X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=secnet.git;a=blobdiff_plain;f=dh.c;h=fff9b998c54062eaa473968640f40acc6b6f8a5d;hp=2ee93fb327399160e4be9272fb5fcdf6fa839389;hb=59230b9b9fc44453f24c6b3cf33a0f4c570a3563;hpb=fe5e9cc422cd72526ccfceffbc7e5af8ac83b407

diff --git a/dh.c b/dh.c
index 2ee93fb..fff9b99 100644
--- a/dh.c
+++ b/dh.c
@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <gmp.h>
+#include <limits.h>
 
 #include "secnet.h"
 #include "util.h"
@@ -113,12 +114,20 @@ static list_t *dh_apply(closure_t *self, struct cloc loc, dict_t *context,
 	    cfgfatal(loc,"diffie-hellman","modulus must be a prime\n");
 	}
     }
-    st->ops.len=mpz_sizeinbase(&st->p,2)/8;
+
+    size_t sz=mpz_sizeinbase(&st->p,2)/8;
+    if (sz>INT_MAX) {
+	cfgfatal(loc,"diffie-hellman","modulus far too large\n");
+    }
+    if (mpz_cmp(&st->g,&st->p) >= 0) {
+	cfgfatal(loc,"diffie-hellman","generator must be less than modulus\n");
+    }
+
+    st->ops.len=sz;
 
     return new_closure(&st->cl);
 }
 
-init_module dh_module;
 void dh_module(dict_t *dict)
 {
     add_closure(dict,"diffie-hellman",dh_apply);