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