onos-sdran.md

Source: https://github.com/OpenNetworkingFoundation/onos-sdran/blob/8e99a8827af956946fa395546328ec021e63f9d3/pipelines/fabric/src/main/resources/include/parser.p4

#ifndef __PARSER__
#define __PARSER__
...
#endif

ifndef being used to make sure the file isn't being included twice

state parse_ethernet {
        packet.extract(hdr.ethernet);
        fabric_metadata.last_eth_type = hdr.ethernet.eth_type;
        fabric_metadata.vlan_id = DEFAULT_VLAN_ID;
        transition select(hdr.ethernet.eth_type){
            ETHERTYPE_VLAN: parse_vlan_tag;
            ETHERTYPE_MPLS: parse_mpls;
            ETHERTYPE_IPV4: pre_parse_ipv4;
#ifdef WITH_IPV6
            ETHERTYPE_IPV6: pre_parse_ipv6;
#endif // WITH_IPV6
            default: accept;
        }
    }

Inserting transition state to parse IPV6 packets if the program supports IPV6. Checking if the flag is set using ifdef

#if defined(WITH_XCONNECT) || defined(WITH_BNG) || defined(WITH_DOUBLE_VLAN_TERMINATION)
    state parse_inner_vlan_tag {
        packet.extract(hdr.inner_vlan_tag);
        transition select(hdr.inner_vlan_tag.eth_type){
            ETHERTYPE_IPV4: pre_parse_ipv4;
#ifdef WITH_IPV6
            ETHERTYPE_IPV6: pre_parse_ipv6;
#endif // WITH_IPV6
            ETHERTYPE_MPLS: parse_mpls;
#ifdef WITH_BNG
            ETHERTYPE_PPPOED: parse_pppoe;
            ETHERTYPE_PPPOES: parse_pppoe;
#endif // WITH_BNG
            default: accept;
        }
    }
#endif // WITH_XCONNECT || WITH_BNG || WITH_DOUBLE_VLAN_TERMINATION

Adding new state if any of the flags (WITH_XCONNECT, WITH_BNG, WITH_DOUBLE_VLAN_TERMINATION) are defined. Checking using if and defined function

control FabricDeparser(packet_out packet,in parsed_headers_t hdr) {

    apply {
        ...
#if defined(WITH_XCONNECT) || defined(WITH_BNG) || defined(WITH_DOUBLE_VLAN_TERMINATION)
        packet.emit(hdr.inner_vlan_tag);
#endif // WITH_XCONNECT || WITH_BNG || WITH_DOUBLE_VLAN_TERMINATION
#ifdef WITH_BNG
        packet.emit(hdr.pppoe);
#endif // WITH_BNG
        packet.emit(hdr.mpls);
        ...
        packet.emit(hdr.ipv4);
#ifdef WITH_IPV6
        packet.emit(hdr.ipv6);
#endif // WITH_IPV6
        packet.emit(hdr.tcp);
        packet.emit(hdr.udp);
        packet.emit(hdr.icmp);
#ifdef WITH_INT
        ...
#ifdef WITH_INT_TRANSIT
        ...
#endif // WITH_INT_TRANSIT
#ifdef WITH_INT_SINK
        packet.emit(hdr.int_data);
#endif // WITH_INT_SINK
        packet.emit(hdr.intl4_tail);
#endif // WITH_INT
    }
}

#endif

Adding new deparser statements to emit specific header fields if they are supported. Using ifdef and if to check if the corresponding flags are set, and if so, we insert those emit statements

    state parse_tcp {
        packet.extract(hdr.tcp);
        fabric_metadata.l4_sport = hdr.tcp.sport;
        fabric_metadata.l4_dport = hdr.tcp.dport;
#ifdef WITH_INT
        transition parse_int;
#else
        transition accept;
#endif // WITH_INT
    }

Adding a new statement to parse the intl4_shim part in the header if the WITH_INT flag is defined. Otherwise the state transitions to accept by default.

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Source: https://github.com/OpenNetworkingFoundation/onos-sdran/blob/8e99a8827af956946fa395546328ec021e63f9d3/pipelines/fabric/src/main/resources/include/size.p4

#define BNG_MAX_SUBSC_NET BNG_MAX_NET_PER_SUBSC * BNG_MAX_SUBSC
#ifdef WITH_BNG
    #define PORT_VLAN_TABLE_SIZE BNG_MAX_SUBSC
#else
    #define PORT_VLAN_TABLE_SIZE 1024
#endif // WITH_BNG

Using define to create a variable whose value is computed using two other variables. Also using ifdef to see if a flag is set and define a variable based on the flag (set the PORT_VLAN_TABLE_SIZE to 1024 by default or to BNG_MAX_SUBSC if BNG is defined)

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Source: https://github.com/OpenNetworkingFoundation/onos-sdran/blob/8e99a8827af956946fa395546328ec021e63f9d3/pipelines/basic/src/main/resources/include/defines.p4

#ifndef __DEFINES__
#define __DEFINES__

#define ETH_TYPE_IPV4 0x0800
#define IP_PROTO_TCP 8w6
#define IP_PROTO_UDP 8w17
#define IP_VERSION_4 4w4
#define IPV4_IHL_MIN 4w5
#define MAX_PORTS 511

#ifndef _BOOL
#define _BOOL bool
#endif
#ifndef _TRUE
#define _TRUE true
#endif
#ifndef _FALSE
#define _FALSE false
#endif
...

Using the define directive to define variables with a value, and also uses ifdef to check if certain flags are not set, and if not, it sets them using define