handle an error case

[xonotic/d0_blind_id.git] / d0_bignum-gmp.c

diff --git a/d0_bignum-gmp.c b/d0_bignum-gmp.c
index 93bf0f72154d3c5c5da75de81c58344eb7794434..4e8a11b68ab47b6322a879fd6c3ea2c58ca08d84 100644 (file)
--- a/d0_bignum-gmp.c
+++ b/d0_bignum-gmp.c
@@ -17,9 +17,16 @@ License along with this library; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
+#ifdef WIN32
+#include <windows.h>
+#include <wincrypt.h>
+#endif
+
 #include "d0_bignum.h"
 
 #include <gmp.h>
+#include <string.h>
+#include <stdlib.h>
 
 struct d0_bignum_s
 {
@@ -31,24 +38,52 @@ static d0_bignum_t temp;
 
 #include <time.h>
 #include <stdio.h>
+
 void d0_bignum_INITIALIZE(void)
 {
        FILE *f;
+       unsigned char buf[256];
        d0_bignum_init(&temp);
        gmp_randinit_mt(RANDSTATE);
        gmp_randseed_ui(RANDSTATE, time(NULL));
-       f = fopen("/dev/random", "rb");
-       if(f)
+       * (time_t *) (&buf[0]) = time(0); // if everything else fails, we use the current time + uninitialized data
+#ifdef WIN32
        {
-               unsigned char buf[256];
-               setbuf(f, NULL);
-               if(fread(buf, sizeof(buf), 1, f) == 1)
+               HCRYPTPROV hCryptProv;
+               if(CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
                {
-                       mpz_import(temp.z, sizeof(buf), 1, 1, 0, 0, buf);
-                       gmp_randseed(RANDSTATE, temp.z);
+                       if(!CryptGenRandom(hCryptProv, sizeof(buf), (PBYTE) &buf[0]))
+                               fprintf(stderr, "WARNING: could not initialize random number generator (CryptGenRandom failed)\n");
+                       CryptReleaseContext(hCryptProv, 0);
                }
+               else
+               {
+                       if(CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_NEWKEYSET))
+                       {
+                               if(!CryptGenRandom(hCryptProv, sizeof(buf), (PBYTE) &buf[0]))
+                                       fprintf(stderr, "WARNING: could not initialize random number generator (CryptGenRandom failed)\n");
+                               CryptReleaseContext(hCryptProv, 0);
+                       }
+                       fprintf(stderr, "WARNING: could not initialize random number generator (CryptAcquireContext failed)\n");
+               }
+       }
+#else
+       f = fopen("/dev/urandom", "rb");
+       if(!f)
+               f = fopen("/dev/random", "rb");
+       if(f)
+       {
+               setbuf(f, NULL);
+               if(fread(buf, sizeof(buf), 1, f) != 1)
+                       fprintf(stderr, "WARNING: could not initialize random number generator (read from random device failed)\n");
                fclose(f);
        }
+       else
+               fprintf(stderr, "WARNING: could not initialize random number generator (no random device found)\n");
+#endif
+
+       mpz_import(temp.z, sizeof(buf), 1, 1, 0, 0, buf);
+       gmp_randseed(RANDSTATE, temp.z);
 }
 
 void d0_bignum_SHUTDOWN(void)
@@ -94,6 +129,54 @@ d0_bignum_t *d0_iobuf_read_bignum(d0_iobuf_t *buf, d0_bignum_t *bignum)
        return bignum;
 }
 
+ssize_t d0_bignum_export_unsigned(const d0_bignum_t *bignum, void *buf, size_t bufsize)
+{
+       size_t count;
+       count = (mpz_sizeinbase(bignum->z, 2) + 7) / 8;
+       if(count > bufsize)
+               return -1;
+       if(bufsize > count)
+       {
+               // pad from left (big endian numbers!)
+               memset(buf, 0, bufsize - count);
+               buf += bufsize - count;
+       }
+       bufsize = count;
+       mpz_export(buf, &bufsize, 1, 1, 0, 0, bignum->z);
+       if(bufsize > count)
+       {
+               // REALLY BAD
+               // mpz_sizeinbase lied to us
+               // buffer overflow
+               // there is no sane way whatsoever to handle this
+               abort();
+       }
+       if(bufsize < count)
+       {
+               // BAD
+               // mpz_sizeinbase lied to us
+               // move the number
+               if(bufsize == 0)
+               {
+                       memset(buf, 0, count);
+               }
+               else
+               {
+                       memmove(buf + count - bufsize, buf, bufsize);
+                       memset(buf, 0, count - bufsize);
+               }
+       }
+       return bufsize;
+}
+
+d0_bignum_t *d0_bignum_import_unsigned(d0_bignum_t *bignum, const void *buf, size_t bufsize)
+{
+       size_t count;
+       if(!bignum) bignum = d0_bignum_new(); if(!bignum) return NULL;
+       mpz_import(bignum->z, bufsize, 1, 1, 0, 0, buf);
+       return bignum;
+}
+
 d0_bignum_t *d0_bignum_new(void)
 {
        d0_bignum_t *b = d0_malloc(sizeof(d0_bignum_t));