squeezelite-esp32/components/spotify/cspot/bell/src/HTTPServer.cpp

#include "HTTPServer.h"
#include <cstring>

bell::HTTPServer::HTTPServer(int serverPort) { this->serverPort = serverPort; }

unsigned char bell::HTTPServer::h2int(char c) {
    if (c >= '0' && c <= '9') {
        return ((unsigned char)c - '0');
    }
    if (c >= 'a' && c <= 'f') {
        return ((unsigned char)c - 'a' + 10);
    }
    if (c >= 'A' && c <= 'F') {
        return ((unsigned char)c - 'A' + 10);
    }
    return (0);
}

std::string bell::HTTPServer::urlDecode(std::string str) {
    std::string encodedString = "";
    char c;
    char code0;
    char code1;
    for (int i = 0; i < str.length(); i++) {
        c = str[i];
        if (c == '+') {
            encodedString += ' ';
        } else if (c == '%') {
            i++;
            code0 = str[i];
            i++;
            code1 = str[i];
            c = (h2int(code0) << 4) | h2int(code1);
            encodedString += c;
        } else {

            encodedString += c;
        }
    }

    return encodedString;
}

std::vector<std::string> bell::HTTPServer::splitUrl(const std::string &url,
                                                    char delimiter) {
    std::stringstream ssb(url);
    std::string segment;
    std::vector<std::string> seglist;

    while (std::getline(ssb, segment, delimiter)) {
        seglist.push_back(segment);
    }
    return seglist;
}

void bell::HTTPServer::registerHandler(RequestType requestType,
                                       const std::string &routeUrl,
                                       httpHandler handler) {
    if (routes.find(routeUrl) == routes.end()) {
        routes.insert({routeUrl, std::vector<HTTPRoute>()});
    }
    this->routes[routeUrl].push_back(HTTPRoute{
        .requestType = requestType,
        .handler = handler,
    });
}

void bell::HTTPServer::listen() {
    BELL_LOG(info, "http", "Starting server at port %d", this->serverPort);

    // setup address
    struct addrinfo hints, *server;
    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_PASSIVE;
    getaddrinfo(NULL, std::to_string(serverPort).c_str(), &hints, &server);

    int sockfd =
        socket(server->ai_family, server->ai_socktype, server->ai_protocol);
    struct sockaddr_in clientname;
    socklen_t incomingSockSize;
    int yes = true;
    if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (const char*) &yes, sizeof(int)) < 0) {
        throw std::runtime_error("setsockopt failed: " +
                                 std::string(strerror(errno)));
    }
    if (bind(sockfd, server->ai_addr, server->ai_addrlen) < 0) {
        throw std::runtime_error("bind failed on port " +
                                 std::to_string(this->serverPort) + ": " +
                                 std::string(strerror(errno)));
    }
    if (::listen(sockfd, 5) < 0) {
        throw std::runtime_error("listen failed on port " +
                                 std::to_string(this->serverPort) + ": " +
                                 std::string(strerror(errno)));
    }

    FD_ZERO(&activeFdSet);
    FD_SET(sockfd, &activeFdSet);

    for (int maxfd = sockfd;;) {
        /* Block until input arrives on one or more active sockets. */
        readFdSet = activeFdSet;
        struct timeval tv = {0, 100000};
 
        if (select(maxfd + 1, &readFdSet, NULL, NULL, &tv) < 0) {
            BELL_LOG(error, "http", "Error in select");
            perror("select");
            // exit(EXIT_FAILURE);
        }

        /* Service listening socket. */
        if (FD_ISSET(sockfd, &readFdSet)) {
            int newFd;
            incomingSockSize = sizeof(clientname);
            newFd = accept(sockfd, (struct sockaddr*)&clientname,
                    &incomingSockSize);
            if (newFd < 0) {
                perror("accept");
                exit(EXIT_FAILURE);
             }

             FD_SET(newFd, &activeFdSet);

             HTTPConnection conn = { .buffer = std::vector<uint8_t>(128),
                                     .httpMethod = "" };

             this->connections.insert({ newFd, conn });
         }

        /* Service other sockets and update set & max */
        maxfd = sockfd;
        for (auto it = this->connections.cbegin();
            it != this->connections.cend() /* not hoisted */;
            /* no increment */) {
            int fd = (*it).first;
            if ((*it).second.toBeClosed) {
                close(fd);
                FD_CLR(fd, &activeFdSet);
                this->connections.erase(
                    it++); // or "it = m.erase(it)" since C++11
            }
            else {
                if (fd != sockfd && FD_ISSET(fd, &readFdSet)) {
                    /* Data arriving on an already-connected socket. */
                    readFromClient(fd);
                }
                if (fd > maxfd) maxfd = fd;
                ++it;
            }
        }

    }
}

void bell::HTTPServer::readFromClient(int clientFd) {
    HTTPConnection &conn = this->connections[clientFd];

    int nbytes = recv(clientFd, (char*) &conn.buffer[0], conn.buffer.size(), 0);
    if (nbytes < 0) {
        BELL_LOG(error, "http", "Error reading from client");
        perror("recv");
        this->closeConnection(clientFd);
    } else if (nbytes == 0) {
        this->closeConnection(clientFd);
    } else {
        conn.currentLine +=
            std::string(conn.buffer.data(), conn.buffer.data() + nbytes);
    READBODY:
        if (!conn.isReadingBody) {
            while (conn.currentLine.find("\r\n") != std::string::npos) {
                auto line =
                    conn.currentLine.substr(0, conn.currentLine.find("\r\n"));
                conn.currentLine = conn.currentLine.substr(
                    conn.currentLine.find("\r\n") + 2, conn.currentLine.size());
                if (line.find("GET ") != std::string::npos ||
                    line.find("POST ") != std::string::npos ||
                    line.find("OPTIONS ") != std::string::npos) {
                    conn.httpMethod = line;
                }

                if (line.find("Content-Length: ") != std::string::npos) {
                    conn.contentLength =
                        std::stoi(line.substr(16, line.size() - 1));
                }
                // detect hostname for captive portal
                if (line.find("Host: connectivitycheck.gstatic.com") !=
                    std::string::npos) {
                    conn.isCaptivePortal = true;
                    BELL_LOG(info, "http", "Captive portal request detected");
                }
                if (line.size() == 0) {
                    if (conn.contentLength != 0) {
                        conn.isReadingBody = true;
                        goto READBODY;
                    } else {
                        if (!conn.isCaptivePortal) {
                            findAndHandleRoute(conn.httpMethod,
                                               conn.currentLine, clientFd);
                        } else {
                            this->redirectCaptivePortal(clientFd);
                        }
                    }
                }
            }
        } else {
            if (conn.currentLine.size() >= conn.contentLength) {
                findAndHandleRoute(conn.httpMethod, conn.currentLine, clientFd);
            }
        }
    }
}

void bell::HTTPServer::closeConnection(int connection) {

    this->connections[connection].toBeClosed = true;
}

void bell::HTTPServer::writeResponseEvents(int connFd) {
    std::lock_guard lock(this->responseMutex);

    std::stringstream stream;
    stream << "HTTP/1.1 200 OK\r\n";
    stream << "Server: bell-http\r\n";
    stream << "Connection: keep-alive\r\n";
    stream << "Content-type: text/event-stream\r\n";
    stream << "Cache-Control: no-cache\r\n";
    stream << "Access-Control-Allow-Origin: *\r\n";
    stream << "Access-Control-Allow-Methods: GET, POST, PATCH, PUT, DELETE, "
              "OPTIONS\r\n";
    stream << "Access-Control-Allow-Headers: Origin, Content-Type, "
              "X-Auth-Token\r\n";
    stream << "\r\n";

    auto responseStr = stream.str();

    write(connFd, responseStr.c_str(), responseStr.size());
    this->connections[connFd].isEventConnection = true;
}

void bell::HTTPServer::writeResponse(const HTTPResponse &response) {
    std::lock_guard lock(this->responseMutex);

    auto fileSize = response.body.size();

    if (response.responseReader != nullptr) {
        fileSize = response.responseReader->getTotalSize();
    }

    std::stringstream stream;
    stream << "HTTP/1.1 " << response.status << " OK\r\n";
    stream << "Server: bell-http\r\n";
    stream << "Connection: close\r\n";
    stream << "Content-type: " << response.contentType << "\r\n";

    if (response.useGzip) {
        stream << "Content-encoding: gzip"
               << "\r\n";
    }

    stream << "Access-Control-Allow-Origin: *\r\n";
    stream << "Access-Control-Allow-Methods: GET, POST, DELETE, OPTIONS\r\n";
    stream << "Access-Control-Expose-Headers: Location\r\n";
    stream << "Access-Control-Allow-Headers: Origin, Content-Type, "
              "X-Auth-Token\r\n";

    // go over every item in request->extraHeaders
    for (auto &header : response.extraHeaders) {
        stream << header << "\r\n";
    }

    stream << "\r\n";

    if (response.body.size() > 0) {
        stream << response.body;
    }

    auto responseStr = stream.str();

    write(response.connectionFd, responseStr.c_str(), responseStr.size());

    if (response.responseReader != nullptr) {
        size_t read;
        do {
            read = response.responseReader->read(responseBuffer.data(),
                                                 responseBuffer.size());
            if (read > 0) {
                write(response.connectionFd, responseBuffer.data(), read);
            }
        } while (read > 0);
    }

    this->closeConnection(response.connectionFd);
}

void bell::HTTPServer::respond(const HTTPResponse &response) {
    writeResponse(response);
}

void bell::HTTPServer::redirectCaptivePortal(int connectionFd) {
    std::lock_guard lock(this->responseMutex);
    std::stringstream stream;
    stream << "HTTP/1.1 302 Found\r\n";
    stream << "Server: bell-http\r\n";
    stream << "Connection: close\r\n";
    stream << "Location: http://euphonium.audio\r\n\r\n";
    stream << "Content-Length: 9\r\n";
    stream << "302 Found";
    auto responseStr = stream.str();

    write(connectionFd, responseStr.c_str(), responseStr.size());
    this->closeConnection(connectionFd);
}

void bell::HTTPServer::redirectTo(const std::string &url, int connectionFd) {
    std::lock_guard lock(this->responseMutex);
    std::stringstream stream;
    stream << "HTTP/1.1 301 Moved Permanently\r\n";
    stream << "Server: bell-http\r\n";
    stream << "Connection: close\r\n";
    stream << "Location: " << url << "\r\n\r\n";
    auto responseStr = stream.str();

    write(connectionFd, responseStr.c_str(), responseStr.size());
    this->closeConnection(connectionFd);
}

void bell::HTTPServer::publishEvent(std::string eventName,
                                    std::string eventData) {
    std::lock_guard lock(this->responseMutex);
    BELL_LOG(info, "http", "Publishing event");

    std::stringstream stream;
    stream << "event: " << eventName << "\n";
    stream << "data: " << eventData << "\n\n";
    auto responseStr = stream.str();

    // Reply to all event-connections
    for (auto it = this->connections.cbegin(); it != this->connections.cend();
         ++it) {
        if ((*it).second.isEventConnection) {
            write(it->first, responseStr.c_str(), responseStr.size());
        }
    }
}

std::map<std::string, std::string>
bell::HTTPServer::parseQueryString(const std::string &queryString) {
    std::map<std::string, std::string> query;
    auto prefixedString = "&" + queryString;
    while (prefixedString.find('&') != std::string::npos) {
        auto keyStart = prefixedString.find('&');
        auto keyEnd = prefixedString.find('=');
        // Find second occurence of "&" in prefixedString
        auto valueEnd = prefixedString.find('&', keyStart + 1);
        if (valueEnd == std::string::npos) {
            valueEnd = prefixedString.size();
        }

        auto key = prefixedString.substr(keyStart + 1, keyEnd - 1);
        auto value = prefixedString.substr(keyEnd + 1, valueEnd - keyEnd - 1);
        query[key] = urlDecode(value);
        prefixedString = prefixedString.substr(valueEnd);
    }

    return query;
}

void bell::HTTPServer::findAndHandleRoute(std::string &url, std::string &body,
                                          int connectionFd) {
    std::map<std::string, std::string> pathParams;
    std::map<std::string, std::string> queryParams;

    if (url.find("OPTIONS /") != std::string::npos) {
        std::stringstream stream;
        stream << "HTTP/1.1 200 OK\r\n";
        stream << "Server: bell-http\r\n";
        stream << "Allow: OPTIONS, GET, HEAD, POST\r\n";
        stream << "Connection: close\r\n";
        stream << "Access-Control-Allow-Origin: *\r\n";
        stream << "Access-Control-Allow-Methods: GET, POST, OPTIONS\r\n";
        stream << "Access-Control-Allow-Headers: Origin, Content-Type, "
                  "X-Auth-Token\r\n";
        stream << "\r\n";

        auto responseStr = stream.str();

        write(connectionFd, responseStr.c_str(), responseStr.size());
        closeConnection(connectionFd);
        return;
    }

    if (url.find("GET /events") != std::string::npos) {
        // Handle SSE endpoint here
        writeResponseEvents(connectionFd);
        return;
    }

    for (const auto &routeSet : this->routes) {
        for (const auto &route : routeSet.second) {

            std::string path = url;
            if (url.find("GET ") != std::string::npos &&
                route.requestType == RequestType::GET) {
                path = path.substr(4);
            } else if (url.find("POST ") != std::string::npos &&
                       route.requestType == RequestType::POST) {
                path = path.substr(5);
            } else {
                continue;
            }

            path = path.substr(0, path.find(' '));

            if (path.find('?') != std::string::npos) {
                auto urlEncodedSplit = splitUrl(path, '?');
                path = urlEncodedSplit[0];
                queryParams = this->parseQueryString(urlEncodedSplit[1]);
            }

            auto routeSplit = splitUrl(routeSet.first, '/');
            auto urlSplit = splitUrl(path, '/');
            bool matches = true;

            pathParams.clear();

            if (routeSplit.size() == urlSplit.size()) {
                for (int x = 0; x < routeSplit.size(); x++) {
                    if (routeSplit[x] != urlSplit[x]) {
                        if (routeSplit[x][0] == ':') {
                            pathParams.insert(
                                {routeSplit[x].substr(1), urlSplit[x]});
                        } else {
                            matches = false;
                        }
                    }
                }
            } else {
                matches = false;
            }

            if (routeSplit.back().find('*') != std::string::npos &&
                urlSplit[1] == routeSplit[1]) {
                matches = true;
                for (int x = 1; x <= routeSplit.size() - 2; x++) {
                    if (urlSplit[x] != routeSplit[x]) {
                        matches = false;
                    }
                }
            }

            if (matches) {
                if (body.find('&') != std::string::npos) {
                    queryParams = this->parseQueryString(body);
                }

                HTTPRequest req = {.urlParams = pathParams,
                                   .queryParams = queryParams,
                                   .body = body,
                                   .url = path,
                                   .handlerId = 0,
                                   .connection = connectionFd};

                route.handler(req);
                return;
            }
        }
    }
    writeResponse(HTTPResponse{
        .connectionFd = connectionFd,
        .status = 404,
        .body = "Not found",
    });
}