DPP: Move Authentication Response building into a separate function

This cleans up old dpp_auth_build_resp() (now dpp_auth_build_resp_ok())
a bit by separating initialization steps for a DPP authentication
session from the code needed to build the frame. This allows
dpp_auth_build_resp_status() to share the helper function instead of
having to maintain a duplicated message construction implementation. In
addition, this makes it easier to remove some of the attributes for
protocol testing purposes.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

diff --git a/src/common/dpp.c b/src/common/dpp.c
index a24829567da09c6534b52577f55f1d289184809f..5e5b87976a527f51bb329bf5644a1cd2dfa7cbc1 100644 (file)
--- a/src/common/dpp.c
+++ b/src/common/dpp.c
@@ -1479,6 +1479,159 @@ skip_wrapped_data:
 }
 
 
+static struct wpabuf * dpp_auth_build_resp(struct dpp_authentication *auth,
+                                          enum dpp_status_error status,
+                                          const struct wpabuf *pr,
+                                          size_t nonce_len,
+                                          const u8 *r_pubkey_hash,
+                                          const u8 *i_pubkey_hash,
+                                          const u8 *r_nonce, const u8 *i_nonce,
+                                          const u8 *wrapped_r_auth,
+                                          size_t wrapped_r_auth_len,
+                                          const u8 *siv_key)
+{
+       struct wpabuf *msg;
+#define DPP_AUTH_RESP_CLEAR_LEN 2 * (4 + DPP_MAX_NONCE_LEN) + 4 + 1 + \
+               4 + 4 + DPP_MAX_HASH_LEN + AES_BLOCK_SIZE
+       u8 clear[DPP_AUTH_RESP_CLEAR_LEN];
+       u8 wrapped_data[DPP_AUTH_RESP_CLEAR_LEN + AES_BLOCK_SIZE];
+       const u8 *addr[2];
+       size_t len[2], siv_len, attr_len;
+       u8 *attr_start, *attr_end, *pos;
+
+       /* Build DPP Authentication Response frame attributes */
+       attr_len = 4 + 1 + 2 * (4 + SHA256_MAC_LEN) +
+               4 + (pr ? wpabuf_len(pr) : 0) + 4 + sizeof(wrapped_data);
+#ifdef CONFIG_TESTING_OPTIONS
+       if (dpp_test == DPP_TEST_AFTER_WRAPPED_DATA_AUTH_RESP)
+               attr_len += 4;
+#endif /* CONFIG_TESTING_OPTIONS */
+       msg = dpp_alloc_msg(DPP_PA_AUTHENTICATION_RESP, attr_len);
+       if (!msg)
+               return NULL;
+       wpabuf_free(auth->resp_msg);
+
+       attr_start = wpabuf_put(msg, 0);
+
+       /* DPP Status */
+       if (status >= 0) {
+               wpa_printf(MSG_DEBUG, "DPP: Status %d", status);
+               wpabuf_put_le16(msg, DPP_ATTR_STATUS);
+               wpabuf_put_le16(msg, 1);
+               wpabuf_put_u8(msg, status);
+       }
+
+       /* Responder Bootstrapping Key Hash */
+       if (r_pubkey_hash) {
+               wpabuf_put_le16(msg, DPP_ATTR_R_BOOTSTRAP_KEY_HASH);
+               wpabuf_put_le16(msg, SHA256_MAC_LEN);
+               wpabuf_put_data(msg, r_pubkey_hash, SHA256_MAC_LEN);
+       }
+
+       /* Initiator Bootstrapping Key Hash */
+       if (i_pubkey_hash) {
+               /* Mutual authentication */
+               wpabuf_put_le16(msg, DPP_ATTR_I_BOOTSTRAP_KEY_HASH);
+               wpabuf_put_le16(msg, SHA256_MAC_LEN);
+               wpabuf_put_data(msg, i_pubkey_hash, SHA256_MAC_LEN);
+       }
+
+       /* Responder Protocol Key */
+       if (pr) {
+               wpabuf_put_le16(msg, DPP_ATTR_R_PROTOCOL_KEY);
+               wpabuf_put_le16(msg, wpabuf_len(pr));
+               wpabuf_put_buf(msg, pr);
+       }
+
+       attr_end = wpabuf_put(msg, 0);
+
+       /* Wrapped data ({R-nonce, I-nonce, R-capabilities, {R-auth}ke}k2) */
+       pos = clear;
+
+       if (r_nonce) {
+               /* R-nonce */
+               WPA_PUT_LE16(pos, DPP_ATTR_R_NONCE);
+               pos += 2;
+               WPA_PUT_LE16(pos, nonce_len);
+               pos += 2;
+               os_memcpy(pos, r_nonce, nonce_len);
+               pos += nonce_len;
+       }
+
+       if (i_nonce) {
+               /* I-nonce */
+               WPA_PUT_LE16(pos, DPP_ATTR_I_NONCE);
+               pos += 2;
+               WPA_PUT_LE16(pos, nonce_len);
+               pos += 2;
+               os_memcpy(pos, i_nonce, nonce_len);
+               pos += nonce_len;
+       }
+
+       /* R-capabilities */
+       WPA_PUT_LE16(pos, DPP_ATTR_R_CAPABILITIES);
+       pos += 2;
+       WPA_PUT_LE16(pos, 1);
+       pos += 2;
+       auth->r_capab = auth->configurator ? DPP_CAPAB_CONFIGURATOR :
+               DPP_CAPAB_ENROLLEE;
+       *pos++ = auth->r_capab;
+#ifdef CONFIG_TESTING_OPTIONS
+       if (dpp_test == DPP_TEST_ZERO_R_CAPAB) {
+               wpa_printf(MSG_INFO, "DPP: TESTING - zero R-capabilities");
+               pos[-1] = 0;
+       }
+#endif /* CONFIG_TESTING_OPTIONS */
+
+       if (wrapped_r_auth) {
+               /* {R-auth}ke */
+               WPA_PUT_LE16(pos, DPP_ATTR_WRAPPED_DATA);
+               pos += 2;
+               WPA_PUT_LE16(pos, wrapped_r_auth_len);
+               pos += 2;
+               os_memcpy(pos, wrapped_r_auth, wrapped_r_auth_len);
+               pos += wrapped_r_auth_len;
+       }
+
+       /* OUI, OUI type, Crypto Suite, DPP frame type */
+       addr[0] = wpabuf_head_u8(msg) + 2;
+       len[0] = 3 + 1 + 1 + 1;
+       wpa_hexdump(MSG_DEBUG, "DDP: AES-SIV AD[0]", addr[0], len[0]);
+
+       /* Attributes before Wrapped Data */
+       addr[1] = attr_start;
+       len[1] = attr_end - attr_start;
+       wpa_hexdump(MSG_DEBUG, "DDP: AES-SIV AD[1]", addr[1], len[1]);
+
+       siv_len = pos - clear;
+       wpa_hexdump(MSG_DEBUG, "DPP: AES-SIV cleartext", clear, siv_len);
+       if (aes_siv_encrypt(siv_key, auth->curve->hash_len, clear, siv_len,
+                           2, addr, len, wrapped_data) < 0) {
+               wpabuf_free(msg);
+               return NULL;
+       }
+       siv_len += AES_BLOCK_SIZE;
+       wpa_hexdump(MSG_DEBUG, "DPP: AES-SIV ciphertext",
+                   wrapped_data, siv_len);
+
+       wpabuf_put_le16(msg, DPP_ATTR_WRAPPED_DATA);
+       wpabuf_put_le16(msg, siv_len);
+       wpabuf_put_data(msg, wrapped_data, siv_len);
+
+#ifdef CONFIG_TESTING_OPTIONS
+       if (dpp_test == DPP_TEST_AFTER_WRAPPED_DATA_AUTH_RESP) {
+               wpa_printf(MSG_INFO, "DPP: TESTING - attr after Wrapped Data");
+               wpabuf_put_le16(msg, DPP_ATTR_TESTING);
+               wpabuf_put_le16(msg, 0);
+       }
+#endif /* CONFIG_TESTING_OPTIONS */
+
+       wpa_hexdump_buf(MSG_DEBUG,
+                       "DPP: Authentication Response frame attributes", msg);
+       return msg;
+}
+
+
 struct dpp_authentication * dpp_auth_init(void *msg_ctx,
                                          struct dpp_bootstrap_info *peer_bi,
                                          struct dpp_bootstrap_info *own_bi,
@@ -1974,7 +2127,7 @@ fail:
 }
 
 
-static int dpp_auth_build_resp(struct dpp_authentication *auth)
+static int dpp_auth_build_resp_ok(struct dpp_authentication *auth)
 {
        size_t nonce_len;
        EVP_PKEY_CTX *ctx = NULL;
@@ -1982,15 +2135,9 @@ static int dpp_auth_build_resp(struct dpp_authentication *auth)
        struct wpabuf *msg, *pr = NULL;
        u8 r_auth[4 + DPP_MAX_HASH_LEN];
        u8 wrapped_r_auth[4 + DPP_MAX_HASH_LEN + AES_BLOCK_SIZE];
-#define DPP_AUTH_RESP_CLEAR_LEN 2 * (4 + DPP_MAX_NONCE_LEN) + 4 + 1 + \
-               4 + sizeof(wrapped_r_auth)
        size_t wrapped_r_auth_len;
-       u8 clear[DPP_AUTH_RESP_CLEAR_LEN];
-       u8 wrapped_data[DPP_AUTH_RESP_CLEAR_LEN + AES_BLOCK_SIZE];
-       u8 *pos;
-       const u8 *addr[2];
-       size_t len[2], siv_len, attr_len;
-       u8 *attr_start, *attr_end;
+       int ret = -1;
+       const u8 *r_pubkey_hash, *i_pubkey_hash;
 
        wpa_printf(MSG_DEBUG, "DPP: Build Authentication Response");
 
@@ -2053,242 +2200,49 @@ static int dpp_auth_build_resp(struct dpp_authentication *auth)
        wpa_hexdump(MSG_DEBUG, "DPP: {R-auth}ke",
                    wrapped_r_auth, wrapped_r_auth_len);
 
-       /* Build DPP Authentication Response frame attributes */
-       attr_len = 4 + 1 + 2 * (4 + SHA256_MAC_LEN) +
-               4 + wpabuf_len(pr) + 4 + sizeof(wrapped_data);
-#ifdef CONFIG_TESTING_OPTIONS
-       if (dpp_test == DPP_TEST_AFTER_WRAPPED_DATA_AUTH_RESP)
-               attr_len += 4;
-#endif /* CONFIG_TESTING_OPTIONS */
-       msg = dpp_alloc_msg(DPP_PA_AUTHENTICATION_RESP, attr_len);
+       r_pubkey_hash = auth->own_bi->pubkey_hash;
+       if (auth->peer_bi)
+               i_pubkey_hash = auth->peer_bi->pubkey_hash;
+       else
+               i_pubkey_hash = NULL;
+
+       msg = dpp_auth_build_resp(auth, DPP_STATUS_OK, pr, nonce_len,
+                                 r_pubkey_hash, i_pubkey_hash,
+                                 auth->r_nonce, auth->i_nonce,
+                                 wrapped_r_auth, wrapped_r_auth_len,
+                                 auth->k2);
        if (!msg)
                goto fail;
-       wpabuf_free(auth->resp_msg);
        auth->resp_msg = msg;
-
-       attr_start = wpabuf_put(msg, 0);
-
-       /* DPP Status */
-       wpabuf_put_le16(msg, DPP_ATTR_STATUS);
-       wpabuf_put_le16(msg, 1);
-       wpabuf_put_u8(msg, DPP_STATUS_OK);
-
-       /* Responder Bootstrapping Key Hash */
-       wpabuf_put_le16(msg, DPP_ATTR_R_BOOTSTRAP_KEY_HASH);
-       wpabuf_put_le16(msg, SHA256_MAC_LEN);
-       wpabuf_put_data(msg, auth->own_bi->pubkey_hash, SHA256_MAC_LEN);
-
-       if (auth->peer_bi) {
-               /* Mutual authentication */
-               /* Initiator Bootstrapping Key Hash */
-               wpabuf_put_le16(msg, DPP_ATTR_I_BOOTSTRAP_KEY_HASH);
-               wpabuf_put_le16(msg, SHA256_MAC_LEN);
-               wpabuf_put_data(msg, auth->peer_bi->pubkey_hash,
-                               SHA256_MAC_LEN);
-       }
-
-       /* Responder Protocol Key */
-       wpabuf_put_le16(msg, DPP_ATTR_R_PROTOCOL_KEY);
-       wpabuf_put_le16(msg, wpabuf_len(pr));
-       wpabuf_put_buf(msg, pr);
-       wpabuf_free(pr);
-       pr = NULL;
-
-       attr_end = wpabuf_put(msg, 0);
-
-       /* Wrapped data ({R-nonce, I-nonce, R-capabilities, {R-auth}ke}k2) */
-       pos = clear;
-       /* R-nonce */
-       WPA_PUT_LE16(pos, DPP_ATTR_R_NONCE);
-       pos += 2;
-       WPA_PUT_LE16(pos, nonce_len);
-       pos += 2;
-       os_memcpy(pos, auth->r_nonce, nonce_len);
-       pos += nonce_len;
-       /* I-nonce */
-       WPA_PUT_LE16(pos, DPP_ATTR_I_NONCE);
-       pos += 2;
-       WPA_PUT_LE16(pos, nonce_len);
-       pos += 2;
-       os_memcpy(pos, auth->i_nonce, nonce_len);
-       pos += nonce_len;
-       /* R-capabilities */
-       WPA_PUT_LE16(pos, DPP_ATTR_R_CAPABILITIES);
-       pos += 2;
-       WPA_PUT_LE16(pos, 1);
-       pos += 2;
-       auth->r_capab = auth->configurator ? DPP_CAPAB_CONFIGURATOR :
-               DPP_CAPAB_ENROLLEE;
-       *pos++ = auth->r_capab;
-#ifdef CONFIG_TESTING_OPTIONS
-       if (dpp_test == DPP_TEST_ZERO_R_CAPAB) {
-               wpa_printf(MSG_INFO, "DPP: TESTING - zero R-capabilities");
-               pos[-1] = 0;
-       }
-#endif /* CONFIG_TESTING_OPTIONS */
-       /* {R-auth}ke */
-       WPA_PUT_LE16(pos, DPP_ATTR_WRAPPED_DATA);
-       pos += 2;
-       WPA_PUT_LE16(pos, wrapped_r_auth_len);
-       pos += 2;
-       os_memcpy(pos, wrapped_r_auth, wrapped_r_auth_len);
-       pos += wrapped_r_auth_len;
-
-       /* OUI, OUI type, Crypto Suite, DPP frame type */
-       addr[0] = wpabuf_head_u8(msg) + 2;
-       len[0] = 3 + 1 + 1 + 1;
-       wpa_hexdump(MSG_DEBUG, "DDP: AES-SIV AD[0]", addr[0], len[0]);
-
-       /* Attributes before Wrapped Data */
-       addr[1] = attr_start;
-       len[1] = attr_end - attr_start;
-       wpa_hexdump(MSG_DEBUG, "DDP: AES-SIV AD[1]", addr[1], len[1]);
-
-       siv_len = pos - clear;
-       wpa_hexdump(MSG_DEBUG, "DPP: AES-SIV cleartext", clear, siv_len);
-       if (aes_siv_encrypt(auth->k2, auth->curve->hash_len, clear, siv_len,
-                           2, addr, len, wrapped_data) < 0)
-               goto fail;
-       siv_len += AES_BLOCK_SIZE;
-       wpa_hexdump(MSG_DEBUG, "DPP: AES-SIV ciphertext",
-                   wrapped_data, siv_len);
-
-       wpabuf_put_le16(msg, DPP_ATTR_WRAPPED_DATA);
-       wpabuf_put_le16(msg, siv_len);
-       wpabuf_put_data(msg, wrapped_data, siv_len);
-
-#ifdef CONFIG_TESTING_OPTIONS
-       if (dpp_test == DPP_TEST_AFTER_WRAPPED_DATA_AUTH_RESP) {
-               wpa_printf(MSG_INFO, "DPP: TESTING - attr after Wrapped Data");
-               wpabuf_put_le16(msg, DPP_ATTR_TESTING);
-               wpabuf_put_le16(msg, 0);
-       }
-#endif /* CONFIG_TESTING_OPTIONS */
-
-       wpa_hexdump_buf(MSG_DEBUG,
-                       "DPP: Authentication Response frame attributes", msg);
-
-       return 0;
-
+       ret = 0;
 fail:
        wpabuf_free(pr);
-       return -1;
+       return ret;
 }
 
 
 static int dpp_auth_build_resp_status(struct dpp_authentication *auth,
                                      enum dpp_status_error status)
 {
-       size_t nonce_len;
        struct wpabuf *msg;
-#define DPP_AUTH_RESP_CLEAR_LEN2 4 + DPP_MAX_NONCE_LEN + 4 + 1
-       u8 clear[DPP_AUTH_RESP_CLEAR_LEN2];
-       u8 wrapped_data[DPP_AUTH_RESP_CLEAR_LEN2 + AES_BLOCK_SIZE];
-       u8 *pos;
-       const u8 *addr[2];
-       size_t len[2], siv_len, attr_len;
-       u8 *attr_start, *attr_end;
+       const u8 *r_pubkey_hash, *i_pubkey_hash;
 
        wpa_printf(MSG_DEBUG, "DPP: Build Authentication Response");
 
-       /* Build DPP Authentication Response frame attributes */
-       attr_len = 4 + 1 + 2 * (4 + SHA256_MAC_LEN) + 4 + sizeof(wrapped_data);
-#ifdef CONFIG_TESTING_OPTIONS
-       if (dpp_test == DPP_TEST_AFTER_WRAPPED_DATA_AUTH_RESP)
-               attr_len += 4;
-#endif /* CONFIG_TESTING_OPTIONS */
-       msg = dpp_alloc_msg(DPP_PA_AUTHENTICATION_RESP, attr_len);
+       r_pubkey_hash = auth->own_bi->pubkey_hash;
+       if (auth->peer_bi)
+               i_pubkey_hash = auth->peer_bi->pubkey_hash;
+       else
+               i_pubkey_hash = NULL;
+
+       msg = dpp_auth_build_resp(auth, status, NULL, auth->curve->nonce_len,
+                                 r_pubkey_hash, i_pubkey_hash,
+                                 NULL, auth->i_nonce, NULL, 0,
+                                 auth->k1);
        if (!msg)
-               goto fail;
-       wpabuf_free(auth->resp_msg);
+               return -1;
        auth->resp_msg = msg;
-
-       attr_start = wpabuf_put(msg, 0);
-
-       /* DPP Status */
-       wpabuf_put_le16(msg, DPP_ATTR_STATUS);
-       wpabuf_put_le16(msg, 1);
-       wpabuf_put_u8(msg, status);
-
-       /* Responder Bootstrapping Key Hash */
-       wpabuf_put_le16(msg, DPP_ATTR_R_BOOTSTRAP_KEY_HASH);
-       wpabuf_put_le16(msg, SHA256_MAC_LEN);
-       wpabuf_put_data(msg, auth->own_bi->pubkey_hash, SHA256_MAC_LEN);
-
-       if (auth->peer_bi) {
-               /* Mutual authentication */
-               /* Initiator Bootstrapping Key Hash */
-               wpabuf_put_le16(msg, DPP_ATTR_I_BOOTSTRAP_KEY_HASH);
-               wpabuf_put_le16(msg, SHA256_MAC_LEN);
-               wpabuf_put_data(msg, auth->peer_bi->pubkey_hash,
-                               SHA256_MAC_LEN);
-       }
-
-       attr_end = wpabuf_put(msg, 0);
-
-       /* Wrapped data ({I-nonce, R-capabilities}k1) */
-       pos = clear;
-       /* I-nonce */
-       nonce_len = auth->curve->nonce_len;
-       WPA_PUT_LE16(pos, DPP_ATTR_I_NONCE);
-       pos += 2;
-       WPA_PUT_LE16(pos, nonce_len);
-       pos += 2;
-       os_memcpy(pos, auth->i_nonce, nonce_len);
-       pos += nonce_len;
-       /* R-capabilities */
-       WPA_PUT_LE16(pos, DPP_ATTR_R_CAPABILITIES);
-       pos += 2;
-       WPA_PUT_LE16(pos, 1);
-       pos += 2;
-       auth->r_capab = auth->configurator ? DPP_CAPAB_CONFIGURATOR :
-               DPP_CAPAB_ENROLLEE;
-       *pos++ = auth->r_capab;
-#ifdef CONFIG_TESTING_OPTIONS
-       if (dpp_test == DPP_TEST_ZERO_R_CAPAB) {
-               wpa_printf(MSG_INFO, "DPP: TESTING - zero R-capabilities");
-               pos[-1] = 0;
-       }
-#endif /* CONFIG_TESTING_OPTIONS */
-
-       /* OUI, OUI type, Crypto Suite, DPP frame type */
-       addr[0] = wpabuf_head_u8(msg) + 2;
-       len[0] = 3 + 1 + 1 + 1;
-       wpa_hexdump(MSG_DEBUG, "DDP: AES-SIV AD[0]", addr[0], len[0]);
-
-       /* Attributes before Wrapped Data */
-       addr[1] = attr_start;
-       len[1] = attr_end - attr_start;
-       wpa_hexdump(MSG_DEBUG, "DDP: AES-SIV AD[1]", addr[1], len[1]);
-
-       siv_len = pos - clear;
-       wpa_hexdump(MSG_DEBUG, "DPP: AES-SIV cleartext", clear, siv_len);
-       if (aes_siv_encrypt(auth->k1, auth->curve->hash_len, clear, siv_len,
-                           2, addr, len, wrapped_data) < 0)
-               goto fail;
-       siv_len += AES_BLOCK_SIZE;
-       wpa_hexdump(MSG_DEBUG, "DPP: AES-SIV ciphertext",
-                   wrapped_data, siv_len);
-
-       wpabuf_put_le16(msg, DPP_ATTR_WRAPPED_DATA);
-       wpabuf_put_le16(msg, siv_len);
-       wpabuf_put_data(msg, wrapped_data, siv_len);
-
-#ifdef CONFIG_TESTING_OPTIONS
-       if (dpp_test == DPP_TEST_AFTER_WRAPPED_DATA_AUTH_RESP) {
-               wpa_printf(MSG_INFO, "DPP: TESTING - attr after Wrapped Data");
-               wpabuf_put_le16(msg, DPP_ATTR_TESTING);
-               wpabuf_put_le16(msg, 0);
-       }
-#endif /* CONFIG_TESTING_OPTIONS */
-
-       wpa_hexdump_buf(MSG_DEBUG,
-                       "DPP: Authentication Response frame attributes", msg);
-
        return 0;
-
-fail:
-       return -1;
 }
 
 
@@ -2475,7 +2429,7 @@ dpp_auth_req_rx(void *msg_ctx, u8 dpp_allowed_roles, int qr_mutual,
                        "%s", hex);
                return auth;
        }
-       if (dpp_auth_build_resp(auth) < 0)
+       if (dpp_auth_build_resp_ok(auth) < 0)
                goto fail;
 
        return auth;
@@ -2516,7 +2470,7 @@ int dpp_notify_new_qr_code(struct dpp_authentication *auth,
                   MACSTR, MAC2STR(auth->peer_mac_addr));
        auth->peer_bi = peer_bi;
 
-       if (dpp_auth_build_resp(auth) < 0)
+       if (dpp_auth_build_resp_ok(auth) < 0)
                return -1;
 
        return 1;