diff options
Diffstat (limited to 'vendor/github.com/miekg/dns/msg_truncate.go')
-rw-r--r-- | vendor/github.com/miekg/dns/msg_truncate.go | 117 |
1 files changed, 0 insertions, 117 deletions
diff --git a/vendor/github.com/miekg/dns/msg_truncate.go b/vendor/github.com/miekg/dns/msg_truncate.go deleted file mode 100644 index 2ddc9a7da..000000000 --- a/vendor/github.com/miekg/dns/msg_truncate.go +++ /dev/null @@ -1,117 +0,0 @@ -package dns - -// Truncate ensures the reply message will fit into the requested buffer -// size by removing records that exceed the requested size. -// -// It will first check if the reply fits without compression and then with -// compression. If it won't fit with compression, Truncate then walks the -// record adding as many records as possible without exceeding the -// requested buffer size. -// -// If the message fits within the requested size without compression, -// Truncate will set the message's Compress attribute to false. It is -// the caller's responsibility to set it back to true if they wish to -// compress the payload regardless of size. -// -// The TC bit will be set if any records were excluded from the message. -// If the TC bit is already set on the message it will be retained. -// TC indicates that the client should retry over TCP. -// -// According to RFC 2181, the TC bit should only be set if not all of the -// "required" RRs can be included in the response. Unfortunately, we have -// no way of knowing which RRs are required so we set the TC bit if any RR -// had to be omitted from the response. -// -// The appropriate buffer size can be retrieved from the requests OPT -// record, if present, and is transport specific otherwise. dns.MinMsgSize -// should be used for UDP requests without an OPT record, and -// dns.MaxMsgSize for TCP requests without an OPT record. -func (dns *Msg) Truncate(size int) { - if dns.IsTsig() != nil { - // To simplify this implementation, we don't perform - // truncation on responses with a TSIG record. - return - } - - // RFC 6891 mandates that the payload size in an OPT record - // less than 512 (MinMsgSize) bytes must be treated as equal to 512 bytes. - // - // For ease of use, we impose that restriction here. - if size < MinMsgSize { - size = MinMsgSize - } - - l := msgLenWithCompressionMap(dns, nil) // uncompressed length - if l <= size { - // Don't waste effort compressing this message. - dns.Compress = false - return - } - - dns.Compress = true - - edns0 := dns.popEdns0() - if edns0 != nil { - // Account for the OPT record that gets added at the end, - // by subtracting that length from our budget. - // - // The EDNS(0) OPT record must have the root domain and - // it's length is thus unaffected by compression. - size -= Len(edns0) - } - - compression := make(map[string]struct{}) - - l = headerSize - for _, r := range dns.Question { - l += r.len(l, compression) - } - - var numAnswer int - if l < size { - l, numAnswer = truncateLoop(dns.Answer, size, l, compression) - } - - var numNS int - if l < size { - l, numNS = truncateLoop(dns.Ns, size, l, compression) - } - - var numExtra int - if l < size { - _, numExtra = truncateLoop(dns.Extra, size, l, compression) - } - - // See the function documentation for when we set this. - dns.Truncated = dns.Truncated || len(dns.Answer) > numAnswer || - len(dns.Ns) > numNS || len(dns.Extra) > numExtra - - dns.Answer = dns.Answer[:numAnswer] - dns.Ns = dns.Ns[:numNS] - dns.Extra = dns.Extra[:numExtra] - - if edns0 != nil { - // Add the OPT record back onto the additional section. - dns.Extra = append(dns.Extra, edns0) - } -} - -func truncateLoop(rrs []RR, size, l int, compression map[string]struct{}) (int, int) { - for i, r := range rrs { - if r == nil { - continue - } - - l += r.len(l, compression) - if l > size { - // Return size, rather than l prior to this record, - // to prevent any further records being added. - return size, i - } - if l == size { - return l, i + 1 - } - } - - return l, len(rrs) -} |