Refactor faasd and faas-containerd merge

The use of containerd and CNI functions has been refactored to reuse
the same codebase.

Added all network functionality to own directory and package. Removed
netlink and weave library in favor of using CNI plugin result files.

Rename containers handler to functions to clear-up functionality.

Signed-off-by: Carlos de Paula <me@carlosedp.com>

vendor/github.com/vishvananda/netlink/nl/seg6_linux.go

@@ -99,6 +99,49 @@ func DecodeSEG6Encap(buf []byte) (int, []net.IP, error) {
 	return mode, srh.Segments, nil
 }
 
+func DecodeSEG6Srh(buf []byte) ([]net.IP, error) {
+	native := NativeEndian()
+	srh := IPv6SrHdr{
+		nextHdr:      buf[0],
+		hdrLen:       buf[1],
+		routingType:  buf[2],
+		segmentsLeft: buf[3],
+		firstSegment: buf[4],
+		flags:        buf[5],
+		reserved:     native.Uint16(buf[6:8]),
+	}
+	buf = buf[8:]
+	if len(buf)%16 != 0 {
+		err := fmt.Errorf("DecodeSEG6Srh: error parsing Segment List (buf len: %d)", len(buf))
+		return nil, err
+	}
+	for len(buf) > 0 {
+		srh.Segments = append(srh.Segments, net.IP(buf[:16]))
+		buf = buf[16:]
+	}
+	return srh.Segments, nil
+}
+func EncodeSEG6Srh(segments []net.IP) ([]byte, error) {
+	nsegs := len(segments) // nsegs: number of segments
+	if nsegs == 0 {
+		return nil, errors.New("EncodeSEG6Srh: No Segments")
+	}
+	b := make([]byte, 8, 8+len(segments)*16)
+	native := NativeEndian()
+	b[0] = 0                      // srh.nextHdr (0 when calling netlink)
+	b[1] = uint8(16 * nsegs >> 3) // srh.hdrLen (in 8-octets unit)
+	b[2] = IPV6_SRCRT_TYPE_4      // srh.routingType (assigned by IANA)
+	b[3] = uint8(nsegs - 1)       // srh.segmentsLeft
+	b[4] = uint8(nsegs - 1)       // srh.firstSegment
+	b[5] = 0                      // srh.flags (SR6_FLAG1_HMAC for srh_hmac)
+	// srh.reserved: Defined as "Tag" in draft-ietf-6man-segment-routing-header-07
+	native.PutUint16(b[6:], 0) // srh.reserved
+	for _, netIP := range segments {
+		b = append(b, netIP...) // srh.Segments
+	}
+	return b, nil
+}
+
 // Helper functions
 func SEG6EncapModeString(mode int) string {
 	switch mode {