feat: Initial revision
This commit is contained in:
Adrian Rumpold
23
.gitignore
vendored
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23
.gitignore
vendored
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# If you prefer the allow list template instead of the deny list, see community template:
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# https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
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#
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# Binaries for programs and plugins
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*.exe
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*.exe~
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*.dll
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*.so
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*.dylib
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go-dhcp
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# Test binary, built with `go test -c`
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*.test
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# Output of the go coverage tool, specifically when used with LiteIDE
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*.out
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# Dependency directories (remove the comment below to include it)
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# vendor/
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# Go workspace file
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go.work
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9
go.mod
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9
go.mod
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module github.com/adrianokf/go-dhcp
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go 1.17
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require (
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go.uber.org/atomic v1.9.0 // indirect
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go.uber.org/multierr v1.7.0 // indirect
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go.uber.org/zap v1.20.0 // indirect
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)
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51
go.sum
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51
go.sum
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github.com/benbjohnson/clock v1.1.0/go.mod h1:J11/hYXuz8f4ySSvYwY0FKfm+ezbsZBKZxNJlLklBHA=
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github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
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github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
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github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
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github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
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github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
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github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
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github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
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github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
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github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
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github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
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github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
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go.uber.org/atomic v1.7.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
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go.uber.org/atomic v1.9.0 h1:ECmE8Bn/WFTYwEW/bpKD3M8VtR/zQVbavAoalC1PYyE=
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go.uber.org/atomic v1.9.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
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go.uber.org/goleak v1.1.11/go.mod h1:cwTWslyiVhfpKIDGSZEM2HlOvcqm+tG4zioyIeLoqMQ=
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go.uber.org/multierr v1.6.0/go.mod h1:cdWPpRnG4AhwMwsgIHip0KRBQjJy5kYEpYjJxpXp9iU=
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go.uber.org/multierr v1.7.0 h1:zaiO/rmgFjbmCXdSYJWQcdvOCsthmdaHfr3Gm2Kx4Ec=
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go.uber.org/multierr v1.7.0/go.mod h1:7EAYxJLBy9rStEaz58O2t4Uvip6FSURkq8/ppBp95ak=
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go.uber.org/zap v1.20.0 h1:N4oPlghZwYG55MlU6LXk/Zp00FVNE9X9wrYO8CEs4lc=
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go.uber.org/zap v1.20.0/go.mod h1:wjWOCqI0f2ZZrJF/UufIOkiC8ii6tm1iqIsLo76RfJw=
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golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
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golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
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golang.org/x/lint v0.0.0-20190930215403-16217165b5de/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
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golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
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golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
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golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
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golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
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golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
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golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
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golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
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golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
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golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
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golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
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golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
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golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
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golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
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golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
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golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
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golang.org/x/tools v0.1.5/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
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golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
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golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
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golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
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gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
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gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
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gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
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gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
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gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
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166
main.go
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166
main.go
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package main
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import (
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"bytes"
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"encoding/binary"
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"net"
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"unsafe"
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"go.uber.org/zap"
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)
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type DhcpOp uint8
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const (
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BOOTREQUEST DhcpOp = iota + 1
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BOOTREPLY
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)
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type DhcpMessage struct {
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Op DhcpOp
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Htype uint8
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Hlen uint8
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Hops uint8
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Xid uint32
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Secs uint16
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Flags uint16
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Ciaddr uint32
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Yiaddr uint32
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Siaddr uint32
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Giaddr uint32
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Chaddr [16]byte
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Sname [64]byte
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File [128]byte
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Magic [4]byte
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}
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func (dhcp DhcpMessage) Debug(s *zap.SugaredLogger) {
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s.Debugf("op=%x, htype=%x, hlen=%x, hops=%x", dhcp.Op, dhcp.Htype, dhcp.Hlen, dhcp.Hops)
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s.Debugf("xid=%x", dhcp.Xid)
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s.Debugf("secs=%d, flags=%x", dhcp.Secs, dhcp.Flags)
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s.Debugf("ciaddr=%x", dhcp.Ciaddr)
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s.Debugf("siaddr=%x", dhcp.Siaddr)
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s.Debugf("giaddr=%x", dhcp.Giaddr)
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s.Debugf("chaddr=%x", dhcp.Chaddr)
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s.Debugf("sname=%s", string(dhcp.Sname[:]))
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s.Debugf("file=%s", string(dhcp.File[:]))
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s.Debugf("magic=%x", dhcp.Magic)
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}
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func parseOptions(data []byte) {
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s := zap.S()
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i := 0
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for i < len(data) {
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code := data[i]
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if code == 255 {
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s.Debug("Found END option at offset ", i)
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break
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}
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if code == 0 {
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s.Debug("Found padding option at offset ", i)
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i += 1
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continue
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}
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size := int(data[i+1])
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payload := data[i+2 : i+2+size]
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s.Debugf("code=%d, size=%d, payload=%x", code, size, payload)
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i += size + 2
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}
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}
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func prepareOffer(request DhcpMessage) DhcpMessage {
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var sname [64]byte
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var file [128]byte
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copy(sname[:], "go-dhcp-server")
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dhcp := DhcpMessage{
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Op: BOOTREPLY,
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Htype: 1, // Ethernet
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Hlen: 6, // Ethernet address length
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Hops: 0,
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Secs: 0,
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Flags: request.Flags,
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Xid: request.Xid,
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Siaddr: binary.BigEndian.Uint32(net.IPv4(10, 0, 0, 1).To4()),
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Ciaddr: 0,
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Yiaddr: binary.BigEndian.Uint32(net.IPv4(10, 0, 0, 2).To4()),
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Giaddr: request.Giaddr,
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Chaddr: request.Chaddr,
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Magic: [4]byte{0x63, 0x82, 0x53, 0x63},
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Sname: sname,
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File: file,
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}
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return dhcp
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}
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func handleMsg(data []byte, remote *net.UDPAddr) {
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s := zap.S()
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s.Debugf("Connection from client %v", remote.IP)
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var dhcp DhcpMessage
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reader := bytes.NewReader(data)
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binary.Read(reader, binary.BigEndian, &dhcp)
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dhcp.Debug(s)
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if dhcp.Magic != [4]byte{0x63, 0x82, 0x53, 0x63} {
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panic("Invalid DHCP magic field")
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}
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optDataOffset := int(unsafe.Sizeof(dhcp))
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optData := data[optDataOffset:]
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s.Debug("Raw options data:", optData)
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parseOptions(optData)
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offer := prepareOffer(dhcp)
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localAddr, _ := net.ResolveUDPAddr("udp", "172.17.0.1:68")
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clientAddr, _ := net.ResolveUDPAddr("udp", "255.255.255.255:68")
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conn, err := net.DialUDP("udp", localAddr, clientAddr)
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if err != nil {
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panic(err)
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}
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defer conn.Close()
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s.Info("Sending DHCPOFFER...")
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buf := make([]byte, 0)
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w := bytes.NewBuffer(buf)
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binary.Write(w, binary.BigEndian, offer)
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w.Write([]byte{53, 1, 2})
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w.WriteByte(255)
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msg := w.Bytes()
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s.Debug("Msg", msg)
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conn.Write(msg)
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}
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func main() {
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// Set up logging
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logger, _ := zap.NewDevelopment()
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defer logger.Sync() // flushes buffer, if any
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zap.ReplaceGlobals(logger)
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addr, _ := net.ResolveUDPAddr("udp4", ":67")
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conn, err := net.ListenUDP("udp4", addr)
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if err != nil {
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panic(err)
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}
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defer conn.Close()
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zap.L().Info("Listening for incoming connections")
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for {
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buf := make([]byte, 1024)
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rlen, remote, err := conn.ReadFromUDP(buf[:])
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if err != nil {
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panic(err)
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}
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// Do stuff with the read bytes
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handleMsg(buf[0:rlen], remote)
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}
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}
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Reference in New Issue
Block a user