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/* enc_read.c */
/* Copyright (C) 1993 Eric Young - see README for more details */
/*-
* $Id: enc_read.c,v 1.2 1994/07/19 19:21:54 g89r4222 Exp $
*/
#include <errno.h>
#include "des_locl.h"
/* This has some uglies in it but it works - even over sockets. */
extern int errno;
int des_rw_mode=DES_PCBC_MODE;
int des_enc_read(fd,buf,len,sched,iv)
int fd;
char *buf;
int len;
des_key_schedule sched;
des_cblock *iv;
{
/* data to be unencrypted */
int net_num=0;
unsigned char net[BSIZE];
/* extra unencrypted data
* for when a block of 100 comes in but is des_read one byte at
* a time. */
static char unnet[BSIZE];
static int unnet_start=0;
static int unnet_left=0;
int i;
long num=0,rnum;
unsigned char *p;
/* left over data from last decrypt */
if (unnet_left != 0)
{
if (unnet_left < len)
{
/* we still still need more data but will return
* with the number of bytes we have - should always
* check the return value */
bcopy(&(unnet[unnet_start]),buf,unnet_left);
/* eay 26/08/92 I had the next 2 lines
* reversed :-( */
i=unnet_left;
unnet_start=unnet_left=0;
}
else
{
bcopy(&(unnet[unnet_start]),buf,len);
unnet_start+=len;
unnet_left-=len;
i=len;
}
return(i);
}
/* We need to get more data. */
if (len > MAXWRITE) len=MAXWRITE;
/* first - get the length */
net_num=0;
while (net_num < HDRSIZE)
{
i=read(fd,&(net[net_num]),HDRSIZE-net_num);
if ((i == -1) && (errno == EINTR)) continue;
if (i <= 0) return(0);
net_num+=i;
}
/* we now have at net_num bytes in net */
p=net;
num=0;
n2l(p,num);
/* num should be rounded up to the next group of eight
* we make sure that we have read a multiple of 8 bytes from the net.
*/
if ((num > MAXWRITE) || (num < 0)) /* error */
return(-1);
rnum=(num < 8)?8:((num+7)/8*8);
net_num=0;
while (net_num < rnum)
{
i=read(fd,&(net[net_num]),rnum-net_num);
if ((i == -1) && (errno == EINTR)) continue;
if (i <= 0) return(0);
net_num+=i;
}
/* Check if there will be data left over. */
if (len < num)
{
if (des_rw_mode & DES_PCBC_MODE)
pcbc_encrypt((des_cblock *)net,(des_cblock *)unnet,
num,sched,iv,DES_DECRYPT);
else
cbc_encrypt((des_cblock *)net,(des_cblock *)unnet,
num,sched,iv,DES_DECRYPT);
bcopy(unnet,buf,len);
unnet_start=len;
unnet_left=num-len;
/* The following line is done because we return num
* as the number of bytes read. */
num=len;
}
else
{
/* >output is a multiple of 8 byes, if len < rnum
* >we must be careful. The user must be aware that this
* >routine will write more bytes than he asked for.
* >The length of the buffer must be correct.
* FIXED - Should be ok now 18-9-90 - eay */
if (len < rnum)
{
char tmpbuf[BSIZE];
if (des_rw_mode & DES_PCBC_MODE)
pcbc_encrypt((des_cblock *)net,
(des_cblock *)tmpbuf,
num,sched,iv,DES_DECRYPT);
else
cbc_encrypt((des_cblock *)net,
(des_cblock *)tmpbuf,
num,sched,iv,DES_DECRYPT);
/* eay 26/08/92 fix a bug that returned more
* bytes than you asked for (returned len bytes :-( */
bcopy(tmpbuf,buf,num);
}
else
{
if (des_rw_mode & DES_PCBC_MODE)
pcbc_encrypt((des_cblock *)net,
(des_cblock *)buf,num,sched,iv,
DES_DECRYPT);
else
cbc_encrypt((des_cblock *)net,
(des_cblock *)buf,num,sched,iv,
DES_DECRYPT);
}
}
return(num);
}
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