commit 7db1f7a9752d121e185ad3714cd946c271537999 Author: ps Date: Thu Jan 20 22:15:41 2011 +0000 initial commit git-svn-id: file:///home/ps/projects/distributor/trunk@1 4c72226d-0938-4c61-bee9-4ad40ed711b9 diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..e830699 --- /dev/null +++ b/Makefile @@ -0,0 +1,8 @@ +CFLAGS=-DHOSTNAME=\"`hostname -f`\" -g + +all: dist + +dist: dist.o utils.o + +clean: + rm -f dist *.o diff --git a/dist.c b/dist.c new file mode 100644 index 0000000..4bb8e41 --- /dev/null +++ b/dist.c @@ -0,0 +1,155 @@ +#include +#include +#include + +#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; +}; + +char *domains[]={"fakehermes.org","iteisa.net",NULL}; +struct serverinfo servers[]={ + {"mail.gutierrezdequevedo.com",2525}, + {"94.23.193.98",25} +}; + +unsigned long connid=0; + +struct serverinfo *get_server(char *domain) +{ + int i; + for(i=0;domains[i];i++) + if(!cmp(domain,domains[i])) + return &servers[i]; + + 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); +} diff --git a/utils.c b/utils.c new file mode 100644 index 0000000..e6945a0 --- /dev/null +++ b/utils.c @@ -0,0 +1,203 @@ +/** + * Copyright (C) 2007 Juan José Gutiérrez de Quevedo + * + * 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 + */ +#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%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); + + /* 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;i0)?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); +} diff --git a/utils.h b/utils.h new file mode 100644 index 0000000..4261e50 --- /dev/null +++ b/utils.h @@ -0,0 +1,68 @@ +/** + * Copyright (C) 2007 Juan José Gutiérrez de Quevedo + * + * 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 + */ +#ifndef UTILS_H +#define UTILS_H + +#include +#include +#include +#include +#include +#include +#ifdef WIN32 + #include + #include +#else + #include + #include + #include + #include + #include +#endif /* WIN32 */ + +#define BUFLEN 512 /* max length of strings */ + +#ifndef MSG_NOSIGNAL + #define MSG_NOSIGNAL 0 +#endif /* MSG_NOSIGNAL */ + +/* utility macros */ +#define cmp(x,y) (NULL==x||NULL==y||strncasecmp(x,y,strlen(y))) +#define write_string(x,y) do { snprintf(m_buffer,sizeof(m_buffer),"w>%s",y); debug(m_buffer); send(x,y,strlen(y),MSG_NOSIGNAL); send(x,"\r\n",2,MSG_NOSIGNAL); } while(0) +#define condfree(x) do { if(NULL!=x) free(x); x=NULL; } while(0) +#ifndef WIN32 + #define safestrdup(x,y) do { assert(NULL!=y); if(NULL==(x=strndup(y,strlen(y)))) { perror("Error duplicating string"); exit(-1); } } while(0) + #define closeskt(x); do { if(-1!=x) { close(x); x=-1; } } while(0) +#else + #define safestrdup(x,y) do { assert(NULL!=y); if(NULL==(x=strdup(y))) { perror("Error duplicating string"); exit(-1); } } while(0) + #define closeskt(x); do { if(-1!=x) { closesocket(x); x=-1; } } while(0) +#endif /* WIN32 */ +#define _(x) x +#define MAX(x,y) (((x)>(y))?(x):(y)) +#define free_and_read_string(x,y) do { condfree(x); x=read_string(y); } while(0) +#define debug(x) do { syslog(LOG_DEBUG,"%s:%d [%ld] %s",__FILE__,__LINE__,connid,x); printf("%s:%d [%ld] %s\n",__FILE__,__LINE__,connid,x); } while(0) + +char *read_string(int); +int create_listening_socket(unsigned int); +int create_connected_socket(char *,unsigned int); +unsigned long resolve(char *); +unsigned char can_read(int *,int,float); +unsigned char socketeof(int); + +#endif /* UTILS_H */