diff options
Diffstat (limited to 'vendor/golang.org/x/net/dns/dnsmessage/message.go')
| -rw-r--r-- | vendor/golang.org/x/net/dns/dnsmessage/message.go | 41 |
1 files changed, 37 insertions, 4 deletions
diff --git a/vendor/golang.org/x/net/dns/dnsmessage/message.go b/vendor/golang.org/x/net/dns/dnsmessage/message.go index ea94bd495..e98fda66e 100644 --- a/vendor/golang.org/x/net/dns/dnsmessage/message.go +++ b/vendor/golang.org/x/net/dns/dnsmessage/message.go @@ -436,7 +436,13 @@ func (p *Parser) Question() (Question, error) { // AllQuestions parses all Questions. func (p *Parser) AllQuestions() ([]Question, error) { - qs := make([]Question, 0, p.header.questions) + // Multiple questions are valid according to the spec, + // but servers don't actually support them. There will + // be at most one question here. + // + // Do not pre-allocate based on info in p.header, since + // the data is untrusted. + qs := []Question{} for { q, err := p.Question() if err == ErrSectionDone { @@ -492,7 +498,16 @@ func (p *Parser) Answer() (Resource, error) { // AllAnswers parses all Answer Resources. func (p *Parser) AllAnswers() ([]Resource, error) { - as := make([]Resource, 0, p.header.answers) + // The most common query is for A/AAAA, which usually returns + // a handful of IPs. + // + // Pre-allocate up to a certain limit, since p.header is + // untrusted data. + n := int(p.header.answers) + if n > 20 { + n = 20 + } + as := make([]Resource, 0, n) for { a, err := p.Answer() if err == ErrSectionDone { @@ -533,7 +548,16 @@ func (p *Parser) Authority() (Resource, error) { // AllAuthorities parses all Authority Resources. func (p *Parser) AllAuthorities() ([]Resource, error) { - as := make([]Resource, 0, p.header.authorities) + // Authorities contains SOA in case of NXDOMAIN and friends, + // otherwise it is empty. + // + // Pre-allocate up to a certain limit, since p.header is + // untrusted data. + n := int(p.header.authorities) + if n > 10 { + n = 10 + } + as := make([]Resource, 0, n) for { a, err := p.Authority() if err == ErrSectionDone { @@ -574,7 +598,16 @@ func (p *Parser) Additional() (Resource, error) { // AllAdditionals parses all Additional Resources. func (p *Parser) AllAdditionals() ([]Resource, error) { - as := make([]Resource, 0, p.header.additionals) + // Additionals usually contain OPT, and sometimes A/AAAA + // glue records. + // + // Pre-allocate up to a certain limit, since p.header is + // untrusted data. + n := int(p.header.additionals) + if n > 10 { + n = 10 + } + as := make([]Resource, 0, n) for { a, err := p.Additional() if err == ErrSectionDone { |