serval-dna/overlay_buffer.c

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2011-12-21 09:55:05 +00:00
/*
Serval Distributed Numbering Architecture (DNA)
Copyright (C) 2010 Paul Gardner-Stephen
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "serval.h"
#include "overlay_buffer.h"
/*
When writing to a buffer, sizeLimit may place an upper bound on the amount of space to use
When reading from a buffer, sizeLimit should first be set to the length of any existing data.
In either case, functions that don't take an offset use and advance the position.
*/
struct overlay_buffer *ob_new(void)
{
struct overlay_buffer *ret=calloc(sizeof(struct overlay_buffer),1);
if (!ret) return NULL;
ob_unlimitsize(ret);
return ret;
}
// index an existing static buffer.
// and allow other callers to use the ob_ convenience methods for reading and writing up to size bytes.
struct overlay_buffer *ob_static(unsigned char *bytes, int size){
struct overlay_buffer *ret=calloc(sizeof(struct overlay_buffer),1);
if (!ret) return NULL;
ret->bytes = bytes;
ret->allocSize = size;
ret->allocated = 0;
ob_unlimitsize(ret);
return ret;
}
// create a new overlay buffer from an existing piece of another buffer.
// Both buffers will point to the same memory region.
// It is up to the caller to ensure this buffer is not used after the parent buffer is freed.
struct overlay_buffer *ob_slice(struct overlay_buffer *b, int offset, int length){
if (offset+length > b->allocSize) {
WHY("Buffer isn't long enough to slice");
return NULL;
}
struct overlay_buffer *ret=calloc(sizeof(struct overlay_buffer),1);
if (!ret)
return NULL;
ret->bytes = b->bytes+offset;
ret->allocSize = length;
ret->allocated = 0;
ob_unlimitsize(ret);
return ret;
}
struct overlay_buffer *ob_dup(struct overlay_buffer *b){
struct overlay_buffer *ret=calloc(sizeof(struct overlay_buffer),1);
ret->sizeLimit = b->sizeLimit;
ret->position = b->position;
ret->checkpointLength = b->checkpointLength;
if (b->bytes && b->allocSize){
// duplicate any bytes that might be relevant
int byteCount = b->sizeLimit;
if (byteCount < b->position)
byteCount = b->position;
if (byteCount > b->allocSize)
byteCount = b->allocSize;
ob_append_bytes(ret, b->bytes, byteCount);
}
return ret;
}
int ob_free(struct overlay_buffer *b)
{
if (!b) return WHY("Asked to free NULL");
if (b->bytes && b->allocated) free(b->bytes);
b->bytes=NULL;
b->allocSize=0;
b->sizeLimit=0;
free(b);
return 0;
}
int ob_checkpoint(struct overlay_buffer *b)
{
if (!b) return WHY("Asked to checkpoint NULL");
b->checkpointLength=b->position;
return 0;
}
int ob_rewind(struct overlay_buffer *b)
{
if (!b) return WHY("Asked to rewind NULL");
b->position=b->checkpointLength;
return 0;
}
int ob_limitsize(struct overlay_buffer *b,int bytes)
{
if (!b) return WHY("Asked to limit size of NULL");
if (b->position>bytes) return WHY("Length of data in buffer already exceeds size limit");
if (b->checkpointLength>bytes) return WHY("Checkpointed length of data in buffer already exceeds size limit");
if (b->bytes && (!b->allocated) && bytes > b->allocSize) return WHY("Size limit exceeds buffer size");
if (bytes<0) return WHY("Can't limit buffer to a negative size");
b->sizeLimit=bytes;
return 0;
}
int ob_unlimitsize(struct overlay_buffer *b)
{
if (!b) return WHY("b is NULL");
b->sizeLimit=-1;
return 0;
}
int ob_makespace(struct overlay_buffer *b,int bytes)
{
if (b->sizeLimit!=-1 && b->position+bytes>b->sizeLimit) {
if (debug&DEBUG_PACKETFORMATS) WHY("Asked to make space beyond size limit");
return -1;
}
// already enough space?
if (b->position + bytes < b->allocSize)
return 0;
if (b->bytes && !b->allocated)
return WHY("Can't resize a static buffer");
if (0)
DEBUGF("ob_makespace(%p,%d)\n b->bytes=%p,b->position=%d,b->allocSize=%d\n",
b,bytes,b->bytes,b->position,b->allocSize);
int newSize=b->position+bytes;
if (newSize<64) newSize=64;
if (newSize&63) newSize+=64-(newSize&63);
if (newSize>1024) {
if (newSize&1023) newSize+=1024-(newSize&1023);
}
if (newSize>65536) {
if (newSize&65535) newSize+=65536-(newSize&65535);
}
if (0) DEBUGF("realloc(b->bytes=%p,newSize=%d)", b->bytes,newSize);
/* XXX OSX realloc() seems to be able to corrupt things if the heap is not happy when calling realloc(), making debugging memory corruption much harder.
So will do a three-stage malloc,bcopy,free to see if we can tease the bug out that way. */
/*
unsigned char *r=realloc(b->bytes,newSize);
if (!r) return WHY("realloc() failed");
b->bytes=r;
*/
#ifdef MALLOC_PARANOIA
#warning adding lots of padding to try to catch overruns
if (b->bytes) {
int i;
int corrupt=0;
for(i=0;i<4096;i++) if (b->bytes[b->allocSize+i]!=0xbd) corrupt++;
if (corrupt) {
WHYF("!!!!!! %d corrupted bytes in overrun catch tray", corrupt);
dump("overrun catch tray",&b->bytes[b->allocSize],4096);
sleep(3600);
}
}
unsigned char *new=malloc(newSize+4096);
if (!new) return WHY("realloc() failed");
{
int i;
for(i=0;i<4096;i++) new[newSize+i]=0xbd;
}
#else
unsigned char *new=malloc(newSize);
#endif
bcopy(b->bytes,new,b->position);
if (b->bytes) free(b->bytes);
b->bytes=new;
b->allocated=1;
b->allocSize=newSize;
return 0;
}
/*
Functions that append data and increase the size of the buffer if possible / required
*/
int ob_append_byte(struct overlay_buffer *b,unsigned char byte)
{
if (ob_makespace(b,1)) return WHY("ob_makespace() failed");
b->bytes[b->position++] = byte;
return 0;
}
unsigned char *ob_append_space(struct overlay_buffer *b,int count)
{
if (ob_makespace(b,count)) {
WHY("ob_makespace() failed");
return NULL;
}
unsigned char *r=&b->bytes[b->position];
b->position+=count;
return r;
}
int ob_append_bytes(struct overlay_buffer *b,unsigned char *bytes,int count)
{
if (ob_makespace(b,count)) return WHY("ob_makespace() failed");
bcopy(bytes,&b->bytes[b->position],count);
b->position+=count;
return 0;
}
int ob_append_ui16(struct overlay_buffer *b, uint16_t v)
{
if (ob_makespace(b, 2)) return WHY("ob_makespace() failed");
b->bytes[b->position] = (v >> 8) & 0xFF;
b->bytes[b->position+1] = v & 0xFF;
b->position+=2;
return 0;
}
int ob_append_ui32(struct overlay_buffer *b, uint32_t v)
{
if (ob_makespace(b, 4)) return WHY("ob_makespace() failed");
b->bytes[b->position] = (v >> 24) & 0xFF;
b->bytes[b->position+1] = (v >> 16) & 0xFF;
b->bytes[b->position+2] = (v >> 8) & 0xFF;
b->bytes[b->position+3] = v & 0xFF;
b->position+=4;
return 0;
}
int ob_append_rfs(struct overlay_buffer *b,int l)
{
/* Encode the specified length and append it to the buffer */
if (l<0||l>0xffff) return -1;
/* First work out how long the field needs to be, then write dummy bytes
and use ob_patch_rfs to set the value. That way we have only one
lot of code that does the encoding. */
b->var_length_offset=b->position;
b->var_length_bytes=rfs_length(l);
unsigned char c[3]={0,0,0};
if (ob_append_bytes(b,c,b->var_length_bytes)) {
b->var_length_offset=0;
return -1;
}
return ob_patch_rfs(b,l);
}
/*
Functions that read / write data within the existing length limit
*/
// make sure a range of bytes is valid for reading
int test_offset(struct overlay_buffer *b,int start,int length){
if (!b) return -1;
if (start<0) return -1;
if (b->sizeLimit>=0 && start+length>b->sizeLimit) return -1;
if (start+length>b->allocSize) return -1;
return 0;
}
int ob_getbyte(struct overlay_buffer *b, int ofs)
{
if (test_offset(b, ofs, 1))
return -1;
return b->bytes[ofs];
}
int ob_get_bytes(struct overlay_buffer *b, unsigned char *buff, int len){
if (test_offset(b, b->position, len))
return -1;
bcopy(b->bytes + b->position, buff, len);
b->position+=len;
return 0;
}
unsigned char * ob_get_bytes_ptr(struct overlay_buffer *b, int len){
if (test_offset(b, b->position, len))
return NULL;
unsigned char *ret = b->bytes + b->position;
b->position+=len;
return ret;
}
uint32_t ob_get_ui32(struct overlay_buffer *b)
{
if (test_offset(b, b->position, 4))
return 0xFFFFFFFF; // ... unsigned
uint32_t ret = b->bytes[b->position] << 24
| b->bytes[b->position +1] << 16
| b->bytes[b->position +2] << 8
| b->bytes[b->position +3];
b->position+=4;
return ret;
}
uint16_t ob_get_ui16(struct overlay_buffer *b)
{
if (test_offset(b, b->position, 2))
return 0xFFFF; // ... unsigned
uint16_t ret = b->bytes[b->position] << 8
| b->bytes[b->position +1];
b->position+=2;
return ret;
}
int ob_get(struct overlay_buffer *b){
if (test_offset(b, b->position, 1))
return -1;
return b->bytes[b->position++];
}
int rfs_length(int l)
{
if (l<0) return -1;
if (l<250) return 1;
else if (l<(255+250+(256*4))) return 2;
else if (l<=0xffff) return 3;
else return -1;
}
int rfs_encode(int l, unsigned char *b)
{
if (l<250) { b[0]=l; }
else if (l<(255+250+(256*4))) {
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l-=250;
int page=(l>>8);
l&=0xff;
b[0]=RFS_PLUS250+page;
b[1]=l;
} else {
b[0]=RFS_3BYTE;
b[1]=l>>8;
b[2]=l&0xff;
}
return 0;
}
int rfs_decode(unsigned char *b,int *ofs)
{
int rfs=b[*ofs];
switch(rfs) {
case RFS_PLUS250: case RFS_PLUS456: case RFS_PLUS762: case RFS_PLUS1018: case RFS_PLUS1274:
rfs=250+256*(rfs-RFS_PLUS250)+b[++(*ofs)];
break;
case RFS_3BYTE: rfs=(b[(*ofs)+1]<<8)+b[(*ofs)+2]; (*ofs)+=2;
default: /* Length is natural value of field, so nothing to do */
break;
}
(*ofs)++;
return rfs;
}
// move the data at offset, by shift bytes
int ob_indel_space(struct overlay_buffer *b,int offset,int shift)
{
if (offset>=b->position) return -1;
if (shift>0 && ob_makespace(b, shift)) return -1;
bcopy(&b->bytes[offset],&b->bytes[offset+shift],b->position-offset);
b->position+=shift;
return 0;
}
int ob_patch_rfs(struct overlay_buffer *b,int l)
{
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if (l==COMPUTE_RFS_LENGTH){
// assume the payload has been written, we can now calculate the actual length
l = b->position - (b->var_length_offset + b->var_length_bytes);
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}
if (l<0||l>0xffff) return -1;
/* Adjust size of field */
int new_size=rfs_length(l);
int shift=new_size - b->var_length_bytes;
if (shift) {
if (debug&DEBUG_PACKETCONSTRUCTION) {
DEBUGF("Patching RFS for rfs_size=%d (was %d), so indel %d btyes",
new_size,b->var_length_bytes,shift);
dump("before indel",
&b->bytes[b->var_length_offset],
b->position-b->var_length_offset);
}
if (ob_indel_space(b, b->var_length_offset + b->var_length_bytes, shift)) return -1;
if (debug&DEBUG_PACKETCONSTRUCTION) {
dump("after indel",
&b->bytes[b->var_length_offset],
b->position-b->var_length_offset);
}
}
if (rfs_encode(l,&b->bytes[b->var_length_offset])) return -1;
if (debug&DEBUG_PACKETCONSTRUCTION) {
dump("after patch",
&b->bytes[b->var_length_offset],
b->position-b->var_length_offset);
}
return 0;
}
int asprintable(int c)
{
if (c<' ') return '.';
if (c>0x7e) return '.';
return c;
}
int ob_dump(struct overlay_buffer *b,char *desc)
{
DEBUGF("overlay_buffer '%s' at %p : length=%d", desc, b, b->position);
dump(NULL, b->bytes, b->position);
return 0;
}
#undef malloc
#undef calloc
#undef free
#undef realloc
#define SDM_GUARD_AFTER 16384
void *_serval_debug_malloc(unsigned int bytes, struct __sourceloc where)
{
void *r=malloc(bytes+SDM_GUARD_AFTER);
logMessage(LOG_LEVEL_DEBUG, where, "malloc(%d) -> %p", bytes, r);
return r;
}
void *_serval_debug_calloc(unsigned int bytes, unsigned int count, struct __sourceloc where)
{
void *r=calloc((bytes*count)+SDM_GUARD_AFTER,1);
logMessage(LOG_LEVEL_DEBUG, where, "calloc(%d,%d) -> %p", bytes, count, r);
return r;
}
void _serval_debug_free(void *p, struct __sourceloc where)
{
free(p);
logMessage(LOG_LEVEL_DEBUG, where, "free(%p)", p);
}