435c0d9fc8
This PR switches the Nomad repository from using govendor to Go modules for managing dependencies. Aspects of the Nomad workflow remain pretty much the same. The usual Makefile targets should continue to work as they always did. The API submodule simply defers to the parent Nomad version on the repository, keeping the semantics of API versioning that currently exists.
62 lines
1.8 KiB
Go
62 lines
1.8 KiB
Go
package dns
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// MsgAcceptFunc is used early in the server code to accept or reject a message with RcodeFormatError.
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// It returns a MsgAcceptAction to indicate what should happen with the message.
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type MsgAcceptFunc func(dh Header) MsgAcceptAction
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// DefaultMsgAcceptFunc checks the request and will reject if:
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//
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// * isn't a request (don't respond in that case)
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//
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// * opcode isn't OpcodeQuery or OpcodeNotify
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//
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// * Zero bit isn't zero
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//
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// * has more than 1 question in the question section
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//
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// * has more than 1 RR in the Answer section
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//
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// * has more than 0 RRs in the Authority section
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//
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// * has more than 2 RRs in the Additional section
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//
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var DefaultMsgAcceptFunc MsgAcceptFunc = defaultMsgAcceptFunc
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// MsgAcceptAction represents the action to be taken.
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type MsgAcceptAction int
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const (
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MsgAccept MsgAcceptAction = iota // Accept the message
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MsgReject // Reject the message with a RcodeFormatError
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MsgIgnore // Ignore the error and send nothing back.
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MsgRejectNotImplemented // Reject the message with a RcodeNotImplemented
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)
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func defaultMsgAcceptFunc(dh Header) MsgAcceptAction {
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if isResponse := dh.Bits&_QR != 0; isResponse {
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return MsgIgnore
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}
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// Don't allow dynamic updates, because then the sections can contain a whole bunch of RRs.
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opcode := int(dh.Bits>>11) & 0xF
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if opcode != OpcodeQuery && opcode != OpcodeNotify {
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return MsgRejectNotImplemented
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}
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if dh.Qdcount != 1 {
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return MsgReject
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}
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// NOTIFY requests can have a SOA in the ANSWER section. See RFC 1996 Section 3.7 and 3.11.
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if dh.Ancount > 1 {
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return MsgReject
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}
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// IXFR request could have one SOA RR in the NS section. See RFC 1995, section 3.
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if dh.Nscount > 1 {
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return MsgReject
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}
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if dh.Arcount > 2 {
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return MsgReject
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}
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return MsgAccept
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}
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