[cubemap] / cubemap.cpp

#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <assert.h>
#include <arpa/inet.h>
#include <curl/curl.h>
#include <sys/socket.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/epoll.h>
#include <errno.h>
#include <vector>
#include <string>
#include <map>
#include "metacube.h"

#define NUM_SERVERS 4
#define STREAM_ID "stream"
#define STREAM_URL "http://gruessi.zrh.sesse.net:4013/"
#define BACKLOG_SIZE 1048576
#define PORT 9094

using namespace std;

// Locks a pthread mutex, RAII-style.
class MutexLock {
public:
        MutexLock(pthread_mutex_t *mutex);
        ~MutexLock();

private:
        pthread_mutex_t *mutex;
};
        
MutexLock::MutexLock(pthread_mutex_t *mutex)
        : mutex(mutex)
{
        pthread_mutex_lock(mutex);
}

MutexLock::~MutexLock()
{
        pthread_mutex_unlock(mutex);
}

struct Client {
        enum State { READING_REQUEST, SENDING_HEADER, SENDING_DATA };
        State state;

        // The HTTP request, as sent by the client. If we are in READING_REQUEST,
        // this might not be finished.
        string client_request;

#if 0
        // What stream we're connecting to; parsed from client_request.
        // Not relevant for READING_REQUEST.
        string stream_id;
#endif

        // Number of bytes we've sent of the header. Only relevant for SENDING_HEADER.
        size_t header_bytes_sent;

        // Number of bytes we've sent of data. Only relevant for SENDING_DATA.
        size_t bytes_sent;
};

struct Stream {
        // The HTTP response header, plus the video stream header (if any).
        string header;

        // The stream data itself, stored in a circular buffer.
        char data[BACKLOG_SIZE];

        // How many bytes <data> contains. Can very well be larger than BACKLOG_SIZE,
        // since the buffer wraps.
        size_t data_size;
};

class Server {
public:
        Server();

        // Start a new thread that handles clients.
        void run();
        void add_client(int sock);
        void add_stream(const string &stream_id);
        void set_header(const string &stream_id, const string &header);
        void add_data(const string &stream_id, const char *data, size_t bytes);

private:
        pthread_mutex_t mutex;

        // Map from stream ID to stream.
        map<string, Stream> streams;

        // Map from file descriptor to client.
        map<int, Client> clients;

        int epoll_fd;

        // Recover the this pointer, and call do_work().
        static void *do_work_thunk(void *arg);

        // The actual worker thread.
        void do_work();
};

Server *servers = NULL;

Server::Server()
{
        pthread_mutex_init(&mutex, NULL);

        epoll_fd = epoll_create(1024);  // Size argument is ignored.
        if (epoll_fd == -1) {
                perror("epoll_fd");
                exit(1);
        }
}

void Server::run()
{
        pthread_t thread;
        pthread_create(&thread, NULL, Server::do_work_thunk, this);
}

void *Server::do_work_thunk(void *arg)
{
        Server *server = static_cast<Server *>(arg);
        server->do_work();
        return NULL;
}

void Server::do_work()
{
        for ( ;; ) {
                MutexLock lock(&mutex);
                printf("server thread running\n");
                sleep(1);
        }
}
        
void Server::add_client(int sock)
{
        MutexLock lock(&mutex);
        Client new_client;
        new_client.state = Client::READING_REQUEST;
        new_client.header_bytes_sent = 0;
        new_client.bytes_sent = 0;

        clients.insert(make_pair(sock, new_client));

        // Start listening on data from this socket.
        epoll_event ev;
        ev.events = EPOLLIN;
        ev.data.fd = sock;
        if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, sock, &ev) == -1) {
                perror("epoll_ctl(EPOLL_CTL_ADD)");
                exit(1);
        }
}
        
void Server::add_stream(const string &stream_id)
{
        // TODO
}
        
void Server::set_header(const string &stream_id, const string &header)
{
        // TODO
        printf("got header! %lu bytes\n", header.size());
}
        
void Server::add_data(const string &stream_id, const char *data, size_t bytes)
{
        // TODO
}

class Input {
public:
        Input(const string &stream_id);

        // Connect to the given URL and start streaming.
        // WARNING: Currently this blocks; it does not run in a separate thread!
        void run(const string &url);

private:
        // Recovers the this pointer and calls curl_callback().
        static size_t curl_callback_thunk(char *ptr, size_t size, size_t nmemb, void *userdata);

        // Stores the given data, looks for Metacube blocks (skipping data if needed),
        // and calls process_block() for each one.
        void curl_callback(char *ptr, size_t bytes);
        void process_block(const char *data, uint32_t size, uint32_t flags);

        // Drops <num_bytes> bytes from the head of <pending_data>,
        // and outputs a warning.
        void drop_pending_data(size_t num_bytes);

        string stream_id;

        // Data we have received but not fully processed yet.
        vector<char> pending_data;

        // If <pending_data> starts with a Metacube header,
        // this is true.
        bool has_metacube_header;
};

Input::Input(const string &stream_id)
        : stream_id(stream_id),
          has_metacube_header(false)
{
}

void Input::run(const string &url)
{
        CURL *curl = curl_easy_init();
        curl_easy_setopt(curl, CURLOPT_URL, STREAM_URL);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &Input::curl_callback_thunk);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, this);
        curl_easy_perform(curl);
}

size_t Input::curl_callback_thunk(char *ptr, size_t size, size_t nmemb, void *userdata)
{
        Input *input = static_cast<Input *>(userdata);
        size_t bytes = size * nmemb;
        input->curl_callback(ptr, bytes);       
        return bytes;
}
        
void Input::curl_callback(char *ptr, size_t bytes)
{
        pending_data.insert(pending_data.end(), ptr, ptr + bytes);

        for ( ;; ) {
                // If we don't have enough data (yet) for even the Metacube header, just return.
                if (pending_data.size() < sizeof(metacube_block_header)) {
                        return;
                }

                // Make sure we have the Metacube sync header at the start.
                // We may need to skip over junk data (it _should_ not happen, though).
                if (!has_metacube_header) {
                        char *ptr = static_cast<char *>(
                                memmem(pending_data.data(), pending_data.size(),
                                       METACUBE_SYNC, strlen(METACUBE_SYNC)));
                        if (ptr == NULL) {
                                // OK, so we didn't find the sync marker. We know then that
                                // we do not have the _full_ marker in the buffer, but we
                                // could have N-1 bytes. Drop everything before that,
                                // and then give up.
                                drop_pending_data(pending_data.size() - (strlen(METACUBE_SYNC) - 1));
                                return;
                        } else {
                                // Yay, we found the header. Drop everything (if anything) before it.
                                drop_pending_data(ptr - pending_data.data());
                                has_metacube_header = true;

                                // Re-check that we have the entire header; we could have dropped data.
                                if (pending_data.size() < sizeof(metacube_block_header)) {
                                        return;
                                }
                        }
                }

                // Now it's safe to read the header.
                metacube_block_header *hdr = reinterpret_cast<metacube_block_header *>(pending_data.data());    
                assert(memcmp(hdr->sync, METACUBE_SYNC, sizeof(hdr->sync)) == 0);
                uint32_t size = ntohl(hdr->size);
                uint32_t flags = ntohl(hdr->flags);

                // See if we have the entire block. If not, wait for more data.
                if (pending_data.size() < sizeof(metacube_block_header) + size) {
                        return;
                }

                process_block(pending_data.data(), size, flags);

                // Consume this block. This isn't the most efficient way of dealing with things
                // should we have many blocks, but these routines don't need to be too efficient
                // anyway.
                pending_data.erase(pending_data.begin(), pending_data.begin() + sizeof(metacube_block_header) + size);
        }
}
                
void Input::process_block(const char *data, uint32_t size, uint32_t flags)
{       
        if (flags & METACUBE_FLAGS_HEADER) {
                string header(data, data + size);
                for (int i = 0; i < NUM_SERVERS; ++i) {
                        servers[i].set_header(stream_id, header);
                }
        } else { 
                for (int i = 0; i < NUM_SERVERS; ++i) {
                        servers[i].add_data(stream_id, data, size);
                }
        }
}

void Input::drop_pending_data(size_t num_bytes)
{
        if (num_bytes == 0) {
                return;
        }
        fprintf(stderr, "Warning: Dropping %lld junk bytes from stream, maybe it is not a Metacube stream?\n",
                (long long)num_bytes);
        pending_data.erase(pending_data.begin(), pending_data.begin() + num_bytes);
}

int create_server_socket(int port)
{
        int server_sock = socket(PF_INET6, SOCK_STREAM, IPPROTO_TCP);
        if (server_sock == -1) {
                perror("socket");
                exit(1);
        }

        // We want dual-stack sockets. (Sorry, OpenBSD and Windows XP...)
        int zero = 0;
        if (setsockopt(server_sock, IPPROTO_IPV6, IPV6_V6ONLY, &zero, sizeof(zero)) == -1) {
                perror("setsockopt(IPV6_V6ONLY)");
                exit(1);
        }

        sockaddr_in6 addr;
        memset(&addr, 0, sizeof(addr));
        addr.sin6_family = AF_INET6;
        addr.sin6_port = htons(port);

        if (bind(server_sock, reinterpret_cast<sockaddr *>(&addr), sizeof(addr)) == -1) {
                perror("bind");
                exit(1);
        }

        if (listen(server_sock, 128) == -1) {
                perror("listen");
                exit(1);
        }

        return server_sock;
}

void *acceptor_thread_run(void *arg)
{
        int server_sock = int(intptr_t(arg));
        int num_accepted = 0;
        for ( ;; ) {
                sockaddr_in6 addr;
                socklen_t addrlen = sizeof(addr);

                // Get a new socket.
                int sock = accept(server_sock, reinterpret_cast<sockaddr *>(&addr), &addrlen);
                if (sock == -1 && errno == EINTR) {
                        continue;
                }
                if (sock == -1) {
                        perror("accept");
                        exit(1);
                }

                // Set the socket as nonblocking.
                int one = 1;
                if (ioctl(sock, FIONBIO, &one) == -1) {
                        perror("FIONBIO");
                        exit(1);
                }

                // Pick a server, round-robin, and hand over the socket to it.
                servers[num_accepted % NUM_SERVERS].add_client(sock);
                ++num_accepted; 
        }
}

int main(int argc, char **argv)
{
        servers = new Server[NUM_SERVERS];
        for (int i = 0; i < NUM_SERVERS; ++i) {
                servers[i].add_stream(STREAM_ID);
                servers[i].run();
        }

        int server_sock = create_server_socket(PORT);

        pthread_t acceptor_thread;
        pthread_create(&acceptor_thread, NULL, acceptor_thread_run, reinterpret_cast<void *>(server_sock));

        Input input(STREAM_ID);
        input.run(STREAM_URL);
}