/* tinyproxy - A fast light-weight HTTP proxy
 * Copyright (C) 2002, 2004 Robert James Kaes <rjkaes@users.sourceforge.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

/* The functions found here are used for communicating across a
 * network.  They include both safe reading and writing (which are
 * the basic building blocks) along with two functions for
 * easily reading a line of text from the network, and a function
 * to write an arbitrary amount of data to the network.
 */

#include "main.h"

#include "heap.h"
#include "network.h"

/*
 * Write the buffer to the socket. If an EINTR occurs, pick up and try
 * again. Keep sending until the buffer has been sent.
 */
ssize_t
safe_write (int fd, const char *buffer, size_t count)
{
  ssize_t len;
  size_t bytestosend;

  assert (fd >= 0);
  assert (buffer != NULL);
  assert (count > 0);

  bytestosend = count;

  while (1)
    {
      len = send (fd, buffer, bytestosend, MSG_NOSIGNAL);

      if (len < 0)
        {
          if (errno == EINTR)
            continue;
          else
            return -errno;
        }

      if ((size_t)len == bytestosend)
        break;

      buffer += len;
      bytestosend -= len;
    }

  return count;
}

/*
 * Matched pair for safe_write(). If an EINTR occurs, pick up and try
 * again.
 */
ssize_t
safe_read (int fd, char *buffer, size_t count)
{
  ssize_t len;

  do
    {
      len = read (fd, buffer, count);
    }
  while (len < 0 && errno == EINTR);

  return len;
}

/*
 * Send a "message" to the file descriptor provided. This handles the
 * differences between the various implementations of vsnprintf. This code
 * was basically stolen from the snprintf() man page of Debian Linux
 * (although I did fix a memory leak. :)
 */
int
write_message (int fd, const char *fmt, ...)
{
  ssize_t n;
  size_t size = (1024 * 8);     /* start with 8 KB and go from there */
  char *buf, *tmpbuf;
  va_list ap;

  if ((buf = safemalloc (size)) == NULL)
    return -1;

  while (1)
    {
      va_start (ap, fmt);
      n = vsnprintf (buf, size, fmt, ap);
      va_end (ap);

      /* If that worked, break out so we can send the buffer */
      if (n > -1 && n < size)
        break;

      /* Else, try again with more space */
      if (n > -1)
        /* precisely what is needed (glibc2.1) */
        size = n + 1;
      else
        /* twice the old size (glibc2.0) */
        size *= 2;

      if ((tmpbuf = saferealloc (buf, size)) == NULL)
        {
          safefree (buf);
          return -1;
        }
      else
        buf = tmpbuf;
    }

  if (safe_write (fd, buf, n) < 0)
    {
      safefree (buf);
      return -1;
    }

  safefree (buf);
  return 0;
}

/*
 * Read in a "line" from the socket. It might take a few loops through
 * the read sequence. The full string is allocate off the heap and stored
 * at the whole_buffer pointer. The caller needs to free the memory when
 * it is no longer in use. The returned line is NULL terminated.
 *
 * Returns the length of the buffer on success (not including the NULL
 * termination), 0 if the socket was closed, and -1 on all other errors.
 */
#define SEGMENT_LEN (512)
#define MAXIMUM_BUFFER_LENGTH (128 * 1024)
ssize_t
readline (int fd, char **whole_buffer)
{
  ssize_t whole_buffer_len;
  char buffer[SEGMENT_LEN];
  char *ptr;

  ssize_t ret;
  ssize_t diff;

  struct read_lines_s
  {
    char *data;
    size_t len;
    struct read_lines_s *next;
  };
  struct read_lines_s *first_line, *line_ptr;

  first_line = safecalloc (sizeof (struct read_lines_s), 1);
  if (!first_line)
    return -ENOMEM;

  line_ptr = first_line;

  whole_buffer_len = 0;
  for (;;)
    {
      ret = recv (fd, buffer, SEGMENT_LEN, MSG_PEEK);
      if (ret <= 0)
        goto CLEANUP;

      ptr = memchr (buffer, '\n', ret);
      if (ptr)
        diff = ptr - buffer + 1;
      else
        diff = ret;

      whole_buffer_len += diff;

      /*
       * Don't allow the buffer to grow without bound. If we
       * get to more than MAXIMUM_BUFFER_LENGTH close.
       */
      if (whole_buffer_len > MAXIMUM_BUFFER_LENGTH)
        {
          ret = -ERANGE;
          goto CLEANUP;
        }

      line_ptr->data = safemalloc (diff);
      if (!line_ptr->data)
        {
          ret = -ENOMEM;
          goto CLEANUP;
        }

      recv (fd, line_ptr->data, diff, 0);
      line_ptr->len = diff;

      if (ptr)
        {
          line_ptr->next = NULL;
          break;
        }

      line_ptr->next = safecalloc (sizeof (struct read_lines_s), 1);
      if (!line_ptr->next)
        {
          ret = -ENOMEM;
          goto CLEANUP;
        }
      line_ptr = line_ptr->next;
    }

  *whole_buffer = safemalloc (whole_buffer_len + 1);
  if (!*whole_buffer)
    {
      ret = -ENOMEM;
      goto CLEANUP;
    }

  *(*whole_buffer + whole_buffer_len) = '\0';

  whole_buffer_len = 0;
  line_ptr = first_line;
  while (line_ptr)
    {
      memcpy (*whole_buffer + whole_buffer_len, line_ptr->data,
              line_ptr->len);
      whole_buffer_len += line_ptr->len;

      line_ptr = line_ptr->next;
    }

  ret = whole_buffer_len;

CLEANUP:
  do
    {
      line_ptr = first_line->next;
      if (first_line->data)
        safefree (first_line->data);
      safefree (first_line);
      first_line = line_ptr;
    }
  while (first_line);

  return ret;
}

/*
 * Convert the network address into either a dotted-decimal or an IPv6
 * hex string.
 */
char *
get_ip_string (struct sockaddr *sa, char *buf, size_t buflen)
{
  assert (sa != NULL);
  assert (buf != NULL);
  assert (buflen != 0);
  buf[0] = '\0';                /* start with an empty string */

  switch (sa->sa_family)
    {
    case AF_INET:
      {
        struct sockaddr_in *sa_in = (struct sockaddr_in *) sa;

        inet_ntop (AF_INET, &sa_in->sin_addr, buf, buflen);
        break;
      }
    case AF_INET6:
      {
        struct sockaddr_in6 *sa_in6 = (struct sockaddr_in6 *) sa;

        inet_ntop (AF_INET6, &sa_in6->sin6_addr, buf, buflen);
        break;
      }
    default:
      /* no valid family */
      return NULL;
    }

  return buf;
}

/*
 * Convert a numeric character string into an IPv6 network address
 * (in binary form.)  The function works just like inet_pton(), but it
 * will accept both IPv4 and IPv6 numeric addresses.
 *
 * Returns the same as inet_pton().
 */
int
full_inet_pton (const char *ip, void *dst)
{
  char buf[24], tmp[24];        /* IPv4->IPv6 = ::FFFF:xxx.xxx.xxx.xxx\0 */
  int n;

  assert (ip != NULL && strlen (ip) != 0);
  assert (dst != NULL);

  /*
   * Check if the string is an IPv4 numeric address.  We use the
   * older inet_aton() call since it handles more IPv4 numeric
   * address formats.
   */
  n = inet_aton (ip, (struct in_addr *) dst);
  if (n == 0)
    {
      /*
       * Simple case: "ip" wasn't an IPv4 numeric address, so
       * try doing the conversion as an IPv6 address.  This
       * will either succeed or fail, but we can't do any
       * more processing anyway.
       */
      return inet_pton (AF_INET6, ip, dst);
    }

  /*
   * "ip" was an IPv4 address, so we need to convert it to
   * an IPv4-mapped IPv6 address and do the conversion
   * again to get the IPv6 network structure.
   *
   * We convert the IPv4 binary address back into the
   * standard dotted-decimal format using inet_ntop()
   * so we can be sure that inet_pton will accept the
   * full string.
   */
  snprintf (buf, sizeof (buf), "::ffff:%s",
            inet_ntop (AF_INET, dst, tmp, sizeof (tmp)));
  return inet_pton (AF_INET6, buf, dst);
}