src/marshal.c

   1 /* -*- mode: c; c-file-style: "openbsd" -*- */
   2 /*
   3  * Copyright (c) 2012 Vincent Bernat <bernat@luffy.cx>
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #define MARSHAL_EXPORT
  19 #include "marshal.h"
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <sys/types.h>
  24 #include <sys/queue.h>
  25 #include <string.h>
  26
  27 #include "compat/compat.h"
  28 #include "log.h"
  29
  30 #include "lldpd-structs.h"
  31
  32 /* Stolen from CCAN */
  33 #if HAVE_ALIGNOF
  34 # define ALIGNOF(t) (__alignof__(t))
  35 #else
  36 # define ALIGNOF(t) ((sizeof(t) > 1)?((char *)(&((struct { char c; t _h; } *)0)->_h) - (char *)0):1)
  37 #endif
  38
  39 /* A serialized object */
  40 struct marshal_serialized {
  41         void         *orig;     /* Original reference. Also enforce alignment. */
  42         size_t        size;
  43         unsigned char object[0];
  44 };
  45
  46 struct marshal_info marshal_info_string = {
  47         .name = "null string",
  48         .size = 0,
  49         .pointers = {MARSHAL_SUBINFO_NULL},
  50 };
  51 struct marshal_info marshal_info_fstring = {
  52         .name = "fixed string",
  53         .size = 0,
  54         .pointers = {MARSHAL_SUBINFO_NULL},
  55 };
  56 struct marshal_info marshal_info_ignore = {
  57         .name = "ignored",
  58         .size = 0,
  59         .pointers = {MARSHAL_SUBINFO_NULL},
  60 };
  61
  62 /* List of already seen pointers */
  63 struct ref {
  64         TAILQ_ENTRY(ref) next;
  65         void *pointer;
  66         uintptr_t dummy;        /* To renumerate pointers */
  67 };
  68 TAILQ_HEAD(ref_l, ref);
  69
  70 /* Serialize the given object. */
  71 ssize_t
  72 marshal_serialize_(struct marshal_info *mi, void *unserialized, void **input,
  73     int skip, void *_refs, int osize)
  74 {
  75         struct ref_l *refs = _refs;
  76         struct ref *cref;
  77         int size;
  78         size_t len;
  79         struct marshal_subinfo *current;
  80         struct marshal_serialized *new = NULL, *serialized = NULL;
  81         uintptr_t dummy = 1;
  82
  83         log_debug("marshal", "start serialization of %s", mi->name);
  84
  85         /* Check if we have already serialized this one. */
  86         if (!refs) {
  87                 refs = calloc(1, sizeof(struct ref_l));
  88                 if (!refs) {
  89                         log_warnx("marshal", "unable to allocate memory for list of references");
  90                         return -1;
  91                 }
  92                 TAILQ_INIT(refs);
  93         }
  94         TAILQ_FOREACH(cref, refs, next) {
  95                 if (unserialized == cref->pointer)
  96                         return 0;
  97                 /* dummy should be higher than any existing dummy */
  98                 if (cref->dummy >= dummy) dummy = cref->dummy + 1;
  99         }
 100
 101         /* Handle special cases. */
 102         size = mi->size;
 103         if (!strcmp(mi->name, "null string"))
 104                 /* We know we can't be called with NULL */
 105                 size = strlen((char *)unserialized) + 1;
 106         else if (!strcmp(mi->name, "fixed string"))
 107                 size = osize;
 108
 109         /* Allocate serialized structure */
 110         len = sizeof(struct marshal_serialized) + (skip?0:size);
 111         serialized = calloc(1, len);
 112         if (!serialized) {
 113                 log_warnx("marshal", "unable to allocate memory to serialize structure %s",
 114                     mi->name);
 115                 len = -1;
 116                 goto marshal_error;
 117         }
 118         /* We don't use the original pointer but a dummy one. */
 119         serialized->orig = (unsigned char*)dummy;
 120
 121         /* Append the new reference */
 122         if (!(cref = calloc(1, sizeof(struct ref)))) {
 123                 log_warnx("marshal", "unable to allocate memory for list of references");
 124                 free(serialized);
 125                 len = -1;
 126                 goto marshal_error;
 127         }
 128         cref->pointer = unserialized;
 129         cref->dummy = dummy;
 130         TAILQ_INSERT_TAIL(refs, cref, next);
 131
 132         /* First, serialize the main structure */
 133         if (!skip)
 134                 memcpy(serialized->object, unserialized, size);
 135
 136         /* Then, serialize inner structures */
 137         for (current = mi->pointers; current->mi; current++) {
 138                 size_t sublen;
 139                 size_t padlen;
 140                 void  *source;
 141                 void  *target = NULL;
 142                 if (current->kind == ignore) continue;
 143                 if (current->kind == pointer) {
 144                         memcpy(&source,
 145                             (unsigned char *)unserialized + current->offset,
 146                             sizeof(void *));
 147                         if (source == NULL) continue;
 148                 } else
 149                         source = (void *)((unsigned char *)unserialized + current->offset);
 150                 if (current->offset2)
 151                         memcpy(&osize, (unsigned char*)unserialized + current->offset2, sizeof(int));
 152                 target = NULL;
 153                 sublen = marshal_serialize_(current->mi,
 154                     source, &target,
 155                     current->kind == substruct, refs, osize);
 156                 if (sublen == -1) {
 157                         log_warnx("marshal", "unable to serialize substructure %s for %s",
 158                             current->mi->name, mi->name);
 159                         free(serialized);
 160                         return -1;
 161                 }
 162                 /* We want to put the renumerated pointer instead of the real one. */
 163                 if (current->kind == pointer && !skip) {
 164                         TAILQ_FOREACH(cref, refs, next) {
 165                                 if (source == cref->pointer) {
 166                                         void *fakepointer = (unsigned char*)cref->dummy;
 167                                         memcpy((unsigned char *)serialized->object + current->offset,
 168                                             &fakepointer, sizeof(void *));
 169                                         break;
 170                                 }
 171                         }
 172                 }
 173                 if (sublen == 0) continue; /* This was already serialized */
 174                 /* Append the result, force alignment to be able to unserialize it */
 175                 padlen = ALIGNOF(struct marshal_serialized);
 176                 padlen = (padlen - (len % padlen)) % padlen;
 177                 new = realloc(serialized, len + padlen + sublen);
 178                 if (!new) {
 179                         log_warnx("marshal", "unable to allocate more memory to serialize structure %s",
 180                             mi->name);
 181                         free(serialized);
 182                         free(target);
 183                         len = -1;
 184                         goto marshal_error;
 185                 }
 186                 memset((unsigned char *)new + len, 0, padlen);
 187                 memcpy((unsigned char *)new + len + padlen, target, sublen);
 188                 free(target);
 189                 len += sublen + padlen;
 190                 serialized = (struct marshal_serialized *)new;
 191         }
 192
 193         serialized->size = len;
 194         *input = serialized;
 195 marshal_error:
 196         if (refs && !_refs) {
 197                 struct ref *cref, *cref_next;
 198                 for (cref = TAILQ_FIRST(refs);
 199                      cref != NULL;
 200                      cref = cref_next) {
 201                         cref_next = TAILQ_NEXT(cref, next);
 202                         TAILQ_REMOVE(refs, cref, next);
 203                         free(cref);
 204                 }
 205                 free(refs);
 206         }
 207         return len;
 208 }
 209
 210 /* This structure is used to track memory allocation when serializing */
 211 struct gc {
 212         TAILQ_ENTRY(gc) next;
 213         void *pointer;
 214         void *orig;             /* Original reference (not valid anymore !) */
 215 };
 216 TAILQ_HEAD(gc_l, gc);
 217
 218 static void*
 219 marshal_alloc(struct gc_l *pointers, size_t len, void *orig)
 220 {
 221         struct gc *gpointer = NULL;
 222
 223         void *result = calloc(1, len);
 224         if (!result) return NULL;
 225         if ((gpointer = (struct gc *)calloc(1,
 226                     sizeof(struct gc))) == NULL) {
 227                 free(result);
 228                 return NULL;
 229         }
 230         gpointer->pointer = result;
 231         gpointer->orig = orig;
 232         TAILQ_INSERT_TAIL(pointers, gpointer, next);
 233         return result;
 234 }
 235 static void
 236 marshal_free(struct gc_l *pointers, int gconly)
 237 {
 238         struct gc *pointer, *pointer_next;
 239         for (pointer = TAILQ_FIRST(pointers);
 240              pointer != NULL;
 241              pointer = pointer_next) {
 242                 pointer_next = TAILQ_NEXT(pointer, next);
 243                 TAILQ_REMOVE(pointers, pointer, next);
 244                 if (!gconly)
 245                         free(pointer->pointer);
 246                 free(pointer);
 247         }
 248 }
 249
 250
 251 /* Unserialize the given object. */
 252 size_t
 253 marshal_unserialize_(struct marshal_info *mi, void *buffer, size_t len, void **output,
 254     void *_pointers, int skip, int osize)
 255 {
 256         int    total_len = sizeof(struct marshal_serialized) + (skip?0:mi->size);
 257         struct marshal_serialized *serialized = buffer;
 258         struct gc_l *pointers = _pointers;
 259         int size, already, extra = 0;
 260         void *new;
 261         struct marshal_subinfo *current;
 262         struct gc *apointer;
 263
 264         log_debug("marshal", "start unserialization of %s", mi->name);
 265
 266         if (len < sizeof(struct marshal_serialized) || len < total_len) {
 267                 log_warnx("marshal", "data to deserialize is too small (%zu) for structure %s",
 268                     len, mi->name);
 269                 return 0;
 270         }
 271
 272         /* Initialize garbage collection */
 273         if (!pointers) {
 274                 pointers = calloc(1, sizeof(struct gc_l));
 275                 if (!pointers) {
 276                         log_warnx("marshal", "unable to allocate memory for garbage collection");
 277                         return 0;
 278                 }
 279                 TAILQ_INIT(pointers);
 280         }
 281
 282         /* Special cases */
 283         size = mi->size;
 284         if (!strcmp(mi->name, "null string") || !strcmp(mi->name, "fixed string")) {
 285                 switch (mi->name[0]) {
 286                 case 'n': size = strnlen((char *)serialized->object,
 287                     len - sizeof(struct marshal_serialized)) + 1; break;
 288                 case 'f': size = osize; extra=1; break; /* The extra byte is to ensure that
 289                                                            the string is null terminated. */
 290                 }
 291                 if (size > len - sizeof(struct marshal_serialized)) {
 292                         log_warnx("marshal", "data to deserialize contains a string too long");
 293                         total_len = 0;
 294                         goto unmarshal_error;
 295                 }
 296                 total_len += size;
 297         }
 298
 299         /* First, the main structure */
 300         if (!skip) {
 301                 if ((*output = marshal_alloc(pointers, size + extra, serialized->orig)) == NULL) {
 302                         log_warnx("marshal", "unable to allocate memory to unserialize structure %s",
 303                             mi->name);
 304                         total_len = 0;
 305                         goto unmarshal_error;
 306                 }
 307                 memcpy(*output, serialized->object, size);
 308         }
 309
 310         /* Then, each substructure */
 311         for (current = mi->pointers; current->mi; current++) {
 312                 size_t  sublen;
 313                 size_t  padlen;
 314                 new = (unsigned char *)*output + current->offset;
 315                 if (current->kind == ignore) {
 316                         memset((unsigned char *)*output + current->offset,
 317                                0, sizeof(void *));
 318                         continue;
 319                 }
 320                 if (current->kind == pointer) {
 321                         if (*(void **)new == NULL) continue;
 322
 323                         /* Did we already see this reference? */
 324                         already = 0;
 325                         TAILQ_FOREACH(apointer, pointers, next)
 326                                 if (apointer->orig == *(void **)new) {
 327                                         memcpy((unsigned char *)*output + current->offset,
 328                                             &apointer->pointer, sizeof(void *));
 329                                         already = 1;
 330                                         break;
 331                                 }
 332                         if (already) continue;
 333                 }
 334                 /* Deserialize */
 335                 if (current->offset2)
 336                         memcpy(&osize, (unsigned char *)*output + current->offset2, sizeof(int));
 337                 padlen = ALIGNOF(struct marshal_serialized);
 338                 padlen = (padlen - (total_len % padlen)) % padlen;
 339                 if (len < total_len + padlen || ((sublen = marshal_unserialize_(current->mi,
 340                                 (unsigned char *)buffer + total_len + padlen,
 341                                 len - total_len - padlen, &new, pointers,
 342                                 current->kind == substruct, osize)) == 0)) {
 343                         log_warnx("marshal", "unable to serialize substructure %s for %s",
 344                             current->mi->name, mi->name);
 345                         total_len = 0;
 346                         goto unmarshal_error;
 347                 }
 348                 /* Link the result */
 349                 if (current->kind == pointer)
 350                         memcpy((unsigned char *)*output + current->offset,
 351                             &new, sizeof(void *));
 352                 total_len += sublen + padlen;
 353         }
 354
 355 unmarshal_error:
 356         if (pointers && !_pointers) {
 357                 marshal_free(pointers, (total_len > 0));
 358                 free(pointers);
 359         }
 360         return total_len;
 361 }