Uri.cc

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/*
 * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */
 
/* DEBUG: section 23    URL Parsing */
 
#include "squid.h"
#include "anyp/Uri.h"
#include "base/Raw.h"
#include "globals.h"
#include "HttpRequest.h"
#include "parser/Tokenizer.h"
#include "rfc1738.h"
#include "SquidConfig.h"
#include "SquidMath.h"
#include "SquidString.h"
 
static const char valid_hostname_chars_u[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789-._"
    "[:]"
    ;
static const char valid_hostname_chars[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789-."
    "[:]"
    ;
 
static const CharacterSet &
UserInfoChars()
{
    /*
     * RFC 3986 section 3.2.1
     *
     *  userinfo      = *( unreserved / pct-encoded / sub-delims / ":" )
     *  unreserved    = ALPHA / DIGIT / "-" / "." / "_" / "~"
     *  pct-encoded   = "%" HEXDIG HEXDIG
     *  sub-delims    = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
     */
    static const auto userInfoValid = CharacterSet("userinfo", ":-._~%!$&'()*+,;=") +
                                      CharacterSet::ALPHA +
                                      CharacterSet::DIGIT;
    return userInfoValid;
}
 
SBuf
AnyP::Uri::Encode(const SBuf &buf, const CharacterSet &ignore)
{
    if (buf.isEmpty())
        return buf;
 
    Parser::Tokenizer tk(buf);
    SBuf goodSection;
    // optimization for the arguably common "no encoding necessary" case
    if (tk.prefix(goodSection, ignore) && tk.atEnd())
        return buf;
 
    SBuf output;
    output.reserveSpace(buf.length() * 3); // worst case: encode all chars
    output.append(goodSection); // may be empty
 
    while (!tk.atEnd()) {
        // TODO: Add Tokenizer::parseOne(void).
        const auto ch = tk.remaining()[0];
        output.appendf("%%%02X", static_cast<unsigned int>(static_cast<unsigned char>(ch))); // TODO: Optimize using a table
        (void)tk.skip(ch);
 
        if (tk.prefix(goodSection, ignore))
            output.append(goodSection);
    }
 
    return output;
}
 
const SBuf &
AnyP::Uri::Asterisk()
{
    static SBuf star("*");
    return star;
}
 
const SBuf &
AnyP::Uri::SlashPath()
{
    static SBuf slash("/");
    return slash;
}
 
void
AnyP::Uri::host(const char *src)
{
    hostAddr_.fromHost(src);
    if (hostAddr_.isAnyAddr()) {
        xstrncpy(host_, src, sizeof(host_));
        hostIsNumeric_ = false;
    } else {
        hostAddr_.toHostStr(host_, sizeof(host_));
        debugs(23, 3, "given IP: " << hostAddr_);
        hostIsNumeric_ = 1;
    }
    touch();
}
 
SBuf
AnyP::Uri::hostOrIp() const
{
    if (hostIsNumeric()) {
        static char ip[MAX_IPSTRLEN];
        const auto hostStrLen = hostIP().toHostStr(ip, sizeof(ip));
        return SBuf(ip, hostStrLen);
    } else
        return SBuf(host());
}
 
const SBuf &
AnyP::Uri::path() const
{
    // RFC 3986 section 3.3 says path can be empty (path-abempty).
    // RFC 7230 sections 2.7.3, 5.3.1, 5.7.2 - says path cannot be empty, default to "/"
    // at least when sending and using. We must still accept path-abempty as input.
    if (path_.isEmpty() && (scheme_ == AnyP::PROTO_HTTP || scheme_ == AnyP::PROTO_HTTPS))
        return SlashPath();
 
    return path_;
}
 
void
urlInitialize(void)
{
    debugs(23, 5, "urlInitialize: Initializing...");
    /* this ensures that the number of protocol strings is the same as
     * the enum slots allocated because the last enum is always 'MAX'.
     */
    assert(strcmp(AnyP::ProtocolType_str[AnyP::PROTO_MAX], "MAX") == 0);
    /*
     * These test that our matchDomainName() function works the
     * way we expect it to.
     */
    assert(0 == matchDomainName("foo.com", "foo.com"));
    assert(0 == matchDomainName(".foo.com", "foo.com"));
    assert(0 == matchDomainName("foo.com", ".foo.com"));
    assert(0 == matchDomainName(".foo.com", ".foo.com"));
    assert(0 == matchDomainName("x.foo.com", ".foo.com"));
    assert(0 == matchDomainName("y.x.foo.com", ".foo.com"));
    assert(0 != matchDomainName("x.foo.com", "foo.com"));
    assert(0 != matchDomainName("foo.com", "x.foo.com"));
    assert(0 != matchDomainName("bar.com", "foo.com"));
    assert(0 != matchDomainName(".bar.com", "foo.com"));
    assert(0 != matchDomainName(".bar.com", ".foo.com"));
    assert(0 != matchDomainName("bar.com", ".foo.com"));
    assert(0 < matchDomainName("zzz.com", "foo.com"));
    assert(0 > matchDomainName("aaa.com", "foo.com"));
    assert(0 == matchDomainName("FOO.com", "foo.COM"));
    assert(0 < matchDomainName("bfoo.com", "afoo.com"));
    assert(0 > matchDomainName("afoo.com", "bfoo.com"));
    assert(0 < matchDomainName("x-foo.com", ".foo.com"));
 
    assert(0 == matchDomainName(".foo.com", ".foo.com", mdnRejectSubsubDomains));
    assert(0 == matchDomainName("x.foo.com", ".foo.com", mdnRejectSubsubDomains));
    assert(0 != matchDomainName("y.x.foo.com", ".foo.com", mdnRejectSubsubDomains));
    assert(0 != matchDomainName(".x.foo.com", ".foo.com", mdnRejectSubsubDomains));
 
    assert(0 == matchDomainName("*.foo.com", "x.foo.com", mdnHonorWildcards));
    assert(0 == matchDomainName("*.foo.com", ".x.foo.com", mdnHonorWildcards));
    assert(0 == matchDomainName("*.foo.com", ".foo.com", mdnHonorWildcards));
    assert(0 != matchDomainName("*.foo.com", "foo.com", mdnHonorWildcards));
 
    assert(0 != matchDomainName("foo.com", ""));
    assert(0 != matchDomainName("foo.com", "", mdnHonorWildcards));
    assert(0 != matchDomainName("foo.com", "", mdnRejectSubsubDomains));
 
    /* more cases? */
}
 
static AnyP::UriScheme
uriParseScheme(Parser::Tokenizer &tok)
{
    /*
     * RFC 3986 section 3.1 paragraph 2:
     *
     * Scheme names consist of a sequence of characters beginning with a
     * letter and followed by any combination of letters, digits, plus
     * ("+"), period ("."), or hyphen ("-").
     */
    static const auto schemeChars = CharacterSet("scheme", "+.-") + CharacterSet::ALPHA + CharacterSet::DIGIT;
 
    SBuf str;
    if (tok.prefix(str, schemeChars, 16) && tok.skip(':') && CharacterSet::ALPHA[str.at(0)]) {
        const auto protocol = AnyP::UriScheme::FindProtocolType(str);
        if (protocol == AnyP::PROTO_UNKNOWN)
            return AnyP::UriScheme(protocol, str.c_str());
        return AnyP::UriScheme(protocol, nullptr);
    }
 
    throw TextException("invalid URI scheme", Here());
}
 
bool
urlAppendDomain(char *host)
{
    /* For IPv4 addresses check for a dot */
    /* For IPv6 addresses also check for a colon */
    if (Config.appendDomain && !strchr(host, '.') && !strchr(host, ':')) {
        const uint64_t dlen = strlen(host);
        const uint64_t want = dlen + Config.appendDomainLen;
        if (want > SQUIDHOSTNAMELEN - 1) {
            debugs(23, 2, "URL domain too large (" << dlen << " bytes)");
            return false;
        }
        strncat(host, Config.appendDomain, SQUIDHOSTNAMELEN - dlen - 1);
    }
    return true;
}
 
/*
 * Parse a URI/URL.
 *
 * It is assumed that the URL is complete -
 * ie, the end of the string is the end of the URL. Don't pass a partial
 * URL here as this routine doesn't have any way of knowing whether
 * it is partial or not (ie, it handles the case of no trailing slash as
 * being "end of host with implied path of /".
 *
 * method is used to switch parsers. If method is Http::METHOD_CONNECT,
 * then rather than a URL a hostname:port is looked for.
 */
bool
AnyP::Uri::parse(const HttpRequestMethod& method, const SBuf &rawUrl)
{
    try {
 
        LOCAL_ARRAY(char, login, MAX_URL);
        LOCAL_ARRAY(char, foundHost, MAX_URL);
        LOCAL_ARRAY(char, urlpath, MAX_URL);
        char *t = nullptr;
        char *q = nullptr;
        int foundPort;
        int l;
        int i;
        const char *src;
        char *dst;
        foundHost[0] = urlpath[0] = login[0] = '\0';
 
        if ((l = rawUrl.length()) + Config.appendDomainLen > (MAX_URL - 1)) {
            debugs(23, DBG_IMPORTANT, MYNAME << "URL too large (" << l << " bytes)");
            return false;
        }
 
        if ((method == Http::METHOD_OPTIONS || method == Http::METHOD_TRACE) &&
                Asterisk().cmp(rawUrl) == 0) {
            // XXX: these methods might also occur in HTTPS traffic. Handle this better.
            setScheme(AnyP::PROTO_HTTP, nullptr);
            port(getScheme().defaultPort());
            path(Asterisk());
            return true;
        }
 
        Parser::Tokenizer tok(rawUrl);
        AnyP::UriScheme scheme;
 
        if (method == Http::METHOD_CONNECT) {
            // For CONNECTs, RFC 9110 Section 9.3.6 requires "only the host and
            // port number of the tunnel destination, separated by a colon".
 
            const auto rawHost = parseHost(tok);
            Assure(rawHost.length() < sizeof(foundHost));
            SBufToCstring(foundHost, rawHost);
 
            if (!tok.skip(':'))
                throw TextException("missing required :port in CONNECT target", Here());
            foundPort = parsePort(tok);
 
            if (!tok.remaining().isEmpty())
                throw TextException("garbage after host:port in CONNECT target", Here());
        } else {
 
            scheme = uriParseScheme(tok);
 
            if (scheme == AnyP::PROTO_NONE)
                return false; // invalid scheme
 
            if (scheme == AnyP::PROTO_URN) {
                parseUrn(tok); // throws on any error
                return true;
            }
 
            // URLs then have "//"
            static const SBuf doubleSlash("//");
            if (!tok.skip(doubleSlash))
                return false;
 
            auto B = tok.remaining();
            const char *url = B.c_str();
 
            /* Parse the URL: */
            src = url;
            i = 0;
 
            /* Then everything until first /; that's host (and port; which we'll look for here later) */
            // bug 1881: If we don't get a "/" then we imply it was there
            // bug 3074: We could just be given a "?" or "#". These also imply "/"
            // bug 3233: whitespace is also a hostname delimiter.
            for (dst = foundHost; i < l && *src != '/' && *src != '?' && *src != '#' && *src != '\0' && !xisspace(*src); ++i, ++src, ++dst) {
                *dst = *src;
            }
 
            /*
             * We can't check for "i >= l" here because we could be at the end of the line
             * and have a perfectly valid URL w/ no trailing '/'. In this case we assume we've
             * been -given- a valid URL and the path is just '/'.
             */
            if (i > l)
                return false;
            *dst = '\0';
 
            // We are looking at path-abempty.
            if (*src != '/') {
                // path-empty, including the end of the `src` c-string cases
                urlpath[0] = '/';
                dst = &urlpath[1];
            } else {
                dst = urlpath;
            }
            /* Then everything from / (inclusive) until \r\n or \0 - that's urlpath */
            for (; i < l && *src != '\r' && *src != '\n' && *src != '\0'; ++i, ++src, ++dst) {
                *dst = *src;
            }
 
            /* We -could- be at the end of the buffer here */
            if (i > l)
                return false;
            *dst = '\0';
 
            // If the parsed scheme has no (known) default port, and there is no
            // explicit port, then we will reject the zero port during foundPort
            // validation, often resulting in a misleading 400/ERR_INVALID_URL.
            // TODO: Remove this hack when switching to Tokenizer-based parsing.
            foundPort = scheme.defaultPort().value_or(0); // may be reset later
 
            /* Is there any login information? (we should eventually parse it above) */
            t = strrchr(foundHost, '@');
            if (t != nullptr) {
                strncpy((char *) login, (char *) foundHost, sizeof(login)-1);
                login[sizeof(login)-1] = '\0';
                t = strrchr(login, '@');
                *t = 0;
                strncpy((char *) foundHost, t + 1, sizeof(foundHost)-1);
                foundHost[sizeof(foundHost)-1] = '\0';
                // Bug 4498: URL-unescape the login info after extraction
                rfc1738_unescape(login);
            }
 
            /* Is there any host information? (we should eventually parse it above) */
            if (*foundHost == '[') {
                /* strip any IPA brackets. valid under IPv6. */
                dst = foundHost;
                /* only for IPv6 sadly, pre-IPv6/URL code can't handle the clean result properly anyway. */
                src = foundHost;
                ++src;
                l = strlen(foundHost);
                i = 1;
                for (; i < l && *src != ']' && *src != '\0'; ++i, ++src, ++dst) {
                    *dst = *src;
                }
 
                /* we moved in-place, so truncate the actual hostname found */
                *dst = '\0';
                ++dst;
 
                /* skip ahead to either start of port, or original EOS */
                while (*dst != '\0' && *dst != ':')
                    ++dst;
                t = dst;
            } else {
                t = strrchr(foundHost, ':');
 
                if (t != strchr(foundHost,':') ) {
                    /* RFC 2732 states IPv6 "SHOULD" be bracketed. allowing for times when its not. */
                    /* RFC 3986 'update' simply modifies this to an "is" with no emphasis at all! */
                    /* therefore we MUST accept the case where they are not bracketed at all. */
                    t = nullptr;
                }
            }
 
            // Bug 3183 sanity check: If scheme is present, host must be too.
            if (scheme != AnyP::PROTO_NONE && foundHost[0] == '\0') {
                debugs(23, DBG_IMPORTANT, "SECURITY ALERT: Missing hostname in URL '" << url << "'. see access.log for details.");
                return false;
            }
 
            if (t && *t == ':') {
                *t = '\0';
                ++t;
                foundPort = atoi(t);
            }
        }
 
        for (t = foundHost; *t; ++t)
            *t = xtolower(*t);
 
        if (stringHasWhitespace(foundHost)) {
            if (URI_WHITESPACE_STRIP == Config.uri_whitespace) {
                t = q = foundHost;
                while (*t) {
                    if (!xisspace(*t)) {
                        *q = *t;
                        ++q;
                    }
                    ++t;
                }
                *q = '\0';
            }
        }
 
        debugs(23, 3, "Split URL '" << rawUrl << "' into proto='" << scheme.image() << "', host='" << foundHost << "', port='" << foundPort << "', path='" << urlpath << "'");
 
        if (Config.onoff.check_hostnames &&
                strspn(foundHost, Config.onoff.allow_underscore ? valid_hostname_chars_u : valid_hostname_chars) != strlen(foundHost)) {
            debugs(23, DBG_IMPORTANT, MYNAME << "Illegal character in hostname '" << foundHost << "'");
            return false;
        }
 
        if (!urlAppendDomain(foundHost))
            return false;
 
        /* remove trailing dots from hostnames */
        while ((l = strlen(foundHost)) > 0 && foundHost[--l] == '.')
            foundHost[l] = '\0';
 
        /* reject duplicate or leading dots */
        if (strstr(foundHost, "..") || *foundHost == '.') {
            debugs(23, DBG_IMPORTANT, MYNAME << "Illegal hostname '" << foundHost << "'");
            return false;
        }
 
        if (foundPort < 1 || foundPort > 65535) {
            debugs(23, 3, "Invalid port '" << foundPort << "'");
            return false;
        }
 
        if (stringHasWhitespace(urlpath)) {
            debugs(23, 2, "URI has whitespace: {" << rawUrl << "}");
 
            switch (Config.uri_whitespace) {
 
            case URI_WHITESPACE_DENY:
                return false;
 
            case URI_WHITESPACE_ALLOW:
                break;
 
            case URI_WHITESPACE_ENCODE:
                t = rfc1738_escape_unescaped(urlpath);
                xstrncpy(urlpath, t, MAX_URL);
                break;
 
            case URI_WHITESPACE_CHOP:
                *(urlpath + strcspn(urlpath, w_space)) = '\0';
                break;
 
            case URI_WHITESPACE_STRIP:
            default:
                t = q = urlpath;
                while (*t) {
                    if (!xisspace(*t)) {
                        *q = *t;
                        ++q;
                    }
                    ++t;
                }
                *q = '\0';
            }
        }
 
        setScheme(scheme);
        path(urlpath);
        host(foundHost);
        userInfo(SBuf(login));
        port(foundPort);
        return true;
 
    } catch (...) {
        debugs(23, 2, "error: " << CurrentException << " " << Raw("rawUrl", rawUrl.rawContent(), rawUrl.length()));
        return false;
    }
}
 
void
AnyP::Uri::parseUrn(Parser::Tokenizer &tok)
{
    static const auto nidChars = CharacterSet("NID","-") + CharacterSet::ALPHA + CharacterSet::DIGIT;
    static const auto alphanum = (CharacterSet::ALPHA + CharacterSet::DIGIT).rename("alphanum");
    SBuf nid;
    if (!tok.prefix(nid, nidChars, 32))
        throw TextException("NID not found", Here());
 
    if (!tok.skip(':'))
        throw TextException("NID too long or missing ':' delimiter", Here());
 
    if (nid.length() < 2)
        throw TextException("NID too short", Here());
 
    if (!alphanum[*nid.begin()])
        throw TextException("NID prefix is not alphanumeric", Here());
 
    if (!alphanum[*nid.rbegin()])
        throw TextException("NID suffix is not alphanumeric", Here());
 
    setScheme(AnyP::PROTO_URN, nullptr);
    host(nid.c_str());
    // TODO validate path characters
    path(tok.remaining());
    debugs(23, 3, "Split URI into proto=urn, nid=" << nid << ", " << Raw("path",path().rawContent(),path().length()));
}
 
SBuf
AnyP::Uri::parseHost(Parser::Tokenizer &tok) const
{
    // host = IP-literal / IPv4address / reg-name
 
    // XXX: CharacterSets below reject uri-host values containing whitespace
    // (e.g., "10.0.0. 1"). That is not a bug, but the uri_whitespace directive
    // can be interpreted as if it applies to uri-host and this code. TODO: Fix
    // uri_whitespace and the code using it to exclude uri-host (and URI scheme,
    // port, etc.) from that directive scope.
 
    // IP-literal = "[" ( IPv6address / IPvFuture  ) "]"
    if (tok.skip('[')) {
        // Add "." because IPv6address in RFC 3986 includes ls32, which includes
        // IPv4address: ls32 = ( h16 ":" h16 ) / IPv4address
        // This set rejects IPvFuture that needs a "v" character.
        static const CharacterSet IPv6chars = (
                CharacterSet::HEXDIG + CharacterSet("colon", ":") + CharacterSet("period", ".")).rename("IPv6");
        SBuf ipv6ish;
        if (!tok.prefix(ipv6ish, IPv6chars))
            throw TextException("malformed or unsupported bracketed IP address in uri-host", Here());
 
        if (!tok.skip(']'))
            throw TextException("IPv6 address is missing a closing bracket in uri-host", Here());
 
        // This rejects bracketed IPv4address and domain names because they lack ":".
        if (ipv6ish.find(':') == SBuf::npos)
            throw TextException("bracketed IPv6 address is missing a colon in uri-host", Here());
 
        // This rejects bracketed non-IP addresses that our caller would have
        // otherwise mistaken for a domain name (e.g., '[127.0.0:1]').
        Ip::Address ipv6check;
        if (!ipv6check.fromHost(ipv6ish.c_str()))
            throw TextException("malformed bracketed IPv6 address in uri-host", Here());
 
        return ipv6ish;
    }
 
    // no brackets implies we are looking at IPv4address or reg-name
 
    // XXX: This code does not detect/reject some bad host values (e.g. "!#$%&"
    // and "1.2.3.4.5"). TODO: Add more checks here, after migrating the
    // non-CONNECT uri-host parsing code to use us.
 
    SBuf otherHost; // IPv4address-ish or reg-name-ish;
    // ":" is not in TCHAR so we will stop before any port specification
    if (tok.prefix(otherHost, CharacterSet::TCHAR))
        return otherHost;
 
    throw TextException("malformed IPv4 address or host name in uri-host", Here());
}
 
int
AnyP::Uri::parsePort(Parser::Tokenizer &tok) const
{
    if (tok.skip('0'))
        throw TextException("zero or zero-prefixed port", Here());
 
    int64_t rawPort = 0;
    if (!tok.int64(rawPort, 10, false)) // port = *DIGIT
        throw TextException("malformed or missing port", Here());
 
    Assure(rawPort > 0);
    constexpr KnownPort portMax = 65535; // TODO: Make this a class-scope constant and REuse it.
    constexpr auto portStorageMax = std::numeric_limits<Port::value_type>::max();
    static_assert(!Less(portStorageMax, portMax), "Port type can represent the maximum valid port number");
    if (Less(portMax, rawPort))
        throw TextException("huge port", Here());
 
    // TODO: Return KnownPort after migrating the non-CONNECT uri-host parsing
    // code to use us (so that foundPort "int" disappears or starts using Port).
    return NaturalCast<int>(rawPort);
}
 
void
AnyP::Uri::touch()
{
    absolute_.clear();
    authorityHttp_.clear();
    authorityWithPort_.clear();
}
 
SBuf &
AnyP::Uri::authority(bool requirePort) const
{
    if (authorityHttp_.isEmpty()) {
 
        // both formats contain Host/IP
        authorityWithPort_.append(host());
        authorityHttp_ = authorityWithPort_;
 
        if (port().has_value()) {
            authorityWithPort_.appendf(":%hu", *port());
            // authorityHttp_ only has :port for known non-default ports
            if (port() != getScheme().defaultPort())
                authorityHttp_ = authorityWithPort_;
        }
        // else XXX: We made authorityWithPort_ that does not have a port.
        // TODO: Audit callers and refuse to give out broken authorityWithPort_.
    }
 
    return requirePort ? authorityWithPort_ : authorityHttp_;
}
 
SBuf &
AnyP::Uri::absolute() const
{
    if (absolute_.isEmpty()) {
        // TODO: most URL will be much shorter, avoid allocating this much
        absolute_.reserveCapacity(MAX_URL);
 
        absolute_.append(getScheme().image());
        absolute_.append(":",1);
        if (getScheme() != AnyP::PROTO_URN) {
            absolute_.append("//", 2);
            const bool allowUserInfo = getScheme() == AnyP::PROTO_FTP ||
                                       getScheme() == AnyP::PROTO_UNKNOWN;
 
            if (allowUserInfo && !userInfo().isEmpty()) {
                static const CharacterSet uiChars = CharacterSet(UserInfoChars())
                                                    .remove('%')
                                                    .rename("userinfo-reserved");
                absolute_.append(Encode(userInfo(), uiChars));
                absolute_.append("@", 1);
            }
            absolute_.append(authority());
        } else {
            absolute_.append(host());
            absolute_.append(":", 1);
        }
        absolute_.append(path()); // TODO: Encode each URI subcomponent in path_ as needed.
    }
 
    return absolute_;
}
 
/* XXX: Performance: This is an *almost* duplicate of HttpRequest::effectiveRequestUri(). But elides the query-string.
 *        After copying it on in the first place! Would be less code to merge the two with a flag parameter.
 *        and never copy the query-string part in the first place
 */
char *
urlCanonicalCleanWithoutRequest(const SBuf &url, const HttpRequestMethod &method, const AnyP::UriScheme &scheme)
{
    LOCAL_ARRAY(char, buf, MAX_URL);
 
    snprintf(buf, sizeof(buf), SQUIDSBUFPH, SQUIDSBUFPRINT(url));
    buf[sizeof(buf)-1] = '\0';
 
    // URN, CONNECT method, and non-stripped URIs can go straight out
    if (Config.onoff.strip_query_terms && !(method == Http::METHOD_CONNECT || scheme == AnyP::PROTO_URN)) {
        // strip anything AFTER a question-mark
        // leaving the '?' in place
        if (auto t = strchr(buf, '?')) {
            *(++t) = '\0';
        }
    }
 
    if (stringHasCntl(buf))
        xstrncpy(buf, rfc1738_escape_unescaped(buf), MAX_URL);
 
    return buf;
}
 
const char *
urlCanonicalFakeHttps(const HttpRequest * request)
{
    LOCAL_ARRAY(char, buf, MAX_URL);
 
    // method CONNECT and port HTTPS
    if (request->method == Http::METHOD_CONNECT && request->url.port() == 443) {
        snprintf(buf, MAX_URL, "https://%s/*", request->url.host());
        return buf;
    }
 
    // else do the normal complete canonical thing.
    return request->canonicalCleanUrl();
}
 
bool
urlIsRelative(const char *url)
{
    if (!url)
        return false; // no URL
 
    /*
     * RFC 3986 section 5.2.3
     *
     * path          = path-abempty    ; begins with "/" or is empty
     *               / path-absolute   ; begins with "/" but not "//"
     *               / path-noscheme   ; begins with a non-colon segment
     *               / path-rootless   ; begins with a segment
     *               / path-empty      ; zero characters
     */
 
    if (*url == '\0')
        return true; // path-empty
 
    if (*url == '/') {
        // RFC 3986 section 5.2.3
        // path-absolute   ; begins with "/" but not "//"
        if (url[1] == '/')
            return true; // network-path reference, aka. 'scheme-relative URI'
        else
            return true; // path-absolute, aka 'absolute-path reference'
    }
 
    for (const auto *p = url; *p != '\0' && *p != '/' && *p != '?' && *p != '#'; ++p) {
        if (*p == ':')
            return false; // colon is forbidden in first segment
    }
 
    return true; // path-noscheme, path-abempty, path-rootless
}
 
void
AnyP::Uri::addRelativePath(const char *relUrl)
{
    // URN cannot be merged
    if (getScheme() == AnyP::PROTO_URN)
        return;
 
    // TODO: Handle . and .. segment normalization
 
    const auto lastSlashPos = path_.rfind('/');
    // TODO: To optimize and simplify, add and use SBuf::replace().
    const auto relUrlLength = strlen(relUrl);
    if (lastSlashPos == SBuf::npos) {
        // start replacing the whole path
        path_.reserveCapacity(1 + relUrlLength);
        path_.assign("/", 1);
    } else {
        // start replacing just the last segment
        path_.reserveCapacity(lastSlashPos + 1 + relUrlLength);
        path_.chop(0, lastSlashPos+1);
    }
    path_.append(relUrl, relUrlLength);
}
 
int
matchDomainName(const char *h, const char *d, MatchDomainNameFlags flags)
{
    int dl;
    int hl;
 
    const bool hostIncludesSubdomains = (*h == '.');
    while ('.' == *h)
        ++h;
 
    hl = strlen(h);
 
    if (hl == 0)
        return -1;
 
    dl = strlen(d);
    if (dl == 0)
        return 1;
 
    /*
     * Start at the ends of the two strings and work towards the
     * beginning.
     */
    while (xtolower(h[--hl]) == xtolower(d[--dl])) {
        if (hl == 0 && dl == 0) {
            /*
             * We made it all the way to the beginning of both
             * strings without finding any difference.
             */
            return 0;
        }
 
        if (0 == hl) {
            /*
             * The host string is shorter than the domain string.
             * There is only one case when this can be a match.
             * If the domain is just one character longer, and if
             * that character is a leading '.' then we call it a
             * match.
             */
 
            if (1 == dl && '.' == d[0])
                return 0;
            else
                return -1;
        }
 
        if (0 == dl) {
            /*
             * The domain string is shorter than the host string.
             * This is a match only if the first domain character
             * is a leading '.'.
             */
 
            if ('.' == d[0]) {
                if (flags & mdnRejectSubsubDomains) {
                    // Check for sub-sub domain and reject
                    while(--hl >= 0 && h[hl] != '.');
                    if (hl < 0) {
                        // No sub-sub domain found, but reject if there is a
                        // leading dot in given host string (which is removed
                        // before the check is started).
                        return hostIncludesSubdomains ? 1 : 0;
                    } else
                        return 1; // sub-sub domain, reject
                } else
                    return 0;
            } else
                return 1;
        }
    }
 
    /*
     * We found different characters in the same position (from the end).
     */
 
    // If the h has a form of "*.foo.com" and d has a form of "x.foo.com"
    // then the h[hl] points to '*', h[hl+1] to '.' and d[dl] to 'x'
    // The following checks are safe, the "h[hl + 1]" in the worst case is '\0'.
    if ((flags & mdnHonorWildcards) && h[hl] == '*' && h[hl + 1] == '.')
        return 0;
 
    /*
     * If one of those character is '.' then its special.  In order
     * for splay tree sorting to work properly, "x-foo.com" must
     * be greater than ".foo.com" even though '-' is less than '.'.
     */
    if ('.' == d[dl])
        return 1;
 
    if ('.' == h[hl])
        return -1;
 
    return (xtolower(h[hl]) - xtolower(d[dl]));
}
 
/*
 * return true if we can serve requests for this method.
 */
bool
urlCheckRequest(const HttpRequest * r)
{
    /* protocol "independent" methods
     *
     * actually these methods are specific to HTTP:
     * they are methods we receive on our HTTP port,
     * and if we had a FTP listener would not be relevant
     * there.
     *
     * So, we should delegate them to HTTP. The problem is that we
     * do not have a default protocol from the client side of HTTP.
     */
 
    if (r->method == Http::METHOD_CONNECT)
        return true;
 
    // we support OPTIONS and TRACE directed at us (with a 501 reply, for now)
    // we also support forwarding OPTIONS and TRACE, except for the *-URI ones
    if (r->method == Http::METHOD_OPTIONS || r->method == Http::METHOD_TRACE)
        return (r->header.getInt64(Http::HdrType::MAX_FORWARDS) == 0 || r->url.path() != AnyP::Uri::Asterisk());
 
    if (r->method == Http::METHOD_PURGE)
        return true;
 
    /* does method match the protocol? */
    switch (r->url.getScheme()) {
 
    case AnyP::PROTO_URN:
    case AnyP::PROTO_HTTP:
        return true;
 
    case AnyP::PROTO_FTP:
        if (r->method == Http::METHOD_PUT ||
                r->method == Http::METHOD_GET ||
                r->method == Http::METHOD_HEAD )
            return true;
        return false;
 
    case AnyP::PROTO_WAIS:
    case AnyP::PROTO_WHOIS:
        if (r->method == Http::METHOD_GET ||
                r->method == Http::METHOD_HEAD)
            return true;
        return false;
 
    case AnyP::PROTO_HTTPS:
#if USE_OPENSSL || USE_GNUTLS
        return true;
#else
        /*
         * Squid can't originate an SSL connection, so it should
         * never receive an "https:" URL.  It should always be
         * CONNECT instead.
         */
        return false;
#endif
 
    default:
        return false;
    }
 
    /* notreached */
    return false;
}
 
AnyP::Uri::Uri(AnyP::UriScheme const &aScheme) :
    scheme_(aScheme),
    hostIsNumeric_(false)
{
    *host_=0;
}
 
// TODO: fix code duplication with AnyP::Uri::parse()
char *
AnyP::Uri::cleanup(const char *uri)
{
    char *cleanedUri = nullptr;
    switch (Config.uri_whitespace) {
    case URI_WHITESPACE_ALLOW: {
        const auto flags = RFC1738_ESCAPE_NOSPACE | RFC1738_ESCAPE_UNESCAPED;
        cleanedUri = xstrndup(rfc1738_do_escape(uri, flags), MAX_URL);
        break;
    }
 
    case URI_WHITESPACE_ENCODE:
        cleanedUri = xstrndup(rfc1738_do_escape(uri, RFC1738_ESCAPE_UNESCAPED), MAX_URL);
        break;
 
    case URI_WHITESPACE_CHOP: {
        const auto pos = strcspn(uri, w_space);
        char *choppedUri = nullptr;
        if (pos < strlen(uri))
            choppedUri = xstrndup(uri, pos + 1);
        cleanedUri = xstrndup(rfc1738_do_escape(choppedUri ? choppedUri : uri,
                                                RFC1738_ESCAPE_UNESCAPED), MAX_URL);
        cleanedUri[pos] = '\0';
        xfree(choppedUri);
        break;
    }
 
    case URI_WHITESPACE_DENY:
    case URI_WHITESPACE_STRIP:
    default: {
        // TODO: avoid duplication with urlParse()
        const char *t;
        char *tmp_uri = static_cast<char*>(xmalloc(strlen(uri) + 1));
        char *q = tmp_uri;
        t = uri;
        while (*t) {
            if (!xisspace(*t)) {
                *q = *t;
                ++q;
            }
            ++t;
        }
        *q = '\0';
        cleanedUri = xstrndup(rfc1738_escape_unescaped(tmp_uri), MAX_URL);
        xfree(tmp_uri);
        break;
    }
    }
 
    assert(cleanedUri);
    return cleanedUri;
}