sig: Move unmarshalling responsibility into algorithm

[secnet.git] / rsa.c

diff --git a/rsa.c b/rsa.c
index f17c2567f1ae8f669f57a60e3582b8ad6c4f2eae..49672c2511bb26a5ed38dfb841ba4b4f1ab0b755 100644 (file)
--- a/rsa.c
+++ b/rsa.c
@@ -35,6 +35,7 @@
 #include <gmp.h>
 #include "secnet.h"
 #include "util.h"
+#include "unaligned.h"
 
 #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n"
 
@@ -114,11 +115,13 @@ static void emsa_pkcs1(MP_INT *n, MP_INT *m,
     mpz_set_str(m, buff, 16);
 }
 
-static string_t rsa_sign(void *sst, uint8_t *data, int32_t datalen)
+static bool_t rsa_sign(void *sst, uint8_t *data, int32_t datalen,
+                      struct buffer_if *msg)
 {
     struct rsapriv *st=sst;
     MP_INT a, b, u, v, tmp, tmp2;
-    string_t signature;
+    string_t signature = 0;
+    bool_t ok;
 
     mpz_init(&a);
     mpz_init(&b);
@@ -162,14 +165,45 @@ static string_t rsa_sign(void *sst, uint8_t *data, int32_t datalen)
 
     signature=write_mpstring(&b);
 
+    uint8_t *op = buf_append(msg,2);
+    if (!op) { ok=False; goto out; }
+    size_t l = strlen(signature);
+    assert(l < 65536);
+    put_uint16(op, l);
+    op = buf_append(msg,l);
+    if (!op) { ok=False; goto out; }
+    memcpy(op, signature, l);
+
+    ok = True;
+
+ out:
+    free(signature);
     mpz_clear(&b);
     mpz_clear(&a);
-    return signature;
+    return ok;
+}
+
+static bool_t rsa_sig_unpick(void *sst, struct buffer_if *msg,
+                            struct alg_msg_data *sig)
+{
+    uint8_t *lp = buf_unprepend(msg, 2);
+    if (!lp) return False;
+    sig->siglen = get_uint16(lp);
+    sig->sigstart = buf_unprepend(msg, sig->siglen);
+    if (!sig->sigstart) return False;
+
+    /* In `rsa_sig_check' below, we assume that we can write a nul
+     * terminator following the signature.  Make sure there's enough space.
+     */
+    if (msg->start >= msg->base + msg->alloclen)
+       return False;
+
+    return True;
 }
 
 static sig_checksig_fn rsa_sig_check;
 static bool_t rsa_sig_check(void *sst, uint8_t *data, int32_t datalen,
-                           cstring_t signature)
+                           const struct alg_msg_data *sig)
 {
     struct rsapub *st=sst;
     MP_INT a, b, c;
@@ -181,7 +215,11 @@ static bool_t rsa_sig_check(void *sst, uint8_t *data, int32_t datalen,
 
     emsa_pkcs1(&st->n, &a, data, datalen);
 
-    mpz_set_str(&b, signature, 16);
+    /* Terminate signature with a '0' - already checked that this will fit */
+    int save = sig->sigstart[sig->siglen];
+    sig->sigstart[sig->siglen] = 0;
+    mpz_set_str(&b, sig->sigstart, 16);
+    sig->sigstart[sig->siglen] = save;
 
     mpz_powm(&c, &b, &st->e, &st->n);
 
@@ -207,6 +245,7 @@ static list_t *rsapub_apply(closure_t *self, struct cloc loc, dict_t *context,
     st->cl.apply=NULL;
     st->cl.interface=&st->ops;
     st->ops.st=st;
+    st->ops.unpick=rsa_sig_unpick;
     st->ops.check=rsa_sig_check;
     st->loc=loc;