ray/src/common/io.c

#include "io.h"

#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <string.h>
#include <stdio.h>
#include <inttypes.h>
#include <stdarg.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <utstring.h>

#include "common.h"

/**
 * Binds to an Internet socket at the given port. Removes any existing file at
 * the pathname. Returns a non-blocking file descriptor for the socket, or -1
 * if an error occurred.
 *
 * @note Since the returned file descriptor is non-blocking, it is not
 * recommended to use the Linux read and write calls directly, since these
 * might read or write a partial message. Instead, use the provided
 * write_message and read_message methods.
 *
 * @param port The port to bind to.
 * @param shall_listen Are we also starting to listen on the socket?
 * @return A non-blocking file descriptor for the socket, or -1 if an error
 *         occurs.
 */
int bind_inet_sock(const int port, bool shall_listen) {
  struct sockaddr_in name;
  int socket_fd = socket(PF_INET, SOCK_STREAM, 0);
  if (socket_fd < 0) {
    LOG_ERROR("socket() failed for port %d.", port);
    return -1;
  }
  name.sin_family = AF_INET;
  name.sin_port = htons(port);
  name.sin_addr.s_addr = htonl(INADDR_ANY);
  int on = 1;
  /* TODO(pcm): http://stackoverflow.com/q/1150635 */
  if (ioctl(socket_fd, FIONBIO, (char *) &on) < 0) {
    LOG_ERROR("ioctl failed");
    close(socket_fd);
    return -1;
  }
  int *const pon = (char const *) &on;
  if (setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, pon, sizeof(on)) < 0) {
    LOG_ERROR("setsockopt failed for port %d", port);
    close(socket_fd);
    return -1;
  }
  if (bind(socket_fd, (struct sockaddr *) &name, sizeof(name)) < 0) {
    LOG_ERROR("Bind failed for port %d", port);
    close(socket_fd);
    return -1;
  }
  if (shall_listen && listen(socket_fd, 5) == -1) {
    LOG_ERROR("Could not listen to socket %d", port);
    close(socket_fd);
    return -1;
  }
  return socket_fd;
}

/**
 * Binds to a Unix domain streaming socket at the given
 * pathname. Removes any existing file at the pathname.
 *
 * @param socket_pathname The pathname for the socket.
 * @param shall_listen Are we also starting to listen on the socket?
 * @return A blocking file descriptor for the socket, or -1 if an error
 *         occurs.
 */
int bind_ipc_sock(const char *socket_pathname, bool shall_listen) {
  struct sockaddr_un socket_address;
  int socket_fd = socket(AF_UNIX, SOCK_STREAM, 0);
  if (socket_fd < 0) {
    LOG_ERROR("socket() failed for pathname %s.", socket_pathname);
    return -1;
  }
  /* Tell the system to allow the port to be reused. */
  int on = 1;
  if (setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, (char *) &on,
                 sizeof(on)) < 0) {
    LOG_ERROR("setsockopt failed for pathname %s", socket_pathname);
    close(socket_fd);
    return -1;
  }

  unlink(socket_pathname);
  memset(&socket_address, 0, sizeof(socket_address));
  socket_address.sun_family = AF_UNIX;
  if (strlen(socket_pathname) + 1 > sizeof(socket_address.sun_path)) {
    LOG_ERROR("Socket pathname is too long.");
    close(socket_fd);
    return -1;
  }
  strncpy(socket_address.sun_path, socket_pathname,
          strlen(socket_pathname) + 1);

  if (bind(socket_fd, (struct sockaddr *) &socket_address,
           sizeof(socket_address)) != 0) {
    LOG_ERROR("Bind failed for pathname %s.", socket_pathname);
    close(socket_fd);
    return -1;
  }
  if (shall_listen && listen(socket_fd, 5) == -1) {
    LOG_ERROR("Could not listen to socket %s", socket_pathname);
    close(socket_fd);
    return -1;
  }
  return socket_fd;
}

/**
 * Connects to a Unix domain streaming socket at the given
 * pathname. Returns a file descriptor for the socket, or -1 if
 * an error occurred.
 */
int connect_ipc_sock(const char *socket_pathname) {
  struct sockaddr_un socket_address;
  int socket_fd;

  socket_fd = socket(AF_UNIX, SOCK_STREAM, 0);
  if (socket_fd < 0) {
    LOG_ERROR("socket() failed for pathname %s.", socket_pathname);
    return -1;
  }

  memset(&socket_address, 0, sizeof(socket_address));
  socket_address.sun_family = AF_UNIX;
  if (strlen(socket_pathname) + 1 > sizeof(socket_address.sun_path)) {
    LOG_ERROR("Socket pathname is too long.");
    return -1;
  }
  strncpy(socket_address.sun_path, socket_pathname,
          strlen(socket_pathname) + 1);

  if (connect(socket_fd, (struct sockaddr *) &socket_address,
              sizeof(socket_address)) != 0) {
    LOG_ERROR("Connection to socket failed for pathname %s.", socket_pathname);
    return -1;
  }

  return socket_fd;
}

/**
 * Accept a new client connection on the given socket
 * descriptor. Returns a descriptor for the new socket.
 */
int accept_client(int socket_fd) {
  int client_fd = accept(socket_fd, NULL, NULL);
  if (client_fd < 0) {
    LOG_ERROR("Error reading from socket.");
    return -1;
  }
  return client_fd;
}

/**
 * Write a sequence of bytes into a file descriptor. This will block until one
 * of the following happens: (1) there is an error (2) end of file, or (3) all
 * length bytes have been written.
 *
 * @param fd The file descriptor to write to. It can be non-blocking.
 * @param cursor The cursor pointing to the beginning of the bytes to send.
 * @param length The size of the bytes sequence to write.
 * @return int Whether there was an error while writing. 0 corresponds to
 *         success and -1 corresponds to an error (errno will be set).
 */
int write_bytes(int fd, uint8_t *cursor, size_t length) {
  ssize_t nbytes = 0;
  size_t bytesleft = length;
  size_t offset = 0;
  while (bytesleft > 0) {
    /* While we haven't written the whole message, write to the file
     * descriptor, advance the cursor, and decrease the amount left to write. */
    nbytes = write(fd, cursor + offset, bytesleft);
    if (nbytes < 0) {
      if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) {
        continue;
      }
      return -1; /* Errno will be set. */
    } else if (0 == nbytes) {
      /* Encountered early EOF. */
      return -1;
    }
    CHECK(nbytes > 0);
    bytesleft -= nbytes;
    offset += nbytes;
  }

  return 0;
}

/**
 * Write a sequence of bytes on a file descriptor. The bytes should then be read
 * by read_message.
 *
 * @param fd The file descriptor to write to. It can be non-blocking.
 * @param type The type of the message to send.
 * @param length The size in bytes of the bytes parameter.
 * @param bytes The address of the message to send.
 * @return int Whether there was an error while writing. 0 corresponds to
 *         success and -1 corresponds to an error (errno will be set).
 */
int write_message(int fd, int64_t type, int64_t length, uint8_t *bytes) {
  int closed;
  closed = write_bytes(fd, (uint8_t *) &type, sizeof(type));
  if (closed) {
    return closed;
  }
  closed = write_bytes(fd, (uint8_t *) &length, sizeof(length));
  if (closed) {
    return closed;
  }
  closed = write_bytes(fd, bytes, length * sizeof(char));
  if (closed) {
    return closed;
  }
  return 0;
}

/**
 * Read a sequence of bytes from a file descriptor into a buffer. This will
 * block until one of the following happens: (1) there is an error (2) end of
 * file, or (3) all length bytes have been written.
 *
 * @note The buffer pointed to by cursor must already have length number of
 * bytes allocated before calling this method.
 *
 * @param fd The file descriptor to read from. It can be non-blocking.
 * @param cursor The cursor pointing to the beginning of the buffer.
 * @param length The size of the byte sequence to read.
 * @return int Whether there was an error while reading. 0 corresponds to
 *         success and -1 corresponds to an error (errno will be set).
 */
int read_bytes(int fd, uint8_t *cursor, size_t length) {
  ssize_t nbytes = 0;
  /* Termination condition: EOF or read 'length' bytes total. */
  size_t bytesleft = length;
  size_t offset = 0;
  while (bytesleft > 0) {
    nbytes = read(fd, cursor + offset, bytesleft);
    if (nbytes < 0) {
      if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) {
        continue;
      }
      return -1; /* Errno will be set. */
    } else if (0 == nbytes) {
      /* Encountered early EOF. */
      return -1;
    }
    CHECK(nbytes > 0);
    bytesleft -= nbytes;
    offset += nbytes;
  }

  return 0;
}

/**
 * Read a sequence of bytes written by write_message from a file descriptor.
 * This allocates space for the message.
 *
 * @note The caller must free the memory.
 *
 * @param fd The file descriptor to read from. It can be non-blocking.
 * @param type The type of the message that is read will be written at this
 *        address. If there was an error while reading, this will be
 *        DISCONNECT_CLIENT.
 * @param length The size in bytes of the message that is read will be written
 *        at this address. This size does not include the bytes used to encode
 *        the type and length. If there was an error while reading, this will
 *        be 0.
 * @param bytes The address at which to write the pointer to the bytes that are
 *        read and allocated by this function. If there was an error while
 *        reading, this will be NULL.
 * @return Void.
 */
void read_message(int fd, int64_t *type, int64_t *length, uint8_t **bytes) {
  int closed = read_bytes(fd, (uint8_t *) type, sizeof(*type));
  if (closed) {
    goto disconnected;
  }
  closed = read_bytes(fd, (uint8_t *) length, sizeof(*length));
  if (closed) {
    goto disconnected;
  }
  *bytes = malloc(*length * sizeof(uint8_t));
  closed = read_bytes(fd, *bytes, *length);
  if (closed) {
    free(*bytes);
    goto disconnected;
  }
  return;

disconnected:
  /* Handle the case in which the socket is closed. */
  *type = DISCONNECT_CLIENT;
  *length = 0;
  *bytes = NULL;
  return;
}

/**
 * Read a sequence of bytes written by write_message from a file descriptor.
 * This does not allocate space for the message if the provided buffer is
 * large enough and can therefore often avoid allocations.
 *
 * @note The caller must create and free the buffer.
 *
 * @param fd The file descriptor to read from. It can be non-blocking.
 * @param type The type of the message that is read will be written at this
 *        address. If there was an error while reading, this will be
 *        DISCONNECT_CLIENT.
 * @param buffer The array the message will be written to. If it is not
 *        large enough to hold the message, it will be enlarged by read_buffer.
 * @return Number of bytes of the message that were read. This size does not
 *         include the bytes used to encode the type and length. If there was
 *         an error while reading, this will be 0.
 */
int64_t read_buffer(int fd, int64_t *type, UT_array *buffer) {
  int64_t length;
  int closed = read_bytes(fd, (uint8_t *) type, sizeof(*type));
  if (closed) {
    goto disconnected;
  }
  closed = read_bytes(fd, (uint8_t *) &length, sizeof(length));
  if (closed) {
    goto disconnected;
  }
  if (length > utarray_len(buffer)) {
    utarray_resize(buffer, length);
  }
  closed = read_bytes(fd, (uint8_t *) utarray_front(buffer), length);
  if (closed) {
    goto disconnected;
  }
  return length;
disconnected:
  /* Handle the case in which the socket is closed. */
  *type = DISCONNECT_CLIENT;
  return 0;
}

/* Write a null-terminated string to a file descriptor. */
void write_log_message(int fd, char *message) {
  /* Account for the \0 at the end of the string. */
  write_message(fd, LOG_MESSAGE, strlen(message) + 1, (uint8_t *) message);
}

/* Reads a null-terminated string from the file descriptor that has been
 * written by write_log_message. Allocates and returns a pointer to the string.
 * NOTE: Caller must free the memory! */
char *read_log_message(int fd) {
  uint8_t *bytes;
  int64_t type;
  int64_t length;
  read_message(fd, &type, &length, &bytes);
  CHECK(type == LOG_MESSAGE);
  return (char *) bytes;
}

void write_formatted_log_message(int socket_fd, const char *format, ...) {
  UT_string *cmd;
  va_list ap;

  utstring_new(cmd);
  va_start(ap, format);
  utstring_printf_va(cmd, format, ap);
  va_end(ap);

  write_log_message(socket_fd, utstring_body(cmd));
  utstring_free(cmd);
}