tor/src/or/buffers.c

/* Copyright 2001,2002 Roger Dingledine, Matej Pfajfar. */
/* See LICENSE for licensing information */
/* $Id$ */

/* buffers.c */

#include "or.h"

extern or_options_t options; /* command-line and config-file options */

/* Create a new buf of size MAX_BUF_SIZE. Write a pointer to it
 * into *buf, write MAX_BUF_SIZE into *buflen, and initialize
 * *buf_datalen to 0. Return 0.
 */
int buf_new(char **buf, int *buflen, int *buf_datalen) {

  assert(buf && buflen && buf_datalen);

  *buf = (char *)tor_malloc(MAX_BUF_SIZE);
//  memset(*buf,0,MAX_BUF_SIZE);
  *buflen = MAX_BUF_SIZE;
  *buf_datalen = 0;

  return 0;
}

void buf_free(char *buf) {
  free(buf);
}

/* read from socket s, writing onto buf+buf_datalen.
 * read at most 'at_most' bytes, and in any case don't read more than will fit based on buflen.
 * If read() returns 0, set *reached_eof to 1 and return 0. If you want to tear
 * down the connection return -1, else return the number of bytes read.
 */
int read_to_buf(int s, int at_most, char **buf, int *buflen, int *buf_datalen, int *reached_eof) {

  int read_result;
#ifdef MS_WINDOWS
  int e;
#endif

  assert(buf && *buf && buflen && buf_datalen && reached_eof && (s>=0));

  /* this is the point where you would grow the buffer, if you want to */

  if(at_most > *buflen - *buf_datalen)
    at_most = *buflen - *buf_datalen; /* take the min of the two */

  if(at_most == 0)
    return 0; /* we shouldn't read anything */

//  log_fn(LOG_DEBUG,"reading at most %d bytes.",at_most);
  read_result = read(s, *buf+*buf_datalen, at_most);
  if (read_result < 0) {
    if(!ERRNO_EAGAIN(errno)) { /* it's a real error */
      return -1;
    }
#ifdef MS_WINDOWS
    e = correct_socket_errno(s);
    if(!ERRNO_EAGAIN(e)) { /* no, it *is* a real error! */
      return -1;
    }
#endif
    return 0;
  } else if (read_result == 0) {
    log_fn(LOG_DEBUG,"Encountered eof");
    *reached_eof = 1;
    return 0;
  } else { /* we read some bytes */
    *buf_datalen += read_result;
//    log_fn(LOG_DEBUG,"Read %d bytes. %d on inbuf.",read_result, *buf_datalen);
    return read_result;
  }
}

int read_to_buf_tls(tor_tls *tls, int at_most, char **buf, int *buflen, int *buf_datalen) {
  int r;
  assert(tls && *buf && buflen && buf_datalen);
  
  if (at_most > *buflen - *buf_datalen)
    at_most = *buflen - *buf_datalen;

  if (at_most == 0)
    return 0;
  
  r = tor_tls_read(tls, *buf+*buf_datalen, at_most);
  if (r<0) 
    return r;
  *buf_datalen += r;
  return r;
} 

int flush_buf(int s, char **buf, int *buflen, int *buf_flushlen, int *buf_datalen) {

  /* push from buf onto s
   * then memmove to front of buf
   * return -1 or how many bytes remain to be flushed */

  int write_result;
#ifdef MS_WINDOWS
  int e;
#endif

  assert(buf && *buf && buflen && buf_flushlen && buf_datalen && (s>=0) && (*buf_flushlen <= *buf_datalen));

  if(*buf_flushlen == 0) /* nothing to flush */
    return 0;

  /* this is the point where you would grow the buffer, if you want to */

  write_result = write(s, *buf, *buf_flushlen);
  if (write_result < 0) {
    if(!ERRNO_EAGAIN(errno)) { /* it's a real error */
      return -1;
    }
#ifdef MS_WINDOWS
    e = correct_socket_errno(s);
    if(!ERRNO_EAGAIN(e)) { /* no, it *is* a real error! */
      return -1;
    }
#endif
    log_fn(LOG_DEBUG,"write() would block, returning.");
    return 0;
  } else {
    *buf_datalen -= write_result;
    *buf_flushlen -= write_result;
    memmove(*buf, *buf+write_result, *buf_datalen);
    log_fn(LOG_DEBUG,"%d: flushed %d bytes, %d ready to flush, %d remain.",
      s,write_result,*buf_flushlen,*buf_datalen);
    return *buf_flushlen;
    /* XXX USE_TLS should change to return write_result like any sane function would */
  }
}

int flush_buf_tls(tor_tls *tls, char **buf, int *buflen, int *buf_flushlen, int *buf_datalen)
{
  int r;
  assert(tls && *buf && buflen && buf_datalen);

  /* we want to let tls write even if flushlen is zero, because it might
   * have a partial record pending */
  r = tor_tls_write(tls, *buf, *buf_flushlen);
  if (r < 0) {
    return r;
  }
  *buf_datalen -= r;
  *buf_flushlen -= r;
  memmove(*buf, *buf+r, *buf_datalen);
  return r;
}

int write_to_buf(char *string, int string_len,
                 char **buf, int *buflen, int *buf_datalen) {

  /* append string to buf (growing as needed, return -1 if "too big")
   * return total number of bytes on the buf
   */

  assert(string && buf && *buf && buflen && buf_datalen);

  /* this is the point where you would grow the buffer, if you want to */

  if (string_len + *buf_datalen > *buflen) { /* we're out of luck */
    log_fn(LOG_DEBUG, "buflen too small. Time to implement growing dynamic bufs.");
    return -1;
  }

  memcpy(*buf+*buf_datalen, string, string_len);
  *buf_datalen += string_len;
//  log_fn(LOG_DEBUG,"added %d bytes to buf (now %d total).",string_len, *buf_datalen);
  return *buf_datalen;
}

int fetch_from_buf(char *string, int string_len,
                   char **buf, int *buflen, int *buf_datalen) {

  /* There must be string_len bytes in buf; write them onto string,
   * then memmove buf back (that is, remove them from buf).
   *
   * Return the number of bytes still on the buffer. */

  assert(string && buf && *buf && buflen && buf_datalen);
  assert(string_len <= *buf_datalen); /* make sure we don't ask for too much */

  memcpy(string,*buf,string_len);
  *buf_datalen -= string_len;
  memmove(*buf, *buf+string_len, *buf_datalen);
  return *buf_datalen;
}

/* There is a (possibly incomplete) http statement on *buf, of the
 * form "%s\r\n\r\n%s", headers, body.
 * If a) the headers include a Content-Length field and all bytes in
 * the body are present, or b) there's no Content-Length field and
 * all headers are present, then:
 *   copy headers and body into the supplied args (and null terminate
 *   them), remove them from buf, and return 1.
 *   (If headers or body is NULL, discard that part of the buf.)
 *   If a headers or body doesn't fit in the arg, return -1.
 * 
 * Else, change nothing and return 0.
 */
int fetch_from_buf_http(char *buf, int *buf_datalen,
                        char *headers_out, int max_headerlen,
                        char *body_out, int max_bodylen) {
  char *headers, *body;
  int i;
  int headerlen, bodylen, contentlen;

  assert(buf && buf_datalen);

  headers = buf;
  i = find_on_inbuf("\r\n\r\n", 4, buf, *buf_datalen);
  if(i < 0) {
    log_fn(LOG_DEBUG,"headers not all here yet.");
    return 0;
  }
  body = buf+i;
  headerlen = body-headers; /* includes the CRLFCRLF */
  bodylen = *buf_datalen - headerlen;
  log_fn(LOG_DEBUG,"headerlen %d, bodylen %d.",headerlen,bodylen);

  if(headers_out && max_headerlen <= headerlen) {
    log_fn(LOG_DEBUG,"headerlen %d larger than %d. Failing.", headerlen, max_headerlen-1);
    return -1;
  }
  if(body_out && max_bodylen <= bodylen) {
    log_fn(LOG_DEBUG,"bodylen %d larger than %d. Failing.", bodylen, max_bodylen-1);
    return -1;
  }

#define CONTENT_LENGTH "Content-Length: "
  i = find_on_inbuf(CONTENT_LENGTH, strlen(CONTENT_LENGTH), headers, headerlen);
  /* This includes headers like Not-Content-Length. But close enough. */
  if(i > 0) {
    contentlen = atoi(headers+i);
    if(bodylen < contentlen) {
      log_fn(LOG_DEBUG,"body not all here yet.");
      return 0; /* not all there yet */
    }
    bodylen = contentlen;
    log_fn(LOG_DEBUG,"bodylen reduced to %d.",bodylen);
  }
  /* all happy. copy into the appropriate places, and return 1 */
  if(headers_out) {
    memcpy(headers_out,buf,headerlen);
    headers_out[headerlen] = 0; /* null terminate it */
  }
  if(body_out) {
    memcpy(body_out,buf+headerlen,bodylen);
    body_out[bodylen] = 0; /* null terminate it */
  }
  *buf_datalen -= (headerlen+bodylen);
  memmove(buf, buf+headerlen+bodylen, *buf_datalen);

  return 1;
}

/* There is a (possibly incomplete) socks handshake on *buf, of the
 * forms
 *   socks4: "socksheader || username\0".
 *   socks4a: "socksheader || username\0 || destaddr\0".
 * If it's a complete and valid handshake, and destaddr fits in addr_out,
 *   then pull the handshake off the buf, assign to addr_out and port_out,
 *   and return 1.
 * If it's invalid or too big, return -1.
 * Else it's not all there yet, change nothing return 0.
 */
int fetch_from_buf_socks(char *buf, int *buf_datalen,
                         char *addr_out, int max_addrlen,
                         uint16_t *port_out) {
  socks4_t *socks4_info;
  char tmpbuf[512];
  uint16_t port;
  enum {socks4, socks4a } socks_prot = socks4a;
  char *next, *startaddr;

  if(*buf_datalen < sizeof(socks4_t)) /* basic info available? */
    return 0; /* not yet */

  socks4_info = (socks4_t *)buf;

  if(socks4_info->version != 4) {
    log_fn(LOG_NOTICE,"Unrecognized version %d.",socks4_info->version);
    return -1;
  }

  if(socks4_info->command != 1) { /* not a connect? we don't support it. */
    log_fn(LOG_NOTICE,"command %d not '1'.",socks4_info->command);
    return -1;
  }

  port = ntohs(*(uint16_t*)&socks4_info->destport);
  if(!port) {
    log_fn(LOG_NOTICE,"Port is zero.");
    return -1;
  }

  if(socks4_info->destip[0] || socks4_info->destip[1] ||
     socks4_info->destip[2] || !socks4_info->destip[3]) { /* not 0.0.0.x */
    log_fn(LOG_NOTICE,"destip not in form 0.0.0.x.");
    sprintf(tmpbuf, "%d.%d.%d.%d", socks4_info->destip[0],
      socks4_info->destip[1], socks4_info->destip[2], socks4_info->destip[3]);
    if(max_addrlen <= strlen(tmpbuf)) {
      log_fn(LOG_DEBUG,"socks4-addr too long.");
      return -1;
    }
    log_fn(LOG_DEBUG,"Successfully read destip (%s)", tmpbuf);
    socks_prot = socks4;
  }

  next = memchr(buf+sizeof(socks4_t), 0, *buf_datalen);
  if(!next) {
    log_fn(LOG_DEBUG,"Username not here yet.");
    return 0;
  }

  startaddr = next+1;
  if(socks_prot == socks4a) {
    next = memchr(startaddr, 0, buf+*buf_datalen-startaddr);
    if(!next) {
      log_fn(LOG_DEBUG,"Destaddr not here yet.");
      return 0;
    }
    if(max_addrlen <= next-startaddr) {
      log_fn(LOG_DEBUG,"Destaddr not here yet.");
      return -1;
    }
  }
  log_fn(LOG_DEBUG,"Everything is here. Success.");
  *port_out = port; 
  strcpy(addr_out, socks_prot == socks4 ? tmpbuf : startaddr);
  *buf_datalen -= (next-buf+1); /* next points to the final \0 on inbuf */
  memmove(buf, next+1, *buf_datalen);
//  log_fn(LOG_DEBUG,"buf_datalen is now %d:'%s'",*buf_datalen,buf);
  return 1;
}

int find_on_inbuf(char *string, int string_len,
                  char *buf, int buf_datalen) {
  /* find first instance of needle 'string' on haystack 'buf'. return how
   * many bytes from the beginning of buf to the end of string.
   * If it's not there, return -1.
   */

  char *location;
  char *last_possible = buf + buf_datalen - string_len;

  assert(string && string_len > 0 && buf);

  if(buf_datalen < string_len)
    return -1;

  for(location = buf; location <= last_possible; location++)
    if((*location == *string) && !memcmp(location+1, string+1, string_len-1))
      return location-buf+string_len;

  return -1;
}

/*
  Local Variables:
  mode:c
  indent-tabs-mode:nil
  c-basic-offset:2
  End:
*/