apps/dsaparam.c generates code that is intended to be pasted or included

into an existing source file: the function is static, and the code
doesn't include dsa.h.  Match the generated C source style of dsaparam.

Adjust apps/dhparam.c to match, and rename the BIGNUMs to their more
usual single-letter names.  Add an error return in the generated C source.

both: simplify the callback function
Signed-off-by: NBeat Bolli <dev@drbeat.li>
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NPaul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/6797)

apps/dhparam.c

@@ -309,33 +309,31 @@ int dhparam_main(int argc, char **argv)
         bits = DH_bits(dh);
         DH_get0_pqg(dh, &pbn, NULL, &gbn);
         data = app_malloc(len, "print a BN");
-        BIO_printf(out, "#ifndef HEADER_DH_H\n"
-                        "# include <openssl/dh.h>\n"
-                        "#endif\n"
-                        "\n");
-        BIO_printf(out, "DH *get_dh%d()\n{\n", bits);
+
+        BIO_printf(out, "static DH *get_dh%d(void)\n{\n", bits);
         print_bignum_var(out, pbn, "dhp", bits, data);
         print_bignum_var(out, gbn, "dhg", bits, data);
         BIO_printf(out, "    DH *dh = DH_new();\n"
-                        "    BIGNUM *dhp_bn, *dhg_bn;\n"
+                        "    BIGNUM *p, *g;\n"
                         "\n"
                         "    if (dh == NULL)\n"
                         "        return NULL;\n");
-        BIO_printf(out, "    dhp_bn = BN_bin2bn(dhp_%d, sizeof(dhp_%d), NULL);\n",
+        BIO_printf(out, "    p = BN_bin2bn(dhp_%d, sizeof(dhp_%d), NULL);\n",
                    bits, bits);
-        BIO_printf(out, "    dhg_bn = BN_bin2bn(dhg_%d, sizeof(dhg_%d), NULL);\n",
+        BIO_printf(out, "    g = BN_bin2bn(dhg_%d, sizeof(dhg_%d), NULL);\n",
                    bits, bits);
-        BIO_printf(out, "    if (dhp_bn == NULL || dhg_bn == NULL\n"
-                        "            || !DH_set0_pqg(dh, dhp_bn, NULL, dhg_bn)) {\n"
+        BIO_printf(out, "    if (p == NULL || g == NULL\n"
+                        "            || !DH_set0_pqg(dh, p, NULL, g)) {\n"
                         "        DH_free(dh);\n"
-                        "        BN_free(dhp_bn);\n"
-                        "        BN_free(dhg_bn);\n"
+                        "        BN_free(p);\n"
+                        "        BN_free(g);\n"
                         "        return NULL;\n"
                         "    }\n");
         if (DH_get_length(dh) > 0)
             BIO_printf(out,
                         "    if (!DH_set_length(dh, %ld)) {\n"
                         "        DH_free(dh);\n"
+                        "        return NULL;\n"
                         "    }\n", DH_get_length(dh));
         BIO_printf(out, "    return dh;\n}\n");
         OPENSSL_free(data);
@@ -371,16 +369,9 @@ int dhparam_main(int argc, char **argv)
 
 static int dh_cb(int p, int n, BN_GENCB *cb)
 {
-    char c = '*';
-
-    if (p == 0)
-        c = '.';
-    if (p == 1)
-        c = '+';
-    if (p == 2)
-        c = '*';
-    if (p == 3)
-        c = '\n';
+    static const char symbols[] = ".+*\n";
+    char c = (p >= 0 && (size_t)p < sizeof(symbols) - 1) ? symbols[p] : '?';
+
     BIO_write(BN_GENCB_get_arg(cb), &c, 1);
     (void)BIO_flush(BN_GENCB_get_arg(cb));
     return 1;

apps/dsaparam.c

@@ -248,16 +248,9 @@ int dsaparam_main(int argc, char **argv)
 
 static int dsa_cb(int p, int n, BN_GENCB *cb)
 {
-    char c = '*';
+    static const char symbols[] = ".+*\n";
+    char c = (p >= 0 && (size_t)p < sizeof(symbols) - 1) ? symbols[p] : '?';
 
-    if (p == 0)
-        c = '.';
-    if (p == 1)
-        c = '+';
-    if (p == 2)
-        c = '*';
-    if (p == 3)
-        c = '\n';
     BIO_write(BN_GENCB_get_arg(cb), &c, 1);
     (void)BIO_flush(BN_GENCB_get_arg(cb));
     return 1;