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Diffstat (limited to 'utils/checkisomd5.c')
| -rw-r--r-- | utils/checkisomd5.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/utils/checkisomd5.c b/utils/checkisomd5.c new file mode 100644 index 000000000..0f427164e --- /dev/null +++ b/utils/checkisomd5.c @@ -0,0 +1,184 @@ +/* simple program to check implanted md5sum in an iso 9660 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" + + +/* number of sectors to ignore at end of iso when computing sum */ +#define SKIPSECTORS 150 + +#define APPDATA_OFFSET 883 +#define SIZE_OFFSET 84 + +#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 */ + 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; + + /* 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 */ +int checkmd5sum(int isofd, char *mediasum, char *computedsum) { + int nread; + int i; + int appdata_start_offset, appdata_end_offset; + int nattempt; + unsigned int bufsize = 32768; + unsigned char md5sum[16]; + unsigned int len; + unsigned char *buf; + unsigned long tally_inc, tally; + long long isosize, offset, pvd_offset, apoff; + MD5_CTX md5ctx; + + if ((pvd_offset = parsepvd(isofd, mediasum, &isosize)) < 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)); + tally_inc = 50*1000*1000; + tally = 0; + 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; + + /* 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); + offset = offset + nread; + if (offset >= tally) { + printf("Read %5d MB\n", tally/1000/1000); + tally += tally_inc; + } + } + + 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]); + strcat(computedsum, tmpstr); + } + + /* printf("mediasum, computedsum = %s %s\n", mediasum, computedsum); */ + + if (strcmp(mediasum, computedsum)) + return 0; + else + return 1; + } + + +int main(int argc, char **argv) { + int isofd; + int rc; + unsigned char mediasum[33], computedsum[33]; + + if (argc < 2) { + printf("Usage: checkisomd5 <isofilename>\n\n"); + exit(1); + } + + isofd = open(argv[1], O_RDONLY); + + if (isofd < 0) { + fprintf(stderr, "Error - Unable to open file %s\n\n", argv[1]); + exit(1); + } + + rc = checkmd5sum(isofd, mediasum, computedsum); + printf("%s\n%s\n", mediasum, computedsum); + if ( rc == 0) + printf("Md5sums differ.\n"); + else if (rc > 0) + printf("Md5sums match.\n"); + else + printf("No checksum information in iso, check skipped.\n"); + + close(isofd); +} + |