78 lines
1.8 KiB
Go
78 lines
1.8 KiB
Go
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package http
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import (
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"bufio"
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"bytes"
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"net/http"
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)
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// httpHostHeader returns the HTTP Host header from br without
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// consuming any of its bytes. It returns ""if it can't find one.
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func httpHostHeader(br *bufio.Reader) (method, host string) {
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const maxPeek = 4 << 10
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peekSize := 0
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for {
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peekSize++
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if peekSize > maxPeek {
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b, _ := br.Peek(br.Buffered())
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return method, httpHostHeaderFromBytes(b)
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}
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b, err := br.Peek(peekSize)
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if n := br.Buffered(); n > peekSize {
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b, _ = br.Peek(n)
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peekSize = n
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}
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if len(b) > 0 {
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if b[0] < 'A' || b[0] > 'Z' {
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// Doesn't look like an HTTP verb
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// (GET, POST, etc).
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return
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}
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if bytes.Index(b, crlfcrlf) != -1 || bytes.Index(b, lflf) != -1 {
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req, err := http.ReadRequest(bufio.NewReader(bytes.NewReader(b)))
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if err != nil {
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return
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}
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if len(req.Header["Host"]) > 1 {
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// TODO(bradfitz): what does
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// ReadRequest do if there are
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// multiple Host headers?
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return
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}
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return req.Method, req.Host
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}
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}
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if err != nil {
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return method, httpHostHeaderFromBytes(b)
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}
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}
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}
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var (
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lfHostColon = []byte("\nHost:")
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lfhostColon = []byte("\nhost:")
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crlf = []byte("\r\n")
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lf = []byte("\n")
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crlfcrlf = []byte("\r\n\r\n")
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lflf = []byte("\n\n")
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)
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func httpHostHeaderFromBytes(b []byte) string {
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if i := bytes.Index(b, lfHostColon); i != -1 {
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return string(bytes.TrimSpace(untilEOL(b[i+len(lfHostColon):])))
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}
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if i := bytes.Index(b, lfhostColon); i != -1 {
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return string(bytes.TrimSpace(untilEOL(b[i+len(lfhostColon):])))
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}
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return ""
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}
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// untilEOL returns v, truncated before the first '\n' byte, if any.
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// The returned slice may include a '\r' at the end.
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func untilEOL(v []byte) []byte {
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if i := bytes.IndexByte(v, '\n'); i != -1 {
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return v[:i]
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}
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return v
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}
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