enc_writ.c

Netscape公司提供的安全套接字层

/* enc_writ.c */
/* Copyright (C) 1993 Eric Young - see README for more details */
#include <errno.h>
#include "des_locl.h"

int des_enc_write(fd,buf,len,sched,iv)
int fd;
char *buf;
int len;
des_key_schedule sched;
des_cblock *iv;
    {
    long rnum;
    int i,j,k,outnum;
    char outbuf[BSIZE+HDRSIZE];
    char shortbuf[8];
    char *p;
    static int start=1;

    /* If we are sending less than 8 bytes, the same char will look
     * the same if we don't pad it out with random bytes */
    if (start)
        {
        start=0;
        srandom(time(NULL));
        }

    /* lets recurse if we want to send the data in small chunks */
    if (len > MAXWRITE)
        {
        j=0;
        for (i=0; i<len; i+=k)
            {
            k=des_enc_write(fd,&(buf[i]),
                ((len-i) > MAXWRITE)?MAXWRITE:(len-i),sched,iv);
            if (k < 0)
                return(k);
            else
                j+=k;
            }
        return(j);
        }

    /* write length first */
    p=outbuf;
    l2n(len,p);

    /* pad short strings */
    if (len < 8)
        {
        p=shortbuf;
        bcopy(buf,shortbuf,len);
        for (i=len; i<8; i++)
            shortbuf[i]=random();
        rnum=8;
        }
    else
        {
        p=buf;
        rnum=((len+7)/8*8); /* round up to nearest eight */
        }

    if (des_rw_mode & DES_PCBC_MODE)
        pcbc_encrypt((des_cblock *)p,(des_cblock *)&(outbuf[HDRSIZE]),
            (long)((len<8)?8:len),sched,iv,DES_ENCRYPT); 
    else
        cbc_encrypt((des_cblock *)p,(des_cblock *)&(outbuf[HDRSIZE]),
            (long)((len<8)?8:len),sched,iv,DES_ENCRYPT); 

    /* output */
    outnum=rnum+HDRSIZE;

    for (j=0; j<outnum; j+=i)
        {
        /* eay 26/08/92 I was not doing writing from where we
         * got upto. */
        i=write(fd,&(outbuf[j]),(int)(outnum-j));
        if (i == -1)
            {
            if (errno == EINTR)
                i=0;
            else    /* This is really a bad error - very bad
                 * It will stuff-up both ends. */
                return(-1);
            }
        }

    return(len);
    }