diff options
Diffstat (limited to 'pkg/dhcp/dhcp.go')
| -rw-r--r-- | pkg/dhcp/dhcp.go | 99 |
1 files changed, 54 insertions, 45 deletions
diff --git a/pkg/dhcp/dhcp.go b/pkg/dhcp/dhcp.go index 18c318fc8..ceaba34c3 100644 --- a/pkg/dhcp/dhcp.go +++ b/pkg/dhcp/dhcp.go @@ -26,19 +26,21 @@ import ( // Config is standard DHCP configuration. type Config struct { - ServerAddress tcpip.Address // address of the server - SubnetMask tcpip.AddressMask // client address subnet mask - Gateway tcpip.Address // client default gateway - DomainNameServer tcpip.Address // client domain name server - LeaseLength time.Duration // length of the address lease + Error error + ServerAddress tcpip.Address // address of the server + SubnetMask tcpip.AddressMask // client address subnet mask + Gateway tcpip.Address // client default gateway + DNS []tcpip.Address // client DNS server addresses + LeaseLength time.Duration // length of the address lease } func (cfg *Config) decode(opts []option) error { *cfg = Config{} for _, opt := range opts { b := opt.body - if l := opt.code.len(); l != -1 && l != len(b) { - return fmt.Errorf("%s bad length: %d", opt.code, len(b)) + if !opt.code.lenValid(len(b)) { + // TODO: s/%v/%s/ when `go vet` is smarter. + return fmt.Errorf("%v: bad length: %d", opt.code, len(b)) } switch opt.code { case optLeaseTime: @@ -51,7 +53,12 @@ func (cfg *Config) decode(opts []option) error { case optDefaultGateway: cfg.Gateway = tcpip.Address(b) case optDomainNameServer: - cfg.DomainNameServer = tcpip.Address(b) + for ; len(b) > 0; b = b[4:] { + if len(b) < 4 { + return fmt.Errorf("DNS bad length: %d", len(b)) + } + cfg.DNS = append(cfg.DNS, tcpip.Address(b[:4])) + } } } return nil @@ -67,8 +74,12 @@ func (cfg Config) encode() (opts []option) { if cfg.Gateway != "" { opts = append(opts, option{optDefaultGateway, []byte(cfg.Gateway)}) } - if cfg.DomainNameServer != "" { - opts = append(opts, option{optDomainNameServer, []byte(cfg.DomainNameServer)}) + if len(cfg.DNS) > 0 { + dns := make([]byte, 0, 4*len(cfg.DNS)) + for _, addr := range cfg.DNS { + dns = append(dns, addr...) + } + opts = append(opts, option{optDomainNameServer, dns}) } if l := cfg.LeaseLength / time.Second; l != 0 { v := make([]byte, 4) @@ -82,8 +93,10 @@ func (cfg Config) encode() (opts []option) { } const ( - serverPort = 67 - clientPort = 68 + // ServerPort is the well-known UDP port number for a DHCP server. + ServerPort = 67 + // ClientPort is the well-known UDP port number for a DHCP client. + ClientPort = 68 ) var magicCookie = []byte{99, 130, 83, 99} // RFC 1497 @@ -107,10 +120,10 @@ func (h header) isValid() bool { if o := h.op(); o != opRequest && o != opReply { return false } - if h[1] != 0x01 || h[2] != 0x06 || h[3] != 0x00 { + if h[1] != 0x01 || h[2] != 0x06 { return false } - return bytes.Equal(h[236:240], magicCookie) && h[len(h)-1] == 0 + return bytes.Equal(h[236:240], magicCookie) } func (h header) op() op { return op(h[0]) } @@ -141,7 +154,7 @@ func (h header) options() (opts options, err error) { } optlen := int(h[i+1]) if len(h) < i+2+optlen { - return nil, fmt.Errorf("option too long") + return nil, fmt.Errorf("option %v too long i=%d, optlen=%d", optionCode(h[i]), i, optlen) } opts = append(opts, option{ code: optionCode(h[i]), @@ -160,6 +173,8 @@ func (h header) setOptions(opts []option) { copy(h[i+2:i+2+len(opt.body)], opt.body) i += 2 + len(opt.body) } + h[i] = 255 // End option + i++ for ; i < len(h); i++ { h[i] = 0 } @@ -182,47 +197,31 @@ const ( optSubnetMask optionCode = 1 optDefaultGateway optionCode = 3 optDomainNameServer optionCode = 6 + optDomainName optionCode = 15 optReqIPAddr optionCode = 50 optLeaseTime optionCode = 51 optDHCPMsgType optionCode = 53 // dhcpMsgType optDHCPServer optionCode = 54 optParamReq optionCode = 55 + optMessage optionCode = 56 + optClientID optionCode = 61 ) -func (code optionCode) len() int { +func (code optionCode) lenValid(l int) bool { switch code { - case optSubnetMask, optDefaultGateway, optDomainNameServer, + case optSubnetMask, optDefaultGateway, optReqIPAddr, optLeaseTime, optDHCPServer: - return 4 + return l == 4 case optDHCPMsgType: - return 1 - case optParamReq: - return -1 // no fixed length - default: - return -1 - } -} - -func (code optionCode) String() string { - switch code { - case optSubnetMask: - return "option(subnet-mask)" - case optDefaultGateway: - return "option(default-gateway)" + return l == 1 case optDomainNameServer: - return "option(dns)" - case optReqIPAddr: - return "option(request-ip-address)" - case optLeaseTime: - return "option(least-time)" - case optDHCPMsgType: - return "option(message-type)" - case optDHCPServer: - return "option(server)" + return l%4 == 0 + case optMessage, optDomainName, optClientID: + return l >= 1 case optParamReq: - return "option(parameter-request)" + return true // no fixed length default: - return fmt.Sprintf("option(%d)", code) + return true // unknown option, assume ok } } @@ -232,11 +231,12 @@ func (opts options) dhcpMsgType() (dhcpMsgType, error) { for _, opt := range opts { if opt.code == optDHCPMsgType { if len(opt.body) != 1 { - return 0, fmt.Errorf("%s: bad length: %d", optDHCPMsgType, len(opt.body)) + // TODO: s/%v/%s/ when `go vet` is smarter. + return 0, fmt.Errorf("%v: bad length: %d", opt.code, len(opt.body)) } v := opt.body[0] if v <= 0 || v >= 8 { - return 0, fmt.Errorf("%s: unknown value: %d", optDHCPMsgType, v) + return 0, fmt.Errorf("DHCP bad length: %d", len(opt.body)) } return dhcpMsgType(v), nil } @@ -244,6 +244,15 @@ func (opts options) dhcpMsgType() (dhcpMsgType, error) { return 0, nil } +func (opts options) message() string { + for _, opt := range opts { + if opt.code == optMessage { + return string(opt.body) + } + } + return "" +} + func (opts options) len() int { l := 0 for _, opt := range opts { |