lix/src/libfetchers/github.cc
Jörg Thalheim d9abce4ad4 libfetchers: avoid api.github.com ratelimit if no github token is set
If we don't have any github token, we won't be able to fetch private
repos, but we are also more likely to run into API limits since
we don't have a token. To mitigate this only ever use the github api
if we actually have a token.
2022-10-01 10:38:09 +02:00

451 lines
17 KiB
C++

#include "filetransfer.hh"
#include "cache.hh"
#include "globals.hh"
#include "store-api.hh"
#include "types.hh"
#include "url-parts.hh"
#include "git.hh"
#include "fetchers.hh"
#include "fetch-settings.hh"
#include <optional>
#include <nlohmann/json.hpp>
#include <fstream>
namespace nix::fetchers {
struct DownloadUrl
{
std::string url;
Headers headers;
};
// A github, gitlab, or sourcehut host
const static std::string hostRegexS = "[a-zA-Z0-9.]*"; // FIXME: check
std::regex hostRegex(hostRegexS, std::regex::ECMAScript);
struct GitArchiveInputScheme : InputScheme
{
virtual std::string type() = 0;
virtual std::optional<std::pair<std::string, std::string>> accessHeaderFromToken(const std::string & token) const = 0;
std::optional<Input> inputFromURL(const ParsedURL & url) override
{
if (url.scheme != type()) return {};
auto path = tokenizeString<std::vector<std::string>>(url.path, "/");
std::optional<Hash> rev;
std::optional<std::string> ref;
std::optional<std::string> host_url;
auto size = path.size();
if (size == 3) {
if (std::regex_match(path[2], revRegex))
rev = Hash::parseAny(path[2], htSHA1);
else if (std::regex_match(path[2], refRegex))
ref = path[2];
else
throw BadURL("in URL '%s', '%s' is not a commit hash or branch/tag name", url.url, path[2]);
} else if (size > 3) {
std::string rs;
for (auto i = std::next(path.begin(), 2); i != path.end(); i++) {
rs += *i;
if (std::next(i) != path.end()) {
rs += "/";
}
}
if (std::regex_match(rs, refRegex)) {
ref = rs;
} else {
throw BadURL("in URL '%s', '%s' is not a branch/tag name", url.url, rs);
}
} else if (size < 2)
throw BadURL("URL '%s' is invalid", url.url);
for (auto &[name, value] : url.query) {
if (name == "rev") {
if (rev)
throw BadURL("URL '%s' contains multiple commit hashes", url.url);
rev = Hash::parseAny(value, htSHA1);
}
else if (name == "ref") {
if (!std::regex_match(value, refRegex))
throw BadURL("URL '%s' contains an invalid branch/tag name", url.url);
if (ref)
throw BadURL("URL '%s' contains multiple branch/tag names", url.url);
ref = value;
}
else if (name == "host") {
if (!std::regex_match(value, hostRegex))
throw BadURL("URL '%s' contains an invalid instance host", url.url);
host_url = value;
}
// FIXME: barf on unsupported attributes
}
if (ref && rev)
throw BadURL("URL '%s' contains both a commit hash and a branch/tag name %s %s", url.url, *ref, rev->gitRev());
Input input;
input.attrs.insert_or_assign("type", type());
input.attrs.insert_or_assign("owner", path[0]);
input.attrs.insert_or_assign("repo", path[1]);
if (rev) input.attrs.insert_or_assign("rev", rev->gitRev());
if (ref) input.attrs.insert_or_assign("ref", *ref);
if (host_url) input.attrs.insert_or_assign("host", *host_url);
return input;
}
std::optional<Input> inputFromAttrs(const Attrs & attrs) override
{
if (maybeGetStrAttr(attrs, "type") != type()) return {};
for (auto & [name, value] : attrs)
if (name != "type" && name != "owner" && name != "repo" && name != "ref" && name != "rev" && name != "narHash" && name != "lastModified" && name != "host")
throw Error("unsupported input attribute '%s'", name);
getStrAttr(attrs, "owner");
getStrAttr(attrs, "repo");
Input input;
input.attrs = attrs;
return input;
}
ParsedURL toURL(const Input & input) override
{
auto owner = getStrAttr(input.attrs, "owner");
auto repo = getStrAttr(input.attrs, "repo");
auto ref = input.getRef();
auto rev = input.getRev();
auto path = owner + "/" + repo;
assert(!(ref && rev));
if (ref) path += "/" + *ref;
if (rev) path += "/" + rev->to_string(Base16, false);
return ParsedURL {
.scheme = type(),
.path = path,
};
}
bool hasAllInfo(const Input & input) override
{
return input.getRev() && maybeGetIntAttr(input.attrs, "lastModified");
}
Input applyOverrides(
const Input & _input,
std::optional<std::string> ref,
std::optional<Hash> rev) override
{
auto input(_input);
if (rev && ref)
throw BadURL("cannot apply both a commit hash (%s) and a branch/tag name ('%s') to input '%s'",
rev->gitRev(), *ref, input.to_string());
if (rev) {
input.attrs.insert_or_assign("rev", rev->gitRev());
input.attrs.erase("ref");
}
if (ref) {
input.attrs.insert_or_assign("ref", *ref);
input.attrs.erase("rev");
}
return input;
}
std::optional<std::string> getAccessToken(const std::string & host) const
{
auto tokens = fetchSettings.accessTokens.get();
if (auto token = get(tokens, host))
return *token;
return {};
}
Headers makeHeadersWithAuthTokens(const std::string & host) const
{
Headers headers;
auto accessToken = getAccessToken(host);
if (accessToken) {
auto hdr = accessHeaderFromToken(*accessToken);
if (hdr)
headers.push_back(*hdr);
else
warn("Unrecognized access token for host '%s'", host);
}
return headers;
}
virtual Hash getRevFromRef(nix::ref<Store> store, const Input & input) const = 0;
virtual DownloadUrl getDownloadUrl(const Input & input) const = 0;
std::pair<StorePath, Input> fetch(ref<Store> store, const Input & _input) override
{
Input input(_input);
if (!maybeGetStrAttr(input.attrs, "ref")) input.attrs.insert_or_assign("ref", "HEAD");
auto rev = input.getRev();
if (!rev) rev = getRevFromRef(store, input);
input.attrs.erase("ref");
input.attrs.insert_or_assign("rev", rev->gitRev());
Attrs lockedAttrs({
{"type", "git-tarball"},
{"rev", rev->gitRev()},
});
if (auto res = getCache()->lookup(store, lockedAttrs)) {
input.attrs.insert_or_assign("lastModified", getIntAttr(res->first, "lastModified"));
return {std::move(res->second), input};
}
auto url = getDownloadUrl(input);
auto [tree, lastModified] = downloadTarball(store, url.url, input.getName(), true, url.headers);
input.attrs.insert_or_assign("lastModified", uint64_t(lastModified));
getCache()->add(
store,
lockedAttrs,
{
{"rev", rev->gitRev()},
{"lastModified", uint64_t(lastModified)}
},
tree.storePath,
true);
return {std::move(tree.storePath), input};
}
};
struct GitHubInputScheme : GitArchiveInputScheme
{
std::string type() override { return "github"; }
std::optional<std::pair<std::string, std::string>> accessHeaderFromToken(const std::string & token) const override
{
// Github supports PAT/OAuth2 tokens and HTTP Basic
// Authentication. The former simply specifies the token, the
// latter can use the token as the password. Only the first
// is used here. See
// https://developer.github.com/v3/#authentication and
// https://docs.github.com/en/developers/apps/authorizing-oath-apps
return std::pair<std::string, std::string>("Authorization", fmt("token %s", token));
}
Hash getRevFromRef(nix::ref<Store> store, const Input & input) const override
{
auto host = maybeGetStrAttr(input.attrs, "host").value_or("github.com");
auto url = fmt(
host == "github.com"
? "https://api.%s/repos/%s/%s/commits/%s"
: "https://%s/api/v3/repos/%s/%s/commits/%s",
host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo"), *input.getRef());
Headers headers = makeHeadersWithAuthTokens(host);
auto json = nlohmann::json::parse(
readFile(
store->toRealPath(
downloadFile(store, url, "source", false, headers).storePath)));
auto rev = Hash::parseAny(std::string { json["sha"] }, htSHA1);
debug("HEAD revision for '%s' is %s", url, rev.gitRev());
return rev;
}
DownloadUrl getDownloadUrl(const Input & input) const override
{
auto host = maybeGetStrAttr(input.attrs, "host").value_or("github.com");
Headers headers = makeHeadersWithAuthTokens(host);
// If we have no auth headers then we default to the public archive
// urls so we do not run into rate limits.
const auto urlFmt =
host != "github.com"
? "https://%s/api/v3/repos/%s/%s/tarball/%s"
: headers.empty()
? "https://%s/%s/%s/archive/%s.tar.gz"
: "https://api.%s/repos/%s/%s/tarball/%s";
const auto url = fmt(urlFmt, host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo"),
input.getRev()->to_string(Base16, false));
return DownloadUrl { url, headers };
}
void clone(const Input & input, const Path & destDir) override
{
auto host = maybeGetStrAttr(input.attrs, "host").value_or("github.com");
Input::fromURL(fmt("git+https://%s/%s/%s.git",
host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo")))
.applyOverrides(input.getRef(), input.getRev())
.clone(destDir);
}
};
struct GitLabInputScheme : GitArchiveInputScheme
{
std::string type() override { return "gitlab"; }
std::optional<std::pair<std::string, std::string>> accessHeaderFromToken(const std::string & token) const override
{
// Gitlab supports 4 kinds of authorization, two of which are
// relevant here: OAuth2 and PAT (Private Access Token). The
// user can indicate which token is used by specifying the
// token as <TYPE>:<VALUE>, where type is "OAuth2" or "PAT".
// If the <TYPE> is unrecognized, this will fall back to
// treating this simply has <HDRNAME>:<HDRVAL>. See
// https://docs.gitlab.com/12.10/ee/api/README.html#authentication
auto fldsplit = token.find_first_of(':');
// n.b. C++20 would allow: if (token.starts_with("OAuth2:")) ...
if ("OAuth2" == token.substr(0, fldsplit))
return std::make_pair("Authorization", fmt("Bearer %s", token.substr(fldsplit+1)));
if ("PAT" == token.substr(0, fldsplit))
return std::make_pair("Private-token", token.substr(fldsplit+1));
warn("Unrecognized GitLab token type %s", token.substr(0, fldsplit));
return std::make_pair(token.substr(0,fldsplit), token.substr(fldsplit+1));
}
Hash getRevFromRef(nix::ref<Store> store, const Input & input) const override
{
auto host = maybeGetStrAttr(input.attrs, "host").value_or("gitlab.com");
// See rate limiting note below
auto url = fmt("https://%s/api/v4/projects/%s%%2F%s/repository/commits?ref_name=%s",
host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo"), *input.getRef());
Headers headers = makeHeadersWithAuthTokens(host);
auto json = nlohmann::json::parse(
readFile(
store->toRealPath(
downloadFile(store, url, "source", false, headers).storePath)));
auto rev = Hash::parseAny(std::string(json[0]["id"]), htSHA1);
debug("HEAD revision for '%s' is %s", url, rev.gitRev());
return rev;
}
DownloadUrl getDownloadUrl(const Input & input) const override
{
// This endpoint has a rate limit threshold that may be
// server-specific and vary based whether the user is
// authenticated via an accessToken or not, but the usual rate
// is 10 reqs/sec/ip-addr. See
// https://docs.gitlab.com/ee/user/gitlab_com/index.html#gitlabcom-specific-rate-limits
auto host = maybeGetStrAttr(input.attrs, "host").value_or("gitlab.com");
auto url = fmt("https://%s/api/v4/projects/%s%%2F%s/repository/archive.tar.gz?sha=%s",
host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo"),
input.getRev()->to_string(Base16, false));
Headers headers = makeHeadersWithAuthTokens(host);
return DownloadUrl { url, headers };
}
void clone(const Input & input, const Path & destDir) override
{
auto host = maybeGetStrAttr(input.attrs, "host").value_or("gitlab.com");
// FIXME: get username somewhere
Input::fromURL(fmt("git+https://%s/%s/%s.git",
host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo")))
.applyOverrides(input.getRef(), input.getRev())
.clone(destDir);
}
};
struct SourceHutInputScheme : GitArchiveInputScheme
{
std::string type() override { return "sourcehut"; }
std::optional<std::pair<std::string, std::string>> accessHeaderFromToken(const std::string & token) const override
{
// SourceHut supports both PAT and OAuth2. See
// https://man.sr.ht/meta.sr.ht/oauth.md
return std::pair<std::string, std::string>("Authorization", fmt("Bearer %s", token));
// Note: This currently serves no purpose, as this kind of authorization
// does not allow for downloading tarballs on sourcehut private repos.
// Once it is implemented, however, should work as expected.
}
Hash getRevFromRef(nix::ref<Store> store, const Input & input) const override
{
// TODO: In the future, when the sourcehut graphql API is implemented for mercurial
// and with anonymous access, this method should use it instead.
auto ref = *input.getRef();
auto host = maybeGetStrAttr(input.attrs, "host").value_or("git.sr.ht");
auto base_url = fmt("https://%s/%s/%s",
host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo"));
Headers headers = makeHeadersWithAuthTokens(host);
std::string refUri;
if (ref == "HEAD") {
auto file = store->toRealPath(
downloadFile(store, fmt("%s/HEAD", base_url), "source", false, headers).storePath);
std::ifstream is(file);
std::string line;
getline(is, line);
auto remoteLine = git::parseLsRemoteLine(line);
if (!remoteLine) {
throw BadURL("in '%d', couldn't resolve HEAD ref '%d'", input.to_string(), ref);
}
refUri = remoteLine->target;
} else {
refUri = fmt("refs/(heads|tags)/%s", ref);
}
std::regex refRegex(refUri);
auto file = store->toRealPath(
downloadFile(store, fmt("%s/info/refs", base_url), "source", false, headers).storePath);
std::ifstream is(file);
std::string line;
std::optional<std::string> id;
while(!id && getline(is, line)) {
auto parsedLine = git::parseLsRemoteLine(line);
if (parsedLine && parsedLine->reference && std::regex_match(*parsedLine->reference, refRegex))
id = parsedLine->target;
}
if(!id)
throw BadURL("in '%d', couldn't find ref '%d'", input.to_string(), ref);
auto rev = Hash::parseAny(*id, htSHA1);
debug("HEAD revision for '%s' is %s", fmt("%s/%s", base_url, ref), rev.gitRev());
return rev;
}
DownloadUrl getDownloadUrl(const Input & input) const override
{
auto host = maybeGetStrAttr(input.attrs, "host").value_or("git.sr.ht");
auto url = fmt("https://%s/%s/%s/archive/%s.tar.gz",
host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo"),
input.getRev()->to_string(Base16, false));
Headers headers = makeHeadersWithAuthTokens(host);
return DownloadUrl { url, headers };
}
void clone(const Input & input, const Path & destDir) override
{
auto host = maybeGetStrAttr(input.attrs, "host").value_or("git.sr.ht");
Input::fromURL(fmt("git+https://%s/%s/%s",
host, getStrAttr(input.attrs, "owner"), getStrAttr(input.attrs, "repo")))
.applyOverrides(input.getRef(), input.getRev())
.clone(destDir);
}
};
static auto rGitHubInputScheme = OnStartup([] { registerInputScheme(std::make_unique<GitHubInputScheme>()); });
static auto rGitLabInputScheme = OnStartup([] { registerInputScheme(std::make_unique<GitLabInputScheme>()); });
static auto rSourceHutInputScheme = OnStartup([] { registerInputScheme(std::make_unique<SourceHutInputScheme>()); });
}