ref: 53fbb0515159465421053c3165b1aa9da196aa4d
dir: /sys/src/cmd/upas/pop3/pop3.c/
#include "common.h"
#include <ctype.h>
#include <auth.h>
#include <libsec.h>
typedef struct Cmd Cmd;
struct Cmd
{
char *name;
int needauth;
int (*f)(char*);
};
static void hello(void);
static int apopcmd(char*);
static int capacmd(char*);
static int delecmd(char*);
static int listcmd(char*);
static int noopcmd(char*);
static int passcmd(char*);
static int quitcmd(char*);
static int rsetcmd(char*);
static int retrcmd(char*);
static int statcmd(char*);
static int stlscmd(char*);
static int topcmd(char*);
static int synccmd(char*);
static int uidlcmd(char*);
static int usercmd(char*);
static char *nextarg(char*);
static int getcrnl(char*, int);
static int readmbox(char*);
static void sendcrnl(char*, ...);
static int senderr(char*, ...);
static int sendok(char*, ...);
#pragma varargck argpos sendcrnl 1
#pragma varargck argpos senderr 1
#pragma varargck argpos sendok 1
Cmd cmdtab[] =
{
"apop", 0, apopcmd,
"capa", 0, capacmd,
"dele", 1, delecmd,
"list", 1, listcmd,
"noop", 0, noopcmd,
"pass", 0, passcmd,
"quit", 0, quitcmd,
"rset", 0, rsetcmd,
"retr", 1, retrcmd,
"stat", 1, statcmd,
"stls", 0, stlscmd,
"sync", 1, synccmd,
"top", 1, topcmd,
"uidl", 1, uidlcmd,
"user", 0, usercmd,
0, 0, 0,
};
static Biobuf in;
static Biobuf out;
static int passwordinclear;
static int didtls;
typedef struct Msg Msg;
struct Msg
{
int upasnum;
char digest[64];
int bytes;
int deleted;
};
static int totalbytes;
static int totalmsgs;
static Msg *msg;
static int nmsg;
static int loggedin;
static int debug;
static uchar *tlscert;
static int ntlscert;
static char *peeraddr;
static char tmpaddr[64];
void
usage(void)
{
fprint(2, "usage: upas/pop3 [-a authmboxfile] [-d debugfile] [-p] "
"[-r remote] [-t cert]\n");
exits("usage");
}
void
main(int argc, char **argv)
{
int fd;
char *arg, cmdbuf[1024];
Cmd *c;
NetConnInfo *n;
rfork(RFNAMEG);
Binit(&in, 0, OREAD);
Binit(&out, 1, OWRITE);
tmfmtinstall();
ARGBEGIN{
case 'a':
loggedin = 1;
if(readmbox(EARGF(usage())) < 0)
exits(nil);
break;
case 'd':
debug++;
if((fd = create(EARGF(usage()), OWRITE, 0666)) >= 0 && fd != 2){
dup(fd, 2);
close(fd);
}
break;
case 'r':
strecpy(tmpaddr, tmpaddr+sizeof tmpaddr, EARGF(usage()));
if(arg = strchr(tmpaddr, '!'))
*arg = '\0';
peeraddr = tmpaddr;
break;
case 't':
tlscert = readcert(EARGF(usage()), &ntlscert);
if(tlscert == nil){
senderr("cannot read TLS certificate: %r");
exits(nil);
}
break;
case 'p':
passwordinclear = 1;
break;
}ARGEND
/* do before TLS */
if(peeraddr == nil)
if(n = getnetconninfo(0, 0)){
peeraddr = strdup(n->rsys);
freenetconninfo(n);
}
hello();
while(Bflush(&out), getcrnl(cmdbuf, sizeof cmdbuf) > 0){
arg = nextarg(cmdbuf);
for(c=cmdtab; c->name; c++)
if(cistrcmp(c->name, cmdbuf) == 0)
break;
if(c->name == 0){
senderr("unknown command %s", cmdbuf);
continue;
}
if(c->needauth && !loggedin){
senderr("%s requires authentication", cmdbuf);
continue;
}
(*c->f)(arg);
}
exits(nil);
}
/* sort directories in increasing message number order */
static int
dircmp(void *a, void *b)
{
return atoi(((Dir*)a)->name) - atoi(((Dir*)b)->name);
}
static int
readmbox(char *box)
{
int fd, i, n, nd, lines, pid;
char buf[100], err[ERRMAX];
char *p;
Biobuf *b;
Dir *d, *draw;
Msg *m;
Waitmsg *w;
unmount(nil, "/mail/fs");
switch(pid = fork()){
case -1:
return senderr("can't fork to start upas/fs");
case 0:
close(0);
close(1);
open("/dev/null", OREAD);
open("/dev/null", OWRITE);
execl("/bin/upas/fs", "upas/fs", "-np", "-f", box, nil);
snprint(err, sizeof err, "upas/fs: %r");
_exits(err);
break;
default:
break;
}
if((w = wait()) == nil || w->pid != pid || w->msg[0] != '\0'){
if(w && w->pid==pid)
return senderr("%s", w->msg);
else
return senderr("can't initialize upas/fs");
}
free(w);
if(chdir("/mail/fs/mbox") < 0)
return senderr("can't initialize upas/fs: %r");
if((fd = open(".", OREAD)) < 0)
return senderr("cannot open /mail/fs/mbox: %r");
nd = dirreadall(fd, &d);
close(fd);
if(nd < 0)
return senderr("cannot read from /mail/fs/mbox: %r");
msg = mallocz(sizeof(Msg)*nd, 1);
if(msg == nil)
return senderr("out of memory");
if(nd == 0)
return 0;
qsort(d, nd, sizeof(d[0]), dircmp);
for(i=0; i<nd; i++){
m = &msg[nmsg];
m->upasnum = atoi(d[i].name);
sprint(buf, "%d/digest", m->upasnum);
if((fd = open(buf, OREAD)) < 0)
continue;
n = readn(fd, m->digest, sizeof m->digest - 1);
close(fd);
if(n < 0)
continue;
m->digest[n] = '\0';
/*
* We need the number of message lines so that we
* can adjust the byte count to include \r's.
* Upas/fs gives us the number of lines in the raw body
* in the lines file, but we have to count rawheader ourselves.
* There is one blank line between raw header and raw body.
*/
sprint(buf, "%d/rawheader", m->upasnum);
if((b = Bopen(buf, OREAD)) == nil)
continue;
lines = 0;
for(;;){
p = Brdline(b, '\n');
if(p == nil){
if(Blinelen(b) == 0)
break;
}else
lines++;
}
Bterm(b);
lines++;
sprint(buf, "%d/lines", m->upasnum);
if((fd = open(buf, OREAD)) < 0)
continue;
n = readn(fd, buf, sizeof buf - 1);
close(fd);
if(n < 0)
continue;
buf[n] = '\0';
lines += atoi(buf);
sprint(buf, "%d/raw", m->upasnum);
if((draw = dirstat(buf)) == nil)
continue;
m->bytes = lines+draw->length;
free(draw);
nmsg++;
totalmsgs++;
totalbytes += m->bytes;
}
return 0;
}
/*
* get a line that ends in crnl or cr, turn terminating crnl into a nl
*
* return 0 on EOF
*/
static int
getcrnl(char *buf, int n)
{
int c;
char *ep;
char *bp;
Biobuf *fp = ∈
Bflush(&out);
bp = buf;
ep = bp + n - 1;
while(bp != ep){
c = Bgetc(fp);
if(debug) {
seek(2, 0, 2);
fprint(2, "%c", c);
}
switch(c){
case -1:
*bp = 0;
if(bp==buf)
return 0;
else
return bp-buf;
case '\r':
c = Bgetc(fp);
if(c == '\n'){
if(debug) {
seek(2, 0, 2);
fprint(2, "%c", c);
}
*bp = 0;
return bp-buf;
}
Bungetc(fp);
c = '\r';
break;
case '\n':
*bp = 0;
return bp-buf;
}
*bp++ = c;
}
*bp = 0;
return bp-buf;
}
static void
sendcrnl(char *fmt, ...)
{
char buf[1024];
va_list arg;
va_start(arg, fmt);
vseprint(buf, buf+sizeof(buf), fmt, arg);
va_end(arg);
if(debug)
fprint(2, "-> %s\n", buf);
Bprint(&out, "%s\r\n", buf);
}
static int
senderr(char *fmt, ...)
{
char buf[1024];
va_list arg;
va_start(arg, fmt);
vseprint(buf, buf+sizeof(buf), fmt, arg);
va_end(arg);
if(debug)
fprint(2, "-> -ERR %s\n", buf);
Bprint(&out, "-ERR %s\r\n", buf);
return -1;
}
static int
sendok(char *fmt, ...)
{
char buf[1024];
va_list arg;
va_start(arg, fmt);
vseprint(buf, buf+sizeof(buf), fmt, arg);
va_end(arg);
if(*buf){
if(debug)
fprint(2, "-> +OK %s\n", buf);
Bprint(&out, "+OK %s\r\n", buf);
} else {
if(debug)
fprint(2, "-> +OK\n");
Bprint(&out, "+OK\r\n");
}
return 0;
}
static int
capacmd(char*)
{
sendok("");
sendcrnl("TOP");
if(passwordinclear || didtls)
sendcrnl("USER");
sendcrnl("PIPELINING");
sendcrnl("UIDL");
sendcrnl("STLS");
sendcrnl(".");
return 0;
}
static int
delecmd(char *arg)
{
int n;
if(*arg==0)
return senderr("DELE requires a message number");
n = atoi(arg)-1;
if(n < 0 || n >= nmsg || msg[n].deleted)
return senderr("no such message");
msg[n].deleted = 1;
totalmsgs--;
totalbytes -= msg[n].bytes;
sendok("message %d deleted", n+1);
return 0;
}
static int
listcmd(char *arg)
{
int i, n;
if(*arg == 0){
sendok("+%d message%s (%d octets)", totalmsgs, totalmsgs==1 ? "":"s", totalbytes);
for(i=0; i<nmsg; i++){
if(msg[i].deleted)
continue;
sendcrnl("%d %d", i+1, msg[i].bytes);
}
sendcrnl(".");
}else{
n = atoi(arg)-1;
if(n < 0 || n >= nmsg || msg[n].deleted)
return senderr("no such message");
sendok("%d %d", n+1, msg[n].bytes);
}
return 0;
}
static int
noopcmd(char*)
{
sendok("");
return 0;
}
static void
_synccmd(char*)
{
int i, fd;
char *s;
Fmt f;
if(!loggedin){
sendok("");
return;
}
fmtstrinit(&f);
fmtprint(&f, "delete mbox");
for(i=0; i<nmsg; i++)
if(msg[i].deleted)
fmtprint(&f, " %d", msg[i].upasnum);
s = fmtstrflush(&f);
if(strcmp(s, "delete mbox") != 0){ /* must have something to delete */
if((fd = open("../ctl", OWRITE)) < 0){
senderr("open ctl to delete messages: %r");
return;
}
if(write(fd, s, strlen(s)) < 0){
senderr("error deleting messages: %r");
return;
}
}
sendok("");
}
static int
synccmd(char*)
{
_synccmd(nil);
return 0;
}
static int
quitcmd(char*)
{
synccmd(nil);
exits(nil);
return 0;
}
static int
retrcmd(char *arg)
{
int n;
Biobuf *b;
char buf[40], *p;
if(*arg == 0)
return senderr("RETR requires a message number");
n = atoi(arg)-1;
if(n < 0 || n >= nmsg || msg[n].deleted)
return senderr("no such message");
snprint(buf, sizeof buf, "%d/raw", msg[n].upasnum);
if((b = Bopen(buf, OREAD)) == nil)
return senderr("message disappeared");
sendok("");
while((p = Brdstr(b, '\n', 1)) != nil){
if(p[0]=='.')
Bwrite(&out, ".", 1);
Bwrite(&out, p, strlen(p));
Bwrite(&out, "\r\n", 2);
free(p);
}
Bterm(b);
sendcrnl(".");
return 0;
}
static int
rsetcmd(char*)
{
int i;
for(i=0; i<nmsg; i++){
if(msg[i].deleted){
msg[i].deleted = 0;
totalmsgs++;
totalbytes += msg[i].bytes;
}
}
return sendok("");
}
static int
statcmd(char*)
{
return sendok("%d %d", totalmsgs, totalbytes);
}
static int
trace(char *fmt, ...)
{
va_list arg;
int n;
va_start(arg, fmt);
n = vfprint(2, fmt, arg);
va_end(arg);
return n;
}
static int
stlscmd(char*)
{
int fd;
TLSconn conn;
if(didtls)
return senderr("tls already started");
if(!tlscert)
return senderr("don't have any tls credentials");
sendok("");
Bflush(&out);
memset(&conn, 0, sizeof conn);
conn.cert = tlscert;
conn.certlen = ntlscert;
if(debug)
conn.trace = trace;
fd = tlsServer(0, &conn);
if(fd < 0)
sysfatal("tlsServer: %r");
dup(fd, 0);
dup(fd, 1);
close(fd);
Binit(&in, 0, OREAD);
Binit(&out, 1, OWRITE);
didtls = 1;
return 0;
}
static int
topcmd(char *arg)
{
int done, i, lines, n;
char buf[40], *p;
Biobuf *b;
if(*arg == 0)
return senderr("TOP requires a message number");
n = atoi(arg)-1;
if(n < 0 || n >= nmsg || msg[n].deleted)
return senderr("no such message");
arg = nextarg(arg);
if(*arg == 0)
return senderr("TOP requires a line count");
lines = atoi(arg);
if(lines < 0)
return senderr("bad args to TOP");
snprint(buf, sizeof buf, "%d/raw", msg[n].upasnum);
if((b = Bopen(buf, OREAD)) == nil)
return senderr("message disappeared");
sendok("");
while(p = Brdstr(b, '\n', 1)){
if(p[0]=='.')
Bputc(&out, '.');
Bwrite(&out, p, strlen(p));
Bwrite(&out, "\r\n", 2);
done = p[0]=='\0';
free(p);
if(done)
break;
}
for(i=0; i<lines; i++){
p = Brdstr(b, '\n', 1);
if(p == nil)
break;
if(p[0]=='.')
Bwrite(&out, ".", 1);
Bwrite(&out, p, strlen(p));
Bwrite(&out, "\r\n", 2);
free(p);
}
sendcrnl(".");
Bterm(b);
return 0;
}
static int
uidlcmd(char *arg)
{
int n;
if(*arg==0){
sendok("");
for(n=0; n<nmsg; n++){
if(msg[n].deleted)
continue;
sendcrnl("%d %s", n+1, msg[n].digest);
}
sendcrnl(".");
}else{
n = atoi(arg)-1;
if(n < 0 || n >= nmsg || msg[n].deleted)
return senderr("no such message");
sendok("%d %s", n+1, msg[n].digest);
}
return 0;
}
static char*
nextarg(char *p)
{
while(*p && *p != ' ' && *p != '\t')
p++;
while(*p == ' ' || *p == '\t')
*p++ = 0;
return p;
}
/*
* authentication
*/
Chalstate *chs;
char user[Pathlen];
char box[Pathlen];
char cbox[Pathlen];
static void
hello(void)
{
fmtinstall('H', encodefmt);
if((chs = auth_challenge("proto=apop role=server")) == nil){
senderr("auth server not responding, try later");
exits(nil);
}
sendok("POP3 server ready %s", chs->chal);
}
static int
setuser(char *arg)
{
char *p;
*user = 0;
strcpy(box, "/mail/box/");
strecpy(box+strlen(box), box+sizeof box-7, arg);
strcpy(cbox, box);
cleanname(cbox);
if(strcmp(cbox, box) != 0)
return senderr("bad mailbox name");
strcat(box, "/mbox");
strecpy(user, user+sizeof user, arg);
if(p = strchr(user, '/'))
*p = '\0';
return 0;
}
static int
usercmd(char *arg)
{
if(loggedin)
return senderr("already authenticated");
if(*arg == 0)
return senderr("USER requires argument");
if(setuser(arg) < 0){
sleep(15*1000);
senderr("you are not expected to understand this"); /* pop3 attack. */
exits("");
}
return sendok("");
}
static void
enableaddr(void)
{
int fd;
char buf[64];
/* hide the peer IP address under a rock in the ratifier FS */
if(peeraddr == 0 || *peeraddr == 0)
return;
sprint(buf, "/mail/ratify/trusted/%s#32", peeraddr);
/*
* if the address is already there and the user owns it,
* remove it and recreate it to give him a new time quanta.
*/
if(access(buf, 0) >= 0 && remove(buf) < 0)
return;
fd = create(buf, OREAD, 0666);
if(fd >= 0){
close(fd);
// syslog(0, "pop3", "ratified %s", peeraddr);
}
}
static int
dologin(char *response)
{
AuthInfo *ai;
static int tries;
static ulong delaysecs = 5;
chs->user = user;
chs->resp = response;
chs->nresp = strlen(response);
if((ai = auth_response(chs)) == nil){
if(tries >= 20){
senderr("authentication failed: %r; server exiting");
exits(nil);
}
if(++tries == 3)
syslog(0, "pop3", "likely password guesser from %s",
peeraddr);
delaysecs *= 2;
if (delaysecs > 30*60)
delaysecs = 30*60; /* half-hour max. */
sleep(delaysecs * 1000); /* prevent beating on our auth server */
return senderr("authentication failed");
}
if(auth_chuid(ai, nil) < 0){
senderr("chuid failed: %r; server exiting");
exits(nil);
} else { /* chown network connection */
Dir nd;
nulldir(&nd);
nd.mode = 0660;
nd.uid = ai->cuid;
dirfwstat(Bfildes(&in), &nd);
}
auth_freeAI(ai);
auth_freechal(chs);
chs = nil;
loggedin = 1;
if(newns(user, 0) < 0){
senderr("newns failed: %r; server exiting");
exits(nil);
}
enableaddr();
if(readmbox(box) < 0)
exits(nil);
return sendok("mailbox is %s", box);
}
static int
passcmd(char *arg)
{
DigestState *s;
uchar digest[MD5dlen];
char response[2*MD5dlen+1];
if(*user == 0){
senderr("inscrutable phase error"); // pop3 attack.
sleep(15*1000);
exits("");
}
if(passwordinclear==0 && didtls==0)
return senderr("password in the clear disallowed");
/* use password to encode challenge */
if((chs = auth_challenge("proto=apop role=server")) == nil)
return senderr("couldn't get apop challenge");
/* hash challenge with secret and convert to ascii */
s = md5((uchar*)chs->chal, chs->nchal, 0, 0);
md5((uchar*)arg, strlen(arg), digest, s);
snprint(response, sizeof response, "%.*H", MD5dlen, digest);
return dologin(response);
}
static int
apopcmd(char *arg)
{
char *resp;
resp = nextarg(arg);
if(setuser(arg) < 0){
senderr("i before e except after c"); // pop3 attack.
sleep(15*1000);
exits("");
}
return dologin(resp);
}