SAE: Split sae_parse_commit() into helper functions

Signed-hostap: Jouni Malinen <j@w1.fi>

diff --git a/src/common/sae.c b/src/common/sae.c
index de5dedd..ad5955f 100644 (file)
--- a/src/common/sae.c
+++ b/src/common/sae.c
@@ -758,23 +758,9 @@ void sae_write_commit(struct sae_data *sae, struct wpabuf *buf,
 }
 
 
-u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
-                    const u8 **token, size_t *token_len, int *allowed_groups)
+static u16 sae_group_allowed(struct sae_data *sae, int *allowed_groups,
+                            u16 group)
 {
-       const u8 *pos = data, *end = data + len;
-       u16 group;
-       struct crypto_bignum *peer_scalar;
-
-       wpa_hexdump(MSG_DEBUG, "SAE: Commit fields", data, len);
-       if (token)
-               *token = NULL;
-       if (token_len)
-               *token_len = 0;
-
-       /* Check Finite Cyclic Group */
-       if (pos + 2 > end)
-               return WLAN_STATUS_UNSPECIFIED_FAILURE;
-       group = WPA_GET_LE16(pos);
        if (allowed_groups) {
                int i;
                for (i = 0; allowed_groups[i] >= 0; i++) {
@@ -788,38 +774,60 @@ u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
                        return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
                }
        }
+
        if (sae->state == SAE_COMMITTED && group != sae->group) {
                wpa_printf(MSG_DEBUG, "SAE: Do not allow group to be changed");
                return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
        }
+
        if (group != sae->group && sae_set_group(sae, group) < 0) {
                wpa_printf(MSG_DEBUG, "SAE: Unsupported Finite Cyclic Group %u",
                           group);
                return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
        }
+
        if (sae->dh && !allowed_groups) {
                wpa_printf(MSG_DEBUG, "SAE: Do not allow FFC group %u without "
                           "explicit configuration enabling it", group);
                return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
        }
-       pos += 2;
 
-       if (pos + (sae->ec ? 3 : 2) * sae->prime_len < end) {
-               size_t tlen = end - (pos + (sae->ec ? 3 : 2) * sae->prime_len);
-               wpa_hexdump(MSG_DEBUG, "SAE: Anti-Clogging Token", pos, tlen);
+       return WLAN_STATUS_SUCCESS;
+}
+
+
+static void sae_parse_commit_token(struct sae_data *sae, const u8 **pos,
+                                  const u8 *end, const u8 **token,
+                                  size_t *token_len)
+{
+       if (*pos + (sae->ec ? 3 : 2) * sae->prime_len < end) {
+               size_t tlen = end - (*pos + (sae->ec ? 3 : 2) * sae->prime_len);
+               wpa_hexdump(MSG_DEBUG, "SAE: Anti-Clogging Token", *pos, tlen);
                if (token)
-                       *token = pos;
+                       *token = *pos;
                if (token_len)
                        *token_len = tlen;
-               pos += tlen;
+               *pos += tlen;
+       } else {
+               if (token)
+                       *token = NULL;
+               if (token_len)
+                       *token_len = 0;
        }
+}
+
 
-       if (pos + sae->prime_len > end) {
+static u16 sae_parse_commit_scalar(struct sae_data *sae, const u8 **pos,
+                                  const u8 *end)
+{
+       struct crypto_bignum *peer_scalar;
+
+       if (*pos + sae->prime_len > end) {
                wpa_printf(MSG_DEBUG, "SAE: Not enough data for scalar");
                return WLAN_STATUS_UNSPECIFIED_FAILURE;
        }
 
-       peer_scalar = crypto_bignum_init_set(pos, sae->prime_len);
+       peer_scalar = crypto_bignum_init_set(*pos, sae->prime_len);
        if (peer_scalar == NULL)
                return WLAN_STATUS_UNSPECIFIED_FAILURE;
 
@@ -839,9 +847,16 @@ u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
 
        crypto_bignum_deinit(sae->peer_commit_scalar, 0);
        sae->peer_commit_scalar = peer_scalar;
-       wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-scalar", pos, sae->prime_len);
-       pos += sae->prime_len;
+       wpa_hexdump(MSG_DEBUG, "SAE: Peer commit-scalar", *pos, sae->prime_len);
+       *pos += sae->prime_len;
+
+       return WLAN_STATUS_SUCCESS;
+}
+
 
+static u16 sae_parse_commit_element(struct sae_data *sae, const u8 *pos,
+                                   const u8 *end)
+{
        if (sae->dh) {
                if (pos + sae->prime_len > end) {
                        wpa_printf(MSG_DEBUG, "SAE: Not enough data for "
@@ -870,6 +885,35 @@ u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
 }
 
 
+u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
+                    const u8 **token, size_t *token_len, int *allowed_groups)
+{
+       const u8 *pos = data, *end = data + len;
+       u16 res;
+
+       wpa_hexdump(MSG_DEBUG, "SAE: Commit fields", data, len);
+
+       /* Check Finite Cyclic Group */
+       if (pos + 2 > end)
+               return WLAN_STATUS_UNSPECIFIED_FAILURE;
+       res = sae_group_allowed(sae, allowed_groups, WPA_GET_LE16(pos));
+       if (res != WLAN_STATUS_SUCCESS)
+               return res;
+       pos += 2;
+
+       /* Optional Anti-Clogging Token */
+       sae_parse_commit_token(sae, &pos, end, token, token_len);
+
+       /* commit-scalar */
+       res = sae_parse_commit_scalar(sae, &pos, end);
+       if (res != WLAN_STATUS_SUCCESS)
+               return res;
+
+       /* commit-element */
+       return sae_parse_commit_element(sae, pos, end);
+}
+
+
 static void sae_cn_confirm(struct sae_data *sae, const u8 *sc,
                           const struct crypto_bignum *scalar1,
                           const u8 *element1,