Stub out DSA paramgen functions.

We don't support DSA EVP_PKEY_CTXs (trying to create one will just
fail), but to aid building projects that try to create them, add the
functions and make them always fail.

In particular, Node calls these two. It calls
EVP_PKEY_CTX_set_dsa_paramgen_q_bits via EVP_PKEY_CTX_ctrl, but I'll
send them a patch to use the wrapper function.

Change-Id: Ic134c50b6ea0b59dc8f15be77243b9ae9dfa6a61
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/54310
Auto-Submit: David Benjamin <davidben@google.com>
Reviewed-by: Bob Beck <bbe@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

crypto/evp/p_dsa_asn1.c

@@ -277,3 +277,15 @@ const EVP_PKEY_ASN1_METHOD dsa_asn1_meth = {
 
   int_dsa_free,
 };
+
+int EVP_PKEY_CTX_set_dsa_paramgen_bits(EVP_PKEY_CTX *ctx, int nbits) {
+  // BoringSSL does not support DSA in |EVP_PKEY_CTX|.
+  OPENSSL_PUT_ERROR(EVP, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
+  return 0;
+}
+
+int EVP_PKEY_CTX_set_dsa_paramgen_q_bits(EVP_PKEY_CTX *ctx, int qbits) {
+  // BoringSSL does not support DSA in |EVP_PKEY_CTX|.
+  OPENSSL_PUT_ERROR(EVP, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
+  return 0;
+}

include/openssl/evp.h

@@ -1018,6 +1018,14 @@ OPENSSL_EXPORT int i2d_EC_PUBKEY(const EC_KEY *ec_key, uint8_t **outp);
 OPENSSL_EXPORT EC_KEY *d2i_EC_PUBKEY(EC_KEY **out, const uint8_t **inp,
                                      long len);
 
+// EVP_PKEY_CTX_set_dsa_paramgen_bits returns zero.
+OPENSSL_EXPORT int EVP_PKEY_CTX_set_dsa_paramgen_bits(EVP_PKEY_CTX *ctx,
+                                                      int nbits);
+
+// EVP_PKEY_CTX_set_dsa_paramgen_q_bits returns zero.
+OPENSSL_EXPORT int EVP_PKEY_CTX_set_dsa_paramgen_q_bits(EVP_PKEY_CTX *ctx,
+                                                        int qbits);
+
 
 // Preprocessor compatibility section (hidden).
 //