distributor/utils.c

/**
 * Copyright (C) 2007 Juan José Gutiérrez de Quevedo <juanjo@iteisa.com>
 *
 * 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; version 2 of the License
 *
 * 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.
 *
 * @author Juan José Gutiérrez de Quevedo <juanjo@gutierrezdequevedo.com>
 */
#include "utils.h"

extern unsigned long connid;
char m_buffer[4096]={0};

/**
 * reads a string as safely as possible.
 *
 * it will read one byte at a time until a '\\n' is read.
 * we store one char at a time in a static buffer, and when
 * we find a '\\n', we do an strndup of the buffer.
 * it might be possible in this special case to just use
 * a static buffer, return a pointer to it and never assign 
 * any memory with strndup or in any other way.
 *
 * @param fd fd to read from
 *
 * @return a pointer to the read string
 */
char *read_string(int fd)
{
  char chr;
  char *buffer=NULL,*tmpbuf=NULL;
  unsigned long strsize=0;
  unsigned long allocsize=0;

  assert(fd>=0);
  /* read one byte at a time */
  while(1)
  {
    if(1!=recv(fd,&chr,1,MSG_NOSIGNAL))
      break;

    if(0==allocsize||allocsize<strsize+2)
    {
      allocsize=MAX(allocsize+512,strsize+2);
      if(NULL==(tmpbuf=realloc(buffer,allocsize)))
      {
        debug("Error reserving memory");
        condfree(buffer);
        break;
      }
      else
        buffer=tmpbuf;
    }
    if(10==chr) break;
    if(13!=chr)
      buffer[strsize++]=chr;
  }

  if(NULL==buffer) return NULL;

  /* finalize string */
  buffer[strsize]='\0';

  snprintf(m_buffer,sizeof(m_buffer),"r>%s",buffer);
  debug(m_buffer);

  /* return a new string with new mem */
  return buffer;
}

/**
* create a new listening socket.
*
* with following options:
* - SO_REUSEADDR
* - INADDR_ANY
*
* @param port the port to listen on
*
* @return the new socket fd
*/
int create_listening_socket(unsigned int port)
{
  int fd_server;
  struct sockaddr_in address;
  int i;

  /* create socket */
  if(-1==(fd_server=socket(PF_INET,SOCK_STREAM,0))) { perror("Error creating socket"); return -1; }

  /* set option for the socket: SO_REUSEADDR (will reuse address between invocations of the same program) */
  i=1;
  if(-1==setsockopt(fd_server,SOL_SOCKET,SO_REUSEADDR,(void *)&i,sizeof(i))) { perror("Error configuring socket reuse"); closeskt(fd_server); return -1; }

  /* bind to address :ANY */
  address.sin_family=AF_INET;
  address.sin_addr.s_addr=INADDR_ANY;
  address.sin_port=htons(port);

  if(-1==bind(fd_server,(struct sockaddr *)&address,sizeof(address))) { perror("Error binding to address"); closeskt(fd_server); return -1; }

  /* listen on socket */
  if(-1==listen(fd_server,10)) { perror("Error listening on socket"); closeskt(fd_server); return -1; }
  snprintf(m_buffer,sizeof(m_buffer),"Listening on 0.0.0.0:%d",port);
  debug(m_buffer);

  return fd_server; 
}

/**
 * create a socket that is connected to an address.
 *
 * @param address address to connect to
 * @param port port to connect to
 *
 * @return fd of the opened connection
 */
int create_connected_socket(char *address,unsigned int port)
{
  int fd;
  struct sockaddr_in addr;

  /* create socket */
  if(-1==(fd=socket(PF_INET,SOCK_STREAM,0))) { perror("Error creating socket"); return -1; }

  /* fill address structure */
  addr.sin_family=AF_INET;
  addr.sin_addr.s_addr=resolve(address);
  addr.sin_port=htons(port);

  if(0==addr.sin_addr.s_addr) return -1; /* error resolving name */
  /* connect to remote host */
  snprintf(m_buffer,sizeof(m_buffer),"Connecting to %s:%d",address,port);
  debug(m_buffer);
  if(-1==connect(fd,(struct sockaddr *)&addr,sizeof(addr))) { perror("Error connecting to host"); return -1; }

  return fd;
}

unsigned long resolve(char *address)
{
  struct hostent *resolved;
  struct in_addr addr;

  if(NULL==(resolved=gethostbyname(address))) { perror("Error resolving"); return 0; }

  memcpy(&addr,resolved->h_addr,sizeof(addr));

  return addr.s_addr;
}

/**
 * whether a fd does have data waiting or not.
 *
 * @param fd array of fd to ask
 * @param nfd number of fds
 * @param time time to wait for data
 *
 * @return 1 on data waiting to be read, else return 0
 */
unsigned char can_read(int *fd,int nfd,float time)
{
  fd_set rfd;
  struct timeval timeout;
  int maxfd=0,i;

  assert(fd>=0);

  /* configure timeout */
  timeout.tv_sec=(int)time;
  timeout.tv_usec=(time-(int)time)*1000000;

  /* configure rfd */
  FD_ZERO(&rfd);
  for(i=0;i<nfd;i++)
  {
    FD_SET(fd[i],&rfd);
    maxfd=MAX(maxfd,fd[i]);
  }

  return (select(maxfd+1,&rfd,NULL,NULL,time<0?NULL:&timeout)>0)?1:0;
}

/**
 * check whether fd is at eof
 * @param fd socket to check
 *
 * @return true on eof, false otherwise
 */
unsigned char socketeof(int fd)
{
  unsigned char buffer;
  return 0==recv(fd,&buffer,1,MSG_PEEK|MSG_DONTWAIT);
}