tim (06/18/82)
/*
*
* TITLE : nmail
*
* PURPOSE : To pre-process network addresses finding the shortest
* path through the network
*
* PROGRAMMER : Timothy W. Curry at University of Central Florida
*
* DATE : April 7, 1982
*
* ENTRY PTS. : main
*
* PARAMETERS : addresses of the form: name or site!name or name@arpa_site
*
*/
/* include the headers to work with standard I/O; isdigit; nmailer defines */
#include <stdio.h>
#include <ctype.h>
#include "nmail.h"
main(argc,argv)
int argc;
char *argv[];
{ /*
* Variable Usage:
* net - the input file descriptor name for the network topology file
* site_name - a storage buffer to hold the name of a site
* plen,psrc,pdest - pointer variables used to build the list of site
* names. plen holds the length of the site name; psrc holds
* the current character position in the source buffer; pdest
* in the destination buffer
* dest - holds the name of the site we are trying to reach
* addr - holds both the name of the destination site and name of the
* user to receive the message
* i,k,j,l,m,n - integer counters
* ppos - keeps track of the current character position in paths
* ptr - index into the list of site links
* used - an array to hold the sites already visited while finding
* the shortest path
* pstk - the stack onto which the breadth first search places values
*/
FILE *net,*fopen();
char site_name[SITENAMELEN];
char *plen,*psrc,*pdest;
char paths[256],dest[14],addr[30];
int i,j,k,l,m,n,ppos;
short int *ptr,used[MAXSITES],pstk[MAXSITES][2];
if (argc == 1)
{ fprintf(stderr,"nmail: no addresses given.\n");
nmailusage();
}
if ((net = fopen(NETFILE,"r")) == NULL)
{ fprintf(stderr,"nmail: can't open network configuration file.\n");
exit(1);
}
/* the SITES buffer will consist of a byte with the length of
the site name in it followed by the site name */
*SITES = '\0';
pdest = SITES;
for (NUMSITES=1; ; NUMSITES++)
{ if ((pdest-SITES+SITENAMELEN) > SITEBUFSZ)
{ fprintf(stderr,"SITES buffer overflowed\n");
exit(1);
}
fscanf(net,"%s",site_name);
if (isdigit(*site_name)) break;
for (plen=pdest,psrc=site_name; *++pdest = *psrc++; (*plen)++);
}
/* LINKS will be an array of numbers indicating which sites are connected
to which. LINDEX is used to index into the LINKS array. */
LINKS[1] = (short int) atoi(site_name);
LINDEX[1] = &LINKS[1];
for (i=2,j=1; i<=NUMSITES+1 ; i++)
{ while (LINKS[j] != 0)
{ fscanf(net,"%d",&k);
j++;
LINKS[j] = (short int) k;
}
LINDEX[i] = &LINKS[j];
j--;
}
/* the last number was the value for the local site */
Local = LINKS[j];
/* initialize the buffer to mail */
strcpy(paths,"mail ");
ppos = 5;
for (i=1; i<argc ;i++)
{ addr[0] = '\0';
/* if its a local address, then no need to process it */
if (!(index(argv[i],'@')) && !(index(argv[i],'!')))
{ strcat(paths,argv[i]);
strcat(paths," ");
ppos += strlen(argv[i]) + 1;
}
/* otherwise a path must be found ! */
else
{ if (index(argv[i],'@') && !(index(argv[i],'!'))) strcpy(addr,ARPA);
strcat(addr,argv[i]);
strcat(addr," ");
/* set dest = name of destination site */
for (j=0; addr[j] != '!' ;j++)
{ dest[j] = addr[j];
dest[j+1] = '\0';
if (dest[j] == '\0')
{ fprintf(stderr,"nmail: improperly formed address.\n");
nmailusage();
}
}
/* find the numeric index of dest for LINDEX to use */
for (j=0,k=1,m = strlen(dest); k<NUMSITES ;k++)
{ l = SITES[j];
if (l == m)
{ for (j++,l+=j,n=0; j<l ; j++,n++)
if (SITES[j] != dest[n]) break;
if (j == l) break;
j = l;
}
else j += l + 1;
}
if (k == NUMSITES)
{ fprintf(stderr,"nmail: site %s is not in the network.\n",dest);
exit(1);
}
/* do a breadth first search to find a path from source to sink */
if (k != Local)
{ for (j=0,l=1,m=0,used[0] = k; k!=Local ;k=pstk[m++][1])
{ for (ptr=LINDEX[k]; ptr<LINDEX[k+1] ;ptr++)
{ for (n=0; n<l ;n++) if (used[n] == *ptr) break;
if (n==l)
{ used[l] = *ptr;
l++;
pstk[j][0] = k;
pstk[j][1] = *ptr;
j++;
}
}
}
/* convert the numeric site values to thier character names
and place them in the paths buffer */
k = pstk[m-1][0];
while (k != pstk[0][0])
{ for (j=0,l=0; j<k-1 ;j++) l += SITES[l] + 1;
n = SITES[l];
for (j=0,l++; j<n ;j++,l++,ppos++) paths[ppos] = SITES[l];
paths[ppos++] = '!';
for ( ; pstk[m][1] != k ;m--);
k = pstk[m][0];
}
paths[ppos] = '\0';
}
strcat(paths,addr);
ppos += strlen(addr);
}
}
/* when all the paths are resolved, pass control over to mail */
printf("%s\n",paths);
execl("/usr/ucb/mail","mail",paths,0);
}
nmailusage()
{ fprintf(stderr,"usage: nmail addr {addr} \nWhere addr = site!name for ");
fprintf(stderr,"uucp-address or name@site for ARPANET-address.\n");
exit(1);
}