1// Copyright 2016 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package httpguts 6 7import ( 8 "net" 9 "strings" 10 "unicode/utf8" 11 12 "golang.org/x/net/idna" 13) 14 15var isTokenTable = [127]bool{ 16 '!': true, 17 '#': true, 18 '$': true, 19 '%': true, 20 '&': true, 21 '\'': true, 22 '*': true, 23 '+': true, 24 '-': true, 25 '.': true, 26 '0': true, 27 '1': true, 28 '2': true, 29 '3': true, 30 '4': true, 31 '5': true, 32 '6': true, 33 '7': true, 34 '8': true, 35 '9': true, 36 'A': true, 37 'B': true, 38 'C': true, 39 'D': true, 40 'E': true, 41 'F': true, 42 'G': true, 43 'H': true, 44 'I': true, 45 'J': true, 46 'K': true, 47 'L': true, 48 'M': true, 49 'N': true, 50 'O': true, 51 'P': true, 52 'Q': true, 53 'R': true, 54 'S': true, 55 'T': true, 56 'U': true, 57 'W': true, 58 'V': true, 59 'X': true, 60 'Y': true, 61 'Z': true, 62 '^': true, 63 '_': true, 64 '`': true, 65 'a': true, 66 'b': true, 67 'c': true, 68 'd': true, 69 'e': true, 70 'f': true, 71 'g': true, 72 'h': true, 73 'i': true, 74 'j': true, 75 'k': true, 76 'l': true, 77 'm': true, 78 'n': true, 79 'o': true, 80 'p': true, 81 'q': true, 82 'r': true, 83 's': true, 84 't': true, 85 'u': true, 86 'v': true, 87 'w': true, 88 'x': true, 89 'y': true, 90 'z': true, 91 '|': true, 92 '~': true, 93} 94 95func IsTokenRune(r rune) bool { 96 i := int(r) 97 return i < len(isTokenTable) && isTokenTable[i] 98} 99 100func isNotToken(r rune) bool { 101 return !IsTokenRune(r) 102} 103 104// HeaderValuesContainsToken reports whether any string in values 105// contains the provided token, ASCII case-insensitively. 106func HeaderValuesContainsToken(values []string, token string) bool { 107 for _, v := range values { 108 if headerValueContainsToken(v, token) { 109 return true 110 } 111 } 112 return false 113} 114 115// isOWS reports whether b is an optional whitespace byte, as defined 116// by RFC 7230 section 3.2.3. 117func isOWS(b byte) bool { return b == ' ' || b == '\t' } 118 119// trimOWS returns x with all optional whitespace removes from the 120// beginning and end. 121func trimOWS(x string) string { 122 // TODO: consider using strings.Trim(x, " \t") instead, 123 // if and when it's fast enough. See issue 10292. 124 // But this ASCII-only code will probably always beat UTF-8 125 // aware code. 126 for len(x) > 0 && isOWS(x[0]) { 127 x = x[1:] 128 } 129 for len(x) > 0 && isOWS(x[len(x)-1]) { 130 x = x[:len(x)-1] 131 } 132 return x 133} 134 135// headerValueContainsToken reports whether v (assumed to be a 136// 0#element, in the ABNF extension described in RFC 7230 section 7) 137// contains token amongst its comma-separated tokens, ASCII 138// case-insensitively. 139func headerValueContainsToken(v string, token string) bool { 140 v = trimOWS(v) 141 if comma := strings.IndexByte(v, ','); comma != -1 { 142 return tokenEqual(trimOWS(v[:comma]), token) || headerValueContainsToken(v[comma+1:], token) 143 } 144 return tokenEqual(v, token) 145} 146 147// lowerASCII returns the ASCII lowercase version of b. 148func lowerASCII(b byte) byte { 149 if 'A' <= b && b <= 'Z' { 150 return b + ('a' - 'A') 151 } 152 return b 153} 154 155// tokenEqual reports whether t1 and t2 are equal, ASCII case-insensitively. 156func tokenEqual(t1, t2 string) bool { 157 if len(t1) != len(t2) { 158 return false 159 } 160 for i, b := range t1 { 161 if b >= utf8.RuneSelf { 162 // No UTF-8 or non-ASCII allowed in tokens. 163 return false 164 } 165 if lowerASCII(byte(b)) != lowerASCII(t2[i]) { 166 return false 167 } 168 } 169 return true 170} 171 172// isLWS reports whether b is linear white space, according 173// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2 174// LWS = [CRLF] 1*( SP | HT ) 175func isLWS(b byte) bool { return b == ' ' || b == '\t' } 176 177// isCTL reports whether b is a control byte, according 178// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2 179// CTL = <any US-ASCII control character 180// (octets 0 - 31) and DEL (127)> 181func isCTL(b byte) bool { 182 const del = 0x7f // a CTL 183 return b < ' ' || b == del 184} 185 186// ValidHeaderFieldName reports whether v is a valid HTTP/1.x header name. 187// HTTP/2 imposes the additional restriction that uppercase ASCII 188// letters are not allowed. 189// 190// RFC 7230 says: 191// header-field = field-name ":" OWS field-value OWS 192// field-name = token 193// token = 1*tchar 194// tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "." / 195// "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA 196func ValidHeaderFieldName(v string) bool { 197 if len(v) == 0 { 198 return false 199 } 200 for _, r := range v { 201 if !IsTokenRune(r) { 202 return false 203 } 204 } 205 return true 206} 207 208// ValidHostHeader reports whether h is a valid host header. 209func ValidHostHeader(h string) bool { 210 // The latest spec is actually this: 211 // 212 // http://tools.ietf.org/html/rfc7230#section-5.4 213 // Host = uri-host [ ":" port ] 214 // 215 // Where uri-host is: 216 // http://tools.ietf.org/html/rfc3986#section-3.2.2 217 // 218 // But we're going to be much more lenient for now and just 219 // search for any byte that's not a valid byte in any of those 220 // expressions. 221 for i := 0; i < len(h); i++ { 222 if !validHostByte[h[i]] { 223 return false 224 } 225 } 226 return true 227} 228 229// See the validHostHeader comment. 230var validHostByte = [256]bool{ 231 '0': true, '1': true, '2': true, '3': true, '4': true, '5': true, '6': true, '7': true, 232 '8': true, '9': true, 233 234 'a': true, 'b': true, 'c': true, 'd': true, 'e': true, 'f': true, 'g': true, 'h': true, 235 'i': true, 'j': true, 'k': true, 'l': true, 'm': true, 'n': true, 'o': true, 'p': true, 236 'q': true, 'r': true, 's': true, 't': true, 'u': true, 'v': true, 'w': true, 'x': true, 237 'y': true, 'z': true, 238 239 'A': true, 'B': true, 'C': true, 'D': true, 'E': true, 'F': true, 'G': true, 'H': true, 240 'I': true, 'J': true, 'K': true, 'L': true, 'M': true, 'N': true, 'O': true, 'P': true, 241 'Q': true, 'R': true, 'S': true, 'T': true, 'U': true, 'V': true, 'W': true, 'X': true, 242 'Y': true, 'Z': true, 243 244 '!': true, // sub-delims 245 '$': true, // sub-delims 246 '%': true, // pct-encoded (and used in IPv6 zones) 247 '&': true, // sub-delims 248 '(': true, // sub-delims 249 ')': true, // sub-delims 250 '*': true, // sub-delims 251 '+': true, // sub-delims 252 ',': true, // sub-delims 253 '-': true, // unreserved 254 '.': true, // unreserved 255 ':': true, // IPv6address + Host expression's optional port 256 ';': true, // sub-delims 257 '=': true, // sub-delims 258 '[': true, 259 '\'': true, // sub-delims 260 ']': true, 261 '_': true, // unreserved 262 '~': true, // unreserved 263} 264 265// ValidHeaderFieldValue reports whether v is a valid "field-value" according to 266// http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2 : 267// 268// message-header = field-name ":" [ field-value ] 269// field-value = *( field-content | LWS ) 270// field-content = <the OCTETs making up the field-value 271// and consisting of either *TEXT or combinations 272// of token, separators, and quoted-string> 273// 274// http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2 : 275// 276// TEXT = <any OCTET except CTLs, 277// but including LWS> 278// LWS = [CRLF] 1*( SP | HT ) 279// CTL = <any US-ASCII control character 280// (octets 0 - 31) and DEL (127)> 281// 282// RFC 7230 says: 283// field-value = *( field-content / obs-fold ) 284// obj-fold = N/A to http2, and deprecated 285// field-content = field-vchar [ 1*( SP / HTAB ) field-vchar ] 286// field-vchar = VCHAR / obs-text 287// obs-text = %x80-FF 288// VCHAR = "any visible [USASCII] character" 289// 290// http2 further says: "Similarly, HTTP/2 allows header field values 291// that are not valid. While most of the values that can be encoded 292// will not alter header field parsing, carriage return (CR, ASCII 293// 0xd), line feed (LF, ASCII 0xa), and the zero character (NUL, ASCII 294// 0x0) might be exploited by an attacker if they are translated 295// verbatim. Any request or response that contains a character not 296// permitted in a header field value MUST be treated as malformed 297// (Section 8.1.2.6). Valid characters are defined by the 298// field-content ABNF rule in Section 3.2 of [RFC7230]." 299// 300// This function does not (yet?) properly handle the rejection of 301// strings that begin or end with SP or HTAB. 302func ValidHeaderFieldValue(v string) bool { 303 for i := 0; i < len(v); i++ { 304 b := v[i] 305 if isCTL(b) && !isLWS(b) { 306 return false 307 } 308 } 309 return true 310} 311 312func isASCII(s string) bool { 313 for i := 0; i < len(s); i++ { 314 if s[i] >= utf8.RuneSelf { 315 return false 316 } 317 } 318 return true 319} 320 321// PunycodeHostPort returns the IDNA Punycode version 322// of the provided "host" or "host:port" string. 323func PunycodeHostPort(v string) (string, error) { 324 if isASCII(v) { 325 return v, nil 326 } 327 328 host, port, err := net.SplitHostPort(v) 329 if err != nil { 330 // The input 'v' argument was just a "host" argument, 331 // without a port. This error should not be returned 332 // to the caller. 333 host = v 334 port = "" 335 } 336 host, err = idna.ToASCII(host) 337 if err != nil { 338 // Non-UTF-8? Not representable in Punycode, in any 339 // case. 340 return "", err 341 } 342 if port == "" { 343 return host, nil 344 } 345 return net.JoinHostPort(host, port), nil 346} 347