client, csr: copy the renewed cert's subject and SAN into reenroll CSRs

CMakeLists.txt

@@ -165,18 +165,20 @@ check_c_source_compiles("
     extern char wc_SetDNSEntry(void);
     extern char wc_SetAltNamesFromList(void);
     extern char SetLength(void);
+    extern char GetASNTag(void);
+    extern char GetLength(void);
     int main(void)
     {
         return FreeAltNames() + wc_SetDNSEntry() + wc_SetAltNamesFromList() +
-            SetLength();
+            SetLength() + GetASNTag() + GetLength();
     }
 " _have_asn_helpers)
 unset(CMAKE_REQUIRED_LIBRARIES)
 if(NOT _have_asn_helpers)
     message(FATAL_ERROR
         "wolfSSL does not export its ASN helpers (wc_SetDNSEntry, "
-        "wc_SetAltNamesFromList, FreeAltNames, SetLength). Rebuild wolfSSL "
-        "with CPPFLAGS=\"-DWOLFSSL_PUBLIC_ASN\".")
+        "wc_SetAltNamesFromList, FreeAltNames, SetLength, GetASNTag, "
+        "GetLength). Rebuild wolfSSL with CPPFLAGS=\"-DWOLFSSL_PUBLIC_ASN\".")
 endif()
 
 # Features that default-on in wolfSSL and that wolfCert depends on

cli/wolfcert_client.c

@@ -152,7 +152,10 @@ static void print_usage(FILE* out)
         "reenroll options:\n"
         "  --cert FILE                     Current certificate (PEM)\n"
         "  --key  FILE                     Current private key (PEM)\n"
-        "  plus the enroll options above to describe the renewed cert.\n"
+        "  --out-cert FILE                 Write renewed certificate (PEM;\n"
+        "                                  default stdout)\n"
+        "  The renewed cert keeps --cert's subject and SAN (RFC 7030\n"
+        "  section 4.2.2), so --subject and --san-* are rejected.\n"
         "  --cert/--key also authenticate the TLS connection, so\n"
         "  --client-cert/--client-key are rejected.\n"
         "\n"
@@ -1455,7 +1458,8 @@ static int cmd_reenroll(int argc, char** argv)
     uint8_t* cert_pem = NULL;
     uint8_t* key_pem = NULL;
     WolfCertKey* current_key = NULL;
-    WolfCertBuffer csr = { 0 };
+    WolfCertKey* new_key = NULL;
+    WolfCertCertMeta meta = { 0 };
     WolfCertBuffer issued = { 0 };
     WolfCertProtocol p = 0;
     size_t cert_len = 0, key_len = 0;
@@ -1485,8 +1489,16 @@ static int cmd_reenroll(int argc, char** argv)
     }
 
     if (ret == 0 &&
-        (opts.subject == NULL || opts.cert_file == NULL || opts.key_file == NULL)) {
-        fprintf(stderr, "reenroll: --subject, --cert, --key required\n");
+        (opts.subject != NULL || opts.san_dns_len != 0 ||
+         opts.san_ip_len != 0 || opts.san_uri_len != 0 ||
+         opts.san_email_len != 0)) {
+        fprintf(stderr, "reenroll: --subject/--san-* are not used; the renewed "
+                        "cert keeps --cert's subject and SAN\n");
+        ret = 1;
+    }
+
+    if (ret == 0 && (opts.cert_file == NULL || opts.key_file == NULL)) {
+        fprintf(stderr, "reenroll: --cert, --key required\n");
         ret = 1;
     }
 
@@ -1505,20 +1517,6 @@ static int cmd_reenroll(int argc, char** argv)
         ret = 2;
     }
 
-    if (ret == 0) {
-        WolfCertCertMeta meta = { .subject_dn = opts.subject,
-                                  .san_dns = opts.san_dns, .san_dns_len = opts.san_dns_len,
-                                  .san_ip = opts.san_ip, .san_ip_len = opts.san_ip_len,
-                                  .san_uri = opts.san_uri, .san_uri_len = opts.san_uri_len,
-                                  .san_email = opts.san_email, .san_email_len = opts.san_email_len,
-                                  .challenge_password = opts.challenge };
-        rc = wolfcert_csr_build(current_key, &meta, &csr);
-        if (rc != WOLFCERT_OK) {
-            fprintf(stderr, "reenroll csr: %s\n", wolfcert_strerror(rc));
-            ret = 2;
-        }
-    }
-
     WolfCertServerCfg srv = { .protocol = p, .server_url = opts.url };
 
     if (ret == 0) {
@@ -1529,14 +1527,17 @@ static int cmd_reenroll(int argc, char** argv)
     }
 
     if (ret == 0) {
-#ifdef WOLFCERT_HAVE_EST
-        rc = wolfcert_est_simple_reenroll(&srv, cert_pem, cert_len, current_key,
-                                          csr.data, csr.len, &issued);
-#else
-        rc = WOLFCERT_ERR_UNSUPPORTED;
-#endif
+        meta.challenge_password = opts.challenge;
+        rc = wolfcert_client_reenroll(NULL, &srv, cert_pem, cert_len,
+                                      current_key, NULL, &meta, &new_key,
+                                      &issued);
         if (rc != WOLFCERT_OK) {
             fprintf(stderr, "reenroll: %s\n", wolfcert_strerror(rc));
+            const char* m = wolfcert_last_error_message();
+            if (m && *m) {
+                fprintf(stderr, "reenroll: detail (wolfssl_err=%d): %s\n",
+                    wolfcert_last_wolfssl_err(), m);
+            }
             ret = 2;
         }
     }
@@ -1553,8 +1554,9 @@ static int cmd_reenroll(int argc, char** argv)
         }
     }
 
-    wolfcert_buffer_free(&csr);
     wolfcert_buffer_free(&issued);
+    if (new_key != NULL)
+        wolfcert_key_free(new_key);
     if (current_key != NULL)
         wolfcert_key_free(current_key);
     free(cert_pem);

configure.ac

@@ -233,14 +233,16 @@ AC_LINK_IFELSE(
 [[extern char FreeAltNames(void);
 extern char wc_SetDNSEntry(void);
 extern char wc_SetAltNamesFromList(void);
-extern char SetLength(void);]],
+extern char SetLength(void);
+extern char GetASNTag(void);
+extern char GetLength(void);]],
    [[return FreeAltNames() + wc_SetDNSEntry() + wc_SetAltNamesFromList() +
-       SetLength();]])],
+       SetLength() + GetASNTag() + GetLength();]])],
   [AC_MSG_RESULT([yes])],
   [AC_MSG_RESULT([no])
    AC_MSG_ERROR([wolfSSL does not export its ASN helpers (wc_SetDNSEntry,
-     wc_SetAltNamesFromList, FreeAltNames, SetLength). Rebuild wolfSSL with
-     CPPFLAGS="-DWOLFSSL_PUBLIC_ASN".])])
+     wc_SetAltNamesFromList, FreeAltNames, SetLength, GetASNTag, GetLength).
+     Rebuild wolfSSL with CPPFLAGS="-DWOLFSSL_PUBLIC_ASN".])])
 LIBS="$save_LIBS"
 
 # wolfSSL default-on features that wolfCert requires unconditionally: AES,

docs/ARCHITECTURE.md

@@ -107,8 +107,11 @@ The layering rules that matter to an integrator:
   can include it without caring whether EST or SCEP is present.
 - **`wolfcert_client_*` is the high-level orchestrator.**
   `wolfcert_client_enroll` / `_reenroll` route to EST or SCEP based on
-  `WolfCertServerCfg.protocol`. Callers that want finer control reach directly
-  into the `wolfcert_est_*` / `wolfcert_scep_*` primitives.
+  `WolfCertServerCfg.protocol`. `_reenroll` copies the Subject and SAN of the
+  certificate being renewed into its CSR byte for byte (RFC 7030 section
+  4.2.2) and refuses a `WolfCertCertMeta` that sets either. Callers that want
+  finer control reach directly into the `wolfcert_est_*` / `wolfcert_scep_*`
+  primitives.
 - **Protocol modules depend on subsystems, never the reverse**, and the test
   server lives below the public API — an embedder can hand it an
   already-accepted socket via `wolfcert_server_serve_fd()` instead of using
@@ -614,7 +617,8 @@ time `#error`s. See [`EMBEDDED.md`](EMBEDDED.md#configuring-wolfcert-without-its
 `WOLFSSL_BASE64_ENCODE`, `WOLFSSL_ALT_NAMES`, `WOLFSSL_CERT_NAME_ALL`. A
 `NO_RSA` build hard-fails unless SCEP is disabled. CMake and autoconf also
 link-probe the `WOLFSSL_ASN_API` helpers wolfCert calls (`wc_SetDNSEntry`,
-`wc_SetAltNamesFromList`, `FreeAltNames`, `SetLength`); a shared libwolfssl
+`wc_SetAltNamesFromList`, `FreeAltNames`, `SetLength`, `GetASNTag`,
+`GetLength`); a shared libwolfssl
 exports them only under one of `WOLFSSL_PUBLIC_ASN` / `OPENSSL_EXTRA` /
 `OPENSSL_EXTRA_X509_SMALL` / `WOLFSSL_TEST_CERT`, a static one always links
 them. `check_config.h` cannot test a link, so a header-only build that misses

docs/EMBEDDED.md

@@ -102,7 +102,7 @@ miscompile.
 | Consumer | Where it lives | Default size | Dominated by |
 |----------|----------------|--------------|--------------|
 | wolfSSL `Cert` (CSR / cert build) | **heap** (`wc_CertNew`) | ~20+ KB | `altNames[16384]` |
-| wolfSSL `DecodedCert` (cert parse) | **stack**, transient | several KB | parse scratch |
+| wolfSSL `DecodedCert` (cert parse) | **stack** or **heap**, transient | several KB | parse scratch |
 | HTTP request handling | **stack** (EST + client); **heap** (SCEP server) | 2-3 KB stack | request read buffer |
 
 The good news: wolfCert never stack-allocates a `Cert`. Every CSR/cert
@@ -120,12 +120,12 @@ the bulk of the size (defaults from `wolfssl/wolfcrypt/asn_public.h`):
 | Macro | Default | Effect |
 |-------|---------|--------|
 | `WC_CTC_MAX_ALT_SIZE` | `16384` | size of `Cert.altNames[]` - the encoded SAN extension. **Single largest contributor.** |
-| `WC_CTC_NAME_SIZE` | `64` | size of every `CertName` string field (CN, O, OU, ...). `CertName` carries ~19 such fields under the `WOLFSSL_CERT_NAME_ALL` + `WOLFSSL_CERT_EXT` config wolfCert requires, ×2 for issuer+subject, plus raw copies. |
+| `WC_CTC_NAME_SIZE` | `64` | size of every `CertName` string field (CN, O, OU, ...). `CertName` carries ~23 such fields under the `WOLFSSL_CERT_NAME_ALL` + `WOLFSSL_CERT_EXT` config wolfCert requires, ×2 for issuer+subject, plus raw copies. |
 
 These are **wolfSSL** settings, not wolfCert ones - set them when you build
 wolfSSL (via `user_settings.h` or `CPPFLAGS`), and wolfCert picks up
 whatever wolfSSL provides. For example, to drop a `Cert` from ~20 KB to
-~3 KB:
+~5 KB:
 
 ```c
 /* user_settings.h, when building wolfSSL */
@@ -142,7 +142,10 @@ Trade-offs:
   `WOLFCERT_ERR_BAD_ARG` rather than truncating it - both when a client
   builds a CSR (`assign_rdn()` in `src/csr.c`) and when the test server
   issues from one (`wolfcert_copy_csr_subject()` in `src/ca_issue.c`) - so
-  shrinking this caps how long a CN you can request.
+  shrinking this caps how long a CN you can request. A renewal instead
+  copies the certificate's subject whole, so there the limit is the total
+  encoded name, `sizeof(CertName)` (about 800 bytes at 32), and a longer one
+  fails with `WOLFCERT_ERR_UNSUPPORTED`.
 - Disabling `WOLFSSL_CERT_NAME_ALL` and/or `WOLFSSL_CERT_EXT` in wolfSSL
   removes the less-common `CertName` fields entirely - but wolfCert's
   build requires both (see `CLAUDE.md` / `CMakeLists.txt`), so prefer

src/client.c

@@ -229,9 +229,6 @@ int wolfcert_client_reenroll(WolfCertClient* client, const WolfCertServerCfg* sr
                              WolfCertKey** out_key, WolfCertBuffer* out_cert_pem)
 {
     (void)client;
-#ifndef WOLFCERT_HAVE_EST
-    (void)current_cert_len;   /* only the EST reenroll path reads it */
-#endif
     if (srv == NULL || current_cert == NULL || current_key == NULL ||
         meta == NULL || out_key == NULL || out_cert_pem == NULL)
         return WOLFCERT_ERR_BAD_ARG;
@@ -246,7 +243,8 @@ int wolfcert_client_reenroll(WolfCertClient* client, const WolfCertServerCfg* sr
     const WolfCertKey* signing_key = nk ? nk : current_key;
 
     WolfCertBuffer csr = { 0 };
-    rc = wolfcert_csr_build(signing_key, meta, &csr);
+    rc = wolfcert_csr_build_ex(signing_key, meta, current_cert,
+                               current_cert_len, &csr);
     if (rc != WOLFCERT_OK) {
         if (nk)
             wolfcert_key_free(nk);