Avoid unnecessary list creations with keys()

scapy/asn1fields.py

@@ -256,7 +256,7 @@ class ASN1F_SEQUENCE(ASN1F_field):
         name = "dummy_seq_name"
         default = [field.default for field in seq]
         for kwarg in ["context", "implicit_tag", "explicit_tag"]:
-            if kwarg in kwargs.keys():
+            if kwarg in kwargs:
                 setattr(self, kwarg, kwargs[kwarg])
             else:
                 setattr(self, kwarg, None)
@@ -401,12 +401,12 @@ class ASN1F_CHOICE(ASN1F_field):
     holds_packets = 1
     ASN1_tag = ASN1_Class_UNIVERSAL.ANY
     def __init__(self, name, default, *args, **kwargs):
-        if "implicit_tag" in kwargs.keys():
+        if "implicit_tag" in kwargs:
             err_msg = "ASN1F_CHOICE has been called with an implicit_tag"
             raise ASN1_Error(err_msg)
         self.implicit_tag = None
         for kwarg in ["context", "explicit_tag"]:
-            if kwarg in kwargs.keys():
+            if kwarg in kwargs:
                 setattr(self, kwarg, kwargs[kwarg])
             else:
                 setattr(self, kwarg, None)
@@ -419,7 +419,7 @@ class ASN1F_CHOICE(ASN1F_field):
         for p in args:
             if hasattr(p, "ASN1_root"):     # should be ASN1_Packet
                 if hasattr(p.ASN1_root, "choices"):
-                    for k,v in p.ASN1_root.choices.items():
+                    for k,v in p.ASN1_root.choices.iteritems():
                         self.choices[k] = v         # ASN1F_CHOICE recursion
                 else:
                     self.choices[p.ASN1_root.network_tag] = p
@@ -462,7 +462,7 @@ class ASN1F_CHOICE(ASN1F_field):
             s = ""
         else:
             s = str(x)
-        if hash(type(x)) in self.pktchoices.keys():
+        if hash(type(x)) in self.pktchoices:
             imp, exp = self.pktchoices[hash(type(x))]
             s = BER_tagging_enc(s, implicit_tag=imp,
                                 explicit_tag=exp)

scapy/layers/x509.py

@@ -622,7 +622,7 @@ class ASN1F_EXT_SEQUENCE(ASN1F_SEQUENCE):
             extnID.set_val(pkt, oid)
             s = critical.dissect(pkt, s)
             encapsed = X509_ExtDefault
-            if oid.val in ext_mapping.keys():
+            if oid.val in ext_mapping:
                 encapsed = ext_mapping[oid.val]
             self.seq[2].cls = encapsed
             self.seq[2].cls.ASN1_root.flexible_tag = True
@@ -788,10 +788,10 @@ class X509_TBSCertificate(ASN1_Packet):
         name_str = ""
         attrsDict = self.get_issuer()
         for attrType, attrSymbol in attrName_mapping:
-            if attrType in attrsDict.keys():
+            if attrType in attrsDict:
                 name_str += "/" + attrSymbol + "="
                 name_str += attrsDict[attrType]
-        for attrType in sorted(attrsDict.keys()):
+        for attrType in sorted(attrsDict):
             if attrType not in attrName_specials:
                 name_str += "/" + attrType + "="
                 name_str += attrsDict[attrType]
@@ -807,10 +807,10 @@ class X509_TBSCertificate(ASN1_Packet):
         name_str = ""
         attrsDict = self.get_subject()
         for attrType, attrSymbol in attrName_mapping:
-            if attrType in attrsDict.keys():
+            if attrType in attrsDict:
                 name_str += "/" + attrSymbol + "="
                 name_str += attrsDict[attrType]
-        for attrType in sorted(attrsDict.keys()):
+        for attrType in sorted(attrsDict):
             if attrType not in attrName_specials:
                 name_str += "/" + attrType + "="
                 name_str += attrsDict[attrType]
@@ -915,10 +915,10 @@ class X509_TBSCertList(ASN1_Packet):
         name_str = ""
         attrsDict = self.get_issuer()
         for attrType, attrSymbol in attrName_mapping:
-            if attrType in attrsDict.keys():
+            if attrType in attrsDict:
                 name_str += "/" + attrSymbol + "="
                 name_str += attrsDict[attrType]
-        for attrType in sorted(attrsDict.keys()):
+        for attrType in sorted(attrsDict):
             if attrType not in attrName_specials:
                 name_str += "/" + attrType + "="
                 name_str += attrsDict[attrType]