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Internet Info 1994 March
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SMTPSERV.C
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C/C++ Source or Header
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1988-07-24
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18KB
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794 lines
/* SMTP Server state machine - see RFC 821
* enhanced 4/88 Dave Trulli nn2z
*/
#include <stdio.h>
#include <time.h>
#ifdef UNIX
#include <sys/types.h>
#endif
#include <ctype.h>
#include "global.h"
#include "mbuf.h"
#include "netuser.h"
#include "timer.h"
#include "tcp.h"
#include "smtp.h"
char *getname();
void mail_delete();
static int rqueuejob();
int queuejob();
int validate_address();
long get_msgid();
struct list *addlist();
struct list * expandalias();
/* Command table */
static char *commands[] = {
"helo",
#define HELO_CMD 0
"noop",
#define NOOP_CMD 1
"mail from:",
#define MAIL_CMD 2
"quit",
#define QUIT_CMD 3
"rcpt to:",
#define RCPT_CMD 4
"help",
#define HELP_CMD 5
"data",
#define DATA_CMD 6
"rset",
#define RSET_CMD 7
NULLCHAR
};
/* Reply messages */
static char help[] = "214-Commands:\r\n214-HELO NOOP MAIL QUIT RCPT HELP DATA RSET\r\n214 End\r\n";
static char banner[] = "220 %s SMTP ready\r\n";
static char closing[] = "221 Closing\r\n";
static char ok[] = "250 Ok\r\n";
static char reset[] = "250 Reset state\r\n";
static char sent[] = "250 Sent\r\n";
static char ourname[] = "250 %s, Share and Enjoy!\r\n";
static char enter[] = "354 Enter mail, end with .\r\n";
static char ioerr[] = "452 Temp file write error\r\n";
static char mboxerr[] = "452 Mailbox write error\r\n";
static char badcmd[] = "500 Command unrecognized\r\n";
static char syntax[] = "501 Syntax error\r\n";
static char needrcpt[] = "503 Need RCPT (recipient)\r\n";
static char unknown[] = "550 <%s> address unknown\r\n";
static struct tcb *smtp_tcb;
/* Start up SMTP receiver service */
smtp1(argc,argv)
int argc;
char *argv[];
{
struct socket lsocket;
void r_mail(),s_mail();
lsocket.address = ip_addr;
if(argc < 2)
lsocket.port = SMTP_PORT;
else
lsocket.port = atoi(argv[1]);
smtp_tcb = open_tcp(&lsocket,NULLSOCK,
TCP_SERVER,0,r_mail,NULLVFP,s_mail,0,(char *)NULL);
}
/* Shutdown SMTP service (existing connections are allowed to finish) */
smtp0()
{
if(smtp_tcb != NULLTCB)
close_tcp(smtp_tcb);
}
/* SMTP connection state change upcall handler */
static void
s_mail(tcb,old,new)
struct tcb *tcb;
char old,new;
{
struct mail *mp,*mail_create();
switch(new){
#ifdef QUICKSTART
case SYN_RECEIVED:
#else
case ESTABLISHED:
#endif
if((mp = mail_create(tcb)) == NULLMAIL){
close_tcp(tcb);
break;
}
(void) tprintf(mp->tcb,banner,hostname);
log(tcb,"open SMTP");
break;
case CLOSE_WAIT:
close_tcp(tcb);
break;
case CLOSED:
log(tcb,"close SMTP");
mp = (struct mail *)tcb->user;
mail_delete(mp);
del_tcp(tcb);
/* Check if server is being shut down */
if(tcb == smtp_tcb)
smtp_tcb = NULLTCB;
break;
}
}
/* SMTP receiver upcall handler */
static void
r_mail(tcb,cnt)
struct tcb *tcb;
int16 cnt;
{
register struct mail *mp;
char c;
struct mbuf *bp;
char *inet_ntoa();
void docommand(),doline();
if((mp = (struct mail *)tcb->user) == NULLMAIL){
/* Unknown session */
close_tcp(tcb);
return;
}
recv_tcp(tcb,&bp,cnt);
/* Assemble an input line in the session buffer.
* Return if incomplete
*/
while(pullup(&bp,&c,1) == 1){
switch(c){
case '\r': /* Strip cr's */
#ifdef MSDOS
case '\032': /* Strip ctrl/Z's */
#endif
continue;
case '\n': /* Complete line; process it */
mp->buf[mp->cnt] = '\0';
doline(mp);
break;
default: /* Assemble line */
if(mp->cnt != LINELEN-1)
mp->buf[mp->cnt++] = c;
break;
}
}
}
/* Process a line read on an SMTP connection (any state) */
static void
doline(mp)
register struct mail *mp;
{
void docommand(),deliver();
switch(mp->state){
case COMMAND_STATE:
docommand(mp);
break;
case DATA_STATE:
tcp_output(mp->tcb); /* Send ACK; disk I/O is slow */
if(mp->buf[0] == '.' && mp->buf[1] == '\0'){
mp->state = COMMAND_STATE;
/* Also sends appropriate response */
deliver(mp);
fclose(mp->data);
mp->data = NULLFILE;
del_list(mp->to);
mp->to = NULLLIST;
break;
}
/* for UNIX mail compatiblity */
if (strncmp(mp->buf,"From ",5) == 0)
(void) putc('>',mp->data);
/* Append to data file */
if(fprintf(mp->data,"%s\n",mp->buf) < 0){
mp->state = COMMAND_STATE;
(void) tprintf(mp->tcb,ioerr);
}
break;
}
mp->cnt = 0;
}
/* Create control block, initialize */
static struct mail *
mail_create(tcb)
register struct tcb *tcb;
{
register struct mail *mp;
if((mp = (struct mail *)calloc(1,sizeof (struct mail))) == NULLMAIL)
return NULLMAIL;
mp->tcb = tcb; /* Downward pointer */
tcb->user = (char *)mp; /* Upward pointer */
return mp;
}
/* Free resources, delete control block */
static void
mail_delete(mp)
register struct mail *mp;
{
if (mp == NULLMAIL)
return;
if(mp->system != NULLCHAR)
free(mp->system);
if(mp->from != NULLCHAR)
free(mp->from);
if(mp->data != NULLFILE)
fclose(mp->data);
del_list(mp->to);
free((char *)mp);
}
/* Parse and execute mail commands */
static void
docommand(mp)
register struct mail *mp;
{
register char **cmdp,*arg,*cp,*cmd;
struct list *ap;
FILE *tmpfile();
long t;
char address_type;
cmd = mp->buf;
if(mp->cnt < 4){
/* Can't be a legal SMTP command */
(void) tprintf(mp->tcb,badcmd);
return;
}
cmd = mp->buf;
/* Translate entire buffer to lower case */
for(cp = cmd;*cp != '\0';cp++)
*cp = tolower(*cp);
/* Find command in table; if not present, return syntax error */
for(cmdp = commands;*cmdp != NULLCHAR;cmdp++)
if(strncmp(*cmdp,cmd,strlen(*cmdp)) == 0)
break;
if(*cmdp == NULLCHAR){
(void) tprintf(mp->tcb,badcmd);
return;
}
arg = &cmd[strlen(*cmdp)];
/* Skip spaces after command */
while(*arg == ' ')
arg++;
/* Execute specific command */
switch(cmdp-commands){
case HELO_CMD:
if(mp->system != NULLCHAR)
free(mp->system);
if((mp->system = malloc((unsigned)strlen(arg)+1)) == NULLCHAR){
/* If the system is out of memory, just close */
close_tcp(mp->tcb);
break;
} else {
strcpy(mp->system,arg);
(void) tprintf(mp->tcb,ourname,hostname);
}
break;
case NOOP_CMD:
(void) tprintf(mp->tcb,ok);
break;
case MAIL_CMD:
if(mp->from != NULLCHAR)
free(mp->from);
if((mp->from = malloc((unsigned)strlen(arg)+1)) == NULLCHAR){
/* If the system is out of memory, just close */
close_tcp(mp->tcb);
break;
} else {
if((cp = getname(arg)) == NULLCHAR){
(void) tprintf(mp->tcb,syntax);
break;
}
strcpy(mp->from,cp);
(void) tprintf(mp->tcb,ok);
}
break;
case QUIT_CMD:
(void) tprintf(mp->tcb,closing);
close_tcp(mp->tcb);
break;
case RCPT_CMD: /* Specify recipient */
if((cp = getname(arg)) == NULLCHAR){
(void) tprintf(mp->tcb,syntax);
break;
}
/* check if address is ok */
if ((address_type = validate_address(cp)) == BADADDR) {
(void) tprintf(mp->tcb,unknown,cp);
break;
}
/* if a local address check for an alias */
if (address_type == LOCAL)
expandalias(&mp->to, cp);
else
/* a remote address is added to the list */
addlist(&mp->to, cp, address_type);
(void) tprintf(mp->tcb,ok);
break;
case HELP_CMD:
(void) tprintf(mp->tcb,help);
break;
case DATA_CMD:
if(mp->to == NULLLIST){
(void) tprintf(mp->tcb,needrcpt);
break;
}
tcp_output(mp->tcb); /* Send ACK; disk I/O is slow */
if((mp->data = tmpfile()) == NULLFILE){
(void) tprintf(mp->tcb,ioerr);
break;
}
/* Add timestamp; ptime adds newline */
time(&t);
fprintf(mp->data,"Received: ");
if(mp->system != NULLCHAR)
fprintf(mp->data,"from %s ",mp->system);
fprintf(mp->data,"by %s with SMTP\n\tid AA%ld ; %s",
hostname, get_msgid(), ptime(&t));
if(ferror(mp->data)){
(void) tprintf(mp->tcb,ioerr);
} else {
mp->state = DATA_STATE;
(void) tprintf(mp->tcb,enter);
}
break;
case RSET_CMD:
del_list(mp->to);
mp->to = NULLLIST;
mp->state = COMMAND_STATE;
(void) tprintf(mp->tcb,reset);
break;
}
}
/* Given a string of the form <user@host>, extract the part inside the
* brackets and return a pointer to it.
*/
static
char *
getname(cp)
register char *cp;
{
register char *cp1;
if((cp = index(cp,'<')) == NULLCHAR)
return NULLCHAR;
cp++; /* cp -> first char of name */
if((cp1 = index(cp,'>')) == NULLCHAR)
return NULLCHAR;
*cp1 = '\0';
return cp;
}
/* Deliver mail to the appropriate mail boxes and delete temp file */
static
void
deliver(mp)
register struct mail *mp;
{
int ret;
/* send to the rqueue */
if ((smtpmode & QUEUE) != 0) {
ret = router_queue(mp->tcb,mp->data,mp->from,mp->to);
if (ret != 0)
(void) tprintf(mp->tcb,ioerr);
} else {
ret = mailit(mp->tcb,mp->data,mp->from,mp->to);
if (ret != 0)
(void) tprintf(mp->tcb,mboxerr);
}
if (ret == 0)
(void) tprintf(mp->tcb,sent);
}
/* used to save local mail or reroute remote mail */
mailit(tcb,data,from,to)
struct tcb *tcb;
FILE *data;
char *from;
struct list *to;
{
register struct list *ap;
register FILE *fp;
int c;
char mailbox[50];
char *cp;
char *desthost;
int fail = 0;
time_t t;
for(ap = to;ap != NULLLIST;ap = ap->next) {
fseek(data,0L,0); /* rewind */
/* non local mail queue it */
if (ap->type == DOMAIN) {
if ((desthost = index(ap->val,'@')) != NULLCHAR);
desthost++;
fail = queuejob(tcb,data,desthost,ap->val,from);
} else {
/* strip off host name */
if ((cp = index(ap->val,'@')) != NULLCHAR)
*cp = '\0';
/* truncate long user names */
if (strlen(ap->val) > MBOXLEN)
ap->val[MBOXLEN] = '\0';
/* if mail file is busy save it in our smtp queue
* and let the smtp daemon try later.
*/
if (mlock(mailspool,ap->val))
fail = queuejob(tcb,data,hostname,ap->val,from);
else {
sprintf(mailbox,"%s/%s.txt",mailspool,ap->val);
if((fp = fopen(mailbox,"a+")) != NULLFILE) {
time(&t);
fprintf(fp,
"From %s %s",from,ctime(&t));
while((c = getc(data)) != EOF)
if(putc(c,fp) == EOF)
break;
if(ferror(fp))
fail = 1;
else
fprintf(fp,"\n");
/* Leave a blank line between msgs */
fclose(fp);
printf("New mail arrived for %s\n",ap->val);
fflush(stdout);
} else
fail = 1;
(void) rmlock(mailspool,ap->val);
if (fail)
break;
log(tcb,
"SMTP recv: To: %s From: %s",ap->val,from);
}
}
}
}
/* Return Date/Time in Arpanet format in passed string */
char *
ptime(t)
long *t;
{
/* Print out the time and date field as
* "DAY day MONTH year hh:mm:ss ZONE"
*/
register struct tm *ltm;
static char tz[4];
static char str[40];
extern char *getenv();
extern struct tm *localtime();
char *p;
static char *days[7] = {
"Sun","Mon","Tue","Wed","Thu","Fri","Sat" };
static char *months[12] = {
"Jan","Feb","Mar","Apr","May","Jun",
"Jul","Aug","Sep","Oct","Nov","Dec" };
/* Read the system time */
ltm = localtime(t);
if (*tz == '\0')
if ((p = getenv("TZ")) == NULL)
strcpy(tz,"GMT");
else
strncpy(tz,p,3);
/* rfc 822 format */
sprintf(str,"%s, %.2d %s %02d %02d:%02d:%02d %.3s\n",
days[ltm->tm_wday],
ltm->tm_mday,
months[ltm->tm_mon],
ltm->tm_year,
ltm->tm_hour,
ltm->tm_min,
ltm->tm_sec,
tz);
return(str);
}
long
get_msgid()
{
char sfilename[LINELEN];
char s[20];
register long sequence = 0;
FILE *sfile;
long atol();
sprintf(sfilename,"%s/sequence.seq",mailqdir);
sfile = fopen(sfilename,"r");
/* if sequence file exists, get the value, otherwise set it */
if (sfile != NULL) {
(void) fgets(s,sizeof(s),sfile);
sequence = atol(s);
/* Keep it in range of and 8 digit number to use for dos name prefix. */
if (sequence < 0L || sequence > 99999999L )
sequence = 0;
fclose(sfile);
}
/* increment sequence number, and write to sequence file */
sfile = fopen(sfilename,"w");
fprintf(sfile,"%ld",++sequence);
fclose(sfile);
return sequence;
}
#ifdef MSDOS
/* Illegal characters in a DOS filename */
static char baddoschars[] = "\"[]:|<>+=;,";
#endif
/* test if mail address is valid */
static int
validate_address(s)
char *s;
{
FILE *fp;
char *cp;
int32 addr;
char address_type;
int32 mailroute();
/* if address has @ in it the check dest address */
if ((cp = index(s,'@')) != NULLCHAR) {
cp++;
/* 1st check if its our hostname
* if not then check the hosts file and see
* if we can resolve ther address to a know site
* or one of our aliases
*/
if (strcmp(cp,hostname) != 0) {
if ((addr = mailroute(cp)) == 0
&& (smtpmode & QUEUE) == 0)
return BADADDR;
if (addr != ip_addr)
return DOMAIN;
}
/* on a local address remove the host name part */
*--cp = '\0';
}
/* if using an external router leave address alone */
if ((smtpmode & QUEUE) != 0)
return LOCAL;
/* check for the user%host hack */
if ((cp = index(s,'%')) != NULLCHAR) {
*cp = '@';
cp++;
/* reroute based on host name following the % seperator */
if (mailroute(cp) == 0)
return BADADDR;
else
return DOMAIN;
}
address_type = LOCAL;
#ifdef MSDOS /* dos file name checks */
/* Check for characters illegal in MS-DOS file names */
for(cp = baddoschars;*cp != '\0';cp++){
if(index(s,*cp) != NULLCHAR)
return BADADDR;
}
#endif
return LOCAL;
}
/* place a mail job in the outbound queue */
int
queuejob(tcb,dfile,host,to,from)
struct tcb *tcb;
FILE *dfile;
char *host,*to,*from;
{
FILE *fp;
char tmpstring[50];
char prefix[9];
register int c;
sprintf(prefix,"%ld",get_msgid());
log(tcb,"SMTP queue job %s To: %s From: %s",prefix,to,from);
mlock(mailqdir,prefix);
sprintf(tmpstring,"%s/%s.txt",mailqdir,prefix);
if((fp = fopen(tmpstring,"w")) == NULLFILE) {
(void) rmlock(mailqdir,prefix);
return 1;
}
while((c = getc(dfile)) != EOF)
if(putc(c,fp) == EOF)
break;
if(ferror(fp)){
fclose(fp);
(void) rmlock(mailqdir,prefix);
return 1;
}
fclose(fp);
sprintf(tmpstring,"%s/%s.wrk",mailqdir,prefix);
if((fp = fopen(tmpstring,"w")) == NULLFILE) {
(void) rmlock(mailqdir,prefix);
return 1;
}
fprintf(fp,"%s\n%s\n%s\n",host,from,to);
fclose(fp);
(void) rmlock(mailqdir,prefix);
return 0;
}
/* Deliver mail to the appropriate mail boxes */
int
router_queue(tcb,data,from,to)
struct tcb *tcb;
FILE *data;
char *from;
struct list *to;
{
int c;
register struct list *ap;
FILE *fp;
char tmpstring[50];
char prefix[9];
sprintf(prefix,"%ld",get_msgid());
mlock(routeqdir,prefix);
sprintf(tmpstring,"%s/%s.txt",routeqdir,prefix);
if((fp = fopen(tmpstring,"w")) == NULLFILE) {
(void) rmlock(routeqdir,prefix);
return 1;
}
fseek(data,0L,0); /* rewind */
while((c = getc(data)) != EOF)
if(putc(c,fp) == EOF)
break;
if(ferror(fp)){
fclose(fp);
(void) rmlock(routeqdir,prefix);
return 1;
}
fclose(fp);
sprintf(tmpstring,"%s/%s.wrk",routeqdir,prefix);
if((fp = fopen(tmpstring,"w")) == NULLFILE) {
(void) rmlock(routeqdir,prefix);
return 1;
}
fprintf(fp,"From: %s\n",from);
for(ap = to;ap != NULLLIST;ap = ap->next) {
fprintf(fp,"To: %s\n",ap->val);
}
fclose(fp);
(void) rmlock(routeqdir,prefix);
log(tcb,"SMTP rqueue job %s From: %s",prefix,from);
return 0;
}
/* add an element to the front of the list pointed to by head
** return NULLLIST if out of memory.
*/
struct list *
addlist(head,val,type)
struct list **head;
char *val;
int type;
{
register struct list *tp;
tp = (struct list *)calloc(1,sizeof(struct list));
if (tp == NULLLIST)
return NULLLIST;
tp->next = NULLLIST;
/* allocate storage for the char string */
if ((tp->val = malloc((unsigned)strlen(val)+1)) == NULLCHAR) {
(void) free((char *)tp);
return NULLLIST;
}
strcpy(tp->val,val);
tp->type = type;
/* add entry to front of existing list */
if (*head == NULLLIST)
*head = tp;
else {
tp->next = *head;
*head = tp;
}
return tp;
}
#define SKIPWORD(X) while(*X && *X!=' ' && *X!='\t' && *X!='\n' && *X!= ',') X++;
#define SKIPSPACE(X) while(*X ==' ' || *X =='\t' || *X =='\n' || *X == ',') X++;
/* check for and alias and expand alias into a address list */
struct list *
expandalias(head, user)
struct list **head;
char *user;
{
FILE *fp;
register char *s,*p,*h;
int inalias;
struct list *tp;
char buf[LINELEN];
/* no alias file found */
if ((fp = fopen(alias, "r")) == NULLFILE)
return addlist(head, user, LOCAL);
inalias = 0;
while (fgets(buf,LINELEN,fp) != NULLCHAR) {
p = buf;
if ( *p == '#' || *p == '\0')
continue;
rip(p);
/* if not in an matching entry skip continuation lines */
if (!inalias && isspace(*p))
continue;
/* when processing an active alias check for a continuation */
if (inalias) {
if (!isspace(*p))
break; /* done */
} else {
s = p;
SKIPWORD(p);
*p++ = '\0'; /* end the alias name */
if (strcmp(s,user) != 0)
continue; /* no match go on */
inalias = 1;
}
/* process the recipients on the alias line */
SKIPSPACE(p);
while(*p != '\0' && *p != '#') {
s = p;
SKIPWORD(p);
if (*p != '\0')
*p++ = '\0';
/* find hostname */
if ((h = index(s,'@')) != NULLCHAR)
tp = addlist(head,s,DOMAIN);
else
tp = addlist(head,s,LOCAL);
SKIPSPACE(p);
}
}
(void) fclose(fp);
if (inalias) /* found and processed and alias. */
return tp;
/* no alias found treat as a local address */
return addlist(head, user, LOCAL);
}