distributor/dist.c

169 lines
3.9 KiB
C

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include "utils.h"
extern char m_buffer[4096];
#define BANNER "220 " HOSTNAME " SMTP"
#define HELOANSWER "250 " HOSTNAME
#define CMDUNKNOWN "502 command unimplemented"
#define DOMAINUNKNOWN "553 unknown domain"
#define TEMPERROR "421 delivery error, please retry later"
#define DEFERROR "521 permanent delivery error, do not retry"
#define PORT 25
#define fail() do { perror(__FILE__ ":"); exit(-1); } while(0);
struct serverinfo
{
char *address;
unsigned port;
};
unsigned long connid=0;
struct serverinfo *get_server(char *domain)
{
char buffer[1024];
unsigned long *longs;
/* connect to mysql and get values */
db=mysql_init(NULL);
if(NULL==mysql_real_connect(db,DBHOST,DBUSER,DBPASS,DBNAME,0,NULL,0)) { fprintf(stderr,"%s\n",mysql_error(db)); mysql_close(db); return NULL; }
/* clean string */
escape(db,domain);
/* generate sql */
snprintf(buffer,sizeof buffer,"SELECT `host`,`port` FROM `domains` WHERE `domain`=\"%s\" ORDER BY RAND();",domain);
/* query! */
if(mysql_query(db,buffer)) { fprintf(stderr,"%s\n",mysql_error(db)); mysql_close(db); return NULL; }
for(i=0;row=mysql_fetch_row(db);i++)
{
longs=mysql_fetch_lengths(row);
}
mysql_close(db);
return NULL;
}
char *get_domain(char *line)
{
char *strtmp=NULL;
char *buf=NULL;
safestrdup(buf,strchr(line,'@')+1);
safestrdup(strtmp,strtok(buf," \"><"));
condfree(buf);
return strtmp;
}
void handle_new_connection(unsigned long p_connid,int fd)
{
char *buf=NULL;
char *from=NULL;
char *to=NULL;
char *domain=NULL;
char *serveraddress=NULL;
int fdin=-1;
int fds[2];
char databuffer[8192];
int bytesread;
int fdread,fdwrite;
struct serverinfo *server;
connid=p_connid;
write_string(fd,BANNER);
while(!socketeof(fd))
{
free_and_read_string(buf,fd);
if(!cmp(buf,"HELO")||!cmp(buf,"EHLO"))
write_string(fd,HELOANSWER);
else if(!cmp(buf,"MAIL FROM"))
{
safestrdup(from,buf);
write_string(fd,"250 Ok");
}
else if(!cmp(buf,"RCPT TO"))
{
safestrdup(to,buf);
domain=get_domain(to);
if(NULL==(server=get_server(domain)))
{
write_string(fd,DOMAINUNKNOWN);
exit(-1);
}
condfree(domain);
break;
}
else
write_string(fd,CMDUNKNOWN);
}
if(-1==(fdin=create_connected_socket(server->address,server->port)))
{
write_string(fd,TEMPERROR);
exit(-1);
}
do /* manage errors as we would do an exception, all in one point */
{
/* reproduce initial conversation on the new server */
free_and_read_string(buf,fdin); /* read banner */
write_string(fdin,"HELO " HOSTNAME); do { free_and_read_string(buf,fdin); } while('-'==buf[3]);
write_string(fdin,from); do { free_and_read_string(buf,fdin); } while('-'==buf[3]);
if(cmp(buf,"250")) { write_string(fd,DEFERROR); break; }
write_string(fdin,to);
/* now just copy data from one server to the other */
while(1)
{
fds[0]=fd; fds[1]=fdin;
can_read(fds,2,-1);
if(can_read(&fd,1,0)) { fdread=fd; fdwrite=fdin; }
else { fdread=fdin; fdwrite=fd; }
bytesread=read(fdread,databuffer,sizeof(databuffer));
if(bytesread<=0||write(fdwrite,databuffer,bytesread)<=0)
{
closeskt(fd);
closeskt(fdin);
break;
}
}
}
while(0);
condfree(buf); condfree(to); condfree(from); closeskt(fd); closeskt(fdin);
exit(0);
}
int main(int argc, char **argv)
{
int fd_server=-1,fd=-1;
unsigned long conn=0;
/* ignore dying child */
signal(SIGCHLD,SIG_IGN);
openlog("dist",0,LOG_MAIL);
if(-1==(fd_server=create_listening_socket(PORT))) fail();
while(-1!=(fd=accept(fd_server,NULL,0)))
{
debug("New connection!");
++conn;
switch(fork())
{
case 0: closeskt(fd_server); handle_new_connection(conn,fd);
case -1: fail();
default: closeskt(fd);
}
}
close(fd_server);
closelog();
exit(0);
}