comm: Provide udp_socks_deregister

[secnet.git] / dh.c

diff --git a/dh.c b/dh.c
index 91d08ced2dc805a839dcc3bf9b471c6387a2f0bc..c37b5386359294f856fb08eaf156a4c2ca586856 100644 (file)
--- 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"
@@ -11,7 +12,7 @@ struct dh {
     MP_INT p,g; /* prime modulus and generator */
 };
 
-static string_t dh_makepublic(void *sst, uint8_t *secret, uint32_t secretlen)
+static string_t dh_makepublic(void *sst, uint8_t *secret, int32_t secretlen)
 {
     struct dh *st=sst;
     string_t r;
@@ -32,9 +33,9 @@ static string_t dh_makepublic(void *sst, uint8_t *secret, uint32_t secretlen)
 }
 
 static dh_makeshared_fn dh_makeshared;
-static void dh_makeshared(void *sst, uint8_t *secret, uint32_t secretlen,
+static void dh_makeshared(void *sst, uint8_t *secret, int32_t secretlen,
                          cstring_t rempublic, uint8_t *sharedsecret,
-                         uint32_t buflen)
+                         int32_t buflen)
 {
     struct dh *st=sst;
     MP_INT a, b, c;
@@ -113,7 +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;
+
+    st->ops.ceil_len=(mpz_sizeinbase(&st->p,2)+7)/8;
+    /* According to the docs, mpz_sizeinbase(,256) is allowed to return
+     * an answer which is 1 too large.  But mpz_sizeinbase(,2) isn't. */
 
     return new_closure(&st->cl);
 }