ref: 40d6302b5f289ad8a617d12fa911197dddafc634
dir: /sys/src/cmd/upas/smtp/spam.c/
#include "common.h"
#include "smtpd.h"
#include <ip.h>
enum {
NORELAY = 0,
DNSVERIFY,
SAVEBLOCK,
DOMNAME,
OURNETS,
OURDOMS,
IP = 0,
STRING,
};
typedef struct Keyword Keyword;
struct Keyword {
char *name;
int code;
};
static Keyword options[] = {
"norelay", NORELAY,
"verifysenderdom", DNSVERIFY,
"saveblockedmsg", SAVEBLOCK,
"defaultdomain", DOMNAME,
"ournets", OURNETS,
"ourdomains", OURDOMS,
0, NONE,
};
static Keyword actions[] = {
"allow", ACCEPT,
"block", BLOCKED,
"deny", DENIED,
"dial", DIALUP,
"delay", DELAY,
0, NONE,
};
static int hisaction;
static List ourdoms;
static List badguys;
static ulong v4peerip;
static char* getline(Biobuf*);
static int cidrcheck(char*);
static int
findkey(char *val, Keyword *p)
{
for(; p->name; p++)
if(strcmp(val, p->name) == 0)
break;
return p->code;
}
char*
actstr(int a)
{
static char buf[32];
Keyword *p;
for(p = actions; p->name; p++)
if(p->code == a)
return p->name;
if(a == NONE)
return "none";
sprint(buf, "%d", a);
return buf;
}
int
getaction(char *s, char *type)
{
char buf[1024];
Keyword *k;
if(s == nil || *s == 0)
return ACCEPT;
for(k = actions; k->name != 0; k++){
snprint(buf, sizeof buf, "/mail/ratify/%s/%s/%s", k->name, type, s);
if(access(buf,0) >= 0)
return k->code;
}
return ACCEPT;
}
int
istrusted(char *s)
{
char buf[Pathlen];
if(s == nil || *s == 0)
return 0;
snprint(buf, sizeof buf, "/mail/ratify/trusted/%s", s);
return access(buf, 0) >= 0;
}
void
getconf(void)
{
Biobuf *bp;
char *cp, *p;
String *s;
char buf[512];
uchar addr[4];
v4parseip(addr, nci->rsys);
v4peerip = nhgetl(addr);
trusted = istrusted(nci->rsys);
hisaction = getaction(nci->rsys, "ip");
if(debug){
fprint(2, "istrusted(%s)=%d\n", nci->rsys, trusted);
fprint(2, "getaction(%s, ip)=%s\n", nci->rsys, actstr(hisaction));
}
snprint(buf, sizeof(buf), "%s/smtpd.conf", UPASLIB);
bp = sysopen(buf, "r", 0);
if(bp == 0)
return;
for(;;){
cp = getline(bp);
if(cp == 0)
break;
p = cp + strlen(cp) + 1;
switch(findkey(cp, options)){
case NORELAY:
if(fflag == 0 && strcmp(p, "on") == 0)
fflag++;
break;
case DNSVERIFY:
if(rflag == 0 && strcmp(p, "on") == 0)
rflag++;
break;
case SAVEBLOCK:
if(sflag == 0 && strcmp(p, "on") == 0)
sflag++;
break;
case DOMNAME:
if(dom == 0)
dom = strdup(p);
break;
case OURNETS:
if (trusted == 0)
trusted = cidrcheck(p);
break;
case OURDOMS:
while(*p){
s = s_new();
s_append(s, p);
listadd(&ourdoms, s);
p += strlen(p) + 1;
}
break;
default:
break;
}
}
sysclose(bp);
}
/*
* match a user name. the only meta-char is '*' which matches all
* characters. we only allow it as "*", which matches anything or
* an * at the end of the name (e.g., "username*") which matches
* trailing characters.
*/
static int
usermatch(char *pathuser, char *specuser)
{
int n;
n = strlen(specuser) - 1;
if(specuser[n] == '*'){
if(n == 0) /* match everything */
return 0;
return strncmp(pathuser, specuser, n);
}
return strcmp(pathuser, specuser);
}
static int
dommatch(char *pathdom, char *specdom)
{
int n;
if (*specdom == '*'){
if (specdom[1] == '.' && specdom[2]){
specdom += 2;
n = strlen(pathdom) - strlen(specdom);
if(n == 0 || (n > 0 && pathdom[n-1] == '.'))
return strcmp(pathdom + n, specdom);
return n;
}
}
return strcmp(pathdom, specdom);
}
/*
* figure out action for this sender
*/
int
blocked(String *path)
{
String *lpath;
int action;
if(debug)
fprint(2, "blocked(%s)\n", s_to_c(path));
/* if the sender's IP address is blessed, ignore sender email address */
if(trusted){
if(debug)
fprint(2, "\ttrusted => trusted\n");
return TRUSTED;
}
/* if sender's IP address is blocked, ignore sender email address */
if(hisaction != ACCEPT){
if(debug)
fprint(2, "\thisaction=%s => %s\n", actstr(hisaction), actstr(hisaction));
return hisaction;
}
/* convert to lower case */
lpath = s_copy(s_to_c(path));
s_tolower(lpath);
/* classify */
action = getaction(s_to_c(lpath), "account");
if(debug)
fprint(2, "\tgetaction account %s => %s\n", s_to_c(lpath), actstr(action));
s_free(lpath);
return action;
}
/*
* get a canonicalized line: a string of null-terminated lower-case
* tokens with a two null bytes at the end.
*/
static char*
getline(Biobuf *bp)
{
char c, *cp, *p, *q;
int n;
static char *buf;
static int bufsize;
for(;;){
cp = Brdline(bp, '\n');
if(cp == 0)
return 0;
n = Blinelen(bp);
cp[n-1] = 0;
if(buf == 0 || bufsize < n + 1){
bufsize += 512;
if(bufsize < n + 1)
bufsize = n + 1;
buf = realloc(buf, bufsize);
if(buf == 0)
break;
}
q = buf;
for (p = cp; *p; p++){
c = *p;
if(c == '\\' && p[1]) /* we don't allow \<newline> */
c = *++p;
else
if(c == '#')
break;
else
if(c == ' ' || c == '\t' || c == ',')
if(q == buf || q[-1] == 0)
continue;
else
c = 0;
*q++ = tolower(c);
}
if(q != buf){
if(q[-1])
*q++ = 0;
*q = 0;
break;
}
}
return buf;
}
static int
isourdom(char *s)
{
Link *l;
if(strchr(s, '.') == nil)
return 1;
for(l = ourdoms.first; l; l = l->next){
if(dommatch(s, s_to_c(l->p)) == 0)
return 1;
}
return 0;
}
int
forwarding(String *path)
{
char *cp, *s;
String *lpath;
if(debug)
fprint(2, "forwarding(%s)\n", s_to_c(path));
/* first check if they want loopback */
lpath = s_copy(s_to_c(s_restart(path)));
if(nci->rsys && *nci->rsys){
cp = s_to_c(lpath);
if(strncmp(cp, "[]!", 3) == 0){
found:
s_append(path, "[");
s_append(path, nci->rsys);
s_append(path, "]!");
s_append(path, cp + 3);
s_terminate(path);
s_free(lpath);
return 0;
}
cp = strchr(cp,'!'); /* skip our domain and check next */
if(cp++ && strncmp(cp, "[]!", 3) == 0)
goto found;
}
/* if mail is from a trusted IP addr, allow it to forward */
if(trusted) {
s_free(lpath);
return 0;
}
/* sender is untrusted; ensure receiver is in one of our domains */
for(cp = s_to_c(lpath); *cp; cp++) /* convert receiver lc */
*cp = tolower(*cp);
for(s = s_to_c(lpath); cp = strchr(s, '!'); s = cp + 1){
*cp = 0;
if(!isourdom(s)){
s_free(lpath);
return 1;
}
}
s_free(lpath);
return 0;
}
int
masquerade(String *path, char *him)
{
char *cp, *s;
String *lpath;
int rv = 0;
if(debug)
fprint(2, "masquerade(%s)\n", s_to_c(path));
if(trusted)
return 0;
if(path == nil)
return 0;
lpath = s_copy(s_to_c(path));
/* sender is untrusted; ensure receiver is in one of our domains */
for(cp = s_to_c(lpath); *cp; cp++) /* convert receiver lc */
*cp = tolower(*cp);
s = s_to_c(lpath);
/* scan first element of ! or last element of @ paths */
if((cp = strchr(s, '!')) != nil){
*cp = 0;
if(isourdom(s))
rv = 1;
} else if((cp = strrchr(s, '@')) != nil){
if(isourdom(cp + 1))
rv = 1;
} else {
if(isourdom(him))
rv = 1;
}
s_free(lpath);
return rv;
}
/* this is a v4 only check */
static int
cidrcheck(char *cp)
{
char *p;
ulong a, m;
uchar addr[IPv4addrlen];
uchar mask[IPv4addrlen];
if(v4peerip == 0)
return 0;
/* parse a list of CIDR addresses comparing each to the peer IP addr */
while(cp && *cp){
v4parsecidr(addr, mask, cp);
a = nhgetl(addr);
m = nhgetl(mask);
/*
* if a mask isn't specified, we build a minimal mask
* instead of using the default mask for that net. in this
* case we never allow a class A mask (0xff000000).
*/
if(strchr(cp, '/') == 0){
m = 0xff000000;
p = cp;
for(p = strchr(p, '.'); p && p[1]; p = strchr(p + 1, '.'))
m = (m>>8)|0xff000000;
/* force at least a class B */
m |= 0xffff0000;
}
if((v4peerip & m) == a)
return 1;
cp += strlen(cp) + 1;
}
return 0;
}
int
isbadguy(void)
{
Link *l;
/* check if this IP address is banned */
for(l = badguys.first; l; l = l->next)
if(cidrcheck(s_to_c(l->p)))
return 1;
return 0;
}
void
addbadguy(char *p)
{
listadd(&badguys, s_copy(p));
};
char*
dumpfile(char *sender)
{
int i, fd;
ulong h;
static char buf[512];
char *cp;
if (sflag == 1){
cp = ctime(time(0));
cp[7] = 0;
if(cp[8] == ' ')
sprint(buf, "%s/queue.dump/%s%c", SPOOL, cp + 4, cp[9]);
else
sprint(buf, "%s/queue.dump/%s%c%c", SPOOL, cp + 4, cp[8], cp[9]);
cp = buf + strlen(buf);
if(access(buf, 0) < 0 && sysmkdir(buf, 0777) < 0)
return "/dev/null";
h = 0;
while(*sender)
h = h*257 + *sender++;
for(i = 0; i < 50; i++){
h += lrand();
sprint(cp, "/%lud", h);
if(access(buf, 0) >= 0)
continue;
fd = create(buf, ORDWR, 0666);
if(fd >= 0){
if(debug)
fprint(2, "saving in %s\n", buf);
close(fd);
return buf;
}
}
}
return "/dev/null";
}
char *validator = "/mail/lib/validateaddress";
int
recipok(char *user)
{
char *cp, *p, c;
char buf[512];
int n;
Biobuf *bp;
int pid;
Waitmsg *w;
if(shellchars(user)){
syslog(0, "smtpd", "shellchars in user name");
return 0;
}
if(access(validator, AEXEC) == 0)
switch(pid = fork()) {
case -1:
break;
case 0:
execl(validator, "validateaddress", user, nil);
exits(0);
default:
while(w = wait()) {
if(w->pid != pid)
continue;
if(w->msg[0] != 0){
/*
syslog(0, "smtpd", "validateaddress %s: %s", user, w->msg);
*/
return 0;
}
break;
}
}
snprint(buf, sizeof(buf), "%s/names.blocked", UPASLIB);
bp = sysopen(buf, "r", 0);
if(bp == 0)
return 1;
for(;;){
cp = Brdline(bp, '\n');
if(cp == 0)
break;
n = Blinelen(bp);
cp[n-1] = 0;
while(*cp == ' ' || *cp == '\t')
cp++;
for(p = cp; c = *p; p++){
if(c == '#')
break;
if(c == ' ' || c == '\t')
break;
}
if(p > cp){
*p = 0;
if(cistrcmp(user, cp) == 0){
syslog(0, "smtpd", "names.blocked blocks %s", user);
Bterm(bp);
return 0;
}
}
}
Bterm(bp);
return 1;
}
/*
* a user can opt out of spam filtering by creating
* a file in his mail directory named 'nospamfiltering'.
*/
int
optoutofspamfilter(char *addr)
{
char *p, *f;
int rv;
p = strchr(addr, '!');
if(p)
p++;
else
p = addr;
rv = 0;
f = smprint("/mail/box/%s/nospamfiltering", p);
if(f != nil){
rv = access(f, 0) == 0;
free(f);
}
return rv;
}