type headerRewriter struct{}

// Clean up IP in case if it is ipv6 address and it has {zone} information in it, like
// "[fe80::d806:a55d:eb1b:49cc%vEthernet (vmxnet3 Ethernet Adapter - Virtual Switch)]:64692"
func ipv6fix(clientIP string) string {
	return strings.Split(clientIP, "%")[0]
}

func (rw *headerRewriter) Rewrite(req *http.Request) {

	"sync"
	"sync/atomic"
)

// The size of a CRC-32 checksum in bytes.
const Size = 4

// Predefined polynomials.
const (
	// IEEE is by far and away the most common CRC-32 polynomial.
	// Used by ethernet (IEEE 802.3), v.42, fddi, gzip, zip, png, ...
	IEEE = 0xedb88320

	// Castagnoli's polynomial, used in iSCSI.
	// Has better error detection characteristics than IEEE.
	// https://dx.doi.org/10.1109/26.231911

000000a0  30 11 06 03 55 04 08 13  0a 53 6f 6d 65 2d 53 74  |0...U....Some-St|
000000b0  61 74 65 31 21 30 1f 06  03 55 04 0a 13 18 49 6e  |ate1!0...U....In|
000000c0  74 65 72 6e 65 74 20 57  69 64 67 69 74 73 20 50  |ternet Widgits P|
000000d0  74 79 20 4c 74 64 30 1e  17 0d 31 32 31 31 32 32  |ty Ltd0...121122|
000000e0  31 35 30 36 33 32 5a 17  0d 32 32 31 31 32 30 31  |150632Z..2211201|

000000a0  30 11 06 03 55 04 08 13  0a 53 6f 6d 65 2d 53 74  |0...U....Some-St|
000000b0  61 74 65 31 21 30 1f 06  03 55 04 0a 13 18 49 6e  |ate1!0...U....In|
000000c0  74 65 72 6e 65 74 20 57  69 64 67 69 74 73 20 50  |ternet Widgits P|
000000d0  74 79 20 4c 74 64 30 1e  17 0d 31 32 31 31 32 32  |ty Ltd0...121122|
000000e0  31 35 30 36 33 32 5a 17  0d 32 32 31 31 32 30 31  |150632Z..2211201|

000000a0  30 11 06 03 55 04 08 13  0a 53 6f 6d 65 2d 53 74  |0...U....Some-St|
000000b0  61 74 65 31 21 30 1f 06  03 55 04 0a 13 18 49 6e  |ate1!0...U....In|
000000c0  74 65 72 6e 65 74 20 57  69 64 67 69 74 73 20 50  |ternet Widgits P|
000000d0  74 79 20 4c 74 64 30 1e  17 0d 31 32 31 31 32 32  |ty Ltd0...121122|
000000e0  31 35 30 36 33 32 5a 17  0d 32 32 31 31 32 30 31  |150632Z..2211201|

000000a0  30 11 06 03 55 04 08 13  0a 53 6f 6d 65 2d 53 74  |0...U....Some-St|
000000b0  61 74 65 31 21 30 1f 06  03 55 04 0a 13 18 49 6e  |ate1!0...U....In|
000000c0  74 65 72 6e 65 74 20 57  69 64 67 69 74 73 20 50  |ternet Widgits P|
000000d0  74 79 20 4c 74 64 30 1e  17 0d 31 32 31 31 32 32  |ty Ltd0...121122|
000000e0  31 35 30 36 33 32 5a 17  0d 32 32 31 31 32 30 31  |150632Z..2211201|

000000a0  30 11 06 03 55 04 08 13  0a 53 6f 6d 65 2d 53 74  |0...U....Some-St|
000000b0  61 74 65 31 21 30 1f 06  03 55 04 0a 13 18 49 6e  |ate1!0...U....In|
000000c0  74 65 72 6e 65 74 20 57  69 64 67 69 74 73 20 50  |ternet Widgits P|
000000d0  74 79 20 4c 74 64 30 1e  17 0d 31 32 31 31 32 32  |ty Ltd0...121122|
000000e0  31 35 30 36 33 32 5a 17  0d 32 32 31 31 32 30 31  |150632Z..2211201|

000000a0  30 11 06 03 55 04 08 13  0a 53 6f 6d 65 2d 53 74  |0...U....Some-St|
000000b0  61 74 65 31 21 30 1f 06  03 55 04 0a 13 18 49 6e  |ate1!0...U....In|
000000c0  74 65 72 6e 65 74 20 57  69 64 67 69 74 73 20 50  |ternet Widgits P|
000000d0  74 79 20 4c 74 64 30 1e  17 0d 31 32 31 31 32 32  |ty Ltd0...121122|
000000e0  31 35 30 36 33 32 5a 17  0d 32 32 31 31 32 30 31  |150632Z..2211201|

000000a0  30 11 06 03 55 04 08 13  0a 53 6f 6d 65 2d 53 74  |0...U....Some-St|
000000b0  61 74 65 31 21 30 1f 06  03 55 04 0a 13 18 49 6e  |ate1!0...U....In|
000000c0  74 65 72 6e 65 74 20 57  69 64 67 69 74 73 20 50  |ternet Widgits P|
000000d0  74 79 20 4c 74 64 30 1e  17 0d 31 32 31 31 32 32  |ty Ltd0...121122|
000000e0  31 35 30 36 33 32 5a 17  0d 32 32 31 31 32 30 31  |150632Z..2211201|