102 lines
2.2 KiB
Go
102 lines
2.2 KiB
Go
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package httphead
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import "io"
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var (
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comma = []byte{','}
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equality = []byte{'='}
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semicolon = []byte{';'}
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quote = []byte{'"'}
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escape = []byte{'\\'}
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)
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// WriteOptions write options list to the dest.
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// It uses the same form as {Scan,Parse}Options functions:
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// values = 1#value
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// value = token *( ";" param )
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// param = token [ "=" (token | quoted-string) ]
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//
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// It wraps valuse into the quoted-string sequence if it contains any
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// non-token characters.
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func WriteOptions(dest io.Writer, options []Option) (n int, err error) {
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w := writer{w: dest}
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for i, opt := range options {
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if i > 0 {
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w.write(comma)
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}
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writeTokenSanitized(&w, opt.Name)
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for _, p := range opt.Parameters.data() {
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w.write(semicolon)
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writeTokenSanitized(&w, p.key)
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if len(p.value) != 0 {
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w.write(equality)
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writeTokenSanitized(&w, p.value)
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}
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}
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}
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return w.result()
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}
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// writeTokenSanitized writes token as is or as quouted string if it contains
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// non-token characters.
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//
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// Note that is is not expects LWS sequnces be in s, cause LWS is used only as
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// header field continuation:
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// "A CRLF is allowed in the definition of TEXT only as part of a header field
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// continuation. It is expected that the folding LWS will be replaced with a
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// single SP before interpretation of the TEXT value."
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// See https://tools.ietf.org/html/rfc2616#section-2
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//
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// That is we sanitizing s for writing, so there could not be any header field
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// continuation.
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// That is any CRLF will be escaped as any other control characters not allowd in TEXT.
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func writeTokenSanitized(bw *writer, bts []byte) {
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var qt bool
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var pos int
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for i := 0; i < len(bts); i++ {
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c := bts[i]
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if !OctetTypes[c].IsToken() && !qt {
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qt = true
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bw.write(quote)
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}
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if OctetTypes[c].IsControl() || c == '"' {
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if !qt {
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qt = true
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bw.write(quote)
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}
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bw.write(bts[pos:i])
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bw.write(escape)
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bw.write(bts[i : i+1])
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pos = i + 1
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}
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}
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if !qt {
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bw.write(bts)
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} else {
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bw.write(bts[pos:])
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bw.write(quote)
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}
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}
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type writer struct {
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w io.Writer
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n int
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err error
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}
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func (w *writer) write(p []byte) {
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if w.err != nil {
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return
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}
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var n int
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n, w.err = w.w.Write(p)
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w.n += n
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return
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}
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func (w *writer) result() (int, error) {
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return w.n, w.err
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}
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