/*========================================================== * Program : accessctrl.c                  Project : smslink * Authors : Philipp Klaus <pklaus@access.ch>. *           Philippe Andersson. * Date    : 11/02/99 * Version : 0.03b * Comment : Handling routines for /etc/gsmaccess ACL. * * Modification History : * - 0.01b (27/01/99) : Initial release. * - 0.02b (06/02/99) : Introduced a boolean to bypass use of *   the ACL system. When the ACCESSFILE is not present, the *   check function always return SUCCESS. Cosmetics. * - 0.03b (11/02/99) : Complete rewrite. Start implementing *   ACL's through "access:network/mask" entries stored in a *   linked list. *========================================================*/#include <stdio.h>#include <stdlib.h>#include <string.h>#include <ctype.h>#include <math.h>                            /* for pow() */#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <dial/modems.h>#include <dial/mdmerrno.h>#include "sms_serv.h"/*========================================================*//**********           GLOBAL VARIABLES             ********//*========================================================*/int use_acl = TRUE;/*========================================================*//**********               FUNCTIONS                ********//*========================================================*/void acl_list_init (acl_list *list){  list->head = NULL;  list->tail = NULL;}                                     /* acl_list_init () *//*========================================================*/int empty_acl_list (acl_list list){  return (list.head == NULL);}                                    /* empty_acl_list () *//*========================================================*/void acl_list_insert (acl_list *list, int action, struct in_addr network,                      unsigned long no_mask){  /* WARNING : the order of the elements IS relevent - has to   * be the same as in the access file => avoid inserting at   * list head. Do it at the tail. */    struct acl_item *element;  /* alloc memory for new element */  element = (struct acl_item *) malloc (sizeof (struct acl_item));  if (!element)    syserr ("sms_serv: can't malloc() for new ACL entry");    /* initialize fields for new element */  element->action = action;  element->network.s_addr = network.s_addr;  element->nomask = no_mask;    /* chain it in the list */  if (empty_acl_list (*list)) {    list->head = element;    list->tail = element;    element->next = NULL;    element->prev = NULL;  }  else {    element->next = NULL;    element->prev = list->tail;    list->tail->next = element;    list->tail = element;  }}                                   /* acl_list_insert () *//*========================================================*/void free_acl_list (acl_list *list){  struct acl_item *cursor;  if (!empty_acl_list (*list)) {    /* hop to element before last */    cursor = list->tail->prev;    /* now go back and clean behind */    while (cursor != NULL) {      free (cursor->next);      cursor->next = NULL;      list->tail = cursor;      cursor = cursor->prev;    }                           /* while (cursor != NULL) */  }                           /* if (!empty_acl_list (... */  /* now clean last element and reset header */  free (list->head);  list->head = NULL;  list->tail = NULL;}                                     /* free_acl_list () *//*========================================================*/#ifdef INCL_DEBUG_CODEvoid print_acl_list (acl_list list){  struct acl_item *cursor;  if (!empty_acl_list (list)) {    cursor = list.head;    fprintf (stdout, "%-5s : [%s] / %d\n",             (cursor->action == ACL_ALLOW) ? "ALLOW" : "DENY", 	    inet_ntoa (cursor->network),            cursor->nomask);    while (cursor->next != NULL) {      cursor = cursor->next;      fprintf (stdout, "%-5s : [%s] / %d\n",               (cursor->action == ACL_ALLOW) ? "ALLOW" : "DENY", 	      inet_ntoa (cursor->network),              cursor->nomask);    }  }  else {    fprintf (stdout, "sms_serv: empty 'ACL' list.\n");  }}                                    /* print_acl_list () */#endif/*========================================================*/int read_acl (acl_list *list) {	  FILE *aclfile;  char *buffer;  int counter = 0;                 /* valid entries count */  int act_char;  int action;  struct in_addr netorip;  int netmask;                       /* as read form file */  unsigned long nomask;  char *ptr, *pptr, *err;	  /*------------------------------------- Initializations */  buffer = mdmalloc (BUFFSIZE);  if (!buffer) {    mdmerrno = -EMDMEM;    return (FAILURE);  }  /* Open input file */  if ((aclfile = fopen (ACCESSFILE, "r")) == NULL) {    use_acl = FALSE;    syslog ((FACILITY | LOG_WARNING), "access control is DISABLED.");    return (SUCCESS);  }  /*------------------------------------ File upload loop */  while ((fgets (buffer, BUFFSIZE, aclfile) != NULL) && (counter < MAXACLS)) {    buffer[strlen (buffer) - 1] = '\0';    /* ignore blank lines and comments */    if (buffer[0] == '#' || buffer[0] == '\0' || buffer[0] == '\n')      continue;    /* parse the line we read - silently ignore invalid ones */#ifdef INCL_DEBUG_CODE   fprintf (stderr, "now parsing : [%s]\n", buffer);#endif    /*.......................................action (int) */    if ((ptr = strchr (buffer, ':')) == NULL)      continue;    *ptr = '\0';    act_char = toupper (buffer[0]);    switch (act_char) {      case 'Y':        action = ACL_ALLOW;	break;      case 'N':        action = ACL_DENY;	break;      default:        continue;    } /* switch () */    ptr++;    /*................................net. or IP (char *) */    if ((pptr = strchr (ptr, '/')) == NULL)      continue;    *pptr = '\0';        if ((strlen (ptr) < 7) || (strlen (ptr) > 15))      continue;        /* convert dotted quad to struct in_addr */    if (!inet_aton (ptr, &netorip)) {#ifdef INCL_DEBUG_CODE      fprintf (stderr, "conversion to s_addr failed for [%s]\n", ptr);#endif      continue;    }          ptr = pptr + 1;    /*......................................netmask (int) */    netmask = strtol (ptr, &err, 10);    if ((*ptr == '\0') || (*err != '\0'))      continue;        if ((netmask < 0) || (netmask > 32))      continue;          /* invert the mask value */    netmask = (32 - netmask);        /* build the mask itself (avoiding overflow) */    if (netmask < 32)      nomask = (pow (2, netmask) - 1);    else      nomask = (unsigned long) 4294967295;    /* now create entry in the list */    acl_list_insert (list, action, netorip, htonl (nomask));        counter++;  }                                    /* while (fgets... */  syslog ((FACILITY | LOG_NOTICE), "successfully loaded %d ACL entries.",         counter);#ifdef INCL_DEBUG_CODE  print_acl_list (*list);#endif  mdmfree (buffer);  return (SUCCESS);}                                          /* read_acl () *//*========================================================*/int check_acl (struct in_addr *address, acl_list list) {  int rule;  struct acl_item *cursor;  if (use_acl) {    if (!empty_acl_list (list)) {      cursor = list.head;      rule = 1;      if ((cursor->network.s_addr | cursor->nomask) ==         (address->s_addr | cursor->nomask)) {        /* we have a match */	if (cursor->action == ACL_DENY) {#ifdef INCL_DEBUG_CODE	  fprintf (stderr, "access denied - rule #%d\n", rule);#endif          return (FAILURE);	}	else {#ifdef INCL_DEBUG_CODE	  fprintf (stderr, "access granted - rule #%d\n", rule);#endif          return (SUCCESS);	}      }      while (cursor->next != NULL) {        cursor = cursor->next;	rule++;        if ((cursor->network.s_addr | cursor->nomask) ==           (address->s_addr | cursor->nomask)) {          /* we have a match */	  if (cursor->action == ACL_DENY) {#ifdef INCL_DEBUG_CODE	    fprintf (stderr, "access denied - rule #%d\n", rule);#endif            return (FAILURE);	  }	  else {#ifdef INCL_DEBUG_CODE	    fprintf (stderr, "access granted - rule #%d\n", rule);#endif            return (SUCCESS);	  }        }      }                                     /* while (... */      /* when nothing matches, defaults to DENY */#ifdef INCL_DEBUG_CODE      fprintf (stderr, "no match found - default deny\n");#endif      return (FAILURE);    }    else {                                  /* empty list */#ifdef INCL_DEBUG_CODE      fprintf (stderr, "empty list - default deny\n");#endif      return (FAILURE);    }  }  else                         /* access control disabled */    return (SUCCESS);}                                         /* check_acl () *//*========================================================*//*========================================================== * EOF : accessctrl.c *===================*/