dot11decrypt: Let dissector feed engine with EAPOL key message type

EAPOL key message type is known by dissector so no need for dot11decrypt
to parse frames to determine this. Instead feed engine with message
type from dissector. With this some code duplication can be avoided.

Change-Id: Icfd119186ebab5b0db29968df3eb94275d921e76
Reviewed-on: https://code.wireshark.org/review/34929
Reviewed-by: Peter Wu <peter@lekensteyn.nl>
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Roland Knall <rknall@gmail.com>

2 files changed, 139 insertions, 143 deletions

diff --git a/epan/crypt/dot11decrypt.c b/epan/crypt/dot11decrypt.c
index a3f7772cce..e73d046a3a 100644
--- a/epan/crypt/dot11decrypt.c
+++ b/epan/crypt/dot11decrypt.c
@@ -159,6 +159,7 @@ static INT Dot11DecryptWepMng(
 
 static INT Dot11DecryptRsna4WHandshake(
     PDOT11DECRYPT_CONTEXT ctx,
+    DOT11DECRYPT_HS_MSG_TYPE msg_type,
     const UCHAR *data,
     DOT11DECRYPT_SEC_ASSOCIATION *sa,
     INT offset,
@@ -713,6 +714,7 @@ INT Dot11DecryptScanTdlsForKeys(
 
 INT Dot11DecryptScanEapolForKeys(
     PDOT11DECRYPT_CONTEXT ctx,
+    DOT11DECRYPT_HS_MSG_TYPE msg_type,
     const guint8 *data,
     const guint tot_len,
     const UCHAR bssid[DOT11DECRYPT_MAC_LEN],
@@ -744,11 +746,6 @@ INT Dot11DecryptScanEapolForKeys(
         return DOT11DECRYPT_RET_NO_VALID_HANDSHAKE;
     }
 
-    /* check if the packet is a EAPOL-Key (0x03) (IEEE 802.1X-2004, pg. 25) */
-    if (data[offset+1]!=3) {
-        DEBUG_PRINT_LINE("Not EAPOL-Key", DEBUG_LEVEL_3);
-        return DOT11DECRYPT_RET_NO_VALID_HANDSHAKE;
-    }
 
     /* get and check the body length (IEEE 802.1X-2004, pg. 25) */
     bodyLength=pntoh16(data+offset+2);
@@ -789,7 +786,7 @@ INT Dot11DecryptScanEapolForKeys(
     }
 
     /* It could be a Pairwise Key exchange, check */
-    if (Dot11DecryptRsna4WHandshake(ctx, data, sa, offset, tot_len,
+    if (Dot11DecryptRsna4WHandshake(ctx, msg_type, data, sa, offset, tot_len,
                                     decrypt_data, decrypt_len, key) == DOT11DECRYPT_RET_SUCCESS_HANDSHAKE)
     {
         return DOT11DECRYPT_RET_SUCCESS_HANDSHAKE;
@@ -800,13 +797,9 @@ INT Dot11DecryptScanEapolForKeys(
         return DOT11DECRYPT_RET_NO_VALID_HANDSHAKE;
     }
 
-    /* Verify the bitfields: Key = 0(groupwise) Mic = 1 Ack = 1 Secure = 1 */
-    if (DOT11DECRYPT_EAP_KEY(data[offset+1])!=0 ||
-        DOT11DECRYPT_EAP_ACK(data[offset+1])!=1 ||
-        DOT11DECRYPT_EAP_MIC(data[offset]) != 1 ||
-        DOT11DECRYPT_EAP_SEC(data[offset]) != 1){
+    if (msg_type != DOT11DECRYPT_HS_MSG_TYPE_GHS_1){
 
-        DEBUG_PRINT_LINE("Key bitfields not correct for Group Key", DEBUG_LEVEL_3);
+        DEBUG_PRINT_LINE("Not Group handshake message 1", DEBUG_LEVEL_3);
         return DOT11DECRYPT_RET_NO_VALID_HANDSHAKE;
     }
 
@@ -1452,6 +1445,7 @@ Dot11DecryptGetRsne(
 static INT
 Dot11DecryptRsna4WHandshake(
     PDOT11DECRYPT_CONTEXT ctx,
+    DOT11DECRYPT_HS_MSG_TYPE msg_type,
     const UCHAR *data,
     DOT11DECRYPT_SEC_ASSOCIATION *sa,
     INT offset,
@@ -1493,9 +1487,7 @@ Dot11DecryptRsna4WHandshake(
     /* manage 4-way handshake packets; this step completes the 802.1X authentication process (IEEE 802.11i-2004, pag. 85) */
 
     /* message 1: Authenticator->Supplicant (Sec=0, Mic=0, Ack=1, Inst=0, Key=1(pairwise), KeyRSC=0, Nonce=ANonce, MIC=0) */
-    if (DOT11DECRYPT_EAP_INST(data[offset+1])==0 &&
-        DOT11DECRYPT_EAP_ACK(data[offset+1])==1 &&
-        DOT11DECRYPT_EAP_MIC(data[offset])==0)
+    if (msg_type == DOT11DECRYPT_HS_MSG_TYPE_4WHS_1)
     {
         DEBUG_PRINT_LINE("4-way handshake message 1", DEBUG_LEVEL_3);
 
@@ -1528,155 +1520,131 @@ Dot11DecryptRsna4WHandshake(
     }
 
     /* message 2|4: Supplicant->Authenticator (Sec=0|1, Mic=1, Ack=0, Inst=0, Key=1(pairwise), KeyRSC=0, Nonce=SNonce|0, MIC=MIC(KCK,EAPOL)) */
-    if (DOT11DECRYPT_EAP_INST(data[offset+1])==0 &&
-        DOT11DECRYPT_EAP_ACK(data[offset+1])==0 &&
-        DOT11DECRYPT_EAP_MIC(data[offset])==1)
-    {
-        /* Check key data length to differentiate between message 2 or 4, same as in epan/dissectors/packet-ieee80211.c */
-        if (tot_len-(offset+92) < 2) {
-            DEBUG_PRINT_LINE("Too short to have a key data length", DEBUG_LEVEL_5);
+    if (msg_type == DOT11DECRYPT_HS_MSG_TYPE_4WHS_2) {
+        DEBUG_PRINT_LINE("4-way handshake message 2", DEBUG_LEVEL_3);
+
+        /* On reception of Message 2, the Authenticator checks that the key replay counter corresponds to the */
+        /* outstanding Message 1. If not, it silently discards the message.                                   */
+        /* If the calculated MIC does not match the MIC that the Supplicant included in the EAPOL-Key frame,  */
+        /* the Authenticator silently discards Message 2.                                                     */
+        /* -> not checked; the Supplicant will send another message 2 (hopefully!)                            */
+
+        if (tot_len - (offset + 12) < 32) {
+            DEBUG_PRINT_LINE("Too short to contain SNonce", DEBUG_LEVEL_5);
             return DOT11DECRYPT_RET_NO_VALID_HANDSHAKE;
         }
-        if (pntoh16(data+offset+92)) {
-            /* message 2 */
-            DEBUG_PRINT_LINE("4-way handshake message 2", DEBUG_LEVEL_3);
-
-            /* On reception of Message 2, the Authenticator checks that the key replay counter corresponds to the */
-            /* outstanding Message 1. If not, it silently discards the message.                                   */
-            /* If the calculated MIC does not match the MIC that the Supplicant included in the EAPOL-Key frame,  */
-            /* the Authenticator silently discards Message 2.                                                     */
-            /* -> not checked; the Supplicant will send another message 2 (hopefully!)                            */
-
-            /* now you can derive the PTK */
-            for (key_index=0; key_index<(INT)ctx->keys_nr || useCache; key_index++) {
-                /* use the cached one, or try all keys */
-                if (!useCache) {
-                    DEBUG_PRINT_LINE("Try WPA key...", DEBUG_LEVEL_3);
+
+        /* now you can derive the PTK */
+        for (key_index=0; key_index<(INT)ctx->keys_nr || useCache; key_index++) {
+            /* use the cached one, or try all keys */
+            if (!useCache) {
+                DEBUG_PRINT_LINE("Try WPA key...", DEBUG_LEVEL_3);
+                tmp_key=&ctx->keys[key_index];
+            } else {
+                /* there is a cached key in the security association, if it's a WPA key try it... */
+                if (sa->key!=NULL &&
+                    (sa->key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PWD ||
+                    sa->key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PSK ||
+                    sa->key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PMK)) {
+                        DEBUG_PRINT_LINE("Try cached WPA key...", DEBUG_LEVEL_3);
+                        tmp_key=sa->key;
+                } else {
+                    DEBUG_PRINT_LINE("Cached key is of a wrong type, try WPA key...", DEBUG_LEVEL_3);
                     tmp_key=&ctx->keys[key_index];
+                }
+            }
+
+            /* obviously, try only WPA keys... */
+            if (tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PWD ||
+                tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PSK ||
+                tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PMK)
+            {
+                if (tmp_key->KeyType == DOT11DECRYPT_KEY_TYPE_WPA_PWD && tmp_key->UserPwd.SsidLen == 0 && ctx->pkt_ssid_len > 0 && ctx->pkt_ssid_len <= DOT11DECRYPT_WPA_SSID_MAX_LEN) {
+                    /* We have a "wildcard" SSID.  Use the one from the packet. */
+                    memcpy(&pkt_key, tmp_key, sizeof(pkt_key));
+                    memcpy(&pkt_key.UserPwd.Ssid, ctx->pkt_ssid, ctx->pkt_ssid_len);
+                    pkt_key.UserPwd.SsidLen = ctx->pkt_ssid_len;
+                    Dot11DecryptRsnaPwd2Psk(pkt_key.UserPwd.Passphrase, pkt_key.UserPwd.Ssid,
+                        pkt_key.UserPwd.SsidLen, pkt_key.KeyData.Wpa.Psk);
+                    tmp_pkt_key = &pkt_key;
                 } else {
-                    /* there is a cached key in the security association, if it's a WPA key try it... */
-                    if (sa->key!=NULL &&
-                        (sa->key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PWD ||
-                         sa->key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PSK ||
-                         sa->key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PMK)) {
-                            DEBUG_PRINT_LINE("Try cached WPA key...", DEBUG_LEVEL_3);
-                            tmp_key=sa->key;
-                    } else {
-                        DEBUG_PRINT_LINE("Cached key is of a wrong type, try WPA key...", DEBUG_LEVEL_3);
-                        tmp_key=&ctx->keys[key_index];
-                    }
+                    tmp_pkt_key = tmp_key;
+                }
+
+                /* verify the MIC (compare the MIC in the packet included in this message with a MIC calculated with the PTK) */
+                eapol_len=pntoh16(data+offset-3)+4;
+                if ((guint)(tot_len-(offset-5)) < (eapol_len<DOT11DECRYPT_EAPOL_MAX_LEN?eapol_len:DOT11DECRYPT_EAPOL_MAX_LEN)) {
+                    DEBUG_PRINT_LINE("Too short to contain ANonce", DEBUG_LEVEL_5);
+                    return DOT11DECRYPT_RET_NO_VALID_HANDSHAKE;
                 }
+                memcpy(eapol, &data[offset-5], (eapol_len<DOT11DECRYPT_EAPOL_MAX_LEN?eapol_len:DOT11DECRYPT_EAPOL_MAX_LEN));
+
+                int key_version = DOT11DECRYPT_EAP_KEY_DESCR_VER(data[offset+1]);
+                int akm = -1;
+                int cipher = -1;
+
+                if (key_version == 0) {
+                /* PTK derivation is based on Authentication Key Management Type */
+                    int group_cipher = -1;
+                    Dot11DecryptGetRsne((const EAPOL_RSN_KEY *)(data + offset - 1),
+                                        tot_len - (offset - 1),
+                                        &group_cipher, &cipher, &akm);
+                }
+
+                /* derive the PTK from the BSSID, STA MAC, PMK, SNonce, ANonce */
+                Dot11DecryptDerivePtk(sa,                            /* authenticator nonce, bssid, station mac */
+                                      tmp_pkt_key->KeyData.Wpa.Psk,  /* PSK == PMK */
+                                      data+offset+12,                /* supplicant nonce */
+                                      key_version,
+                                      akm,
+                                      cipher);
+
+                DEBUG_DUMP("TK",  DOT11DECRYPT_GET_TK(sa->wpa.ptk), 16);
 
-                /* obviously, try only WPA keys... */
-                if (tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PWD ||
-                    tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PSK ||
-                    tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PMK)
-                {
-                    if (tmp_key->KeyType == DOT11DECRYPT_KEY_TYPE_WPA_PWD && tmp_key->UserPwd.SsidLen == 0 && ctx->pkt_ssid_len > 0 && ctx->pkt_ssid_len <= DOT11DECRYPT_WPA_SSID_MAX_LEN) {
-                        /* We have a "wildcard" SSID.  Use the one from the packet. */
-                        memcpy(&pkt_key, tmp_key, sizeof(pkt_key));
-                        memcpy(&pkt_key.UserPwd.Ssid, ctx->pkt_ssid, ctx->pkt_ssid_len);
-                         pkt_key.UserPwd.SsidLen = ctx->pkt_ssid_len;
-                        Dot11DecryptRsnaPwd2Psk(pkt_key.UserPwd.Passphrase, pkt_key.UserPwd.Ssid,
-                            pkt_key.UserPwd.SsidLen, pkt_key.KeyData.Wpa.Psk);
-                        tmp_pkt_key = &pkt_key;
-                    } else {
-                        tmp_pkt_key = tmp_key;
-                    }
-
-                    /* verify the MIC (compare the MIC in the packet included in this message with a MIC calculated with the PTK) */
-                    eapol_len=pntoh16(data+offset-3)+4;
-                    if ((guint)(tot_len-(offset-5)) < (eapol_len<DOT11DECRYPT_EAPOL_MAX_LEN?eapol_len:DOT11DECRYPT_EAPOL_MAX_LEN)) {
-                        DEBUG_PRINT_LINE("Too short to contain ANonce", DEBUG_LEVEL_5);
-                        return DOT11DECRYPT_RET_NO_VALID_HANDSHAKE;
-                    }
-                    memcpy(eapol, &data[offset-5], (eapol_len<DOT11DECRYPT_EAPOL_MAX_LEN?eapol_len:DOT11DECRYPT_EAPOL_MAX_LEN));
-
-                    int key_version = DOT11DECRYPT_EAP_KEY_DESCR_VER(data[offset+1]);
-                    int akm = -1;
-                    int cipher = -1;
-
-                    if (key_version == 0) {
-                        /* PTK derivation is based on Authentication Key Management Type */
-                        int group_cipher = -1;
-                        Dot11DecryptGetRsne((const EAPOL_RSN_KEY *)(data + offset - 1),
-                                            tot_len - (offset - 1),
-                                            &group_cipher, &cipher, &akm);
-                    }
-
-                    /* derive the PTK from the BSSID, STA MAC, PMK, SNonce, ANonce */
-                    Dot11DecryptDerivePtk(sa,                            /* authenticator nonce, bssid, station mac */
-                                          tmp_pkt_key->KeyData.Wpa.Psk,  /* PSK == PMK */
-                                          data+offset+12,                /* supplicant nonce */
-                                          key_version,
-                                          akm,
-                                          cipher);
-
-                    DEBUG_DUMP("TK",  DOT11DECRYPT_GET_TK(sa->wpa.ptk), 16);
-
-                    ret_value=Dot11DecryptRsnaMicCheck(eapol,           /*      eapol frame (header also) */
+                ret_value=Dot11DecryptRsnaMicCheck(eapol,           /*      eapol frame (header also) */
                                                    eapol_len,       /*      eapol frame length        */
                                                    sa->wpa.ptk,     /*      Key Confirmation Key      */
                                                    key_version,     /*  EAPOL-Key description version */
                                                    akm);
-                    /* If the MIC is valid, the Authenticator checks that the RSN information element bit-wise matches       */
-                    /* that from the (Re)Association Request message.                                                        */
-                    /*              i) TODO If these are not exactly the same, the Authenticator uses MLME-DEAUTHENTICATE.request */
-                    /* primitive to terminate the association.                                                               */
-                    /*              ii) If they do match bit-wise, the Authenticator constructs Message 3.                   */
-                }
+                /* If the MIC is valid, the Authenticator checks that the RSN information element bit-wise matches       */
+                /* that from the (Re)Association Request message.                                                        */
+                /*              i) TODO If these are not exactly the same, the Authenticator uses MLME-DEAUTHENTICATE.request */
+                /* primitive to terminate the association.                                                               */
+                /*              ii) If they do match bit-wise, the Authenticator constructs Message 3.                   */
+            }
 
-                if (!ret_value &&
-                    (tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PWD ||
-                    tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PSK ||
-                    tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PMK))
-                {
-                    /* the temporary key is the correct one, cached in the Security Association */
+            if (!ret_value &&
+                (tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PWD ||
+                 tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PSK ||
+                 tmp_key->KeyType==DOT11DECRYPT_KEY_TYPE_WPA_PMK))
+            {
+                /* the temporary key is the correct one, cached in the Security Association */
 
-                    sa->key=tmp_key;
-                    break;
-                } else {
-                    /* the cached key was not valid, try other keys */
+                sa->key=tmp_key;
+                break;
+            } else {
+                /* the cached key was not valid, try other keys */
 
-                    if (useCache==TRUE) {
-                        useCache=FALSE;
-                        key_index--;
-                    }
+                if (useCache==TRUE) {
+                useCache=FALSE;
+                key_index--;
                 }
             }
+        }
 
-            if (ret_value) {
-                DEBUG_PRINT_LINE("handshake step failed", DEBUG_LEVEL_3);
-                return DOT11DECRYPT_RET_NO_VALID_HANDSHAKE;
-            }
-
-            sa->handshake=2;
-            sa->validKey=TRUE; /* we can use the key to decode, even if we have not captured the other eapol packets */
-
-            return DOT11DECRYPT_RET_SUCCESS_HANDSHAKE;
-        } else {
-        /* message 4 */
-
-            /* TODO "Note that when the 4-Way Handshake is first used Message 4 is sent in the clear." */
-
-            /* TODO check MIC and Replay Counter                                                                     */
-            /* On reception of Message 4, the Authenticator verifies that the Key Replay Counter field value is one  */
-            /* that it used on this 4-Way Handshake; if it is not, it silently discards the message.                 */
-            /* If the calculated MIC does not match the MIC that the Supplicant included in the EAPOL-Key frame, the */
-            /* Authenticator silently discards Message 4.                                                            */
-
-            DEBUG_PRINT_LINE("4-way handshake message 4", DEBUG_LEVEL_3);
+        if (ret_value) {
+            DEBUG_PRINT_LINE("handshake step failed", DEBUG_LEVEL_3);
+            return DOT11DECRYPT_RET_NO_VALID_HANDSHAKE;
+        }
 
-            sa->handshake=4;
+        sa->handshake=2;
+        sa->validKey=TRUE; /* we can use the key to decode, even if we have not captured the other eapol packets */
 
-            return DOT11DECRYPT_RET_SUCCESS_HANDSHAKE;
-        }
+        return DOT11DECRYPT_RET_SUCCESS_HANDSHAKE;
     }
 
     /* message 3: Authenticator->Supplicant (Sec=1, Mic=1, Ack=1, Inst=0/1, Key=1(pairwise), KeyRSC=???, Nonce=ANonce, MIC=1) */
-    if (DOT11DECRYPT_EAP_ACK(data[offset+1])==1 &&
-        DOT11DECRYPT_EAP_MIC(data[offset])==1)
-    {
+    if (msg_type == DOT11DECRYPT_HS_MSG_TYPE_4WHS_3) {
         const EAPOL_RSN_KEY *pEAPKey;
         DEBUG_PRINT_LINE("4-way handshake message 3", DEBUG_LEVEL_3);
 
@@ -1707,6 +1675,22 @@ Dot11DecryptRsna4WHandshake(
         }
     }
 
+    /* message 4 */
+    if (msg_type == DOT11DECRYPT_HS_MSG_TYPE_4WHS_4) {
+        /* TODO "Note that when the 4-Way Handshake is first used Message 4 is sent in the clear." */
+
+        /* TODO check MIC and Replay Counter                                                                     */
+        /* On reception of Message 4, the Authenticator verifies that the Key Replay Counter field value is one  */
+        /* that it used on this 4-Way Handshake; if it is not, it silently discards the message.                 */
+        /* If the calculated MIC does not match the MIC that the Supplicant included in the EAPOL-Key frame, the */
+        /* Authenticator silently discards Message 4.                                                            */
+
+        DEBUG_PRINT_LINE("4-way handshake message 4", DEBUG_LEVEL_3);
+
+        sa->handshake=4;
+
+        return DOT11DECRYPT_RET_SUCCESS_HANDSHAKE;
+    }
     return DOT11DECRYPT_RET_NO_VALID_HANDSHAKE;
 }
 
diff --git a/epan/crypt/dot11decrypt_system.h b/epan/crypt/dot11decrypt_system.h
index 28ee5b74b7..b7a18dc60a 100644
--- a/epan/crypt/dot11decrypt_system.h
+++ b/epan/crypt/dot11decrypt_system.h
@@ -140,6 +140,16 @@ typedef struct _DOT11DECRYPT_CONTEXT {
 	INT first_free_index;
 } DOT11DECRYPT_CONTEXT, *PDOT11DECRYPT_CONTEXT;
 
+typedef enum _DOT11DECRYPT_HS_MSG_TYPE {
+	DOT11DECRYPT_HS_MSG_TYPE_INVALID = 0,
+	DOT11DECRYPT_HS_MSG_TYPE_4WHS_1,
+	DOT11DECRYPT_HS_MSG_TYPE_4WHS_2,
+	DOT11DECRYPT_HS_MSG_TYPE_4WHS_3,
+	DOT11DECRYPT_HS_MSG_TYPE_4WHS_4,
+	DOT11DECRYPT_HS_MSG_TYPE_GHS_1,
+	DOT11DECRYPT_HS_MSG_TYPE_GHS_2
+} DOT11DECRYPT_HS_MSG_TYPE;
+
 /************************************************************************/
 /*	Function prototype declarations					*/
 
@@ -203,6 +213,7 @@ extern INT Dot11DecryptDecryptPacket(
  * extracting further keys. If keydata hard to be decrypted the decrypted
  * data will be in decrypt_data buffer.
  * @param ctx [IN] Pointer to the current context
+ * @param msg_type [IN] Handshake message type
  * @param data [IN] Pointer to a buffer with an EAPOL frame
  * @param tot_len [IN] Total length of the EAPOL frame
  * @param bssid [IN] bssid of AP
@@ -237,6 +248,7 @@ extern INT Dot11DecryptDecryptPacket(
  */
 extern INT Dot11DecryptScanEapolForKeys(
     PDOT11DECRYPT_CONTEXT ctx,
+    DOT11DECRYPT_HS_MSG_TYPE msg_type,
     const guint8 *data,
     const guint tot_len,
     const UCHAR bssid[DOT11DECRYPT_MAC_LEN],