/* simple program to insert a md5sum into application data area of */ /* an iso9660 image */ /* Copyright 2001 Red Hat, Inc. */ /* Michael Fulbright msf@redhat.com */ #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include "md5.h" #define APPDATA_OFFSET 883 #define SIZE_OFFSET 84 /* number of sectors to ignore at end of iso when computing sum */ #define SKIPSECTORS 150 #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 */ int parsepvd(int isofd, char *mediasum, long long *isosize) { unsigned char buf[2048]; long long offset; unsigned char *p; if (lseek(isofd, (off_t)(16L * 2048L), SEEK_SET) == -1) return ((long long)-1); offset = (16L * 2048L); for (;1;) { read(isofd, buf, 2048); 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 */ #if 0 memcpy(mediasum, buf + APPDATA_OFFSET + 13, 32); mediasum[32] = '\0'; for (p=mediasum; *p; p++) if (*p != ' ') break; /* if the md5sum was all spaces, we didn't find md5sum */ if (!*p) return -1; #endif /* get isosize */ *isosize = (buf[SIZE_OFFSET]*0x1000000+buf[SIZE_OFFSET+1]*0x10000 + buf[SIZE_OFFSET+2]*0x100 + buf[SIZE_OFFSET+3]) * 2048LL; return offset; } int main(int argc, char **argv) { int isofd; int nread; int i; int dirty; int pvd_offset; int forceit; long long isosize; unsigned char md5sum[16]; /* unsigned int total; */ long long total; unsigned char *fname; unsigned char buf[2048]; unsigned char orig_appdata[512]; unsigned char new_appdata[512]; unsigned char mediasum[33], computedsum[33]; long long tally_inc, tally; char md5str[40]; MD5_CTX md5ctx; if (argc < 2) { printf("Usage: implantisomd5 [-f] <isofilename>\n\n"); exit(1); } if (!strncmp(argv[1] , "-f", 3)) { forceit = 1; fname = argv[2]; } else { forceit = 0; fname = argv[1]; } isofd = open(fname, O_RDWR); if (isofd < 0) { fprintf(stderr, "Error - Unable to open file %s\n\n", fname); exit(1); } pvd_offset = parsepvd(isofd, mediasum, &isosize); if (pvd_offset < 0) { fprintf(stderr, "Could not find primary volumne!\n\n"); exit(1); } lseek(isofd, pvd_offset + APPDATA_OFFSET, SEEK_SET); nread = read(isofd, orig_appdata, 512); if (!forceit) { dirty = 0; for (i=0; i < 512; i++) if (orig_appdata[i] != ' ') dirty = 1; if (dirty) { fprintf(stderr, "Application data has been used - not implanting md5sum!\n"); exit(1); } } lseek(isofd, 0L, SEEK_SET); MD5_Init(&md5ctx); total = 0; /* read up to 15 sectors from end, due to problems reading last few */ /* sectors on burned CDs */ tally_inc = 50*1000*1000; tally = 0; printf("isosize is %10d", isosize); while (total < isosize - SKIPSECTORS*2048) { nread = read(isofd, buf, 2048); if (nread <= 0) break; MD5_Update(&md5ctx, buf, nread); total = total + nread; if (total >= tally) { printf("Read %10d MB\n", tally/1000/1000); printf("total is %10d", total/1000/1000); tally += tally_inc; } } MD5_Final(md5sum, &md5ctx); *md5str = '\0'; for (i=0; i<16; i++) { char tmpstr[4]; snprintf (tmpstr, 4, "%02x", md5sum[i]); strcat(md5str, tmpstr); } printf("Inserting md5sum into iso image...\n"); printf("md5 = %s\n", md5str); /* memcpy(new_appdata, orig_appdata, 512); */ memset(new_appdata, ' ', 512); memcpy(new_appdata, "ISO MD5SUM = ", 13); memcpy(new_appdata+13, md5str, 33); memcpy(new_appdata+47, "THIS IS NOT THE SAME AS RUNNING MD5SUM ON THIS ISO!!", 51); i = lseek(isofd, pvd_offset + APPDATA_OFFSET, SEEK_SET); if (i<0) printf("seek failed\n"); i = write(isofd, new_appdata, 512); if (i<0) { printf("write failed %d\n", i); perror(""); } close(isofd); printf("Done!\n"); }