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+// urllib parses URLs and implements query escaping.
+// See RFC 3986. This module generally follows RFC 3986, except where
+// it deviates for compatibility reasons.
+// Based off: https://github.com/golang/go/blob/master/src/net/url/url.go
+// Last commit: https://github.com/golang/go/commit/fe2ed5054176935d4adcf13e891715ccf2ee3cce
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+module urllib
+
+import strings
+
+enum EncodingMode {
+ encode_path
+ encode_path_segment
+ encode_host
+ encode_zone
+ encode_user_password
+ encode_query_component
+ encode_fragment
+}
+
+const (
+ err_msg_escape = 'unescape: invalid URL escape'
+ err_msg_parse = 'parse: failed parsing url'
+)
+
+fn error_msg(message string, val string) string {
+ mut msg := 'net.urllib.$message'
+ if val != '' {
+ msg = '$msg ($val)'
+ }
+ return msg
+}
+
+// Return true if the specified character should be escaped when
+// appearing in a URL string, according to RFC 3986.
+//
+// Please be informed that for now should_escape does not check all
+// reserved characters correctly. See golang.org/issue/5684.
+fn should_escape(c byte, mode EncodingMode) bool {
+ // §2.3 Unreserved characters (alphanum)
+ if (`a` <= c && c <= `z`) || (`A` <= c && c <= `Z`) || (`0` <= c && c <= `9`) {
+ return false
+ }
+ if mode == .encode_host || mode == .encode_zone {
+ // §3.2.2 host allows
+ // sub-delims = `!` / `$` / `&` / ``` / `(` / `)` / `*` / `+` / `,` / `;` / `=`
+ // as part of reg-name.
+ // We add : because we include :port as part of host.
+ // We add [ ] because we include [ipv6]:port as part of host.
+ // We add < > because they`re the only characters left that
+ // we could possibly allow, and parse will reject them if we
+ // escape them (because hosts can`t use %-encoding for
+ // ASCII bytes).
+ if c in [`!`, `$`, `&`, `\\`, `(`, `)`, `*`, `+`, `,`, `;`, `=`, `:`, `[`, `]`, `<`, `>`,
+ `"`,
+ ] {
+ return false
+ }
+ }
+ match c {
+ `-`, `_`, `.`, `~` {
+ // §2.3 Unreserved characters (mark)
+ return false
+ }
+ `$`, `&`, `+`, `,`, `/`, `:`, `;`, `=`, `?`, `@` {
+ // §2.2 Reserved characters (reserved)
+ // Different sections of the URL allow a few of
+ // the reserved characters to appear unescaped.
+ match mode {
+ .encode_path {
+ // §3.3
+ // The RFC allows : @ & = + $ but saves / ; , for assigning
+ // meaning to individual path segments. This package
+ // only manipulates the path as a whole, so we allow those
+ // last three as well. That leaves only ? to escape.
+ return c == `?`
+ }
+ .encode_path_segment {
+ // §3.3
+ // The RFC allows : @ & = + $ but saves / ; , for assigning
+ // meaning to individual path segments.
+ return c == `/` || c == `;` || c == `,` || c == `?`
+ }
+ .encode_user_password {
+ // §3.2.1
+ // The RFC allows `;`, `:`, `&`, `=`, `+`, `$`, and `,` in
+ // userinfo, so we must escape only `@`, `/`, and `?`.
+ // The parsing of userinfo treats `:` as special so we must escape
+ // that too.
+ return c == `@` || c == `/` || c == `?` || c == `:`
+ }
+ .encode_query_component {
+ // §3.4
+ // The RFC reserves (so we must escape) everything.
+ return true
+ }
+ .encode_fragment {
+ // §4.1
+ // The RFC text is silent but the grammar allows
+ // everything, so escape nothing.
+ return false
+ }
+ else {}
+ }
+ }
+ else {}
+ }
+ if mode == .encode_fragment {
+ // RFC 3986 §2.2 allows not escaping sub-delims. A subset of sub-delims are
+ // included in reserved from RFC 2396 §2.2. The remaining sub-delims do not
+ // need to be escaped. To minimize potential breakage, we apply two restrictions:
+ // (1) we always escape sub-delims outside of the fragment, and (2) we always
+ // escape single quote to avoid breaking callers that had previously assumed that
+ // single quotes would be escaped. See issue #19917.
+ match c {
+ `!`, `(`, `)`, `*` { return false }
+ else {}
+ }
+ }
+ // Everything else must be escaped.
+ return true
+}
+
+// query_unescape does the inverse transformation of query_escape,
+// converting each 3-byte encoded substring of the form '%AB' into the
+// hex-decoded byte 0xAB.
+// It returns an error if any % is not followed by two hexadecimal
+// digits.
+pub fn query_unescape(s string) ?string {
+ return unescape(s, .encode_query_component)
+}
+
+// path_unescape does the inverse transformation of path_escape,
+// converting each 3-byte encoded substring of the form '%AB' into the
+// hex-decoded byte 0xAB. It returns an error if any % is not followed
+// by two hexadecimal digits.
+//
+// path_unescape is identical to query_unescape except that it does not
+// unescape '+' to ' ' (space).
+pub fn path_unescape(s string) ?string {
+ return unescape(s, .encode_path_segment)
+}
+
+// unescape unescapes a string; the mode specifies
+// which section of the URL string is being unescaped.
+fn unescape(s_ string, mode EncodingMode) ?string {
+ mut s := s_
+ // Count %, check that they're well-formed.
+ mut n := 0
+ mut has_plus := false
+ for i := 0; i < s.len; {
+ x := s[i]
+ match x {
+ `%` {
+ if s == '' {
+ break
+ }
+ n++
+ if i + 2 >= s.len || !ishex(s[i + 1]) || !ishex(s[i + 2]) {
+ if mode == .encode_query_component && i + 1 < s.len {
+ s = s[..i] + '%25' + s[(i + 1)..]
+ i += 4 // skip the %25 and the next character
+ continue
+ }
+ s = s[i..]
+ if s.len > 3 {
+ s = s[..3]
+ }
+ return error(error_msg(urllib.err_msg_escape, s))
+ }
+ // Per https://tools.ietf.org/html/rfc3986#page-21
+ // in the host component %-encoding can only be used
+ // for non-ASCII bytes.
+ // But https://tools.ietf.org/html/rfc6874#section-2
+ // introduces %25 being allowed to escape a percent sign
+ // in IPv6 scoped-address literals. Yay.
+ if i + 3 >= s.len && mode == .encode_host && unhex(s[i + 1]) < 8
+ && s[i..i + 3] != '%25' {
+ return error(error_msg(urllib.err_msg_escape, s[i..i + 3]))
+ }
+ if mode == .encode_zone {
+ // RFC 6874 says basically 'anything goes' for zone identifiers
+ // and that even non-ASCII can be redundantly escaped,
+ // but it seems prudent to restrict %-escaped bytes here to those
+ // that are valid host name bytes in their unescaped form.
+ // That is, you can use escaping in the zone identifier but not
+ // to introduce bytes you couldn't just write directly.
+ // But Windows puts spaces here! Yay.
+ if i + 3 >= s.len {
+ return error(error_msg('unescape: invalid escape sequence', ''))
+ }
+ v := ((unhex(s[i + 1]) << byte(4)) | unhex(s[i + 2]))
+ if s[i..i + 3] != '%25' && v != ` ` && should_escape(v, .encode_host) {
+ error(error_msg(urllib.err_msg_escape, s[i..i + 3]))
+ }
+ }
+ i += 3
+ }
+ `+` {
+ has_plus = mode == .encode_query_component
+ i++
+ }
+ else {
+ if (mode == .encode_host || mode == .encode_zone) && s[i] < 0x80
+ && should_escape(s[i], mode) {
+ error(error_msg('unescape: invalid character in host name', s[i..i + 1]))
+ }
+ i++
+ }
+ }
+ }
+ if n == 0 && !has_plus {
+ return s
+ }
+ if s.len < 2 * n {
+ return error(error_msg('unescape: invalid escape sequence', ''))
+ }
+ mut t := strings.new_builder(s.len - 2 * n)
+ for i := 0; i < s.len; i++ {
+ x := s[i]
+ match x {
+ `%` {
+ if i + 2 >= s.len {
+ return error(error_msg('unescape: invalid escape sequence', ''))
+ }
+ t.write_string(((unhex(s[i + 1]) << byte(4)) | unhex(s[i + 2])).ascii_str())
+ i += 2
+ }
+ `+` {
+ if mode == .encode_query_component {
+ t.write_string(' ')
+ } else {
+ t.write_string('+')
+ }
+ }
+ else {
+ t.write_string(s[i].ascii_str())
+ }
+ }
+ }
+ return t.str()
+}
+
+// query_escape escapes the string so it can be safely placed
+// inside a URL query.
+pub fn query_escape(s string) string {
+ return escape(s, .encode_query_component)
+}
+
+// path_escape escapes the string so it can be safely placed inside a URL path segment,
+// replacing special characters (including /) with %XX sequences as needed.
+pub fn path_escape(s string) string {
+ return escape(s, .encode_path_segment)
+}
+
+fn escape(s string, mode EncodingMode) string {
+ mut space_count := 0
+ mut hex_count := 0
+ mut c := byte(0)
+ for i in 0 .. s.len {
+ c = s[i]
+ if should_escape(c, mode) {
+ if c == ` ` && mode == .encode_query_component {
+ space_count++
+ } else {
+ hex_count++
+ }
+ }
+ }
+ if space_count == 0 && hex_count == 0 {
+ return s
+ }
+ buf := []byte{len: (64)}
+ mut t := []byte{}
+ required := s.len + 2 * hex_count
+ if required <= buf.len {
+ t = buf[..required]
+ } else {
+ t = []byte{len: required}
+ }
+ if hex_count == 0 {
+ copy(t, s.bytes())
+ for i in 0 .. s.len {
+ if s[i] == ` ` {
+ t[i] = `+`
+ }
+ }
+ return t.bytestr()
+ }
+ upperhex := '0123456789ABCDEF'
+ mut j := 0
+ for i in 0 .. s.len {
+ c1 := s[i]
+ if c1 == ` ` && mode == .encode_query_component {
+ t[j] = `+`
+ j++
+ } else if should_escape(c1, mode) {
+ t[j] = `%`
+ t[j + 1] = upperhex[c1 >> 4]
+ t[j + 2] = upperhex[c1 & 15]
+ j += 3
+ } else {
+ t[j] = s[i]
+ j++
+ }
+ }
+ return t.bytestr()
+}
+
+// A URL represents a parsed URL (technically, a URI reference).
+//
+// The general form represented is:
+//
+// [scheme:][//[userinfo@]host][/]path[?query][#fragment]
+//
+// URLs that do not start with a slash after the scheme are interpreted as:
+//
+// scheme:opaque[?query][#fragment]
+//
+// Note that the path field is stored in decoded form: /%47%6f%2f becomes /Go/.
+// A consequence is that it is impossible to tell which slashes in the path were
+// slashes in the raw URL and which were %2f. This distinction is rarely important,
+// but when it is, the code should use raw_path, an optional field which only gets
+// set if the default encoding is different from path.
+//
+// URL's String method uses the escaped_path method to obtain the path. See the
+// escaped_path method for more details.
+pub struct URL {
+pub mut:
+ scheme string
+ opaque string // encoded opaque data
+ user &Userinfo // username and password information
+ host string // host or host:port
+ path string // path (relative paths may omit leading slash)
+ raw_path string // encoded path hint (see escaped_path method)
+ force_query bool // append a query ('?') even if raw_query is empty
+ raw_query string // encoded query values, without '?'
+ fragment string // fragment for references, without '#'
+}
+
+// user returns a Userinfo containing the provided username
+// and no password set.
+pub fn user(username string) &Userinfo {
+ return &Userinfo{
+ username: username
+ password: ''
+ password_set: false
+ }
+}
+
+// user_password returns a Userinfo containing the provided username
+// and password.
+//
+// This functionality should only be used with legacy web sites.
+// RFC 2396 warns that interpreting Userinfo this way
+// ``is NOT RECOMMENDED, because the passing of authentication
+// information in clear text (such as URI) has proven to be a
+// security risk in almost every case where it has been used.''
+fn user_password(username string, password string) &Userinfo {
+ return &Userinfo{username, password, true}
+}
+
+// The Userinfo type is an immutable encapsulation of username and
+// password details for a URL. An existing Userinfo value is guaranteed
+// to have a username set (potentially empty, as allowed by RFC 2396),
+// and optionally a password.
+struct Userinfo {
+pub:
+ username string
+ password string
+ password_set bool
+}
+
+fn (u &Userinfo) empty() bool {
+ return isnil(u) || (u.username == '' && u.password == '')
+}
+
+// string returns the encoded userinfo information in the standard form
+// of 'username[:password]'.
+fn (u &Userinfo) str() string {
+ if u.empty() {
+ return ''
+ }
+ mut s := escape(u.username, .encode_user_password)
+ if u.password_set {
+ s += ':' + escape(u.password, .encode_user_password)
+ }
+ return s
+}
+
+// Maybe rawurl is of the form scheme:path.
+// (scheme must be [a-zA-Z][a-zA-Z0-9+-.]*)
+// If so, return [scheme, path]; else return ['', rawurl]
+fn split_by_scheme(rawurl string) ?[]string {
+ for i in 0 .. rawurl.len {
+ c := rawurl[i]
+ if (`a` <= c && c <= `z`) || (`A` <= c && c <= `Z`) {
+ // do nothing
+ } else if (`0` <= c && c <= `9`) || (c == `+` || c == `-` || c == `.`) {
+ if i == 0 {
+ return ['', rawurl]
+ }
+ } else if c == `:` {
+ if i == 0 {
+ return error(error_msg('split_by_scheme: missing protocol scheme', ''))
+ }
+ return [rawurl[..i], rawurl[i + 1..]]
+ } else {
+ // we have encountered an invalid character,
+ // so there is no valid scheme
+ return ['', rawurl]
+ }
+ }
+ return ['', rawurl]
+}
+
+fn get_scheme(rawurl string) ?string {
+ split := split_by_scheme(rawurl) or { return err.msg }
+ return split[0]
+}
+
+// split slices s into two substrings separated by the first occurence of
+// sep. If cutc is true then sep is included with the second substring.
+// If sep does not occur in s then s and the empty string is returned.
+fn split(s string, sep byte, cutc bool) (string, string) {
+ i := s.index_byte(sep)
+ if i < 0 {
+ return s, ''
+ }
+ if cutc {
+ return s[..i], s[i + 1..]
+ }
+ return s[..i], s[i..]
+}
+
+// parse parses rawurl into a URL structure.
+//
+// The rawurl may be relative (a path, without a host) or absolute
+// (starting with a scheme). Trying to parse a hostname and path
+// without a scheme is invalid but may not necessarily return an
+// error, due to parsing ambiguities.
+pub fn parse(rawurl string) ?URL {
+ // Cut off #frag
+ u, frag := split(rawurl, `#`, true)
+ mut url := parse_url(u, false) or { return error(error_msg(urllib.err_msg_parse, u)) }
+ if frag == '' {
+ return url
+ }
+ f := unescape(frag, .encode_fragment) or { return error(error_msg(urllib.err_msg_parse,
+ u)) }
+ url.fragment = f
+ return url
+}
+
+// parse_request_uri parses rawurl into a URL structure. It assumes that
+// rawurl was received in an HTTP request, so the rawurl is interpreted
+// only as an absolute URI or an absolute path.
+// The string rawurl is assumed not to have a #fragment suffix.
+// (Web browsers strip #fragment before sending the URL to a web server.)
+fn parse_request_uri(rawurl string) ?URL {
+ return parse_url(rawurl, true)
+}
+
+// parse_url parses a URL from a string in one of two contexts. If
+// via_request is true, the URL is assumed to have arrived via an HTTP request,
+// in which case only absolute URLs or path-absolute relative URLs are allowed.
+// If via_request is false, all forms of relative URLs are allowed.
+[manualfree]
+fn parse_url(rawurl string, via_request bool) ?URL {
+ if string_contains_ctl_byte(rawurl) {
+ return error(error_msg('parse_url: invalid control character in URL', rawurl))
+ }
+ if rawurl == '' && via_request {
+ return error(error_msg('parse_url: empty URL', rawurl))
+ }
+ mut url := URL{
+ user: 0
+ }
+ if rawurl == '*' {
+ url.path = '*'
+ return url
+ }
+ // Split off possible leading 'http:', 'mailto:', etc.
+ // Cannot contain escaped characters.
+ p := split_by_scheme(rawurl) ?
+ url.scheme = p[0]
+ mut rest := p[1]
+ url.scheme = url.scheme.to_lower()
+ // if rest.ends_with('?') && strings.count(rest, '?') == 1 {
+ if rest.ends_with('?') && !rest[..1].contains('?') {
+ url.force_query = true
+ rest = rest[..rest.len - 1]
+ } else {
+ r, raw_query := split(rest, `?`, true)
+ rest = r
+ url.raw_query = raw_query
+ }
+ if !rest.starts_with('/') {
+ if url.scheme != '' {
+ // We consider rootless paths per RFC 3986 as opaque.
+ url.opaque = rest
+ return url
+ }
+ if via_request {
+ return error(error_msg('parse_url: invalid URI for request', ''))
+ }
+ // Avoid confusion with malformed schemes, like cache_object:foo/bar.
+ // See golang.org/issue/16822.
+ //
+ // RFC 3986, §3.3:
+ // In addition, a URI reference (Section 4.1) may be a relative-path reference,
+ // in which case the first path segment cannot contain a colon (':') character.
+ colon := rest.index(':') or { return error('there should be a : in the URL') }
+ slash := rest.index('/') or { return error('there should be a / in the URL') }
+ if colon >= 0 && (slash < 0 || colon < slash) {
+ // First path segment has colon. Not allowed in relative URL.
+ return error(error_msg('parse_url: first path segment in URL cannot contain colon',
+ ''))
+ }
+ }
+ if ((url.scheme != '' || !via_request) && !rest.starts_with('///')) && rest.starts_with('//') {
+ authority, r := split(rest[2..], `/`, false)
+ rest = r
+ a := parse_authority(authority) ?
+ url.user = a.user
+ url.host = a.host
+ }
+ // Set path and, optionally, raw_path.
+ // raw_path is a hint of the encoding of path. We don't want to set it if
+ // the default escaping of path is equivalent, to help make sure that people
+ // don't rely on it in general.
+ url.set_path(rest) ?
+ return url
+}
+
+struct ParseAuthorityRes {
+ user &Userinfo
+ host string
+}
+
+fn parse_authority(authority string) ?ParseAuthorityRes {
+ i := authority.last_index('@') or { -1 }
+ mut host := ''
+ mut zuser := user('')
+ if i < 0 {
+ h := parse_host(authority) ?
+ host = h
+ } else {
+ h := parse_host(authority[i + 1..]) ?
+ host = h
+ }
+ if i < 0 {
+ return ParseAuthorityRes{
+ host: host
+ user: zuser
+ }
+ }
+ mut userinfo := authority[..i]
+ if !valid_userinfo(userinfo) {
+ return error(error_msg('parse_authority: invalid userinfo', ''))
+ }
+ if !userinfo.contains(':') {
+ u := unescape(userinfo, .encode_user_password) ?
+ userinfo = u
+ zuser = user(userinfo)
+ } else {
+ mut username, mut password := split(userinfo, `:`, true)
+ u := unescape(username, .encode_user_password) ?
+ username = u
+ p := unescape(password, .encode_user_password) ?
+ password = p
+ zuser = user_password(username, password)
+ }
+ return ParseAuthorityRes{
+ user: zuser
+ host: host
+ }
+}
+
+// parse_host parses host as an authority without user
+// information. That is, as host[:port].
+fn parse_host(host string) ?string {
+ if host.starts_with('[') {
+ // parse an IP-Literal in RFC 3986 and RFC 6874.
+ // E.g., '[fe80::1]', '[fe80::1%25en0]', '[fe80::1]:80'.
+ mut i := host.last_index(']') or {
+ return error(error_msg("parse_host: missing ']' in host", ''))
+ }
+ mut colon_port := host[i + 1..]
+ if !valid_optional_port(colon_port) {
+ return error(error_msg('parse_host: invalid port $colon_port after host ',
+ ''))
+ }
+ // RFC 6874 defines that %25 (%-encoded percent) introduces
+ // the zone identifier, and the zone identifier can use basically
+ // any %-encoding it likes. That's different from the host, which
+ // can only %-encode non-ASCII bytes.
+ // We do impose some restrictions on the zone, to avoid stupidity
+ // like newlines.
+ if zone := host[..i].index('%25') {
+ host1 := unescape(host[..zone], .encode_host) or { return err.msg }
+ host2 := unescape(host[zone..i], .encode_zone) or { return err.msg }
+ host3 := unescape(host[i..], .encode_host) or { return err.msg }
+ return host1 + host2 + host3
+ }
+ if idx := host.last_index(':') {
+ colon_port = host[idx..]
+ if !valid_optional_port(colon_port) {
+ return error(error_msg('parse_host: invalid port $colon_port after host ',
+ ''))
+ }
+ }
+ }
+ h := unescape(host, .encode_host) or { return err.msg }
+ return h
+ // host = h
+ // return host
+}
+
+// set_path sets the path and raw_path fields of the URL based on the provided
+// escaped path p. It maintains the invariant that raw_path is only specified
+// when it differs from the default encoding of the path.
+// For example:
+// - set_path('/foo/bar') will set path='/foo/bar' and raw_path=''
+// - set_path('/foo%2fbar') will set path='/foo/bar' and raw_path='/foo%2fbar'
+// set_path will return an error only if the provided path contains an invalid
+// escaping.
+pub fn (mut u URL) set_path(p string) ?bool {
+ path := unescape(p, .encode_path) ?
+ u.path = path
+ escp := escape(path, .encode_path)
+ if p == escp {
+ // Default encoding is fine.
+ u.raw_path = ''
+ } else {
+ u.raw_path = p
+ }
+ return true
+}
+
+// escaped_path returns the escaped form of u.path.
+// In general there are multiple possible escaped forms of any path.
+// escaped_path returns u.raw_path when it is a valid escaping of u.path.
+// Otherwise escaped_path ignores u.raw_path and computes an escaped
+// form on its own.
+// The String and request_uri methods use escaped_path to construct
+// their results.
+// In general, code should call escaped_path instead of
+// reading u.raw_path directly.
+pub fn (u &URL) escaped_path() string {
+ if u.raw_path != '' && valid_encoded_path(u.raw_path) {
+ unescape(u.raw_path, .encode_path) or { return '' }
+ return u.raw_path
+ }
+ if u.path == '*' {
+ return '*' // don't escape (Issue 11202)
+ }
+ return escape(u.path, .encode_path)
+}
+
+// valid_encoded_path reports whether s is a valid encoded path.
+// It must not contain any bytes that require escaping during path encoding.
+fn valid_encoded_path(s string) bool {
+ for i in 0 .. s.len {
+ // RFC 3986, Appendix A.
+ // pchar = unreserved / pct-encoded / sub-delims / ':' / '@'.
+ // should_escape is not quite compliant with the RFC,
+ // so we check the sub-delims ourselves and let
+ // should_escape handle the others.
+ x := s[i]
+ match x {
+ `!`, `$`, `&`, `\\`, `(`, `)`, `*`, `+`, `,`, `;`, `=`, `:`, `@` {
+ // ok
+ }
+ `[`, `]` {
+ // ok - not specified in RFC 3986 but left alone by modern browsers
+ }
+ `%` {
+ // ok - percent encoded, will decode
+ }
+ else {
+ if should_escape(s[i], .encode_path) {
+ return false
+ }
+ }
+ }
+ }
+ return true
+}
+
+// valid_optional_port reports whether port is either an empty string
+// or matches /^:\d*$/
+fn valid_optional_port(port string) bool {
+ if port == '' {
+ return true
+ }
+ if port[0] != `:` {
+ return false
+ }
+ for b in port[1..] {
+ if b < `0` || b > `9` {
+ return false
+ }
+ }
+ return true
+}
+
+// str reassembles the URL into a valid URL string.
+// The general form of the result is one of:
+//
+// scheme:opaque?query#fragment
+// scheme://userinfo@host/path?query#fragment
+//
+// If u.opaque is non-empty, String uses the first form;
+// otherwise it uses the second form.
+// Any non-ASCII characters in host are escaped.
+// To obtain the path, String uses u.escaped_path().
+//
+// In the second form, the following rules apply:
+// - if u.scheme is empty, scheme: is omitted.
+// - if u.user is nil, userinfo@ is omitted.
+// - if u.host is empty, host/ is omitted.
+// - if u.scheme and u.host are empty and u.user is nil,
+// the entire scheme://userinfo@host/ is omitted.
+// - if u.host is non-empty and u.path begins with a /,
+// the form host/path does not add its own /.
+// - if u.raw_query is empty, ?query is omitted.
+// - if u.fragment is empty, #fragment is omitted.
+pub fn (u URL) str() string {
+ mut buf := strings.new_builder(200)
+ if u.scheme != '' {
+ buf.write_string(u.scheme)
+ buf.write_string(':')
+ }
+ if u.opaque != '' {
+ buf.write_string(u.opaque)
+ } else {
+ if u.scheme != '' || u.host != '' || !u.user.empty() {
+ if u.host != '' || u.path != '' || !u.user.empty() {
+ buf.write_string('//')
+ }
+ if !u.user.empty() {
+ buf.write_string(u.user.str())
+ buf.write_string('@')
+ }
+ if u.host != '' {
+ buf.write_string(escape(u.host, .encode_host))
+ }
+ }
+ path := u.escaped_path()
+ if path != '' && path[0] != `/` && u.host != '' {
+ buf.write_string('/')
+ }
+ if buf.len == 0 {
+ // RFC 3986 §4.2
+ // A path segment that contains a colon character (e.g., 'this:that')
+ // cannot be used as the first segment of a relative-path reference, as
+ // it would be mistaken for a scheme name. Such a segment must be
+ // preceded by a dot-segment (e.g., './this:that') to make a relative-
+ // path reference.
+ i := path.index_byte(`:`)
+ if i > -1 {
+ // TODO remove this when autofree handles tmp
+ // expressions like this
+ if i > -1 && path[..i].index_byte(`/`) == -1 {
+ buf.write_string('./')
+ }
+ }
+ }
+ buf.write_string(path)
+ }
+ if u.force_query || u.raw_query != '' {
+ buf.write_string('?')
+ buf.write_string(u.raw_query)
+ }
+ if u.fragment != '' {
+ buf.write_string('#')
+ buf.write_string(escape(u.fragment, .encode_fragment))
+ }
+ return buf.str()
+}
+
+// Values maps a string key to a list of values.
+// It is typically used for query parameters and form values.
+// Unlike in the http.Header map, the keys in a Values map
+// are case-sensitive.
+// parseQuery parses the URL-encoded query string and returns
+// a map listing the values specified for each key.
+// parseQuery always returns a non-nil map containing all the
+// valid query parameters found; err describes the first decoding error
+// encountered, if any.
+//
+// Query is expected to be a list of key=value settings separated by
+// ampersands or semicolons. A setting without an equals sign is
+// interpreted as a key set to an empty value.
+pub fn parse_query(query string) ?Values {
+ mut m := new_values()
+ parse_query_values(mut m, query) ?
+ return m
+}
+
+// parse_query_silent is the same as parse_query
+// but any errors will be silent
+fn parse_query_silent(query string) Values {
+ mut m := new_values()
+ parse_query_values(mut m, query) or {}
+ return m
+}
+
+fn parse_query_values(mut m Values, query string) ?bool {
+ mut had_error := false
+ mut q := query
+ for q != '' {
+ mut key := q
+ mut i := key.index_any('&;')
+ if i >= 0 {
+ q = key[i + 1..]
+ key = key[..i]
+ } else {
+ q = ''
+ }
+ if key == '' {
+ continue
+ }
+ mut value := ''
+ if idx := key.index('=') {
+ i = idx
+ value = key[i + 1..]
+ key = key[..i]
+ }
+ k := query_unescape(key) or {
+ had_error = true
+ continue
+ }
+ key = k
+ v := query_unescape(value) or {
+ had_error = true
+ continue
+ }
+ value = v
+ m.add(key, value)
+ }
+ if had_error {
+ return error(error_msg('parse_query_values: failed parsing query string', ''))
+ }
+ return true
+}
+
+// encode encodes the values into ``URL encoded'' form
+// ('bar=baz&foo=quux') sorted by key.
+pub fn (v Values) encode() string {
+ if v.len == 0 {
+ return ''
+ }
+ mut buf := strings.new_builder(200)
+ mut keys := []string{}
+ for k, _ in v.data {
+ keys << k
+ }
+ keys.sort()
+ for k in keys {
+ vs := v.data[k]
+ key_kscaped := query_escape(k)
+ for _, val in vs.data {
+ if buf.len > 0 {
+ buf.write_string('&')
+ }
+ buf.write_string(key_kscaped)
+ buf.write_string('=')
+ buf.write_string(query_escape(val))
+ }
+ }
+ return buf.str()
+}
+
+// resolve_path applies special path segments from refs and applies
+// them to base, per RFC 3986.
+fn resolve_path(base string, ref string) string {
+ mut full := ''
+ if ref == '' {
+ full = base
+ } else if ref[0] != `/` {
+ i := base.last_index('/') or { -1 }
+ full = base[..i + 1] + ref
+ } else {
+ full = ref
+ }
+ if full == '' {
+ return ''
+ }
+ mut dst := []string{}
+ src := full.split('/')
+ for _, elem in src {
+ match elem {
+ '.' {
+ // drop
+ }
+ '..' {
+ if dst.len > 0 {
+ dst = dst[..dst.len - 1]
+ }
+ }
+ else {
+ dst << elem
+ }
+ }
+ }
+ last := src[src.len - 1]
+ if last == '.' || last == '..' {
+ // Add final slash to the joined path.
+ dst << ''
+ }
+ return '/' + dst.join('/').trim_left('/')
+}
+
+// is_abs reports whether the URL is absolute.
+// Absolute means that it has a non-empty scheme.
+pub fn (u &URL) is_abs() bool {
+ return u.scheme != ''
+}
+
+// parse parses a URL in the context of the receiver. The provided URL
+// may be relative or absolute. parse returns nil, err on parse
+// failure, otherwise its return value is the same as resolve_reference.
+pub fn (u &URL) parse(ref string) ?URL {
+ refurl := parse(ref) ?
+ return u.resolve_reference(refurl)
+}
+
+// resolve_reference resolves a URI reference to an absolute URI from
+// an absolute base URI u, per RFC 3986 Section 5.2. The URI reference
+// may be relative or absolute. resolve_reference always returns a new
+// URL instance, even if the returned URL is identical to either the
+// base or reference. If ref is an absolute URL, then resolve_reference
+// ignores base and returns a copy of ref.
+pub fn (u &URL) resolve_reference(ref &URL) ?URL {
+ mut url := *ref
+ if ref.scheme == '' {
+ url.scheme = u.scheme
+ }
+ if ref.scheme != '' || ref.host != '' || !ref.user.empty() {
+ // The 'absoluteURI' or 'net_path' cases.
+ // We can ignore the error from set_path since we know we provided a
+ // validly-escaped path.
+ url.set_path(resolve_path(ref.escaped_path(), '')) ?
+ return url
+ }
+ if ref.opaque != '' {
+ url.user = user('')
+ url.host = ''
+ url.path = ''
+ return url
+ }
+ if ref.path == '' && ref.raw_query == '' {
+ url.raw_query = u.raw_query
+ if ref.fragment == '' {
+ url.fragment = u.fragment
+ }
+ }
+ // The 'abs_path' or 'rel_path' cases.
+ url.host = u.host
+ url.user = u.user
+ url.set_path(resolve_path(u.escaped_path(), ref.escaped_path())) ?
+ return url
+}
+
+// query parses raw_query and returns the corresponding values.
+// It silently discards malformed value pairs.
+// To check errors use parseQuery.
+pub fn (u &URL) query() Values {
+ v := parse_query_silent(u.raw_query)
+ return v
+}
+
+// request_uri returns the encoded path?query or opaque?query
+// string that would be used in an HTTP request for u.
+pub fn (u &URL) request_uri() string {
+ mut result := u.opaque
+ if result == '' {
+ result = u.escaped_path()
+ if result == '' {
+ result = '/'
+ }
+ } else {
+ if result.starts_with('//') {
+ result = u.scheme + ':' + result
+ }
+ }
+ if u.force_query || u.raw_query != '' {
+ result += '?' + u.raw_query
+ }
+ return result
+}
+
+// hostname returns u.host, stripping any valid port number if present.
+//
+// If the result is enclosed in square brackets, as literal IPv6 addresses are,
+// the square brackets are removed from the result.
+pub fn (u &URL) hostname() string {
+ host, _ := split_host_port(u.host)
+ return host
+}
+
+// port returns the port part of u.host, without the leading colon.
+// If u.host doesn't contain a port, port returns an empty string.
+pub fn (u &URL) port() string {
+ _, port := split_host_port(u.host)
+ return port
+}
+
+// split_host_port separates host and port. If the port is not valid, it returns
+// the entire input as host, and it doesn't check the validity of the host.
+// Per RFC 3986, it requires ports to be numeric.
+fn split_host_port(hostport string) (string, string) {
+ mut host := hostport
+ mut port := ''
+ colon := host.last_index_byte(`:`)
+ if colon != -1 {
+ if valid_optional_port(host[colon..]) {
+ port = host[colon + 1..]
+ host = host[..colon]
+ }
+ }
+ if host.starts_with('[') && host.ends_with(']') {
+ host = host[1..host.len - 1]
+ }
+ return host, port
+}
+
+// valid_userinfo reports whether s is a valid userinfo string per RFC 3986
+// Section 3.2.1:
+// userinfo = *( unreserved / pct-encoded / sub-delims / ':' )
+// unreserved = ALPHA / DIGIT / '-' / '.' / '_' / '~'
+// sub-delims = '!' / '$' / '&' / ''' / '(' / ')'
+// / '*' / '+' / ',' / ';' / '='
+//
+// It doesn't validate pct-encoded. The caller does that via fn unescape.
+pub fn valid_userinfo(s string) bool {
+ for r in s {
+ if `A` <= r && r <= `Z` {
+ continue
+ }
+ if `a` <= r && r <= `z` {
+ continue
+ }
+ if `0` <= r && r <= `9` {
+ continue
+ }
+ match r {
+ `-`, `.`, `_`, `:`, `~`, `!`, `$`, `&`, `\\`, `(`, `)`, `*`, `+`, `,`, `;`, `=`, `%`,
+ `@` {
+ continue
+ }
+ else {
+ return false
+ }
+ }
+ }
+ return true
+}
+
+// string_contains_ctl_byte reports whether s contains any ASCII control character.
+fn string_contains_ctl_byte(s string) bool {
+ for i in 0 .. s.len {
+ b := s[i]
+ if b < ` ` || b == 0x7f {
+ return true
+ }
+ }
+ return false
+}
+
+pub fn ishex(c byte) bool {
+ if `0` <= c && c <= `9` {
+ return true
+ } else if `a` <= c && c <= `f` {
+ return true
+ } else if `A` <= c && c <= `F` {
+ return true
+ }
+ return false
+}
+
+fn unhex(c byte) byte {
+ if `0` <= c && c <= `9` {
+ return c - `0`
+ } else if `a` <= c && c <= `f` {
+ return c - `a` + 10
+ } else if `A` <= c && c <= `F` {
+ return c - `A` + 10
+ }
+ return 0
+}