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/*
* Copyright (C) 2001-2007 Red Hat, Inc.
*
* Michael Fulbright <msf@redhat.com>
* Dustin Kirkland <dustin.dirkland@gmail.com>
* Added support for checkpoint fragment sums;
* Exits media check as soon as bad fragment md5sum'ed
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include "md5.h"
#include "libcheckisomd5.h"
#define APPDATA_OFFSET 883
#define SIZE_OFFSET 84
/* Length in characters of string used for fragment md5sum checking */
#define FRAGMENT_SUM_LENGTH 60
#define MAX(x, y) ((x > y) ? x : y)
#define MIN(x, y) ((x < y) ? x : y)
/* finds primary volume descriptor and returns info from it */
/* mediasum must be a preallocated buffer at least 33 bytes long */
/* fragmentsums must be a preallocated buffer at least FRAGMENT_SUM_LENGTH+1 bytes long */
static int parsepvd(int isofd, char *mediasum, int *skipsectors, long long *isosize, int *supported, char *fragmentsums, long long *fragmentcount) {
unsigned char buf[2048];
char buf2[512];
char tmpbuf[512];
int skipfnd, md5fnd, supportedfnd, fragsumfnd, fragcntfnd;
unsigned int loc;
long long offset;
char *p;
if (lseek(isofd, (off_t)(16L * 2048L), SEEK_SET) == -1)
return ((long long)-1);
offset = (16L * 2048L);
for (;1;) {
if (read(isofd, buf, 2048) <= 0)
return ((long long)-1);
if (buf[0] == 1)
/* found primary volume descriptor */
break;
else if (buf[0] == 255)
/* hit end and didn't find primary volume descriptor */
return ((long long)-1);
offset += 2048L;
}
/* read out md5sum */
memcpy(buf2, buf + APPDATA_OFFSET, 512);
buf2[511] = '\0';
*supported = 0;
md5fnd = 0;
skipfnd = 0;
fragsumfnd = 0;
fragcntfnd = 0;
supportedfnd = 0;
loc = 0;
while (loc < 512) {
if (!strncmp(buf2 + loc, "ISO MD5SUM = ", 13)) {
/* make sure we dont walk off end */
if ((loc + 32 + 13) > 511)
return -1;
memcpy(mediasum, buf2 + loc + 13, 32);
mediasum[32] = '\0';
md5fnd = 1;
loc += 45;
for (p=buf2+loc; *p != ';' && loc < 512; p++, loc++);
} else if (!strncmp(buf2 + loc, "SKIPSECTORS = ", 14)) {
char *errptr;
/* make sure we dont walk off end */
if ((loc + 14) > 511)
return -1;
loc = loc + 14;
for (p=tmpbuf; buf2[loc] != ';' && loc < 512; p++, loc++)
*p = buf2[loc];
*p = '\0';
*skipsectors = strtol(tmpbuf, &errptr, 10);
if (errptr && *errptr) {
return -1;
} else {
skipfnd = 1;
}
for (p=buf2+loc; *p != ';' && loc < 512; p++, loc++);
} else if (!strncmp(buf2 + loc, "RHLISOSTATUS=1", 14)) {
*supported = 1;
supportedfnd = 1;
for (p=buf2+loc; *p != ';' && loc < 512; p++, loc++);
} else if (!strncmp(buf2 + loc, "RHLISOSTATUS=0", 14)) {
*supported = 0;
supportedfnd = 1;
for (p=buf2+loc; *p != ';' && loc < 512; p++, loc++);
} else if (!strncmp(buf2 + loc, "FRAGMENT SUMS = ", 16)) {
/* make sure we dont walk off end */
if ((loc + FRAGMENT_SUM_LENGTH) > 511)
return -1;
memcpy(fragmentsums, buf2 + loc + 16, FRAGMENT_SUM_LENGTH);
fragmentsums[FRAGMENT_SUM_LENGTH] = '\0';
fragsumfnd = 1;
loc += FRAGMENT_SUM_LENGTH + 16;
for (p=buf2+loc; *p != ';' && loc < 512; p++, loc++);
} else if (!strncmp(buf2 + loc, "FRAGMENT COUNT = ", 17)) {
char *errptr;
/* make sure we dont walk off end */
if ((loc + 17) > 511)
return -1;
loc = loc + 17;
for (p=tmpbuf; buf2[loc] != ';' && loc < 512; p++, loc++)
*p = buf2[loc];
*p = '\0';
*fragmentcount = strtol(tmpbuf, &errptr, 10);
if (errptr && *errptr) {
return -1;
} else {
fragcntfnd = 1;
}
for (p=buf2+loc; *p != ';' && loc < 512; p++, loc++);
} else {
loc++;
}
if ((skipfnd & md5fnd & fragsumfnd & fragcntfnd) & supportedfnd)
break;
}
if (!(skipfnd & md5fnd))
return -1;
/* get isosize */
*isosize = (buf[SIZE_OFFSET]*0x1000000+buf[SIZE_OFFSET+1]*0x10000 +
buf[SIZE_OFFSET+2]*0x100 + buf[SIZE_OFFSET+3]) * 2048LL;
return offset;
}
/* returns -1 if no checksum encoded in media, 0 if no match, 1 if match */
/* mediasum is the sum encoded in media, computedsum is one we compute */
/* both strings must be pre-allocated at least 33 chars in length */
static int checkmd5sum(int isofd, char *mediasum, char *computedsum, checkCallback cb, void *cbdata) {
int nread;
int i, j;
int appdata_start_offset, appdata_end_offset;
int nattempt;
int skipsectors;
int supported;
int current_fragment = 0;
int previous_fragment = 0;
unsigned int bufsize = 32768;
unsigned char md5sum[16];
unsigned char fragmd5sum[16];
unsigned int len;
unsigned char *buf;
long long isosize, offset, pvd_offset, apoff;
char fragmentsums[FRAGMENT_SUM_LENGTH];
char thisfragsum[FRAGMENT_SUM_LENGTH];
long long fragmentcount = 0;
MD5_CTX md5ctx, fragmd5ctx;
if ((pvd_offset = parsepvd(isofd, mediasum, &skipsectors, &isosize, &supported, fragmentsums, &fragmentcount)) < 0)
return -1;
/* printf("Mediasum = %s\n",mediasum); */
/* rewind, compute md5sum */
lseek(isofd, 0L, SEEK_SET);
MD5_Init(&md5ctx);
offset = 0;
apoff = pvd_offset + APPDATA_OFFSET;
buf = malloc(bufsize * sizeof(unsigned char));
if (cb)
cb(cbdata, 0, isosize - skipsectors*2048);
while (offset < isosize - skipsectors*2048) {
nattempt = MIN(isosize - skipsectors*2048 - offset, bufsize);
/* printf("%lld %lld %lld %d\n", offset, isosize, isosize-SKIPSECTORS*2048, nattempt); */
nread = read(isofd, buf, nattempt);
if (nread <= 0)
break;
if (nread > nattempt) {
fprintf(stderr, "Warning: read got more data than requested\n");
nread = nattempt;
lseek(isofd, offset+nread, SEEK_SET);
}
/* overwrite md5sum we implanted with original data */
if (offset < apoff && offset+nread >= apoff) {
appdata_start_offset = apoff - offset;
appdata_end_offset = MIN(appdata_start_offset+MIN(nread, 512),
offset + nread - apoff);
len = appdata_end_offset - appdata_start_offset;
memset(buf+appdata_start_offset, ' ', len);
} else if (offset >= apoff && offset+nread < apoff + 512) {
appdata_start_offset = 0;
appdata_end_offset = nread;
len = appdata_end_offset - appdata_start_offset;
memset(buf+appdata_start_offset, ' ', len);
} else if (offset < apoff + 512 && offset+nread >= apoff + 512) {
appdata_start_offset = 0;
appdata_end_offset = apoff + 512 - offset;
len = appdata_end_offset - appdata_start_offset;
memset(buf+appdata_start_offset, ' ', len);
}
MD5_Update(&md5ctx, buf, nread);
if (fragmentcount) {
current_fragment = offset * (fragmentcount+1) / (isosize - skipsectors*2048);
/* if we're onto the next fragment, calculate the previous sum and check */
if ( current_fragment != previous_fragment ) {
memcpy(&fragmd5ctx, &md5ctx, sizeof(MD5_CTX));
MD5_Final(fragmd5sum, &fragmd5ctx);
*computedsum = '\0';
j = (current_fragment-1)*FRAGMENT_SUM_LENGTH/fragmentcount;
for (i=0; i<FRAGMENT_SUM_LENGTH/fragmentcount; i++) {
char tmpstr[2];
snprintf(tmpstr, 2, "%01x", fragmd5sum[i]);
strncat(computedsum, tmpstr, 2);
thisfragsum[i] = fragmentsums[j++];
}
thisfragsum[j] = '\0';
previous_fragment = current_fragment;
/* Exit immediately if current fragment sum is incorrect */
if (strcmp(thisfragsum, computedsum) != 0) {
return 0;
}
}
}
offset = offset + nread;
if (cb)
cb(cbdata, offset, isosize - skipsectors*2048);
}
if (cb)
cb(cbdata, isosize, isosize - skipsectors*2048);
sleep(1);
free(buf);
MD5_Final(md5sum, &md5ctx);
*computedsum = '\0';
for (i=0; i<16; i++) {
char tmpstr[4];
snprintf (tmpstr, 4, "%02x", md5sum[i]);
strncat(computedsum, tmpstr, 2);
}
/* printf("mediasum, computedsum = %s %s\n", mediasum, computedsum); */
if (strcmp(mediasum, computedsum))
return 0;
else
return 1;
}
static int doMediaCheck(int isofd, char *mediasum, char *computedsum, long long *isosize, int *supported, checkCallback cb, void *cbdata) {
int rc;
int skipsectors;
long long fragmentcount = 0;
char fragmentsums[FRAGMENT_SUM_LENGTH+1];
if (parsepvd(isofd, mediasum, &skipsectors, isosize, supported, fragmentsums, &fragmentcount) < 0) {
fprintf(stderr, "Unable to read the disc checksum from the "
"primary volume descriptor.\nThis probably "
"means the disc was created without adding the "
"checksum.");
return -1;
}
rc = checkmd5sum(isofd, mediasum, computedsum, cb, cbdata);
return rc;
}
int mediaCheckFile(char *file, checkCallback cb, void *cbdata) {
int isofd;
int rc;
char mediasum[33], computedsum[33];
long long isosize;
int supported;
isofd = open(file, O_RDONLY);
if (isofd < 0) {
fprintf(stderr, "Unable to find install image %s\n", file);
return -1;
}
rc = doMediaCheck(isofd, mediasum, computedsum, &isosize, &supported, cb, cbdata);
close(isofd);
/* printf("isosize = %lld\n", isosize);
printf("%s\n%s\n", mediasum, computedsum);*/
return rc;
}
void printMD5SUM(char *file) {
int isofd;
char mediasum[64];
long long isosize;
char fragmentsums[FRAGMENT_SUM_LENGTH+1];
long long fragmentcount = 0;
int supported;
int skipsectors;
isofd = open(file, O_RDONLY);
if (isofd < 0) {
fprintf(stderr, "%s: Unable to find install image.\n", file);
exit(1);
}
if (parsepvd(isofd, mediasum, &skipsectors, &isosize, &supported, fragmentsums, &fragmentcount) < 0) {
fprintf(stderr, "%s: Could not get pvd data", file);
fprintf(stderr, "\nUnable to read the disc checksum from the "
"primary volume descriptor.\nThis probably "
"means the disc was created without adding the "
"checksum.");
exit(1);
}
close(isofd);
printf("%s: %s\n", file, mediasum);
if ( (strlen(fragmentsums) > 0) && (fragmentcount > 0) ) {
printf("Fragment sums: %s\n", fragmentsums);
printf("Fragment count: %lld\n", fragmentcount);
}
}
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