// Copyright 2017 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
#define _GNU_SOURCE
#define _DARWIN_C_SOURCE

#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <poll.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <unistd.h>
#include <zircon/boot/netboot.h>

#include <tftp/tftp.h>

#include "bootserver.h"

// Point to user-selected values (or NULL if no values selected)
uint16_t* tftp_block_size;
uint16_t* tftp_window_size;

typedef struct {
  int fd;
  const char* data;
  size_t datalen;
} xferdata;

void file_init(xferdata* xd) {
  xd->fd = -1;
  xd->data = NULL;
  xd->datalen = 0;
}

ssize_t file_open_read(const char* filename, void* cookie) {
  xferdata* xd = cookie;
  if (strcmp(filename, "(cmdline)")) {
    xd->fd = open(filename, O_RDONLY);
    if (xd->fd < 0) {
      fprintf(stderr, "%s: error: Could not open file %s\n", appname, filename);
      return TFTP_ERR_NOT_FOUND;
    }
    struct stat st;
    if (fstat(xd->fd, &st) < 0) {
      fprintf(stderr, "%s: error: Could not stat %s\n", appname, filename);
      goto err;
    }
    xd->datalen = st.st_size;
  }
  initialize_status(filename, xd->datalen);
  return xd->datalen;
err:
  if (xd->fd >= 0) {
    close(xd->fd);
    xd->fd = -1;
  }
  return TFTP_ERR_IO;
}

tftp_status file_open_write(const char* filename, size_t len, void* cookie) {
  xferdata* xd = cookie;
  xd->fd = open(filename, O_WRONLY | O_CREAT);
  if (xd->fd < 0) {
    fprintf(stderr, "%s: error: Could not open file %s\n", appname, filename);
    return TFTP_ERR_NOT_FOUND;
  }
  if (ftruncate(xd->fd, len) < 0) {
    fprintf(stderr, "%s: error: Could not ftruncate %s\n", appname, filename);
    goto err;
  }
  xd->datalen = len;
  initialize_status(filename, xd->datalen);
  return TFTP_NO_ERROR;
err:
  if (xd->fd >= 0) {
    close(xd->fd);
    xd->fd = -1;
  }
  return TFTP_ERR_IO;
}

tftp_status file_read(void* data, size_t* length, off_t offset, void* cookie) {
  xferdata* xd = cookie;
  if (xd->fd < 0) {
    if (((size_t)offset > xd->datalen) || (offset + *length > xd->datalen)) {
      return TFTP_ERR_IO;
    }
    memcpy(data, &xd->data[offset], *length);
  } else {
    ssize_t bytes_read = pread(xd->fd, data, *length, offset);
    if (bytes_read < 0) {
      return TFTP_ERR_IO;
    }
    *length = bytes_read;
  }

  update_status(offset + *length);
  return TFTP_NO_ERROR;
}

tftp_status file_write(const void* data, size_t* length, off_t offset, void* cookie) {
  xferdata* xd = cookie;
  ssize_t bytes_written = pwrite(xd->fd, data, *length, offset);
  if (bytes_written < 0) {
    return TFTP_ERR_IO;
  }
  *length = bytes_written;

  update_status(offset + *length);
  return TFTP_NO_ERROR;
}

void file_close(void* cookie) {
  xferdata* xd = cookie;
  if (xd->fd >= 0) {
    close(xd->fd);
    xd->fd = -1;
  }
}

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

#define SEND_TIMEOUT_US 1000

tftp_status transport_send(void* data, size_t len, void* cookie) {
  transport_state* state = cookie;
  ssize_t send_result;
  do {
    struct pollfd poll_fds = {.fd = state->socket, .events = POLLOUT, .revents = 0};
    int poll_result = poll(&poll_fds, 1, SEND_TIMEOUT_US);
    if (poll_result < 0) {
      return TFTP_ERR_IO;
    }
    if (!state->connected) {
      state->target_addr.sin6_port = htons(NB_TFTP_INCOMING_PORT);
      send_result = sendto(state->socket, data, len, 0, (struct sockaddr*)&state->target_addr,
                           sizeof(state->target_addr));
    } else {
      send_result = send(state->socket, data, len, 0);
    }
  } while ((send_result < 0) &&
           ((errno == EAGAIN) || (errno == EWOULDBLOCK) || (errno == ENOBUFS)));
  if (send_result < 0) {
    fprintf(stderr, "\n%s: Attempted to send %zu bytes\n", appname, len);
    switch (errno) {
      case EADDRNOTAVAIL:
        fprintf(stderr, "%s: Network configuration error: %s (%d)\n", appname, strerror(errno),
                errno);
        break;
      default:
        fprintf(stderr, "%s: Send failed with errno = %d (%s)\n", appname, errno, strerror(errno));
    }
    return TFTP_ERR_IO;
  }
  return TFTP_NO_ERROR;
}

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

int transport_timeout_set(uint32_t timeout_ms, void* cookie) {
  transport_state* state = cookie;
  if (state->previous_timeout_ms != timeout_ms && timeout_ms > 0) {
    state->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(state->socket, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
  }
  return 0;
}

int transport_init(transport_state* state, uint32_t timeout_ms, struct sockaddr_in6* addr) {
  state->socket = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
  if (state->socket < 0) {
    fprintf(stderr, "%s: error: Cannot create socket %d\n", appname, errno);
    return -1;
  }
  state->previous_timeout_ms = 0;
  if (transport_timeout_set(timeout_ms, state) != 0) {
    fprintf(stderr, "%s: error: Unable to set socket timeout\n", appname);
    goto err;
  }
  state->connected = false;
  memcpy(&state->target_addr, addr, sizeof(struct sockaddr_in6));
  return 0;
err:
  close(state->socket);
  state->socket = -1;
  return -1;
}

#define INITIAL_CONNECTION_TIMEOUT 250
#define TFTP_BUF_SZ 2048

int tftp_xfer(struct sockaddr_in6* addr, const char* fn, const char* name, bool push) {
  int result = -1;
  xferdata xd;
  file_init(&xd);
  if (!strcmp(fn, "(cmdline)")) {
    xd.data = name;
    xd.datalen = strlen(name) + 1;
    name = NB_CMDLINE_FILENAME;
  }

  void* session_data = NULL;
  char* inbuf = NULL;
  char* outbuf = NULL;

  transport_state ts = {
      .socket = -1,
      .connected = false,
      .previous_timeout_ms = 0,
      .target_addr = {0},
  };
  tftp_session* session = NULL;
  size_t session_data_sz = tftp_sizeof_session();

  if (!(session_data = calloc(session_data_sz, 1)) || !(inbuf = malloc(TFTP_BUF_SZ)) ||
      !(outbuf = malloc(TFTP_BUF_SZ))) {
    fprintf(stderr, "%s: error: Unable to allocate memory\n", appname);
    goto done;
  }

  if (tftp_init(&session, session_data, session_data_sz) != TFTP_NO_ERROR) {
    fprintf(stderr, "%s: error: Unable to initialize tftp session\n", appname);
    goto done;
  }

  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);

  if (transport_init(&ts, INITIAL_CONNECTION_TIMEOUT, addr) < 0) {
    goto done;
  }
  tftp_transport_interface transport_ifc = {transport_send, transport_recv, transport_timeout_set};
  tftp_session_set_transport_interface(session, &transport_ifc);

  uint16_t default_block_size = DEFAULT_TFTP_BLOCK_SZ;
  uint16_t default_window_size = DEFAULT_TFTP_WIN_SZ;
  tftp_set_options(session, &default_block_size, NULL, &default_window_size);

  char err_msg[128];
  tftp_request_opts opts = {0};
  opts.inbuf_sz = TFTP_BUF_SZ;
  opts.inbuf = inbuf;
  opts.outbuf_sz = TFTP_BUF_SZ;
  opts.outbuf = outbuf;
  opts.err_msg = err_msg;
  opts.err_msg_sz = sizeof(err_msg);
  opts.block_size = tftp_block_size;
  opts.window_size = tftp_window_size;

  tftp_status status;
  if (push) {
    status = tftp_push_file(session, &ts, &xd, fn, name, &opts);
  } else {
    status = tftp_pull_file(session, &ts, &xd, fn, name, &opts);
  }
  if (status < 0) {
    if (status == TFTP_ERR_SHOULD_WAIT) {
      result = -EAGAIN;
    } else {
      fprintf(stderr, "\n%s: %s (status = %d)\n", appname, opts.err_msg, (int)status);
      result = -1;
    }
  } else {
    result = 0;
  }

done:
  if (ts.socket >= 0) {
    close(ts.socket);
  }
  if (session_data) {
    free(session_data);
  }
  if (inbuf) {
    free(inbuf);
  }
  if (outbuf) {
    free(outbuf);
  }
  file_close(&xd);
  return result;
}