Merge pull request #230 from mbudiu-bfn/master

Initial implementation of P4->ebpf compiler.

src/cc/frontends/p4/compiler/README.txt

+This folder contains an implementation of a simple compiler that
+translates a programs written in a subset of P4 into C that can in
+turn be compiled into EBPF using the IOVisor bcc compiler.
+

src/cc/frontends/p4/compiler/compilationException.py

+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+class CompilationException(Exception):
+    """Signals an error during compilation"""
+    def __init__(self, isBug, format, *message):        
+        # isBug: indicates that this is a compiler bug
+        super(CompilationException, self).__init__()
+        
+        assert isinstance(format, str)
+        assert isinstance(isBug, bool)
+        self.message = message
+        self.format = format
+        self.isBug = isBug
+
+    def show(self):
+        # TODO: format this message nicely
+        return self.format.format(*self.message)
+
+
+class NotSupportedException(Exception):
+    archError = " not supported by EBPF"
+
+    def __init__(self, format, *message):
+        super(NotSupportedException, self).__init__()
+
+        assert isinstance(format, str)
+        self.message = message
+        self.format = format
+
+    def show(self):
+        # TODO: format this message nicely
+        return (self.format + NotSupportedException.archError).format(
+            *self.message)

src/cc/frontends/p4/compiler/ebpfConditional.py

+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from p4_hlir.hlir import p4_conditional_node, p4_expression
+from p4_hlir.hlir import p4_header_instance, p4_field
+from programSerializer import ProgramSerializer
+from compilationException import CompilationException
+import ebpfProgram
+import ebpfInstance
+
+
+class EbpfConditional(object):
+    @staticmethod
+    def translate(op):
+        if op == "not":
+            return "!"
+        elif op == "or":
+            return "||"
+        elif op == "and":
+            return "&&"
+        return op
+
+    def __init__(self, p4conditional, program):
+        assert isinstance(p4conditional, p4_conditional_node)
+        assert isinstance(program, ebpfProgram.EbpfProgram)
+        self.hlirconditional = p4conditional
+        self.name = p4conditional.name
+
+    def emitNode(self, node, serializer, program):
+        if isinstance(node, p4_expression):
+            self.emitExpression(node, serializer, program, False)
+        elif node is None:
+            pass
+        elif isinstance(node, int):
+            serializer.append(node)
+        elif isinstance(node, p4_header_instance):
+            header = program.getInstance(node.name)
+            assert isinstance(header, ebpfInstance.EbpfHeader)
+            # TODO: stacks?
+            serializer.appendFormat(
+                "{0}.{1}", program.headerStructName, header.name)
+        elif isinstance(node, p4_field):
+            instance = node.instance
+            einstance = program.getInstance(instance.name)
+            if isinstance(einstance, ebpfInstance.EbpfHeader):
+                base = program.headerStructName
+            else:
+                base = program.metadataStructName
+            serializer.appendFormat(
+                "{0}.{1}.{2}", base, einstance.name, node.name)
+        else:
+            raise CompilationException(True, "{0} Unexpected expression ", node)
+        
+    def emitExpression(self, expression, serializer, program, toplevel):
+        assert isinstance(serializer, ProgramSerializer)
+        assert isinstance(program, ebpfProgram.EbpfProgram)
+        assert isinstance(expression, p4_expression)
+        assert isinstance(toplevel, bool)
+        left = expression.left
+        op = expression.op
+        right = expression.right
+        
+        assert isinstance(op, str)
+        
+        if op == "valid":
+            self.emitNode(right, serializer, program)
+            serializer.append(".valid")
+            return
+
+        if not toplevel:
+            serializer.append("(")
+        self.emitNode(left, serializer, program)
+        op = EbpfConditional.translate(op)
+        serializer.append(op)
+        self.emitNode(right, serializer, program)
+        if not toplevel:
+            serializer.append(")")
+
+    def generateCode(self, serializer, program, nextNode):
+        assert isinstance(serializer, ProgramSerializer)
+        assert isinstance(program, ebpfProgram.EbpfProgram)
+        serializer.emitIndent()
+        serializer.blockStart()
+
+        trueBranch = self.hlirconditional.next_[True]
+        if trueBranch is None:
+            trueBranch = nextNode
+        falseBranch = self.hlirconditional.next_[False]
+        if falseBranch is None:
+            falseBranch = nextNode
+
+        serializer.emitIndent()
+        serializer.appendFormat("{0}:", program.getLabel(self.hlirconditional))
+        serializer.newline()
+
+        serializer.emitIndent()
+        serializer.append("if (")
+        self.emitExpression(
+            self.hlirconditional.condition, serializer, program, True)
+        serializer.appendLine(")")
+
+        serializer.increaseIndent()
+        label = program.getLabel(trueBranch)
+        serializer.emitIndent()
+        serializer.appendFormat("goto {0};", label)
+        serializer.newline()
+        serializer.decreaseIndent()
+
+        serializer.emitIndent()
+        serializer.appendLine("else")
+        serializer.increaseIndent()
+        label = program.getLabel(falseBranch)
+        serializer.emitIndent()
+        serializer.appendFormat("goto {0};", label)
+        serializer.newline()
+        serializer.decreaseIndent()
+
+        serializer.blockEnd(True)

src/cc/frontends/p4/compiler/ebpfCounter.py

+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from p4_hlir.hlir import p4_counter, P4_DIRECT, P4_COUNTER_BYTES
+from programSerializer import ProgramSerializer
+from compilationException import *
+import ebpfTable
+import ebpfProgram
+
+
+class EbpfCounter(object):
+    # noinspection PyUnresolvedReferences
+    def __init__(self, hlircounter, program):
+        assert isinstance(hlircounter, p4_counter)
+        assert isinstance(program, ebpfProgram.EbpfProgram)
+
+        self.name = hlircounter.name
+        self.hlircounter = hlircounter
+
+        width = hlircounter.min_width
+        # ebpf counters only work on 64-bits
+        if width <= 64:
+            self.valueTypeName = program.config.uprefix + "64"
+        else:
+            raise NotSupportedException(
+                "{0}: Counters with {1} bits", hlircounter, width)
+
+        self.dataMapName = self.name
+
+        if ((hlircounter.binding is None) or 
+            (hlircounter.binding[0] != P4_DIRECT)):
+            raise NotSupportedException(
+                "{0}: counter which is not direct", hlircounter)
+
+        self.autoIncrement = (hlircounter.binding != None and
+                              hlircounter.binding[0] == P4_DIRECT)
+
+        if hlircounter.type is P4_COUNTER_BYTES:
+            self.increment = "{0}->len".format(program.packetName)
+        else:
+            self.increment = "1"
+
+    def getSize(self, program):
+        if self.hlircounter.instance_count is not None:
+            return self.hlircounter.instance_count
+        if self.autoIncrement:
+            return self.getTable(program).size
+        program.emitWarning(
+            "{0} does not specify a max_size; using 1024", self.hlircounter)
+        return 1024
+
+    def getTable(self, program):
+        table = program.getTable(self.hlircounter.binding[1].name)
+        assert isinstance(table, ebpfTable.EbpfTable)
+        return table
+
+    def serialize(self, serializer, program):
+        assert isinstance(serializer, ProgramSerializer)
+
+        # Direct counters have the same key as the associated table
+        # Static counters have integer keys
+        if self.autoIncrement:
+            keyTypeName = "struct " + self.getTable(program).keyTypeName
+        else:
+            keyTypeName = program.config.uprefix + "32"
+        program.config.serializeTableDeclaration(
+            serializer, self.dataMapName, True, keyTypeName,
+            self.valueTypeName, self.getSize(program))
+
+    def serializeCode(self, keyname, serializer, program):
+        assert isinstance(serializer, ProgramSerializer)
+        assert isinstance(program, ebpfProgram.EbpfProgram)
+
+        serializer.emitIndent()
+        serializer.appendFormat("/* Update counter {0} */", self.name)
+        serializer.newline()
+
+        valueName = "ctrvalue"
+        initValuename = "init_val"
+
+        serializer.emitIndent()
+        serializer.appendFormat("{0} *{1};", self.valueTypeName, valueName)
+        serializer.newline()
+        serializer.emitIndent()
+        serializer.appendFormat("{0} {1};", self.valueTypeName, initValuename)
+        serializer.newline()
+
+        serializer.emitIndent()
+        serializer.appendLine("/* perform lookup */")
+        serializer.emitIndent()
+        program.config.serializeLookup(
+            serializer, self.dataMapName, keyname, valueName)
+        serializer.newline()
+
+        serializer.emitIndent()
+        serializer.appendFormat("if ({0} != NULL) ", valueName)
+        serializer.newline()
+        serializer.increaseIndent()
+        serializer.emitIndent()
+        serializer.appendFormat("__sync_fetch_and_add({0}, {1});",
+                                valueName, self.increment)
+        serializer.newline()
+        serializer.decreaseIndent()
+        serializer.emitIndent()
+
+        serializer.append("else ")
+        serializer.blockStart()
+        serializer.emitIndent()
+        serializer.appendFormat("{0} = {1};", initValuename, self.increment)
+        serializer.newline()
+
+        serializer.emitIndent()
+        program.config.serializeUpdate(
+            serializer, self.dataMapName, keyname, initValuename)
+        serializer.newline()
+        serializer.blockEnd(True)

src/cc/frontends/p4/compiler/ebpfInstance.py

+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from p4_hlir.hlir import p4_header_instance
+from ebpfType import EbpfType
+from compilationException import CompilationException
+from programSerializer import ProgramSerializer
+import typeFactory
+
+
+class EbpfInstanceBase(object):
+    def __init__(self):
+        pass
+
+
+class SimpleInstance(EbpfInstanceBase):
+    # A header or a metadata instance (but not array elements)
+    def __init__(self, hlirInstance, factory, isMetadata):
+        super(SimpleInstance, self).__init__()
+        self.hlirInstance = hlirInstance
+        self.name = hlirInstance.base_name
+        self.type = factory.build(hlirInstance.header_type, isMetadata)
+
+    def declare(self, serializer):
+        assert isinstance(serializer, ProgramSerializer)
+        self.type.declare(serializer, self.name, False)
+
+
+class EbpfHeader(SimpleInstance):
+    """ Represents a header instance from a P4 program """
+    def __init__(self, hlirHeaderInstance, factory):
+        super(EbpfHeader, self).__init__(hlirHeaderInstance, factory, False)
+        if hlirHeaderInstance.metadata:
+            raise CompilationException(True, "Metadata passed to EpbfHeader")
+        if hlirHeaderInstance.index is not None:
+            self.name += "_" + str(hlirHeaderInstance.index)
+
+
+class EbpfMetadata(SimpleInstance):
+    """Represents a metadata instance from a P4 program"""
+    def __init__(self, hlirMetadataInstance, factory):
+        super(EbpfMetadata, self).__init__(hlirMetadataInstance, factory, True)
+        if not hlirMetadataInstance.metadata:
+            raise CompilationException(
+                True, "Header instance passed to EpbfMetadata {0}",
+                hlirMetadataInstance)
+        if hlirMetadataInstance.index is not None:
+            raise CompilationException(
+                True, "Unexpected metadata array {0}", self.hlirInstance)
+        if hasattr(hlirMetadataInstance, "initializer"):
+            self.initializer = hlirMetadataInstance.initializer
+        else:
+            self.initializer = None
+
+    def emitInitializer(self, serializer):
+        assert isinstance(serializer, ProgramSerializer)
+        if self.initializer is None:
+            self.type.emitInitializer(serializer)
+        else:
+            for key in self.initializer.keys():
+                serializer.appendFormat(
+                    ".{0} = {1},", key, self.initializer[key])
+
+
+class EbpfHeaderStack(EbpfInstanceBase):
+    """Represents a header stack instance; there is one instance of
+    this class for each STACK, and not for each
+    element of the stack, as in the HLIR"""
+    def __init__(self, hlirInstance, indexVar, factory):
+        super(EbpfHeaderStack, self).__init__()
+
+        # indexVar: name of the ebpf variable that
+        # holds the current index for this stack
+        assert isinstance(indexVar, str)
+        assert isinstance(factory, typeFactory.EbpfTypeFactory)
+        assert isinstance(hlirInstance, p4_header_instance)
+
+        self.indexVar = indexVar
+        self.name = hlirInstance.base_name
+        self.basetype = factory.build(hlirInstance.header_type, False)
+        assert isinstance(self.basetype, EbpfType)
+        self.arraySize = hlirInstance.max_index + 1
+        self.hlirInstance = hlirInstance
+
+    def declare(self, serializer):
+        assert isinstance(serializer, ProgramSerializer)
+        self.basetype.declareArray(serializer, self.name, self.arraySize)

src/cc/frontends/p4/compiler/ebpfScalarType.py

+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from p4_hlir.hlir import P4_AUTO_WIDTH
+from ebpfType import *
+from compilationException import *
+from programSerializer import ProgramSerializer
+
+
+class EbpfScalarType(EbpfType):
+    __doc__ = "Represents a scalar type"
+    def __init__(self, parent, widthInBits, isSigned, config):
+        super(EbpfScalarType, self).__init__(None)
+        assert isinstance(widthInBits, int)
+        assert isinstance(isSigned, bool)
+        self.width = widthInBits
+        self.isSigned = isSigned
+        self.config = config
+        if widthInBits is P4_AUTO_WIDTH:
+            raise NotSupportedException("{0} Variable-width field", parent)
+
+    def widthInBits(self):
+        return self.width
+
+    @staticmethod
+    def bytesRequired(width):
+        return (width + 7) / 8
+
+    def asString(self):
+        if self.isSigned:
+            prefix = self.config.iprefix
+        else:
+            prefix = self.config.uprefix
+
+        if self.width <= 8:
+            name = prefix + "8"
+        elif self.width <= 16:
+            name = prefix + "16"
+        elif self.width <= 32:
+            name = prefix + "32"
+        else:
+            name = "char*"
+        return name
+
+    def alignment(self):
+        if self.width <= 8:
+            return 1
+        elif self.width <= 16:
+            return 2
+        elif self.width <= 32:
+            return 4
+        else:
+            return 1  # Char array
+    
+    def serialize(self, serializer):
+        assert isinstance(serializer, ProgramSerializer)
+        serializer.append(self.asString())
+
+    def declareArray(self, serializer, identifier, size):
+        raise CompilationException(
+            True, "Arrays of base type not expected in P4")
+
+    def declare(self, serializer, identifier, asPointer):
+        assert isinstance(serializer, ProgramSerializer)
+        assert isinstance(asPointer, bool)
+        assert isinstance(identifier, str)
+
+        if self.width <= 32:
+            self.serialize(serializer)
+            if asPointer:
+                serializer.append("*")
+            serializer.space()
+            serializer.append(identifier)
+        else:
+            if asPointer:
+                serializer.append("char*")
+            else:
+                serializer.appendFormat(
+                    "char {0}[{1}]", identifier,
+                    EbpfScalarType.bytesRequired(self.width))
+
+    def emitInitializer(self, serializer):
+        assert isinstance(serializer, ProgramSerializer)
+        serializer.append("0")

src/cc/frontends/p4/compiler/ebpfStructType.py

+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from p4_hlir.hlir import P4_SIGNED, P4_SATURATING
+from ebpfScalarType import *
+
+
+class EbpfField(object):
+    __doc__ = "represents a field in a struct type, not in an instance"
+
+    def __init__(self, hlirParentType, name, widthInBits, attributes, config):
+        self.name = name
+        self.width = widthInBits
+        self.hlirType = hlirParentType
+        signed = False
+        if P4_SIGNED in attributes:
+            signed = True
+        if P4_SATURATING in attributes:
+            raise NotSupportedException(
+                "{0}.{1}: Saturated types", self.hlirType, self.name)
+
+        try:
+            self.type = EbpfScalarType(
+                self.hlirType, widthInBits, signed, config)
+        except CompilationException, e:
+            raise CompilationException(
+                e.isBug, "{0}.{1}: {2}", hlirParentType, self.name, e.show())
+
+    def widthInBits(self):
+        return self.width
+
+
+class EbpfStructType(EbpfType):
+    # Abstract base class for HeaderType and MetadataType.
+    # They are both represented by a p4 header_type
+    def __init__(self, hlirHeader, config):
+        super(EbpfStructType, self).__init__(hlirHeader)
+        self.name = hlirHeader.name
+        self.fields = []
+
+        for (fieldName, fieldSize) in self.hlirType.layout.items():
+            attributes = self.hlirType.attributes[fieldName]
+            field = EbpfField(
+                hlirHeader, fieldName, fieldSize, attributes, config)
+            self.fields.append(field)
+
+    def serialize(self, serializer):
+        assert isinstance(serializer, ProgramSerializer)
+
+        serializer.emitIndent()
+        serializer.appendFormat("struct {0} ", self.name)
+        serializer.blockStart()
+
+        for field in self.fields:
+            serializer.emitIndent()
+            field.type.declare(serializer, field.name, False)
+            serializer.appendFormat("; /* {0} bits */", field.widthInBits())
+            serializer.newline()
+
+        serializer.blockEnd(False)
+        serializer.endOfStatement(True)
+
+    def declare(self, serializer, identifier, asPointer):
+        assert isinstance(serializer, ProgramSerializer)
+        assert isinstance(identifier, str)
+        assert isinstance(asPointer, bool)
+
+        serializer.appendFormat("struct {0} ", self.name)
+        if asPointer:
+            serializer.append("*")
+        serializer.append(identifier)
+
+    def widthInBits(self):
+        return self.hlirType.length * 8
+
+    def getField(self, name):
+        assert isinstance(name, str)
+
+        for f in self.fields:
+            assert isinstance(f, EbpfField)
+            if f.name == name:
+                return f
+        raise CompilationException(
+            True, "Could not locate field {0}.{1}", self, name)
+
+
+class EbpfHeaderType(EbpfStructType):
+    def __init__(self, hlirHeader, config):
+        super(EbpfHeaderType, self).__init__(hlirHeader, config)
+        validField = EbpfField(hlirHeader, "valid", 1, set(), config)
+        # check that no "valid" field exists already
+        for f in self.fields:
+            if f.name == "valid":
+                raise CompilationException(
+                    True,
+                    "Header type contains a field named `valid': {0}",
+                    f)
+        self.fields.append(validField)
+
+    def emitInitializer(self, serializer):
+        assert isinstance(serializer, ProgramSerializer)
+        serializer.blockStart()
+        serializer.emitIndent()
+        serializer.appendLine(".valid = 0")
+        serializer.blockEnd(False)
+
+    def declareArray(self, serializer, identifier, size):
+        assert isinstance(serializer, ProgramSerializer)
+        serializer.appendFormat(
+            "struct {0} {1}[{2}]", self.name, identifier, size)
+
+
+class EbpfMetadataType(EbpfStructType):
+    def __init__(self, hlirHeader, config):
+        super(EbpfMetadataType, self).__init__(hlirHeader, config)
+
+    def emitInitializer(self, serializer):
+        assert isinstance(serializer, ProgramSerializer)
+
+        serializer.blockStart()
+        for field in self.fields:
+            serializer.emitIndent()
+            serializer.appendFormat(".{0} = ", field.name)
+
+            field.type.emitInitializer(serializer)
+            serializer.append(",")
+            serializer.newline()
+        serializer.blockEnd(False)

src/cc/frontends/p4/compiler/ebpfType.py

+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from compilationException import CompilationException
+
+class EbpfType(object):
+    __doc__ = "Base class for representing a P4 type"
+
+    def __init__(self, hlirType):
+        self.hlirType = hlirType
+
+    # Methods to override
+
+    def serialize(self, serializer):
+        # the type itself
+        raise CompilationException(True, "Method must be overridden")
+
+    def declare(self, serializer, identifier, asPointer):
+        # declaration of an identifier with this type
+        # asPointer is a boolean;
+        # if true, the identifier is declared as a pointer
+        raise CompilationException(True, "Method must be overridden")
+
+    def emitInitializer(self, serializer):
+        # A default initializer suitable for this type
+        raise CompilationException(True, "Method must be overridden")
+
+    def declareArray(self, serializer, identifier, size):
+        # Declare an identifier with an array type with the specified size
+        raise CompilationException(True, "Method must be overridden")

src/cc/frontends/p4/compiler/p4toEbpf.py

+#!/usr/bin/env python
+
+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+# Compiler from P4 to EBPF
+# (See http://www.slideshare.net/PLUMgrid/ebpf-and-linux-networking).
+# This compiler in fact generates a C source file
+# which can be compiled to EBPF using the LLVM compiler 
+# with the ebpf target.
+#
+# Main entry point.
+
+import argparse
+import os
+import traceback
+import sys
+import target
+from p4_hlir.main import HLIR
+from ebpfProgram import EbpfProgram
+from compilationException import *
+from programSerializer import ProgramSerializer
+
+
+def get_parser():
+    parser = argparse.ArgumentParser(description='p4toEbpf arguments')
+    parser.add_argument('source', metavar='source', type=str,
+                        help='a P4 source file to compile')
+    parser.add_argument('-g', dest='generated', default="router",
+                        help="kind of output produced: filter or router")
+    parser.add_argument('-o', dest='output_file', default="output.c",
+                        help="generated C file name")
+    return parser
+
+
+def process(input_args):
+    parser = get_parser()
+    args, unparsed_args = parser.parse_known_args(input_args)
+
+    has_remaining_args = False
+    preprocessor_args = []
+    for a in unparsed_args:
+        if a[:2] == "-D" or a[:2] == "-I" or a[:2] == "-U":
+            input_args.remove(a)
+            preprocessor_args.append(a)
+        else:
+            has_remaining_args = True
+
+    # trigger error
+    if has_remaining_args:
+        parser.parse_args(input_args)
+
+    if args.generated == "router":
+        isRouter = True
+    elif args.generated == "filter":
+        isRouter = False
+    else:
+        print("-g should be one of 'filter' or 'router'")
+
+    print("*** Compiling ", args.source)
+    return compileP4(args.source, args.output_file, isRouter, preprocessor_args)
+
+
+class CompileResult(object):
+    def __init__(self, kind, error):
+        self.kind = kind
+        self.error = error
+
+    def __str__(self):
+        if self.kind == "OK":
+            return "Compilation successful"
+        else:
+            return "Compilation failed with error: " + self.error
+
+
+def compileP4(inputFile, gen_file, isRouter, preprocessor_args):
+    h = HLIR(inputFile)
+
+    for parg in preprocessor_args:
+        h.add_preprocessor_args(parg)
+    if not h.build():
+        return CompileResult("HLIR", "Error while building HLIR")
+
+    try:
+        basename = os.path.basename(inputFile)
+        basename = os.path.splitext(basename)[0]
+
+        config = target.BccConfig()
+        e = EbpfProgram(basename, h, isRouter, config)
+        serializer = ProgramSerializer()
+        e.toC(serializer)
+        f = open(gen_file, 'w')
+        f.write(serializer.toString())
+        return CompileResult("OK", "")
+    except CompilationException, e:
+        prefix = ""
+        if e.isBug:
+            prefix = "### Compiler bug: "
+        return CompileResult("bug", prefix + e.show())
+    except NotSupportedException, e:
+        return CompileResult("not supported", e.show())
+    except:
+        return CompileResult("exception", traceback.format_exc())
+
+
+# main entry point
+if __name__ == "__main__":
+    result = process(sys.argv[1:])
+    if result.kind != "OK":
+        print(str(result))

src/cc/frontends/p4/compiler/programSerializer.py

+#!/usr/bin/env python
+
+# helper for building C program source text
+
+from compilationException import *
+
+
+class ProgramSerializer(object):
+    def __init__(self):
+        self.program = ""
+        self.eol = "\n"
+        self.currentIndent = 0
+        self.INDENT_AMOUNT = 4  # default indent amount
+
+    def __str__(self):
+        return self.program
+
+    def increaseIndent(self):
+        self.currentIndent += self.INDENT_AMOUNT
+
+    def decreaseIndent(self):
+        self.currentIndent -= self.INDENT_AMOUNT
+        if self.currentIndent < 0:
+            raise CompilationException(True, "Negative indentation level")
+
+    def toString(self):
+        return self.program
+
+    def space(self):
+        self.append(" ")
+
+    def newline(self):
+        self.program += self.eol
+
+    def endOfStatement(self, addNewline):
+        self.append(";")
+        if addNewline:
+            self.newline()
+
+    def append(self, string):
+        self.program += str(string)
+
+    def appendFormat(self, format, *args):
+        string = format.format(*args)
+        self.append(string)
+
+    def appendLine(self, string):
+        self.append(string)
+        self.newline()
+
+    def emitIndent(self):
+        self.program += " " * self.currentIndent
+
+    def blockStart(self):
+        self.append("{")
+        self.newline()
+        self.increaseIndent()
+
+    def blockEnd(self, addNewline):
+        self.decreaseIndent()
+        self.emitIndent()
+        self.append("}")
+        if addNewline:
+            self.newline()

src/cc/frontends/p4/compiler/target.py

+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from programSerializer import ProgramSerializer
+
+# abstraction for isolating target-specific features
+
+# Base class for representing target-specific configuration
+class TargetConfig(object):
+    def __init__(self, target):
+        self.targetName = target
+
+    def getIncludes(self):
+        return ""
+
+    def serializeLookup(self, serializer, tableName, key, value):
+        serializer.appendFormat("{0} = bpf_map_lookup_elem(&{1}, &{2});",
+                                value, tableName, key)
+
+    def serializeUpdate(self, serializer, tableName, key, value):
+        serializer.appendFormat(
+            "bpf_map_update_elem(&{0}, &{1}, &{2}, BPF_ANY);",
+            tableName, key, value)
+
+    def serializeLicense(self, serializer, licenseString):
+        assert isinstance(serializer, ProgramSerializer)
+        serializer.emitIndent()
+        serializer.appendFormat(
+            "char _license[] {0}(\"license\") = \"{1}\";",
+            self.config.section, licenseString)
+        serializer.newline()
+
+    def serializeCodeSection(self, serializer):
+        assert isinstance(serializer, ProgramSerializer)
+        serializer.appendFormat("{0}(\"{1}\")", self.section, self.entrySection)
+
+    def serializeTableDeclaration(self, serializer, tableName,
+                                  isHash, keyType, valueType, size):
+        assert isinstance(serializer, ProgramSerializer)
+        assert isinstance(tableName, str)
+        assert isinstance(isHash, bool)
+        assert isinstance(keyType, str)
+        assert isinstance(valueType, str)
+        assert isinstance(size, int)
+
+        serializer.emitIndent()
+        serializer.appendFormat("struct {0} {1}(\"maps\") {2} = ",
+                                self.tableName, self.section, tableName)
+        serializer.blockStart()
+
+        serializer.emitIndent()
+        serializer.append(".type = ")
+        if isHash:
+            serializer.appendLine("BPF_MAP_TYPE_HASH,")
+        else:
+            serializer.appendLine("BPF_MAP_TYPE_ARRAY,")
+
+        serializer.emitIndent()
+        serializer.appendFormat(".{0} = sizeof(struct {1}), ",
+                                self.tableKeyAttribute, keyType)
+        serializer.newline()
+
+        serializer.emitIndent()
+        serializer.appendFormat(".{0} = sizeof(struct {1}), ",
+                                self.tableValueAttribute, valueType)
+        serializer.newline()
+
+        serializer.emitIndent()
+        serializer.appendFormat(".{0} = {1}, ", self.tableSizeAttribute, size)
+        serializer.newline()
+
+        serializer.blockEnd(False)
+        serializer.endOfStatement(True)
+
+    def generateDword(self, serializer):
+        serializer.appendFormat(
+            "static inline {0}64 load_dword(void *skb, {0}64 off)",
+            self.uprefix)
+        serializer.newline()
+        serializer.blockStart()
+        serializer.emitIndent()
+        serializer.appendFormat(
+            ("return (({0}64)load_word(skb, off) << 32) | " +
+             "load_word(skb, off + 4);"),
+            self.uprefix)
+        serializer.newline()
+        serializer.blockEnd(True)
+
+
+# Represents a target that is compiled within the kernel
+# source tree samples folder and which attaches to a socket
+class KernelSamplesConfig(TargetConfig):
+    def __init__(self):
+        super(SocketConfig, self).__init__("Socket")
+        self.entrySection = "socket1"
+        self.section = "SEC"
+        self.uprefix = "u"
+        self.iprefix = "i"
+        self.tableKeyAttribute = "key_size"
+        self.tableValueAttribute = "value_size"
+        self.tableSizeAttribute = "max_entries"
+        self.tableName = "bpf_map_def"
+        self.postamble = ""
+
+    def getIncludes(self):
+        return """
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/if_ether.h>
+#include <uapi/linux/if_packet.h>
+#include <uapi/linux/ip.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include "bpf_helpers.h"
+"""
+
+    
+# Represents a target compiled by bcc that uses the TC
+class BccConfig(TargetConfig):
+    def __init__(self):
+        super(BccConfig, self).__init__("BCC")
+        self.uprefix = "u"
+        self.iprefix = "i"
+        self.postamble = ""
+
+    def serializeTableDeclaration(self, serializer, tableName,
+                                  isHash, keyType, valueType, size):
+        assert isinstance(serializer, ProgramSerializer)
+        assert isinstance(tableName, str)
+        assert isinstance(isHash, bool)
+        assert isinstance(keyType, str)
+        assert isinstance(valueType, str)
+        assert isinstance(size, int)
+
+        serializer.emitIndent()
+        if isHash:
+            kind = "hash"
+        else:
+            kind = "array"
+        serializer.appendFormat(
+            "BPF_TABLE(\"{0}\", {1}, {2}, {3}, {4});",
+            kind, keyType, valueType, tableName, size)
+        serializer.newline()
+
+    def serializeLookup(self, serializer, tableName, key, value):
+        serializer.appendFormat("{0} = {1}.lookup(&{2});",
+                                value, tableName, key)
+
+    def serializeUpdate(self, serializer, tableName, key, value):
+        serializer.appendFormat("{0}.update(&{1}, &{2});",
+                                tableName, key, value)
+
+    def generateDword(self, serializer):
+        pass
+
+    def serializeCodeSection(self, serializer):
+        pass
+
+    def getIncludes(self):
+        return """
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/if_ether.h>
+#include <uapi/linux/if_packet.h>
+#include <uapi/linux/ip.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/pkt_cls.h>
+"""
+
+    def serializeLicense(self, serializer, licenseString):
+        assert isinstance(serializer, ProgramSerializer)
+        pass

src/cc/frontends/p4/compiler/typeFactory.py

+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from p4_hlir.hlir import p4_header
+from ebpfStructType import *
+
+class EbpfTypeFactory(object):
+    def __init__(self, config):
+        self.type_map = {}
+        self.config = config
+
+    def build(self, hlirType, asMetadata):
+        name = hlirType.name
+        if hlirType.name in self.type_map:
+            retval = self.type_map[name]
+            if ((not asMetadata and isinstance(retval, EbpfMetadataType)) or 
+                (asMetadata and isinstance(retval, EbpfHeaderType))):
+                raise CompilationException(
+                    True, "Same type used both as a header and metadata {0}",
+                    hlirType)
+
+        if isinstance(hlirType, p4_header):
+            if asMetadata:
+                type = EbpfMetadataType(hlirType, self.config)
+            else:
+                type = EbpfHeaderType(hlirType, self.config)
+        else:
+            raise CompilationException(True, "Unexpected type {0}", hlirType)
+        self.registerType(name, type)
+        return type
+
+    def registerType(self, name, ebpfType):
+        self.type_map[name] = ebpfType

src/cc/frontends/p4/test/README.txt

+This folder contains tests for the P4->C->EBPF compiler
+
+- cleanup.sh should be run if for some reason endToEndTest.py crashes
+  and leaves garbage namespaces or links
+
+- testP4toEbpf.py compiles all P4 files in the testprograms folder and
+  deposits the corresponding C files in the testoutputs folder
+
+- endToEndTest.py runs a complete end-to-end test compiling the
+  testprograms/simple.p4 program, creating a virtual network with 3
+  boxes (using network namespaces): client, server, switch, loading
+  the EBPF into the kernel of the switch box using the TC, and
+  implementing the forwarding in the switch solely using the P4
+  program.
+  
+  

src/cc/frontends/p4/test/cleanup.sh

+#!/bin/bash
+# Run this script if for some reason the endToEndTest.py crashed
+# and left some garbage state
+
+ip netns del sw
+ip netns del srv
+ip netns del clt
+
+ip link del dev veth-clt-sw
+ip link del dev veth-srv-sw
+

src/cc/frontends/p4/test/testP4toEbpf.py

+#!/usr/bin/env python
+
+# Copyright (c) Barefoot Networks, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+# Runs the compiler on all files in the 'testprograms' folder
+# Writes outputs in the 'testoutputs' folder
+
+from bcc import BPF
+import os, sys
+sys.path.append("../compiler") # To get hold of p4toEbpf
+                               # We want to run it without installing it
+import p4toEbpf
+import os
+
+def drop_extension(filename):
+    return os.path.splitext(os.path.basename(filename))[0]
+
+filesFailed = {}  # map error kind -> list[ (file, error) ]
+
+def set_error(kind, file, error):
+    if kind in filesFailed:
+        filesFailed[kind].append((file, error))
+    else:
+        filesFailed[kind] = [(file, error)]
+
+def is_root():
+    # Is this code portable?
+    return os.getuid() == 0
+        
+def main():
+    testpath = "testprograms"
+    destFolder = "testoutputs"
+    files = os.listdir(testpath)
+    files.sort()
+    filesDone = 0
+    errors = 0
+
+    if not is_root():
+        print "Loading EBPF programs requires root priviledge."
+        print "Will only test compilation, not loading."
+        print "(Run with sudo to test program loading.)"
+    
+    for f in files:
+        path = os.path.join(testpath, f)
+
+        if not os.path.isfile(path):
+            continue
+        if not path.endswith(".p4"):
+            continue
+
+        destname = drop_extension(path) + ".c"
+        destname = os.path.join(destFolder, destname)
+
+        args = [path, "-o", destname]
+
+        result = p4toEbpf.process(args)
+        if result.kind != "OK":
+            errors += 1
+            print path, result.error
+            set_error(result.kind, path, result.error)
+        else:
+            # Try to load the compiled function
+            if is_root():
+                try:                
+                    print("Compiling and loading BPF program")
+                    b = BPF(src_file=destname, debug=0)
+                    fn = b.load_func("ebpf_filter", BPF.SCHED_CLS)
+                except Exception as e:
+                    print(e)
+                    set_error("BPF error", path, str(e))
+                
+        filesDone += 1
+
+    print "Compiled", filesDone, "files", errors, "errors"
+    for key in sorted(filesFailed):
+        print key, ":", len(filesFailed[key]), "programs"
+        for v in filesFailed[key]:
+            print "\t", v
+    exit(len(filesFailed) != 0)
+    
+        
+if __name__ == "__main__":
+    main()

src/cc/frontends/p4/test/testprograms/arrayKey.p4

+header_type ethernet_t {
+    fields {
+        dstAddr : 48;
+        srcAddr : 48;
+        etherType : 16;
+    }
+}
+
+parser start {
+    return parse_ethernet;
+}
+
+header ethernet_t ethernet;
+
+parser parse_ethernet {
+    extract(ethernet);
+    return ingress;
+}
+
+action nop() 
+{}
+
+table routing {
+   reads {
+      ethernet.dstAddr: exact;
+   }
+   actions { nop; }
+   size : 512;
+}
+
+control ingress
+{
+    apply(routing);
+}
\ No newline at end of file

src/cc/frontends/p4/test/testprograms/bitfields.p4

+header_type ht
+{
+  fields
+  {
+     f1 : 1;
+     f2 : 2;
+     f3 : 3;
+     f4 : 4;
+     f5 : 5;
+     f6 : 6;
+     f7 : 7;
+     f8 : 8;
+     f9 : 9;
+     f10 : 10;
+     f11 : 11;
+     f12 : 12;
+     f13 : 13;
+     f14 : 14;
+     f15 : 15;
+     f16 : 16;
+     f17 : 17;
+     f18 : 18;
+     f19 : 19;
+     f20 : 20;
+     f21 : 21;
+     f22 : 22;
+     f23 : 23;
+     f24 : 24;
+     f25 : 25;
+     f26 : 26;
+     f27 : 27;
+     f28 : 28;
+     f29 : 29;
+     f30 : 30;
+     f31 : 31;
+     f32 : 32;
+  }
+}
+
+header_type larget
+{
+  fields 
+  {
+    f48 : 48;
+    f1: 1;
+    f49 : 48;
+    f2 : 1;
+    f64 : 64;
+    f3 : 1;
+    f128 : 128;
+  }
+}
+
+header ht h;
+header larget large;
+
+parser start
+{
+	extract(h);
+	extract(large);
+	return ingress;
+}
+
+control ingress
+{
+}

src/cc/frontends/p4/test/testprograms/compositeArray.p4

+header_type ethernet_t {
+    fields {
+        dstAddr : 48;
+    }
+}
+
+header_type ipv4_t {
+    fields {
+        srcAddr : 32;
+    }
+}
+
+parser start {
+    return parse_ethernet;
+}
+
+header ethernet_t ethernet;
+
+parser parse_ethernet {
+    extract(ethernet);
+    return parse_ipv4;
+}
+
+action nop() 
+{}
+
+header ipv4_t ipv4;
+
+parser parse_ipv4 {
+    extract(ipv4);
+    return ingress;
+}
+
+table routing {
+   reads {
+      ethernet.dstAddr: exact;
+      ipv4.srcAddr: exact;
+   }
+   actions { nop; }
+   size : 512;
+}
+
+control ingress
+{
+    apply(routing);
+}
\ No newline at end of file

src/cc/frontends/p4/test/testprograms/compositeKey.p4

+header_type ethernet_t {
+    fields {
+        dstAddr : 48;
+        srcAddr : 48;
+        etherType : 16;
+    }
+}
+
+header_type ipv4_t {
+    fields {
+        version : 4;
+        ihl : 4;
+        diffserv : 8;
+        totalLen : 16;
+        identification : 16;
+        flags : 3;
+        fragOffset : 13;
+        ttl : 8;
+        protocol : 8;
+        hdrChecksum : 16;
+        srcAddr : 32;
+        dstAddr: 32;
+    }
+}
+
+parser start {
+    return parse_ethernet;
+}
+
+header ethernet_t ethernet;
+
+parser parse_ethernet {
+    extract(ethernet);
+    return select(latest.etherType) {
+        0x800 : parse_ipv4;
+        default: ingress;
+    }
+}
+
+action nop() 
+{}
+
+action forward(port)
+{
+   modify_field(standard_metadata.egress_port, port);
+}
+
+header ipv4_t ipv4;
+
+parser parse_ipv4 {
+    extract(ipv4);
+    return ingress;
+}
+
+table routing {
+   reads {
+      ipv4.dstAddr: exact;
+      ipv4.srcAddr: exact;
+   }
+   actions { nop; forward; }
+   size : 512;
+}
+
+counter cnt {
+   type: bytes;
+   direct: routing;
+}
+
+control ingress
+{
+    apply(routing);
+}
\ No newline at end of file

src/cc/frontends/p4/test/testprograms/do_nothing.p4

+/* Sample P4 program */
+header_type ethernet_t {
+    fields {
+        dstAddr : 48;
+        srcAddr : 48;
+        etherType : 16;
+    }
+}
+
+parser start {
+    return parse_ethernet;
+}
+
+header ethernet_t ethernet;
+
+parser parse_ethernet {
+    extract(ethernet);
+    return ingress;
+}
+
+action action_0(){
+    no_op();
+}
+
+table table_0 {
+   reads {
+      ethernet.etherType : exact;
+   }
+   actions {
+      action_0;
+   }
+}
+
+control ingress {
+    apply(table_0);
+}

src/cc/frontends/p4/test/testprograms/simple.p4

+// Routes a packet to an interface based on its IPv4 address
+// Maintains a set of counters on the routing table
+
+header_type ethernet_t {
+    fields {
+        dstAddr : 48;
+        srcAddr : 48;
+        etherType : 16;
+    }
+}
+
+header_type ipv4_t {
+    fields {
+        version : 4;
+        ihl : 4;
+        diffserv : 8;
+        totalLen : 16;
+        identification : 16;
+        flags : 3;
+        fragOffset : 13;
+        ttl : 8;
+        protocol : 8;
+        hdrChecksum : 16;
+        srcAddr : 32;
+        dstAddr: 32;
+    }
+}
+
+parser start {
+    return parse_ethernet;
+}
+
+header ethernet_t ethernet;
+
+parser parse_ethernet {
+    extract(ethernet);
+    return select(latest.etherType) {
+        0x800 : parse_ipv4;
+        default: ingress;
+    }
+}
+
+action nop() 
+{}
+
+action forward(port)
+{
+   modify_field(standard_metadata.egress_port, port);
+}
+
+header ipv4_t ipv4;
+
+parser parse_ipv4 {
+    extract(ipv4);
+    return ingress;
+}
+
+table routing {
+   reads {
+      ipv4.dstAddr: exact;
+   }
+   actions { nop; forward; }
+   size : 512;
+}
+
+counter cnt {
+   type: bytes;
+   direct: routing;
+}
+
+control ingress
+{
+    apply(routing);
+}
\ No newline at end of file