/bitcoin/src/httpserver.cpp

Source
// Copyright (c) 2015-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <bitcoin-build-config.h> // IWYU pragma: keep

#include <httpserver.h>

#include <chainparamsbase.h>
#include <common/args.h>
#include <common/messages.h>
#include <common/url.h>
#include <compat/compat.h>
#include <logging.h>
#include <netbase.h>
#include <node/interface_ui.h>
#include <rpc/protocol.h>
#include <span.h>
#include <sync.h>
#include <util/check.h>
#include <util/signalinterrupt.h>
#include <util/sock.h>
#include <util/strencodings.h>
#include <util/thread.h>
#include <util/threadnames.h>
#include <util/time.h>
#include <util/translation.h>

#include <condition_variable>
#include <cstdio>
#include <cstdlib>
#include <deque>
#include <memory>
#include <optional>
#include <span>
#include <string>
#include <thread>
#include <unordered_map>
#include <vector>

#include <sys/types.h>
#include <sys/stat.h>

//! The set of sockets cannot be modified while waiting, so
//! the sleep time needs to be small to avoid new sockets stalling.
static constexpr auto SELECT_TIMEOUT{50ms};

//! Explicit alias for setting socket option methods.
static constexpr int SOCKET_OPTION_TRUE{1};

using common::InvalidPortErrMsg;
using http_bitcoin::HTTPRequest;

/** HTTP request work item */
class HTTPWorkItem final : public HTTPClosure
{
public:
    HTTPWorkItem(std::unique_ptr<HTTPRequest> _req, const std::string &_path, const HTTPRequestHandler& _func):
        req(std::move(_req)), path(_path), func(_func)
    {
    }
    void operator()() override
    {
        func(req.get(), path);
    }

    std::unique_ptr<HTTPRequest> req;

private:
    std::string path;
    HTTPRequestHandler func;
};

/** Simple work queue for distributing work over multiple threads.
 * Work items are simply callable objects.
 */
template <typename WorkItem>
class WorkQueue
{
private:
    Mutex cs;
    std::condition_variable cond GUARDED_BY(cs);
    std::deque<std::unique_ptr<WorkItem>> queue GUARDED_BY(cs);
    bool running GUARDED_BY(cs){true};
    const size_t maxDepth;

public:
    explicit WorkQueue(size_t _maxDepth) : maxDepth(_maxDepth)
    {
    }
    /** Precondition: worker threads have all stopped (they have been joined).
     */
    ~WorkQueue() = default;
    /** Enqueue a work item */
    bool Enqueue(WorkItem* item) EXCLUSIVE_LOCKS_REQUIRED(!cs)
    {
        LOCK(cs);
        if (!running || queue.size() >= maxDepth) {
            return false;
        }
        queue.emplace_back(std::unique_ptr<WorkItem>(item));
        cond.notify_one();
        return true;
    }
    /** Thread function */
    void Run() EXCLUSIVE_LOCKS_REQUIRED(!cs)
    {
        while (true) {
            std::unique_ptr<WorkItem> i;
            {
                WAIT_LOCK(cs, lock);
                while (running && queue.empty())
                    cond.wait(lock);
                if (!running && queue.empty())
                    break;
                i = std::move(queue.front());
                queue.pop_front();
            }
            (*i)();
        }
    }
    /** Interrupt and exit loops */
    void Interrupt() EXCLUSIVE_LOCKS_REQUIRED(!cs)
    {
        LOCK(cs);
        running = false;
        cond.notify_all();
    }
};

struct HTTPPathHandler
{
    HTTPPathHandler(std::string _prefix, bool _exactMatch, HTTPRequestHandler _handler):
        prefix(_prefix), exactMatch(_exactMatch), handler(_handler)
    {
    }
    std::string prefix;
    bool exactMatch;
    HTTPRequestHandler handler;
};

/** HTTP module state */

static std::unique_ptr<http_bitcoin::HTTPServer> g_http_server{nullptr};
//! List of subnets to allow RPC connections from
static std::vector<CSubNet> rpc_allow_subnets;
//! Work queue for handling longer requests off the event loop thread
static std::unique_ptr<WorkQueue<HTTPClosure>> g_work_queue{nullptr};
//! Handlers for (sub)paths
static GlobalMutex g_httppathhandlers_mutex;
static std::vector<HTTPPathHandler> pathHandlers GUARDED_BY(g_httppathhandlers_mutex);

/** Check if a network address is allowed to access the HTTP server */
static bool ClientAllowed(const CNetAddr& netaddr)
{
    if (!netaddr.IsValid())
        return false;
    for(const CSubNet& subnet : rpc_allow_subnets)
        if (subnet.Match(netaddr))
            return true;
    return false;
}

/** Initialize ACL list for HTTP server */
static bool InitHTTPAllowList()
{
    rpc_allow_subnets.clear();
    rpc_allow_subnets.emplace_back(LookupHost("127.0.0.1", false).value(), 8);  // always allow IPv4 local subnet
    rpc_allow_subnets.emplace_back(LookupHost("::1", false).value());  // always allow IPv6 localhost
    for (const std::string& strAllow : gArgs.GetArgs("-rpcallowip")) {
        const CSubNet subnet{LookupSubNet(strAllow)};
        if (!subnet.IsValid()) {
            uiInterface.ThreadSafeMessageBox(
                Untranslated(strprintf("Invalid -rpcallowip subnet specification: %s. Valid values are a single IP (e.g. 1.2.3.4), a network/netmask (e.g. 1.2.3.4/255.255.255.0), a network/CIDR (e.g. 1.2.3.4/24), all ipv4 (0.0.0.0/0), or all ipv6 (::/0). RFC4193 is allowed only if -cjdnsreachable=0.", strAllow)),
                "", CClientUIInterface::MSG_ERROR);
            return false;
        }
        rpc_allow_subnets.push_back(subnet);
    }
    std::string strAllowed;
    for (const CSubNet& subnet : rpc_allow_subnets)
        strAllowed += subnet.ToString() + " ";
    LogDebug(BCLog::HTTP, "Allowing HTTP connections from: %s\n", strAllowed);
    return true;
}

/** HTTP request method as string - use for logging only */
std::string_view RequestMethodString(HTTPRequestMethod m)
{
    switch (m) {
        using enum HTTPRequestMethod;
        case GET: return "GET";
        case POST: return "POST";
        case HEAD: return "HEAD";
        case PUT: return "PUT";
        case UNKNOWN: return "unknown";
    } // no default case, so the compiler can warn about missing cases
    assert(false);
}

static void MaybeDispatchRequestToWorker(std::unique_ptr<HTTPRequest> hreq)
{
    // Early address-based allow check
    if (!ClientAllowed(hreq->GetPeer())) {
        LogDebug(BCLog::HTTP, "HTTP request from %s rejected: Client network is not allowed RPC access\n",
                 hreq->GetPeer().ToStringAddrPort());
        hreq->WriteReply(HTTP_FORBIDDEN);
        return;
    }

    // Early reject unknown HTTP methods
    if (hreq->GetRequestMethod() == HTTPRequestMethod::UNKNOWN) {
        LogDebug(BCLog::HTTP, "HTTP request from %s rejected: Unknown HTTP request method\n",
                 hreq->GetPeer().ToStringAddrPort());
        hreq->WriteReply(HTTP_BAD_METHOD);
        return;
    }

    // Find registered handler for prefix
    std::string strURI = hreq->GetURI();
    std::string path;
    LOCK(g_httppathhandlers_mutex);
    std::vector<HTTPPathHandler>::const_iterator i = pathHandlers.begin();
    std::vector<HTTPPathHandler>::const_iterator iend = pathHandlers.end();
    for (; i != iend; ++i) {
        bool match = false;
        if (i->exactMatch)
            match = (strURI == i->prefix);
        else
            match = strURI.starts_with(i->prefix);
        if (match) {
            path = strURI.substr(i->prefix.size());
            break;
        }
    }

    // Dispatch to worker thread
    if (i != iend) {
        std::unique_ptr<HTTPWorkItem> item(new HTTPWorkItem(std::move(hreq), path, i->handler));
        assert(g_work_queue);
        if (g_work_queue->Enqueue(item.get())) {
            (void)item.release(); /* if true, queue took ownership */
        } else {
            LogWarning("Request rejected because http work queue depth exceeded, it can be increased with the -rpcworkqueue= setting");
            item->req->WriteReply(HTTP_SERVICE_UNAVAILABLE, "Work queue depth exceeded");
        }
    } else {
        hreq->WriteReply(HTTP_NOT_FOUND);
    }
}

static void RejectAllRequests(std::unique_ptr<http_bitcoin::HTTPRequest> hreq)
{
    LogDebug(BCLog::HTTP, "Rejecting request while shutting down\n");
    hreq->WriteReply(HTTP_SERVICE_UNAVAILABLE);
}

static std::vector<std::pair<std::string, uint16_t>> GetBindAddresses()
{
    uint16_t http_port{static_cast<uint16_t>(gArgs.GetIntArg("-rpcport", BaseParams().RPCPort()))};
    std::vector<std::pair<std::string, uint16_t>> endpoints;

    // Determine what addresses to bind to
    // To prevent misconfiguration and accidental exposure of the RPC
    // interface, require -rpcallowip and -rpcbind to both be specified
    // together. If either is missing, ignore both values, bind to localhost
    // instead, and log warnings.
    if (gArgs.GetArgs("-rpcallowip").empty() || gArgs.GetArgs("-rpcbind").empty()) { // Default to loopback if not allowing external IPs
        endpoints.emplace_back("::1", http_port);
        endpoints.emplace_back("127.0.0.1", http_port);
        if (!gArgs.GetArgs("-rpcallowip").empty()) {
            LogWarning("Option -rpcallowip was specified without -rpcbind; this doesn't usually make sense");
        }
        if (!gArgs.GetArgs("-rpcbind").empty()) {
            LogWarning("Option -rpcbind was ignored because -rpcallowip was not specified, refusing to allow everyone to connect");
        }
    } else { // Specific bind addresses
        for (const std::string& strRPCBind : gArgs.GetArgs("-rpcbind")) {
            uint16_t port{http_port};
            std::string host;
            if (!SplitHostPort(strRPCBind, port, host)) {
                LogError("%s\n", InvalidPortErrMsg("-rpcbind", strRPCBind).original);
                return {}; // empty
            }
            endpoints.emplace_back(host, port);
        }
    }
    return endpoints;
}

/** Simple wrapper to set thread name and run work queue */
static void HTTPWorkQueueRun(WorkQueue<HTTPClosure>* queue, int worker_num)
{
    util::ThreadRename(strprintf("httpworker.%i", worker_num));
    queue->Run();
}

void RegisterHTTPHandler(const std::string &prefix, bool exactMatch, const HTTPRequestHandler &handler)
{
    LogDebug(BCLog::HTTP, "Registering HTTP handler for %s (exactmatch %d)\n", prefix, exactMatch);
    LOCK(g_httppathhandlers_mutex);
    pathHandlers.emplace_back(prefix, exactMatch, handler);
}

void UnregisterHTTPHandler(const std::string &prefix, bool exactMatch)
{
    LOCK(g_httppathhandlers_mutex);
    std::vector<HTTPPathHandler>::iterator i = pathHandlers.begin();
    std::vector<HTTPPathHandler>::iterator iend = pathHandlers.end();
    for (; i != iend; ++i)
        if (i->prefix == prefix && i->exactMatch == exactMatch)
            break;
    if (i != iend)
    {
        LogDebug(BCLog::HTTP, "Unregistering HTTP handler for %s (exactmatch %d)\n", prefix, exactMatch);
        pathHandlers.erase(i);
    }
}

namespace http_bitcoin {
using util::Split;

std::optional<std::string> HTTPHeaders::Find(const std::string& key) const
{
    const auto it = m_map.find(key);
    if (it == m_map.end()) return std::nullopt;
    return it->second;
}

void HTTPHeaders::Write(const std::string& key, const std::string& value)
{
    // If present, append value to list
    const auto existing_value = Find(key);
    if (existing_value) {
        m_map[key] = existing_value.value() + ", " + value;
    } else {
        m_map[key] = value;
    }
}

void HTTPHeaders::Remove(const std::string& key)
{
    m_map.erase(key);
}

bool HTTPHeaders::Read(util::LineReader& reader)
{
    // Headers https://httpwg.org/specs/rfc9110.html#rfc.section.6.3
    // A sequence of Field Lines https://httpwg.org/specs/rfc9110.html#rfc.section.5.2
    do {
        auto maybe_line = reader.ReadLine();
        if (!maybe_line) return false;
        const std::string& line = *maybe_line;

        // An empty line indicates end of the headers section https://www.rfc-editor.org/rfc/rfc2616#section-4
        if (line.length() == 0) break;

        // Header line must have at least one ":"
        // keys are not allowed to have delimiters like ":" but values are
        // https://httpwg.org/specs/rfc9110.html#rfc.section.5.6.2
        const size_t pos{line.find(':')};
        if (pos == std::string::npos) throw std::runtime_error("HTTP header missing colon (:)");

        // Whitespace is optional
        std::string key = util::TrimString(std::string_view(line).substr(0, pos));
        std::string value = util::TrimString(std::string_view(line).substr(pos + 1));
        Write(key, value);
    } while (true);

    return true;
}

std::string HTTPHeaders::Stringify() const
{
    std::string out;
    for (const auto& [key, value] : m_map) {
        out += key + ": " + value + "\r\n";
    }

    // Headers are terminated by an empty line
    out += "\r\n";

    return out;
}

std::string HTTPResponse::StringifyHeaders() const
{
    return strprintf("HTTP/%d.%d %d %s\r\n%s", m_version_major, m_version_minor, m_status, m_reason, m_headers.Stringify());
}

bool HTTPRequest::LoadControlData(LineReader& reader)
{
    auto maybe_line = reader.ReadLine();
    if (!maybe_line) return false;
    const std::string& request_line = *maybe_line;

    // Request Line aka Control Data https://httpwg.org/specs/rfc9110.html#rfc.section.6.2
    // Three words separated by spaces, terminated by \n or \r\n
    if (request_line.length() < MIN_REQUEST_LINE_LENGTH) throw std::runtime_error("HTTP request line too short");

    const std::vector<std::string_view> parts{Split<std::string_view>(request_line, " ")};
    if (parts.size() != 3) throw std::runtime_error("HTTP request line malformed");

    if (parts[0] == "GET") {
        m_method = HTTPRequestMethod::GET;
    } else if (parts[0] == "POST") {
        m_method = HTTPRequestMethod::POST;
    } else if (parts[0] == "HEAD") {
        m_method = HTTPRequestMethod::HEAD;
    } else if (parts[0] == "PUT") {
        m_method = HTTPRequestMethod::PUT;
    } else {
        m_method = HTTPRequestMethod::UNKNOWN;
    }

    m_target = parts[1];

    if (parts[2].rfind("HTTP/") != 0) throw std::runtime_error("HTTP request line malformed");
    const std::vector<std::string_view> version_parts{Split<std::string_view>(parts[2].substr(5), ".")};
    if (version_parts.size() != 2) throw std::runtime_error("HTTP request line malformed");
    auto major = ToIntegral<int>(version_parts[0]);
    auto minor = ToIntegral<int>(version_parts[1]);
    if (!major || !minor) throw std::runtime_error("HTTP request line malformed");
    m_version_major = major.value();
    m_version_minor = minor.value();

    return true;
}

bool HTTPRequest::LoadHeaders(LineReader& reader)
{
    return m_headers.Read(reader);
}

bool HTTPRequest::LoadBody(LineReader& reader)
{
    // https://httpwg.org/specs/rfc9112.html#message.body

    auto transfer_encoding_header = m_headers.Find("Transfer-Encoding");
    if (transfer_encoding_header && ToLower(transfer_encoding_header.value()) == "chunked") {
        // Transfer-Encoding: https://datatracker.ietf.org/doc/html/rfc7230.html#section-3.3.1
        // Chunked Transfer Coding: https://datatracker.ietf.org/doc/html/rfc7230.html#section-4.1
        // see evhttp_handle_chunked_read() in libevent http.c
        while (reader.Remaining() > 0) {
            auto maybe_chunk_size = reader.ReadLine();
            if (!maybe_chunk_size) return false;

            const auto chunk_size{ToIntegral<uint64_t>(maybe_chunk_size.value(), /*base=*/16)};
            if (!chunk_size) throw std::runtime_error("Cannot parse chunk length value");

            bool last_chunk{*chunk_size == 0};

            if (!last_chunk) {
                // We are still expecting more data for this chunk
                if (reader.Remaining() < *chunk_size) {
                    return false;
                }
                // Pack chunk onto body
                m_body += reader.ReadLength(*chunk_size);
            }

            // Even though every chunk size is explicitly declared,
            // they are still terminated by a CRLF we don't need.
            auto crlf = reader.ReadLine();
            if (!crlf || !crlf.value().empty()) throw std::runtime_error("Improperly terminated chunk");

            if (last_chunk) return true;
        }

        // We read all the chunks but never got the last chunk, wait for client to send more
        return false;
    } else {
        // No Content-length or Transfer-Encoding header means no body, see libevent evhttp_get_body()
        auto content_length_value{m_headers.Find("Content-Length")};
        if (!content_length_value) return true;

        const auto content_length{ToIntegral<uint64_t>(content_length_value.value())};
        if (!content_length) throw std::runtime_error("Cannot parse Content-Length value");

        // Not enough data in buffer for expected body
        if (reader.Remaining() < *content_length) return false;

        m_body = reader.ReadLength(*content_length);

        return true;
    }
}

void HTTPRequest::WriteReply(HTTPStatusCode status, std::span<const std::byte> reply_body)
{
    HTTPResponse res;

    // Some response headers are determined in advance and stored in the request
    res.m_headers = std::move(m_response_headers);

    // Response version matches request version
    res.m_version_major = m_version_major;
    res.m_version_minor = m_version_minor;

    // Add response code and look up reason string
    res.m_status = status;
    res.m_reason = HTTPReason.find(status)->second;

    // See libevent evhttp_response_needs_body()
    // Response headers are different if no body is needed
    bool needs_body{status != HTTP_NO_CONTENT && (status < 100 || status >= 200)};

    // See libevent evhttp_make_header_response()
    // Expected response headers depend on protocol version
    if (m_version_major == 1) {
        // HTTP/1.0
        if (m_version_minor == 0) {
            auto connection_header{m_headers.Find("Connection")};
            if (connection_header && ToLower(connection_header.value()) == "keep-alive") {
                res.m_headers.Write("Connection", "keep-alive");
                res.m_keep_alive = true;
            }
        }

        // HTTP/1.1
        if (m_version_minor >= 1) {
            const int64_t now_seconds{TicksSinceEpoch<std::chrono::seconds>(NodeClock::now())};
            res.m_headers.Write("Date", FormatRFC1123DateTime(now_seconds));

            if (needs_body) {
                res.m_headers.Write("Content-Length", strprintf("%d", reply_body.size()));
            }

            // Default for HTTP/1.1
            res.m_keep_alive = true;
        }
    }

    if (needs_body && !res.m_headers.Find("Content-Type")) {
        // Default type from libevent evhttp_new_object()
        res.m_headers.Write("Content-Type", "text/html; charset=ISO-8859-1");
    }

    auto connection_header{m_headers.Find("Connection")};
    if (connection_header && ToLower(connection_header.value()) == "close") {
        // Might not exist already but we need to replace it, not append to it
        res.m_headers.Remove("Connection");
        res.m_headers.Write("Connection", "close");
        res.m_keep_alive = false;
    }

    m_client->m_keep_alive = res.m_keep_alive;

    // Serialize the response headers
    const std::string headers{res.StringifyHeaders()};
    const auto headers_bytes{std::as_bytes(std::span(headers.begin(), headers.end()))};

    bool send_buffer_was_empty{false};
    // Fill the send buffer with the complete serialized response headers + body
    {
        LOCK(m_client->m_send_mutex);
        send_buffer_was_empty = m_client->m_send_buffer.empty();
        m_client->m_send_buffer.insert(m_client->m_send_buffer.end(), headers_bytes.begin(), headers_bytes.end());

        // We've been using std::span up until now but it is finally time to copy
        // data. The original data will go out of scope when WriteReply() returns.
        // This is analogous to the memcpy() in libevent's evbuffer_add()
        m_client->m_send_buffer.insert(m_client->m_send_buffer.end(), reply_body.begin(), reply_body.end());
    }

    LogDebug(
        BCLog::HTTP,
        "HTTPResponse (status code: %d size: %lld) added to send buffer for client %s (id=%lld)\n",
        status,
        headers_bytes.size() + reply_body.size(),
        m_client->m_origin,
        m_client->m_id);

    // If the send buffer was empty before we wrote this reply, we can try an
    // optimistic send akin to CConnman::PushMessage() in which we
    // push the data directly out the socket to client right now, instead
    // of waiting for the next iteration of the I/O loop.
    if (send_buffer_was_empty) {
        m_client->MaybeSendBytesFromBuffer();
    } else {
        // Inform HTTPServer I/O that data is ready to be sent to this client
        // in the next loop iteration.
        m_client->m_send_ready = true;
    }

    // Signal to the I/O loop that we are ready to handle the next request.
    m_client->m_req_busy = false;
}

CService HTTPRequest::GetPeer() const
{
    return m_client->m_addr;
}

std::optional<std::string> HTTPRequest::GetQueryParameter(const std::string& key) const
{
    return GetQueryParameterFromUri(GetURI(), key);
}

// See libevent http.c evhttp_parse_query_impl()
// and https://www.rfc-editor.org/rfc/rfc3986#section-3.4
std::optional<std::string> GetQueryParameterFromUri(const std::string& uri, const std::string& key)
{
    // Handle %XX encoding
    std::string decoded_uri{UrlDecode(uri)};

    // find query in URI
    size_t start = decoded_uri.find('?');
    if (start == std::string::npos) return std::nullopt;
    size_t end = decoded_uri.find('#', start);
    if (end == std::string::npos) {
        end = decoded_uri.length();
    }
    const std::string_view query{decoded_uri.data() + start + 1, end - start - 1};
    // find requested parameter in query
    const std::vector<std::string_view> params{Split<std::string_view>(query, "&")};
    for (const std::string_view& param : params) {
        size_t delim = param.find('=');
        if (key == param.substr(0, delim)) {
            if (delim == std::string::npos) {
                return "";
            } else {
                return std::string(param.substr(delim + 1));
            }
        }
    }
    return std::nullopt;
}

std::pair<bool, std::string> HTTPRequest::GetHeader(const std::string& hdr) const
{
    std::optional<std::string> found{m_headers.Find(hdr)};
    if (found.has_value()) {
        return std::make_pair(true, found.value());
    } else
        return std::make_pair(false, "");
}

void HTTPRequest::WriteHeader(const std::string& hdr, const std::string& value)
{
    m_response_headers.Write(hdr, value);
}

util::Result<void> HTTPServer::BindAndStartListening(const CService& to)
{
    // Create socket for listening for incoming connections
    sockaddr_storage storage;
    auto sa = static_cast<sockaddr*>(static_cast<void*>(&storage));
    socklen_t len{sizeof(storage)};
    if (!to.GetSockAddr(sa, &len)) {
        return util::Error{Untranslated(strprintf("Bind address family for %s not supported", to.ToStringAddrPort()))};
    }

    std::unique_ptr<Sock> sock{CreateSock(to.GetSAFamily(), SOCK_STREAM, IPPROTO_TCP)};
    if (!sock) {
        return util::Error{Untranslated(strprintf("Cannot create %s listen socket: %s",
                                                    to.ToStringAddrPort(),
                                                    NetworkErrorString(WSAGetLastError())))};
    }

    int socket_option_true{1};

    // Allow binding if the port is still in TIME_WAIT state after
    // the program was closed and restarted.
    if (sock->SetSockOpt(SOL_SOCKET, SO_REUSEADDR, &socket_option_true, sizeof(socket_option_true)) == SOCKET_ERROR) {
        LogDebug(BCLog::HTTP,
                 "Cannot set SO_REUSEADDR on %s listen socket: %s, continuing anyway",
                 to.ToStringAddrPort(),
                 NetworkErrorString(WSAGetLastError()));
    }

    // some systems don't have IPV6_V6ONLY but are always v6only; others do have the option
    // and enable it by default or not. Try to enable it, if possible.
    if (to.IsIPv6()) {
#ifdef IPV6_V6ONLY
        if (sock->SetSockOpt(IPPROTO_IPV6, IPV6_V6ONLY, &socket_option_true, sizeof(socket_option_true)) == SOCKET_ERROR) {
            LogDebug(BCLog::HTTP,
                     "Cannot set IPV6_V6ONLY on %s listen socket: %s, continuing anyway",
                     to.ToStringAddrPort(),
                     NetworkErrorString(WSAGetLastError()));
        }
#endif
#ifdef WIN32
        int prot_level{PROTECTION_LEVEL_UNRESTRICTED};
        if (sock->SetSockOpt(IPPROTO_IPV6,
                             IPV6_PROTECTION_LEVEL,
                             &prot_level,
                             sizeof(prot_level)) == SOCKET_ERROR) {
            LogDebug(BCLog::HTTP,
                     "Cannot set IPV6_PROTECTION_LEVEL on %s listen socket: %s, continuing anyway",
                     to.ToStringAddrPort(),
                     NetworkErrorString(WSAGetLastError()));
        }
#endif
    }

    if (sock->Bind(sa, len) == SOCKET_ERROR) {
        const int err{WSAGetLastError()};
        if (err == WSAEADDRINUSE) {
            return util::Error{strprintf(_("Unable to bind to %s on this computer. %s is probably already running."),
                                            to.ToStringAddrPort(),
                                            CLIENT_NAME)};
        } else {
            return util::Error{strprintf(_("Unable to bind to %s on this computer (bind returned error %s)"),
                                            to.ToStringAddrPort(),
                                            NetworkErrorString(err))};
        }
    }

    // Listen for incoming connections
    if (sock->Listen(SOMAXCONN) == SOCKET_ERROR) {
        return util::Error{strprintf(_("Cannot listen on %s: %s"),
                                        to.ToStringAddrPort(),
                                        NetworkErrorString(WSAGetLastError()))};
    }

    m_listen.emplace_back(std::move(sock));

    return {};
}

void HTTPServer::StopListening()
{
    m_listen.clear();
}

void HTTPServer::StartSocketsThreads()
{
    m_thread_socket_handler = std::thread(&util::TraceThread,
                                          "http",
                                          [this] { ThreadSocketHandler(); });
}

void HTTPServer::JoinSocketsThreads()
{
    if (m_thread_socket_handler.joinable()) {
        m_thread_socket_handler.join();
    }
}

std::unique_ptr<Sock> HTTPServer::AcceptConnection(const Sock& listen_sock, CService& addr)
{
    // Make sure we only operate on our own listening sockets
    Assume(std::ranges::any_of(m_listen, [&](const auto& sock) { return sock.get() == &listen_sock; }));

    sockaddr_storage storage;
    socklen_t len{sizeof(storage)};
    auto sa = static_cast<sockaddr*>(static_cast<void*>(&storage));

    auto sock{listen_sock.Accept(sa, &len)};

    if (!sock) {
        const int err{WSAGetLastError()};
        if (err != WSAEWOULDBLOCK) {
            LogDebug(BCLog::HTTP,
                     "Cannot accept new connection: %s\n",
                     NetworkErrorString(err));
        }
        return {};
    }

    if (!addr.SetSockAddr(sa, len)) {
        LogDebug(BCLog::HTTP,
                 "Unknown socket family\n");
    }

    return sock;
}

HTTPServer::Id HTTPServer::GetNewId()
{
    return m_next_id.fetch_add(1, std::memory_order_relaxed);
}

void HTTPServer::NewSockAccepted(std::unique_ptr<Sock>&& sock, const CService& them)
{
    if (!sock->IsSelectable()) {
        LogDebug(BCLog::HTTP,
                 "connection from %s dropped: non-selectable socket\n",
                 them.ToStringAddrPort());
        return;
    }

    // According to the internet TCP_NODELAY is not carried into accepted sockets
    // on all platforms.  Set it again here just to be sure.
    if (sock->SetSockOpt(IPPROTO_TCP, TCP_NODELAY, &SOCKET_OPTION_TRUE, sizeof(SOCKET_OPTION_TRUE)) == SOCKET_ERROR) {
        LogDebug(BCLog::HTTP, "connection from %s: unable to set TCP_NODELAY, continuing anyway\n",
                 them.ToStringAddrPort());
    }

    const Id id{GetNewId()};

    m_connected.push_back(std::make_shared<HTTPClient>(id, them, std::move(sock)));
    // Report back to the main thread
    m_connected_size.fetch_add(1, std::memory_order_relaxed);

    LogDebug(BCLog::HTTP,
             "HTTP Connection accepted from %s (id=%d)\n",
             them.ToStringAddrPort(), id);
}

void HTTPServer::SocketHandlerConnected(const IOReadiness& io_readiness) const
{
    for (const auto& [sock, events] : io_readiness.events_per_sock) {
        if (m_interrupt_net) {
            return;
        }

        auto it{io_readiness.httpclients_per_sock.find(sock)};
        if (it == io_readiness.httpclients_per_sock.end()) {
            continue;
        }
        const std::shared_ptr<HTTPClient> client{it->second};

        bool send_ready = events.occurred & Sock::SEND; // Sock::SEND could only be set if ShouldTryToSend() has returned true in GenerateWaitSockets().
        bool recv_ready = events.occurred & Sock::RECV; // Sock::RECV could only be set if ShouldTryToRecv() has returned true in GenerateWaitSockets().
        bool err_ready = events.occurred & Sock::ERR;

        if (send_ready) {
            // Try to send as much data as is ready for this client.
            // If there's an error we can skip the receive phase for this client
            // because we need to disconnect.
            if (!client->MaybeSendBytesFromBuffer()) {
                recv_ready = false;
            }
        }

        if (recv_ready || err_ready) {
            std::byte buf[0x10000]; // typical socket buffer is 8K-64K

            const ssize_t nrecv{WITH_LOCK(
                client->m_sock_mutex,
                return client->m_sock->Recv(buf, sizeof(buf), MSG_DONTWAIT);)};

            if (nrecv < 0) { // In all cases (including -1 and 0) EventIOLoopCompletedForOne() should be executed after this, don't change the code to skip it.
                const int err = WSAGetLastError();
                if (err != WSAEWOULDBLOCK && err != WSAEMSGSIZE && err != WSAEINTR && err != WSAEINPROGRESS) {
                    LogDebug(
                        BCLog::HTTP,
                        "Permanent read error from %s (id=%lld): %s\n",
                        client->m_origin,
                        client->m_id,
                        NetworkErrorString(err));
                    client->m_disconnect = true;
                }
            } else if (nrecv == 0) {
                LogDebug(
                    BCLog::HTTP,
                    "Received EOF from %s (id=%lld)\n",
                    client->m_origin,
                    client->m_id);
                client->m_disconnect = true;
            } else {
                // Reset idle timeout
                client->m_idle_since = Now<SteadySeconds>();

                // Prevent disconnect until all requests are completely handled.
                client->m_prevent_disconnect = true;

                // Copy data from socket buffer to client receive buffer
                client->m_recv_buffer.insert(
                    client->m_recv_buffer.end(),
                    buf,
                    buf + nrecv);
            }
        }
        // Process as much received data as we can.
        // This executes for every client whether or not reading or writing
        // took place because it also (might) parse a request we have already
        // received and pass it to a worker thread.
        MaybeDispatchRequestsFromClient(client);
    }
}

void HTTPServer::SocketHandlerListening(const Sock::EventsPerSock& events_per_sock)
{
    for (const auto& sock : m_listen) {
        if (m_interrupt_net) {
            return;
        }
        const auto it = events_per_sock.find(sock);
        if (it != events_per_sock.end() && it->second.occurred & Sock::RECV) {
            CService addr_accepted;

            auto sock_accepted{AcceptConnection(*sock, addr_accepted)};

            if (sock_accepted) {
                NewSockAccepted(std::move(sock_accepted), addr_accepted);
            }
        }
    }
}

HTTPServer::IOReadiness HTTPServer::GenerateWaitSockets() const
{
    IOReadiness io_readiness;

    for (const auto& sock : m_listen) {
        io_readiness.events_per_sock.emplace(sock, Sock::Events{Sock::RECV});
    }

    for (const auto& http_client : m_connected) {
        // Safely copy the shared pointer to the socket
        std::shared_ptr<Sock> sock{WITH_LOCK(http_client->m_sock_mutex, return http_client->m_sock;)};

        // Check if client is ready to send data. Don't try to receive again
        // until the send buffer is cleared (all data sent to client).
        Sock::Event event = (http_client->m_send_ready ? Sock::SEND : Sock::RECV);
        io_readiness.events_per_sock.emplace(sock, Sock::Events{event});
        io_readiness.httpclients_per_sock.emplace(sock, http_client);
    }

    return io_readiness;
}

void HTTPServer::ThreadSocketHandler()
{
    while (!m_interrupt_net) {
        // Check for the readiness of the already connected sockets and the
        // listening sockets in one call ("readiness" as in poll(2) or
        // select(2)). If none are ready, wait for a short while and return
        // empty sets.
        auto io_readiness{GenerateWaitSockets()};
        if (io_readiness.events_per_sock.empty() ||
            // WaitMany() may as well be a static method, the context of the first Sock in the vector is not relevant.
            !io_readiness.events_per_sock.begin()->first->WaitMany(SELECT_TIMEOUT,
                                                                   io_readiness.events_per_sock)) {
            m_interrupt_net.sleep_for(SELECT_TIMEOUT);
        }

        // Service (send/receive) each of the already connected sockets.
        SocketHandlerConnected(io_readiness);

        // Accept new connections from listening sockets.
        SocketHandlerListening(io_readiness.events_per_sock);

        // Disconnect any clients that have been flagged.
        DisconnectClients();
    }
}

void HTTPServer::MaybeDispatchRequestsFromClient(std::shared_ptr<HTTPClient> client) const
{
    // Try reading (potentially multiple) HTTP requests from the buffer
    while (!client->m_recv_buffer.empty()) {
        // Create a new request object and try to fill it with data from the receive buffer
        auto req = std::make_unique<HTTPRequest>(client);
        try {
            // Stop reading if we need more data from the client to parse a complete request
            if (!client->ReadRequest(req)) break;
        } catch (const std::runtime_error& e) {
            LogDebug(
                BCLog::HTTP,
                "Error reading HTTP request from client %s (id=%lld): %s\n",
                client->m_origin,
                client->m_id,
                e.what());

            // We failed to read a complete request from the buffer
            req->WriteReply(HTTP_BAD_REQUEST);
            client->m_disconnect = true;
            break;
        }

        // We read a complete request from the buffer into the queue
        LogDebug(
            BCLog::HTTP,
            "Received a %s request for %s from %s (id=%lld)\n",
            RequestMethodString(req->m_method),
            req->m_target,
            client->m_origin,
            client->m_id);

        // add request to client queue
        client->m_req_queue.push_back(std::move(req));
    }

    // If we are already handling a request from
    // this client, do nothing. We'll check again on the next I/O
    // loop iteration.
    if (client->m_req_busy) return;

    // Otherwise, if there is a pending request in the queue, handle it.
    if (!client->m_req_queue.empty()) {
        client->m_req_busy = true;
        m_request_dispatcher(std::move(client->m_req_queue.front()));
        client->m_req_queue.pop_front();
    }
}

void HTTPServer::DisconnectClients()
{
    const auto now{Now<SteadySeconds>()};
    size_t erased = std::erase_if(m_connected,
                                  [&](auto& client) {
                                        // Disconnect this client if it is flagged individually or if the
                                        // server is flagged to disconnect all...
                                        if (((client->m_disconnect || m_disconnect_all_clients) &&
                                            // ...but not if this client is specifically flagged to prevent disconnect!
                                            // It is probably still busy.
                                            !client->m_prevent_disconnect) ||
                                            // No matter what, always disconnect if client has timed out.
                                            now - client->m_idle_since > m_rpcservertimeout) {
                                            LogDebug(BCLog::HTTP,
                                                     "Disconnected HTTP client %s (id=%d)\n",
                                                     client->m_origin,
                                                     client->m_id);
                                            return true;
                                        } else {
                                            return false;
                                        }});
    if (erased > 0) {
        // Report back to the main thread
        m_connected_size.fetch_sub(erased, std::memory_order_relaxed);
    }
}

bool HTTPClient::ReadRequest(const std::unique_ptr<HTTPRequest>& req)
{
    LineReader reader(m_recv_buffer, MAX_HEADERS_SIZE);

    if (!req->LoadControlData(reader)) return false;
    if (!req->LoadHeaders(reader)) return false;
    if (!req->LoadBody(reader)) return false;

    // Remove the bytes read out of the buffer.
    // If one of the above calls throws an error, the caller must
    // catch it and disconnect the client.
    m_recv_buffer.erase(
        m_recv_buffer.begin(),
        m_recv_buffer.begin() + (reader.it - reader.start));

    return true;
}

bool HTTPClient::MaybeSendBytesFromBuffer()
{
    // Send as much data from this client's buffer as we can
    LOCK(m_send_mutex);
    if (!m_send_buffer.empty()) {
        // Socket flags (See kernel docs for send(2) and tcp(7) for more details).
        // MSG_NOSIGNAL: If the remote end of the connection is closed,
        //               fail with EPIPE (an error) as opposed to triggering
        //               SIGPIPE which terminates the process.
        // MSG_DONTWAIT: Makes the send operation non-blocking regardless of socket blocking mode.
        // MSG_MORE:     We do not set this flag here because http responses are usually
        //               small and we want the kernel to send them right away. Setting MSG_MORE
        //               would "cork" the socket to prevent sending out partial frames.
        int flags{MSG_NOSIGNAL | MSG_DONTWAIT};

        // Try to send bytes through socket
        ssize_t bytes_sent;
        {
            LOCK(m_sock_mutex);
            bytes_sent = m_sock->Send(m_send_buffer.data(),
                                      m_send_buffer.size(),
                                      flags);
        }

        if (bytes_sent < 0) {
            // Something went wrong
            const int err{WSAGetLastError()};
            // These errors can be safely ignored, and we should try the send again
            // on the next I/O loop. See send(2) for more details.
            // EWOULDBLOCK: The requested operation would block.
            //              The non-blocking socket operation cannot complete immediately.
            // EMSGSIZE:    Message too large. The receive buffer is too small for the incoming message.
            // EINTR:       Interrupted function call. The socket operation was interrupted by another thread.
            // EINPROGRESS: A socket operation in already progress.
            if (err == WSAEWOULDBLOCK || err == WSAEMSGSIZE || err == WSAEINTR || err == WSAEINPROGRESS) {
                return true;
            }

            // Unrecoverbale error, log and disconnect client.
            LogDebug(
                BCLog::HTTP,
                "Error sending HTTP response data to client %s (id=%lld): %s\n",
                m_origin,
                m_id,
                NetworkErrorString(err));

            m_send_ready = false;
            m_prevent_disconnect = false;
            m_disconnect = true;

            // Do not attempt to read from this client.
            return false;
        }

        // Successful send, remove sent bytes from our local buffer.
        Assume(static_cast<size_t>(bytes_sent) <= m_send_buffer.size());
        m_send_buffer.erase(m_send_buffer.begin(),
                            m_send_buffer.begin() + bytes_sent);

        LogDebug(
            BCLog::HTTP,
            "Sent %d bytes to client %s (id=%lld)\n",
            bytes_sent,
            m_origin,
            m_id);

        // This check is inside the if(!empty) block meaning "there was data but now its gone".
        // We shouldn't even be calling SendBytesFromBuffer() when the send buffer is empty,
        // but for belt-and-suspenders, we don't want to modify the disconnect flags if SendBytesFromBuffer() was a no-op.
        if (m_send_buffer.empty()) {
            m_send_ready = false;
            m_prevent_disconnect = false;

            // Our work is done here
            if (!m_keep_alive) {
                m_disconnect = true;
                // Do not attempt to read from this client.
                return false;
            }
        } else {
            // The send buffer isn't flushed yet, try to push more on the next loop.
            m_send_ready = true;
            m_prevent_disconnect = true;
        }
    }

    return true;
}

bool InitHTTPServer()
{
    if (!InitHTTPAllowList()) {
        return false;
    }

    // Create HTTPServer
    g_http_server = std::make_unique<HTTPServer>(MaybeDispatchRequestToWorker);

    g_http_server->SetServerTimeout(std::chrono::seconds(gArgs.GetIntArg("-rpcservertimeout", DEFAULT_HTTP_SERVER_TIMEOUT)));

    // Bind HTTP server to specified addresses
    std::vector<std::pair<std::string, uint16_t>> endpoints{GetBindAddresses()};
    bool bind_success{false};
    for (std::vector<std::pair<std::string, uint16_t>>::iterator i = endpoints.begin(); i != endpoints.end(); ++i) {
        LogInfo("Binding RPC on address %s port %i\n", i->first, i->second);
        const std::optional<CService> addr{Lookup(i->first, i->second, false)};
        if (addr) {
            if (addr->IsBindAny()) {
                LogWarning("The RPC server is not safe to expose to untrusted networks such as the public internet\n");
            }
            auto result{g_http_server->BindAndStartListening(addr.value())};
            if (!result) {
                LogWarning("Binding RPC on address %s failed: %s\n", addr->ToStringAddrPort(), util::ErrorString(result).original);
            } else {
                bind_success = true;
            }
        } else {
            LogWarning("Binding RPC on address %s port %i failed.\n", i->first, i->second);
        }
    }

    if (!bind_success) {
        LogError("Unable to bind any endpoint for RPC server\n");
        return false;
    }

    LogDebug(BCLog::HTTP, "Initialized HTTP server\n");
    int workQueueDepth = std::max((long)gArgs.GetIntArg("-rpcworkqueue", DEFAULT_HTTP_WORKQUEUE), 1L);
    LogDebug(BCLog::HTTP, "creating work queue of depth %d\n", workQueueDepth);

    g_work_queue = std::make_unique<WorkQueue<HTTPClosure>>(workQueueDepth);

    return true;
}

static std::vector<std::thread> g_thread_http_workers;

void StartHTTPServer()
{
    int rpcThreads = std::max((long)gArgs.GetIntArg("-rpcthreads", DEFAULT_HTTP_THREADS), 1L);
    LogInfo("Starting HTTP server with %d worker threads\n", rpcThreads);
    g_http_server->StartSocketsThreads();

    for (int i = 0; i < rpcThreads; i++) {
        g_thread_http_workers.emplace_back(HTTPWorkQueueRun, g_work_queue.get(), i);
    }
}

void InterruptHTTPServer()
{
    LogDebug(BCLog::HTTP, "Interrupting HTTP server\n");
    if (g_http_server) {
        // Reject all new requests
        g_http_server->SetRequestHandler(RejectAllRequests);
    }
    if (g_work_queue) {
        // Stop workers, killing requests we haven't processed or responded to yet
        g_work_queue->Interrupt();
    }
}

void StopHTTPServer()
{
    LogDebug(BCLog::HTTP, "Stopping HTTP server\n");
    if (g_work_queue) {
        LogDebug(BCLog::HTTP, "Waiting for HTTP worker threads to exit\n");
        for (auto& thread : g_thread_http_workers) {
            thread.join();
        }
        g_thread_http_workers.clear();
    }
    if (g_http_server) {
        // Disconnect clients as their remaining responses are flushed
        g_http_server->DisconnectAllClients();
        // Wait for all disconnections
        while (g_http_server->GetConnectionsCount() != 0) {
            std::this_thread::sleep_for(50ms);
        }
        // Break sockman I/O loop: stop accepting connections, sending and receiving data
        g_http_server->InterruptNet();
        // Wait for sockman threads to exit
        g_http_server->JoinSocketsThreads();
        // Close all listening sockets
        g_http_server->StopListening();
    }
    LogDebug(BCLog::HTTP, "Stopped HTTP server\n");
}
} // namespace http_bitcoin

Coverage Report

Created: 2026-01-30 17:38