEM_TYPE_PROGRAM_VERSION:
 380                         if (!packet_disassembly_data_string(&value,elem_data,elem_data_length_guint32,&items))
 381                                 goto err_packet_disassembly_destroy_value_destroy_func_items;
 382                         if (optarg_verbose)
 383                                 g_message(_("Decoded PROGRAM_VERSION: %s"),(const char *)value);
 384                         break;
 385                 case PACKET_ELEM_TYPE_CLIENT_INADDR:
 386                         if (!packet_disassembly_data_guint32(&value,elem_data,elem_data_length_guint32,&items))
 387                                 goto err_packet_disassembly_destroy_value_destroy_func_items;
 388                         if (optarg_verbose)
 389                                 g_message(_("Decoded CLIENT_INADDR: %s"),HOSTIP_GUINT32_TO_STRING(GPOINTER_TO_UINT(value)));
 390                         break;
 391                 case PACKET_ELEM_TYPE_DATA_GUINT32:
 392                         if (!packet_disassembly_data_guint32(&value,elem_data,elem_data_length_guint32,&items))
 393                                 goto err_packet_disassembly_destroy_value_destroy_func_items;
 394                         if (optarg_verbose)
 395                                 g_message(_("Decoded DATA_GUINT32: 0x%08X"),(unsigned)GPOINTER_TO_UINT(value));
 396                         break;
 397                 case PACKET_ELEM_TYPE_CLIENT_PORT:
 398                         if (!packet_disassembly_data_guint16(&value,elem_data,elem_data_length_guint32,&items))
 399                                 goto err_packet_disassembly_destroy_value_destroy_func_items;
 400                         if (optarg_verbose)
 401                                 g_message(_("Decoded CLIENT_PORT: %d"),GPOINTER_TO_UINT(value));
 402                         break;
 403                 default:
 404                         if (elem_type_guint32&PACKET_ELEM_ATTR_MANDATORY) {
 405                                 if (optarg_verbose)
 406                                         g_message(_("Decoding failed on ATTR_MANDATORY ELEM code 0x%08X"),(unsigned)elem_type_guint32);
 407                                 goto err_packet_disassembly_destroy_value_destroy_func_items;
 408                                 }
 409                         else {
 410                                 if (optarg_verbose)
 411                                         g_message(_("Decoding ignores ATTR_OPTIONAL ELEM code 0x%08X"),(unsigned)elem_type_guint32);
 412                                 }
 413                         continue;
 414                         }
 415                 g_hash_table_insert(r,GUINT_TO_POINTER(elem_type_guint32),value);
 416                 }
 417         g_assert(packet==packet_end);
 418
 419         packet_disassembly_destroy_registry_init();
 420         g_hash_table_insert(packet_disassembly_destroy_registry,r,items);
 421
 422         if (optarg_verbose)
 423                 g_message(_("Decoding done."));
 424
 425         return r;
 426 }