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nix/src/libutil/url.cc
John Ericson d2f1860ee5 Revert "Improve Git URI handling"
I (@Ericson2314) messed up. We were supposed to test the status quo
before landing any new chnages, and also there is one change that is not
quite right (relative paths).

I am reverting for now, and then backporting the test suite to the old
situation.

This reverts commit 04ad66af5f.
2025-09-01 16:13:32 -04:00

443 lines
14 KiB
C++

#include "nix/util/url.hh"
#include "nix/util/url-parts.hh"
#include "nix/util/util.hh"
#include "nix/util/split.hh"
#include "nix/util/canon-path.hh"
#include "nix/util/strings-inline.hh"
#include <boost/url.hpp>
namespace nix {
std::regex refRegex(refRegexS, std::regex::ECMAScript);
std::regex revRegex(revRegexS, std::regex::ECMAScript);
ParsedURL::Authority ParsedURL::Authority::parse(std::string_view encodedAuthority)
{
auto parsed = boost::urls::parse_authority(encodedAuthority);
if (!parsed)
throw BadURL("invalid URL authority: '%s': %s", encodedAuthority, parsed.error().message());
auto hostType = [&]() {
switch (parsed->host_type()) {
case boost::urls::host_type::ipv4:
return HostType::IPv4;
case boost::urls::host_type::ipv6:
return HostType::IPv6;
case boost::urls::host_type::ipvfuture:
return HostType::IPvFuture;
case boost::urls::host_type::none:
case boost::urls::host_type::name:
return HostType::Name;
}
unreachable();
}();
auto port = [&]() -> std::optional<uint16_t> {
if (!parsed->has_port() || parsed->port() == "")
return std::nullopt;
/* If the port number is non-zero and representable. */
if (auto portNumber = parsed->port_number())
return portNumber;
throw BadURL("port '%s' is invalid", parsed->port());
}();
return {
.hostType = hostType,
.host = parsed->host_address(),
.user = parsed->has_userinfo() ? parsed->user() : std::optional<std::string>{},
.password = parsed->has_password() ? parsed->password() : std::optional<std::string>{},
.port = port,
};
}
std::ostream & operator<<(std::ostream & os, const ParsedURL::Authority & self)
{
if (self.user) {
os << percentEncode(*self.user);
if (self.password)
os << ":" << percentEncode(*self.password);
os << "@";
}
using HostType = ParsedURL::Authority::HostType;
switch (self.hostType) {
case HostType::Name:
os << percentEncode(self.host);
break;
case HostType::IPv4:
os << self.host;
break;
case HostType::IPv6:
case HostType::IPvFuture:
/* Reencode percent sign for RFC4007 ScopeId literals. */
os << "[" << percentEncode(self.host, ":") << "]";
}
if (self.port)
os << ":" << *self.port;
return os;
}
std::string ParsedURL::Authority::to_string() const
{
std::ostringstream oss;
oss << *this;
return std::move(oss).str();
}
/**
* Additional characters that don't need URL encoding in the fragment.
*/
static constexpr boost::urls::grammar::lut_chars extraAllowedCharsInFragment = " \"^";
/**
* Additional characters that don't need URL encoding in the query.
*/
static constexpr boost::urls::grammar::lut_chars extraAllowedCharsInQuery = " \"";
static std::string percentEncodeCharSet(std::string_view s, auto charSet)
{
std::string res;
for (auto c : s) {
if (charSet(c))
res += percentEncode(std::string_view{&c, &c + 1});
else
res += c;
}
return res;
}
static ParsedURL fromBoostUrlView(boost::urls::url_view url, bool lenient);
ParsedURL parseURL(std::string_view url, bool lenient)
try {
/* Account for several non-standard properties of nix urls (for back-compat):
* - Allow unescaped spaces ' ' and '"' characters in queries.
* - Allow '"', ' ' and '^' characters in the fragment component.
* We could write our own grammar for this, but fixing it up here seems
* more concise, since the deviation is rather minor.
*
* If `!lenient` don't bother initializing, because we can just
* parse `url` directly`.
*/
std::string fixedEncodedUrl;
if (lenient) {
fixedEncodedUrl = [&] {
std::string fixed;
std::string_view view = url;
if (auto beforeQuery = splitPrefixTo(view, '?')) {
fixed += *beforeQuery;
fixed += '?';
auto fragmentStart = view.find('#');
auto queryView = view.substr(0, fragmentStart);
auto fixedQuery = percentEncodeCharSet(queryView, extraAllowedCharsInQuery);
fixed += fixedQuery;
view.remove_prefix(std::min(fragmentStart, view.size()));
}
if (auto beforeFragment = splitPrefixTo(view, '#')) {
fixed += *beforeFragment;
fixed += '#';
auto fixedFragment = percentEncodeCharSet(view, extraAllowedCharsInFragment);
fixed += fixedFragment;
return fixed;
}
fixed += view;
return fixed;
}();
}
return fromBoostUrlView(boost::urls::url_view(lenient ? fixedEncodedUrl : url), lenient);
} catch (boost::system::system_error & e) {
throw BadURL("'%s' is not a valid URL: %s", url, e.code().message());
}
static ParsedURL fromBoostUrlView(boost::urls::url_view urlView, bool lenient)
{
if (!urlView.has_scheme())
throw BadURL("'%s' doesn't have a scheme", urlView.buffer());
auto scheme = urlView.scheme();
auto authority = [&]() -> std::optional<ParsedURL::Authority> {
if (urlView.has_authority())
return ParsedURL::Authority::parse(urlView.authority().buffer());
return std::nullopt;
}();
/* 3.2.2. Host (RFC3986):
* If the URI scheme defines a default for host, then that default
* applies when the host subcomponent is undefined or when the
* registered name is empty (zero length). For example, the "file" URI
* scheme is defined so that no authority, an empty host, and
* "localhost" all mean the end-user's machine, whereas the "http"
* scheme considers a missing authority or empty host invalid. */
auto transportIsFile = parseUrlScheme(scheme).transport == "file";
if (authority && authority->host.size() && transportIsFile)
throw BadURL("file:// URL '%s' has unexpected authority '%s'", urlView.buffer(), *authority);
auto fragment = urlView.fragment(); /* Does pct-decoding */
boost::core::string_view encodedPath = urlView.encoded_path();
if (transportIsFile && encodedPath.empty())
encodedPath = "/";
auto path = std::views::transform(splitString<std::vector<std::string_view>>(encodedPath, "/"), percentDecode)
| std::ranges::to<std::vector<std::string>>();
/* Get the raw query. Store URI supports smuggling doubly nested queries, where
the inner &/? are pct-encoded. */
auto query = std::string_view(urlView.encoded_query());
return ParsedURL{
.scheme = scheme,
.authority = authority,
.path = std::move(path),
.query = decodeQuery(query, lenient),
.fragment = fragment,
};
}
ParsedURL parseURLRelative(std::string_view urlS, const ParsedURL & base)
try {
boost::urls::url resolved;
try {
resolved.set_scheme(base.scheme);
if (base.authority) {
auto & authority = *base.authority;
resolved.set_host_address(authority.host);
if (authority.user)
resolved.set_user(*authority.user);
if (authority.password)
resolved.set_password(*authority.password);
if (authority.port)
resolved.set_port_number(*authority.port);
}
resolved.set_encoded_path(encodeUrlPath(base.path));
resolved.set_encoded_query(encodeQuery(base.query));
resolved.set_fragment(base.fragment);
} catch (boost::system::system_error & e) {
throw BadURL("'%s' is not a valid URL: %s", base.to_string(), e.code().message());
}
boost::urls::url_view url;
try {
url = urlS;
resolved.resolve(url).value();
} catch (boost::system::system_error & e) {
throw BadURL("'%s' is not a valid URL: %s", urlS, e.code().message());
}
auto ret = fromBoostUrlView(resolved, /*lenient=*/false);
/* Hack: Boost `url_view` supports Zone IDs, but `url` does not.
Just manually take the authority from the original URL to work
around it. See https://github.com/boostorg/url/issues/919 for
details. */
if (!url.has_authority()) {
ret.authority = base.authority;
}
/* Hack, work around fragment of base URL improperly being preserved
https://github.com/boostorg/url/issues/920 */
ret.fragment = url.has_fragment() ? std::string{url.fragment()} : "";
return ret;
} catch (BadURL & e) {
e.addTrace({}, "while resolving possibly-relative url '%s' against base URL '%s'", urlS, base);
throw;
}
std::string percentDecode(std::string_view in)
{
auto pctView = boost::urls::make_pct_string_view(in);
if (pctView.has_value())
return pctView->decode();
auto error = pctView.error();
throw BadURL("invalid URI parameter '%s': %s", in, error.message());
}
std::string percentEncode(std::string_view s, std::string_view keep)
{
return boost::urls::encode(
s, [keep](char c) { return boost::urls::unreserved_chars(c) || keep.find(c) != keep.npos; });
}
StringMap decodeQuery(std::string_view query, bool lenient)
try {
/* When `lenient = true`, for back-compat unescaped characters are allowed. */
std::string fixedEncodedQuery;
if (lenient) {
fixedEncodedQuery = percentEncodeCharSet(query, extraAllowedCharsInQuery);
}
StringMap result;
auto encodedQuery = boost::urls::params_encoded_view(lenient ? fixedEncodedQuery : query);
for (auto && [key, value, value_specified] : encodedQuery) {
if (!value_specified) {
warn("dubious URI query '%s' is missing equal sign '%s', ignoring", std::string_view(key), "=");
continue;
}
result.emplace(key.decode(), value.decode());
}
return result;
} catch (boost::system::system_error & e) {
throw BadURL("invalid URI query '%s': %s", query, e.code().message());
}
const static std::string allowedInQuery = ":@/?";
const static std::string allowedInPath = ":@";
std::string encodeUrlPath(std::span<const std::string> urlPath)
{
std::vector<std::string> encodedPath;
for (auto & p : urlPath)
encodedPath.push_back(percentEncode(p, allowedInPath));
return concatStringsSep("/", encodedPath);
}
std::string encodeQuery(const StringMap & ss)
{
std::string res;
bool first = true;
for (auto & [name, value] : ss) {
if (!first)
res += '&';
first = false;
res += percentEncode(name, allowedInQuery);
res += '=';
res += percentEncode(value, allowedInQuery);
}
return res;
}
Path renderUrlPathEnsureLegal(const std::vector<std::string> & urlPath)
{
for (const auto & comp : urlPath) {
/* This is only really valid for UNIX. Windows has more restrictions. */
if (comp.contains('/'))
throw BadURL("URL path component '%s' contains '/', which is not allowed in file names", comp);
if (comp.contains(char(0)))
throw BadURL("URL path component '%s' contains NUL byte which is not allowed", comp);
}
return concatStringsSep("/", urlPath);
}
std::string ParsedURL::renderPath(bool encode) const
{
if (encode)
return encodeUrlPath(path);
return concatStringsSep("/", path);
}
std::string ParsedURL::renderAuthorityAndPath() const
{
std::string res;
/* The following assertions correspond to 3.3. Path [rfc3986]. URL parser
will never violate these properties, but hand-constructed ParsedURLs might. */
if (authority.has_value()) {
/* If a URI contains an authority component, then the path component
must either be empty or begin with a slash ("/") character. */
assert(path.empty() || path.front().empty());
res += authority->to_string();
} else if (std::ranges::equal(std::views::take(path, 2), std::views::repeat("", 2))) {
/* If a URI does not contain an authority component, then the path cannot begin
with two slash characters ("//") */
unreachable();
}
res += encodeUrlPath(path);
return res;
}
std::string ParsedURL::to_string() const
{
std::string res;
res += scheme;
res += ":";
if (authority.has_value())
res += "//";
res += renderAuthorityAndPath();
if (!query.empty()) {
res += "?";
res += encodeQuery(query);
}
if (!fragment.empty()) {
res += "#";
res += percentEncode(fragment);
}
return res;
}
std::ostream & operator<<(std::ostream & os, const ParsedURL & url)
{
os << url.to_string();
return os;
}
ParsedURL ParsedURL::canonicalise()
{
ParsedURL res(*this);
res.path = splitString<std::vector<std::string>>(CanonPath(renderPath()).abs(), "/");
return res;
}
/**
* Parse a URL scheme of the form '(applicationScheme\+)?transportScheme'
* into a tuple '(applicationScheme, transportScheme)'
*
* > parseUrlScheme("http") == ParsedUrlScheme{ {}, "http"}
* > parseUrlScheme("tarball+http") == ParsedUrlScheme{ {"tarball"}, "http"}
*/
ParsedUrlScheme parseUrlScheme(std::string_view scheme)
{
auto application = splitPrefixTo(scheme, '+');
auto transport = scheme;
return ParsedUrlScheme{
.application = application,
.transport = transport,
};
}
ParsedURL fixGitURL(const std::string & url)
{
std::regex scpRegex("([^/]*)@(.*):(.*)");
if (!hasPrefix(url, "/") && std::regex_match(url, scpRegex))
return parseURL(std::regex_replace(url, scpRegex, "ssh://$1@$2/$3"));
if (hasPrefix(url, "file:"))
return parseURL(url);
if (url.find("://") == std::string::npos) {
return ParsedURL{
.scheme = "file",
.authority = ParsedURL::Authority{},
.path = splitString<std::vector<std::string>>(url, "/"),
};
}
return parseURL(url);
}
// https://www.rfc-editor.org/rfc/rfc3986#section-3.1
bool isValidSchemeName(std::string_view s)
{
const static std::string schemeNameRegex = "(?:[a-z][a-z0-9+.-]*)";
static std::regex regex(schemeNameRegex, std::regex::ECMAScript);
return std::regex_match(s.begin(), s.end(), regex, std::regex_constants::match_default);
}
std::ostream & operator<<(std::ostream & os, const ValidURL & url)
{
os << url.to_string();
return os;
}
} // namespace nix