// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#define _POSIX_C_SOURCE 200809L

#include "netprotocol.h"

#include <arpa/inet.h>
#include <netinet/in.h>
#include <poll.h>
#include <sched.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <ifaddrs.h>

#include <fcntl.h>
#include <libgen.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <errno.h>
#include <stdint.h>

#include <zircon/boot/netboot.h>
#include <tftp/tftp.h>

#define TFTP_BUF_SZ 2048

typedef struct {
    int fd;
    size_t size;
} file_info_t;

typedef struct {
    int socket;
    bool connected;
    uint32_t previous_timeout_ms;
    struct sockaddr_in6 target_addr;
} transport_info_t;

static const char* appname;

static ssize_t file_open_read(const char* filename, void* file_cookie) {
    int fd = open(filename, O_RDONLY);
    if (fd < 0) {
        return TFTP_ERR_IO;
    }
    file_info_t *file_info = file_cookie;
    file_info->fd = fd;
    struct stat st;
    if (fstat(file_info->fd, &st) < 0) {
        close(fd);
        return TFTP_ERR_IO;
    }
    file_info->size = st.st_size;
    return st.st_size;
}

static tftp_status file_open_write(const char* filename, size_t size, void* file_cookie) {
    int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
    if (fd < 0) {
        return TFTP_ERR_IO;
    }
    file_info_t* file_info = file_cookie;
    file_info->fd = fd;
    file_info->size = size;
    return TFTP_NO_ERROR;
}

static tftp_status file_read(void* data, size_t* length, off_t offset, void* file_cookie) {
    int fd = ((file_info_t*)file_cookie)->fd;
    ssize_t n = pread(fd, data, *length, offset);
    if (n < 0) {
        return TFTP_ERR_IO;
    }
    *length = n;
    return TFTP_NO_ERROR;
}

static tftp_status file_write(const void* data, size_t* length, off_t offset, void* file_cookie) {
    int fd = ((file_info_t*)file_cookie)->fd;
    ssize_t n = pwrite(fd, data, *length, offset);
    if (n < 0) {
        return TFTP_ERR_IO;
    }
    *length = n;
    return TFTP_NO_ERROR;
}

static void file_close(void* file_cookie) {
    close(((file_info_t*)file_cookie)->fd);
}

// Longest time we will wait for a send operation to succeed
#define MAX_SEND_TIME_MS 1000

static tftp_status transport_send(void* data, size_t len, void* transport_cookie) {
    transport_info_t* transport_info = transport_cookie;
    ssize_t send_result;
    struct pollfd poll_fds = {.fd = transport_info->socket,
                              .events = POLLOUT};
    do {
        int poll_result = poll(&poll_fds, 1, MAX_SEND_TIME_MS);
        if (poll_result <= 0) {
            // We'll treat a timeout as an IO error and not a TFTP_ERR_TIMED_OUT,
            // since the latter is a timeout waiting for a response from the server.
            return TFTP_ERR_IO;
        }
        if (!transport_info->connected) {
            transport_info->target_addr.sin6_port = htons(NB_TFTP_INCOMING_PORT);
            send_result = sendto(transport_info->socket, data, len, 0,
                                 (struct sockaddr*)&transport_info->target_addr,
                                 sizeof(transport_info->target_addr));
        } else {
            send_result = send(transport_info->socket, data, len, 0);
        }
    } while ((send_result < 0) &&
             ((errno == EAGAIN) || (errno == EWOULDBLOCK) ||
              (errno == ENOBUFS && sched_yield() == 0)));

    if (send_result < 0) {
        return TFTP_ERR_IO;
    }
    return TFTP_NO_ERROR;
}

static int transport_recv(void* data, size_t len, bool block, void* transport_cookie) {
    transport_info_t* transport_info = transport_cookie;
    int flags = fcntl(transport_info->socket, F_GETFL, 0);
    if (flags < 0) {
        return TFTP_ERR_IO;
    }
    if (block) {
        flags &= ~O_NONBLOCK;
    } else {
        flags |= O_NONBLOCK;
    }
    if (fcntl(transport_info->socket, F_SETFL, flags)) {
        return TFTP_ERR_IO;
    }
    ssize_t recv_result;
    struct sockaddr_in6 connection_addr;
    socklen_t addr_len = sizeof(connection_addr);
    if (!transport_info->connected) {
        recv_result = recvfrom(transport_info->socket, data, len, 0,
                               (struct sockaddr*)&connection_addr,
                               &addr_len);
    } else {
        recv_result = recv(transport_info->socket, data, len, 0);
    }
    if (recv_result < 0) {
        if ((errno == EAGAIN) || (errno == EWOULDBLOCK)) {
            return TFTP_ERR_TIMED_OUT;
        }
        return TFTP_ERR_INTERNAL;
    }
    if (!transport_info->connected) {
        if (connect(transport_info->socket, (struct sockaddr*)&connection_addr,
                    sizeof(connection_addr)) < 0) {
            return TFTP_ERR_IO;
        }
        memcpy(&transport_info->target_addr, &connection_addr,
               sizeof(transport_info->target_addr));
        transport_info->connected = true;
    }
    return recv_result;
}

static int transport_timeout_set(uint32_t timeout_ms, void* transport_cookie) {
    transport_info_t* transport_info = transport_cookie;
    if (transport_info->previous_timeout_ms != timeout_ms && timeout_ms > 0) {
        transport_info->previous_timeout_ms = timeout_ms;
        struct timeval tv;
        tv.tv_sec = timeout_ms / 1000;
        tv.tv_usec = 1000 * (timeout_ms - 1000 * tv.tv_sec);
        return setsockopt(transport_info->socket, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
    }
    return 0;
}

static int transfer_file(bool push, int s, struct sockaddr_in6* addr, const char* dst,
                         const char* src) {
    // Initialize session
    tftp_session* session = NULL;
    size_t session_data_sz = tftp_sizeof_session();
    void* session_data = calloc(session_data_sz, 1);
    if (session_data == NULL) {
        fprintf(stderr, "%s: unable to allocate tftp session memory\n", appname);
        return 1;
    }
    if (tftp_init(&session, session_data, session_data_sz) != TFTP_NO_ERROR) {
        fprintf(stderr, "%s: unable to initiate tftp session\n", appname);
        free(session_data);
        return 1;
    }

    // Initialize file interface
    file_info_t file_info;
    tftp_file_interface file_ifc = {file_open_read, file_open_write,
                                    file_read, file_write, file_close};
    tftp_session_set_file_interface(session, &file_ifc);

    // Initialize transport interface
    transport_info_t transport_info;
    transport_info.previous_timeout_ms = 0;
    transport_info.socket = s;
    transport_info.connected = false;
    memcpy(&transport_info.target_addr, addr, sizeof(transport_info.target_addr));
    tftp_transport_interface transport_ifc = {transport_send, transport_recv,
                                              transport_timeout_set};
    tftp_session_set_transport_interface(session, &transport_ifc);

    // Set our preferred transport options
    tftp_set_options(session, &tftp_block_size, NULL, &tftp_window_size);

    // Prepare buffers
    char err_msg[128];
    tftp_request_opts opts = { 0 };
    opts.inbuf = malloc(TFTP_BUF_SZ);
    opts.inbuf_sz = TFTP_BUF_SZ;
    opts.outbuf = malloc(TFTP_BUF_SZ);
    opts.outbuf_sz = TFTP_BUF_SZ;
    opts.err_msg = err_msg;
    opts.err_msg_sz = sizeof(err_msg);

    tftp_status status;
    if (push) {
        status = tftp_push_file(session, &transport_info, &file_info, src, dst, &opts);
    } else {
        status = tftp_pull_file(session, &transport_info, &file_info, dst, src, &opts);
    }

    free(session_data);
    free(opts.inbuf);
    free(opts.outbuf);

    if (status < 0) {
        fprintf(stderr, "%s: %s (status = %d)\n", appname, opts.err_msg, (int)status);
        return 1;
    }

    fprintf(stderr, "wrote %zu bytes\n", file_info.size);

    return 0;
}

static void usage(void) {
    fprintf(stderr, "usage: %s [options] [hostname:]src [hostname:]dst\n", appname);
    netboot_usage(true);
}

int main(int argc, char** argv) {
    appname = argv[0];

    int index = netboot_handle_getopt(argc, argv);
    if (index < 0) {
        usage();
        return -1;
    }
    argv += index;
    argc -= index;

    if (argc != 2) {
        usage();
        return -1;
    }

    const char* src = argv[0];
    const char* dst = argv[1];

    int push = -1;
    char* pos;
    const char* hostname;
    if ((pos = strpbrk(src, ":")) != 0) {
        push = 0;
        hostname = src;
        pos[0] = 0;
        src = pos+1;
    }
    if ((pos = strpbrk(dst, ":")) != 0) {
        if (push == 0) {
            fprintf(stderr, "%s: only one of src or dst can have a hostname\n", appname);
            return -1;
        }
        push = 1;
        hostname = dst;
        pos[0] = 0;
        dst = pos+1;
    }
    if (push == -1) {
        fprintf(stderr, "%s: either src or dst needs a hostname\n", appname);
        return -1;
    }

    int s;
    struct sockaddr_in6 server_addr;
    if ((s = netboot_open(hostname, NULL, &server_addr, false)) < 0) {
        if (errno == ETIMEDOUT) {
            fprintf(stderr, "%s: lookup of %s timed out\n", appname, hostname);
        } else {
            fprintf(stderr, "%s: failed to connect to %s: %d\n", appname, hostname, errno);
        }
        return -1;
    }


    int ret = transfer_file(push, s, &server_addr, dst, src);
    close(s);
    return ret;
}