libstore: de-callback-ify FileTransfer

also add a few more tests for exception propagation behavior. using
packaged_tasks and futures (which only allow a single call to a few
of their methods) introduces error paths that weren't there before.

Change-Id: I42ca5236f156fefec17df972f6e9be45989cf805

1 files changed, 123 insertions, 0 deletions

diff --git a/tests/unit/libstore/filetransfer.cc b/tests/unit/libstore/filetransfer.cc
index 192bf81ef..ebd38f19d 100644
--- a/tests/unit/libstore/filetransfer.cc
+++ b/tests/unit/libstore/filetransfer.cc
@@ -1,12 +1,114 @@
 #include "filetransfer.hh"
 
+#include <cstdint>
+#include <exception>
 #include <future>
 #include <gtest/gtest.h>
+#include <netinet/in.h>
+#include <stdexcept>
+#include <string_view>
+#include <sys/poll.h>
+#include <sys/socket.h>
+#include <thread>
+#include <unistd.h>
+
+// local server tests don't work on darwin without some incantations
+// the horrors do not want to look up. contributions welcome though!
+#if __APPLE__
+#define NOT_ON_DARWIN(n) DISABLED_##n
+#else
+#define NOT_ON_DARWIN(n) n
+#endif
 
 using namespace std::chrono_literals;
 
 namespace nix {
 
+static std::tuple<uint16_t, AutoCloseFD>
+serveHTTP(std::string_view status, std::string_view headers, std::function<std::string_view()> content)
+{
+    AutoCloseFD listener(::socket(AF_INET6, SOCK_STREAM, 0));
+    if (!listener) {
+        throw SysError(errno, "socket() failed");
+    }
+
+    Pipe trigger;
+    trigger.create();
+
+    sockaddr_in6 addr = {
+        .sin6_family = AF_INET6,
+        .sin6_addr = IN6ADDR_LOOPBACK_INIT,
+    };
+    socklen_t len = sizeof(addr);
+    if (::bind(listener.get(), reinterpret_cast<const sockaddr *>(&addr), sizeof(addr)) < 0) {
+        throw SysError(errno, "bind() failed");
+    }
+    if (::getsockname(listener.get(), reinterpret_cast<sockaddr *>(&addr), &len) < 0) {
+        throw SysError(errno, "getsockname() failed");
+    }
+    if (::listen(listener.get(), 1) < 0) {
+        throw SysError(errno, "listen() failed");
+    }
+
+    std::thread(
+        [status, headers, content](AutoCloseFD socket, AutoCloseFD trigger) {
+            while (true) {
+                pollfd pfds[2] = {
+                    {
+                        .fd = socket.get(),
+                        .events = POLLIN,
+                    },
+                    {
+                        .fd = trigger.get(),
+                        .events = POLLHUP,
+                    },
+                };
+
+                if (::poll(pfds, 2, -1) <= 0) {
+                    throw SysError(errno, "poll() failed");
+                }
+                if (pfds[1].revents & POLLHUP) {
+                    return;
+                }
+                if (!(pfds[0].revents & POLLIN)) {
+                    continue;
+                }
+
+                AutoCloseFD conn(::accept(socket.get(), nullptr, nullptr));
+                if (!conn) {
+                    throw SysError(errno, "accept() failed");
+                }
+
+                auto send = [&](std::string_view bit) {
+                    while (!bit.empty()) {
+                        auto written = ::write(conn.get(), bit.data(), bit.size());
+                        if (written < 0) {
+                            throw SysError(errno, "write() failed");
+                        }
+                        bit.remove_prefix(written);
+                    }
+                };
+
+                send("HTTP/1.1 ");
+                send(status);
+                send("\r\n");
+                send(headers);
+                send("\r\n");
+                send(content());
+                ::shutdown(conn.get(), SHUT_RDWR);
+            }
+        },
+        std::move(listener),
+        std::move(trigger.readSide)
+    )
+        .detach();
+
+    return {
+        ntohs(addr.sin6_port),
+        std::move(trigger.writeSide),
+    };
+}
+
 TEST(FileTransfer, exceptionAbortsDownload)
 {
     struct Done
@@ -29,4 +131,25 @@ TEST(FileTransfer, exceptionAbortsDownload)
         (void) new auto(std::move(reset));
     }
 }
+
+TEST(FileTransfer, NOT_ON_DARWIN(reportsSetupErrors))
+{
+    auto [port, srv] = serveHTTP("404 not found", "", [] { return ""; });
+    auto ft = makeFileTransfer();
+    ASSERT_THROW(
+        ft->download(FileTransferRequest(fmt("http://[::1]:%d/index", port))),
+        FileTransferError);
+}
+
+TEST(FileTransfer, NOT_ON_DARWIN(reportsTransferError))
+{
+    auto [port, srv] = serveHTTP("200 ok", "content-length: 100\r\n", [] {
+        std::this_thread::sleep_for(10ms);
+        return "";
+    });
+    auto ft = makeFileTransfer();
+    FileTransferRequest req(fmt("http://[::1]:%d/index", port));
+    req.baseRetryTimeMs = 0;
+    ASSERT_THROW(ft->download(req), FileTransferError);
+}
 }