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go test: dynamically calculate ip checksum

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Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2016-07-07 13:42:35 +02:00
parent 35a61c32fa
commit 554d77fbd7
1 changed files with 20 additions and 2 deletions
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22
contrib/external-tests/go/main.go
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@ -16,6 +16,24 @@ import (
"golang.org/x/net/ipv4"
)
func ipChecksum(buf []byte) uint16 {
sum := uint32(0)
for ; len(buf) >= 2; buf = buf[2:] {
sum += uint32(buf[0])<<8 | uint32(buf[1])
}
if len(buf) > 0 {
sum += uint32(buf[0]) << 8
}
for sum > 0xffff {
sum = (sum >> 16) + (sum & 0xffff)
}
csum := ^uint16(sum)
if csum == 0 {
csum = 0xffff
}
return csum
}
func main() {
ourPrivate, _ := base64.StdEncoding.DecodeString("WAmgVYXkbT2bCtdcDwolI88/iVi/aV3/PHcUBTQSYmo=")
ourPublic, _ := base64.StdEncoding.DecodeString("K5sF9yESrSBsOXPd6TcpKNgqoy1Ik3ZFKl4FolzrRyI=")
@ -95,12 +113,12 @@ func main() {
Len: ipv4.HeaderLen,
TotalLen: ipv4.HeaderLen + len(pingMessage),
Protocol: 1, // ICMP
TTL: 2,
Checksum: 0xa15b, // the packet is always the same, hard-code checksum
TTL: 20,
Src: net.IPv4(10, 189, 129, 2),
Dst: net.IPv4(10, 189, 129, 1),
}).Marshal()
binary.BigEndian.PutUint16(pingHeader[2:], uint16(ipv4.HeaderLen+len(pingMessage))) // fix the length endianness on BSDs
binary.BigEndian.PutUint16(pingHeader[10:], ipChecksum(append(pingHeader, pingMessage...)))
if err != nil {
panic(err)
}