/* XXX FIXME: using the Message-ID is unsafe, some messages (spam,
* broken messages) do not have Message-ID headers, and messages without
* those appear to break this code and cause fetchmail (at least version
* 6.2.3) to not delete such messages properly after retrieval.
* See Sourceforge Bug #780933.
*
* The other problem is that the TOP command itself is optional, too... */
static int pop3_gettopid(int sock, int num , char *id, size_t idsize)
{
int ok;
int got_it;
char buf [POPBUFSIZE+1];
snprintf(buf, sizeof(buf), "TOP %d 1", num);
if ((ok = gen_transact(sock, "%s", buf)) != 0)
return ok;
got_it = 0;
while (gen_recv(sock, buf, sizeof(buf)) == 0)
{
if (DOTLINE(buf))
break;
if (!got_it && 0 == strncasecmp("Message-Id:", buf, 11)) {
char *p = buf + 11;
got_it = 1;
p += strspn(p, POSIX_space);
strlcpy(id, p, idsize);
trim(id);
}
}
/* XXX FIXME: do not return success here if no Message-ID header was
* found. */
return 0;
}
static int odmr_logout(int sock, struct query *ctl)
/* send logout command */
{
/* if we have a smtp_socket, then we've turned around and the
local smtp server is in control of the connection (so we don't
send QUIT) */
if (ctl->smtp_socket == -1)
return(gen_transact(sock, "QUIT"));
else
return(PS_SUCCESS);
}
static int pop3_getauth(int sock, struct query *ctl, char *greeting)
/* apply for connection authorization */
{
int ok;
char *start,*end;
char *msg;
#ifdef OPIE_ENABLE
char *challenge;
#endif /* OPIE_ENABLE */
#ifdef SSL_ENABLE
flag connection_may_have_tls_errors = FALSE;
flag got_tls = FALSE;
#endif /* SSL_ENABLE */
done_capa = FALSE;
#if defined(GSSAPI)
has_gssapi = FALSE;
#endif /* defined(GSSAPI) */
#if defined(KERBEROS_V4) || defined(KERBEROS_V5)
has_kerberos = FALSE;
#endif /* defined(KERBEROS_V4) || defined(KERBEROS_V5) */
has_cram = FALSE;
#ifdef OPIE_ENABLE
has_otp = FALSE;
#endif /* OPIE_ENABLE */
#ifdef SSL_ENABLE
has_stls = FALSE;
#endif /* SSL_ENABLE */
/* Set this up before authentication quits early. */
set_peek_capable(ctl);
/* Hack: allow user to force RETR. */
if (peek_capable && getenv("FETCHMAIL_POP3_FORCE_RETR")) {
peek_capable = 0;
}
/*
* The "Maillennium POP3/PROXY server" deliberately truncates
* TOP replies after c. 64 or 80 kByte (we have varying reports), so
* disable TOP. Comcast once spewed marketing babble to the extent
* of protecting Outlook -- pretty overzealous to break a protocol
* for that that Microsoft could have read, too. Comcast aren't
* alone in using this software though.
* <http://lists.ccil.org/pipermail/fetchmail-friends/2004-April/008523.html>
* (Thanks to Ed Wilts for reminding me of that.)
*
* The warning is printed once per server, until fetchmail exits.
* It will be suppressed when --fetchall or other circumstances make
* us use RETR anyhow.
*
* Matthias Andree
*/
if (peek_capable && strstr(greeting, "Maillennium POP3/PROXY server")) {
if ((ctl->server.workarounds & WKA_TOP) == 0) {
report(stdout, GT_("Warning: \"Maillennium POP3/PROXY server\" found, using RETR command instead of TOP.\n"));
ctl->server.workarounds |= WKA_TOP;
}
peek_capable = 0;
}
if (ctl->server.authenticate == A_SSH) {
return PS_SUCCESS;
}
#ifdef SDPS_ENABLE
/*
* This needs to catch both demon.co.uk and demon.net.
* If we see either, and we're in multidrop mode, try to use
* the SDPS *ENV extension.
*/
if (!(ctl->server.sdps) && MULTIDROP(ctl) && strstr(greeting, "demon."))
ctl->server.sdps = TRUE;
#endif /* SDPS_ENABLE */
switch (ctl->server.protocol) {
case P_POP3:
#ifdef RPA_ENABLE
/* XXX FIXME: AUTH probing (RFC1734) should become global */
/* CompuServe POP3 Servers as of 990730 want AUTH first for RPA */
if (strstr(ctl->remotename, "@compuserve.com"))
{
/* AUTH command should return a list of available mechanisms */
if (gen_transact(sock, "AUTH") == 0)
{
char buffer[10];
flag has_rpa = FALSE;
while ((ok = gen_recv(sock, buffer, sizeof(buffer))) == 0)
{
if (DOTLINE(buffer))
break;
if (strncasecmp(buffer, "rpa", 3) == 0)
has_rpa = TRUE;
}
if (has_rpa && !POP3_auth_rpa(ctl->remotename,
ctl->password, sock))
return(PS_SUCCESS);
}
return(PS_AUTHFAIL);
}
#endif /* RPA_ENABLE */
/*
* CAPA command may return a list including available
* authentication mechanisms and STLS capability.
*
* If it doesn't, no harm done, we just fall back to a plain
* login -- if the user allows it.
*
* Note that this code latches the server's authentication type,
* so that in daemon mode the CAPA check only needs to be done
* once at start of run.
*
* If CAPA fails, then force the authentication method to
* PASSWORD, switch off opportunistic and repoll immediately.
* If TLS is mandatory, fail up front.
*/
if ((ctl->server.authenticate == A_ANY) ||
(ctl->server.authenticate == A_GSSAPI) ||
(ctl->server.authenticate == A_KERBEROS_V4) ||
(ctl->server.authenticate == A_KERBEROS_V5) ||
(ctl->server.authenticate == A_OTP) ||
(ctl->server.authenticate == A_CRAM_MD5) ||
maybe_tls(ctl))
{
if ((ok = capa_probe(sock)) != PS_SUCCESS)
/* we are in STAGE_GETAUTH => failure is PS_AUTHFAIL! */
if (ok == PS_AUTHFAIL ||
/* Some servers directly close the socket. However, if we
* have already authenticated before, then a previous CAPA
* must have succeeded. In that case, treat this as a
* genuine socket error and do not change the auth method.
*/
(ok == PS_SOCKET && !ctl->wehaveauthed))
{
#ifdef SSL_ENABLE
if (must_tls(ctl)) {
/* fail with mandatory STLS without repoll */
report(stderr, GT_("TLS is mandatory for this session, but server refused CAPA command.\n"));
report(stderr, GT_("The CAPA command is however necessary for TLS.\n"));
return ok;
} else if (maybe_tls(ctl)) {
/* defeat opportunistic STLS */
xfree(ctl->sslproto);
ctl->sslproto = xstrdup("");
}
#endif
/* If strong authentication was opportunistic, retry without, else fail. */
switch (ctl->server.authenticate) {
case A_ANY:
ctl->server.authenticate = A_PASSWORD;
/* FALLTHROUGH */
case A_PASSWORD: /* this should only happen with TLS enabled */
return PS_REPOLL;
default:
return PS_AUTHFAIL;
}
}
}
#ifdef SSL_ENABLE
if (maybe_tls(ctl)) {
char *commonname;
commonname = ctl->server.pollname;
if (ctl->server.via)
commonname = ctl->server.via;
if (ctl->sslcommonname)
commonname = ctl->sslcommonname;
if (has_stls)
{
/* Use "tls1" rather than ctl->sslproto because tls1 is the only
* protocol that will work with STARTTLS. Don't need to worry
* whether TLS is mandatory or opportunistic unless SSLOpen() fails
* (see below). */
if (gen_transact(sock, "STLS") == PS_SUCCESS
&& SSLOpen(sock, ctl->sslcert, ctl->sslkey, "tls1", ctl->sslcertck,
ctl->sslcertfile, ctl->sslcertpath, ctl->sslfingerprint, commonname,
ctl->server.pollname, &ctl->remotename) != -1)
{
/*
* RFC 2595 says this:
*
* "Once TLS has been started, the client MUST discard cached
* information about server capabilities and SHOULD re-issue the
* CAPABILITY command. This is necessary to protect against
* man-in-the-middle attacks which alter the capabilities list prior
* to STARTTLS. The server MAY advertise different capabilities
* after STARTTLS."
*
* Now that we're confident in our TLS connection we can
* guarantee a secure capability re-probe.
*/
got_tls = TRUE;
done_capa = FALSE;
ok = capa_probe(sock);
if (ok != PS_SUCCESS) {
return ok;
}
if (outlevel >= O_VERBOSE)
{
report(stdout, GT_("%s: upgrade to TLS succeeded.\n"), commonname);
}
}
}
if (!got_tls) {
if (must_tls(ctl)) {
/* Config required TLS but we couldn't guarantee it, so we must
* stop. */
report(stderr, GT_("%s: upgrade to TLS failed.\n"), commonname);
return PS_SOCKET;
} else {
/* We don't know whether the connection is usable, and there's
* no command we can reasonably issue to test it (NOOP isn't
* allowed til post-authentication), so leave it in an unknown
* state, mark it as such, and check more carefully if things
* go wrong when we try to authenticate. */
connection_may_have_tls_errors = TRUE;
if (outlevel >= O_VERBOSE)
{
report(stdout, GT_("%s: opportunistic upgrade to TLS failed, trying to continue.\n"), commonname);
}
}
}
} /* maybe_tls() */
#endif /* SSL_ENABLE */
/*
* OK, we have an authentication type now.
*/
#if defined(KERBEROS_V4)
/*
* Servers doing KPOP have to go through a dummy login sequence
* rather than doing SASL.
*/
if (has_kerberos &&
ctl->server.service && (strcmp(ctl->server.service, KPOP_PORT)!=0)
&& (ctl->server.authenticate == A_KERBEROS_V4
|| ctl->server.authenticate == A_KERBEROS_V5
|| ctl->server.authenticate == A_ANY))
{
ok = do_rfc1731(sock, "AUTH", ctl->server.truename);
if (ok == PS_SUCCESS || ctl->server.authenticate != A_ANY)
break;
}
#endif /* defined(KERBEROS_V4) || defined(KERBEROS_V5) */
#if defined(GSSAPI)
if (has_gssapi &&
(ctl->server.authenticate == A_GSSAPI ||
(ctl->server.authenticate == A_ANY
&& check_gss_creds("pop", ctl->server.truename) == PS_SUCCESS)))
{
ok = do_gssauth(sock,"AUTH","pop",ctl->server.truename,ctl->remotename);
if (ok == PS_SUCCESS || ctl->server.authenticate != A_ANY)
break;
}
#endif /* defined(GSSAPI) */
#ifdef OPIE_ENABLE
if (has_otp &&
(ctl->server.authenticate == A_OTP ||
ctl->server.authenticate == A_ANY))
{
ok = do_otp(sock, "AUTH", ctl);
if (ok == PS_SUCCESS || ctl->server.authenticate != A_ANY)
break;
}
#endif /* OPIE_ENABLE */
#ifdef NTLM_ENABLE
/* MSN servers require the use of NTLM (MSN) authentication */
if (!strcasecmp(ctl->server.pollname, "pop3.email.msn.com") ||
ctl->server.authenticate == A_MSN)
return (do_pop3_ntlm(sock, ctl, 1) == 0) ? PS_SUCCESS : PS_AUTHFAIL;
if (ctl->server.authenticate == A_NTLM || (has_ntlm && ctl->server.authenticate == A_ANY)) {
ok = do_pop3_ntlm(sock, ctl, 0);
if (ok == 0 || ctl->server.authenticate != A_ANY)
break;
}
#else
if (ctl->server.authenticate == A_NTLM || ctl->server.authenticate == A_MSN)
{
report(stderr,
GT_("Required NTLM capability not compiled into fetchmail\n"));
}
#endif
if (ctl->server.authenticate == A_CRAM_MD5 ||
(has_cram && ctl->server.authenticate == A_ANY))
{
ok = do_cram_md5(sock, "AUTH", ctl, NULL);
if (ok == PS_SUCCESS || ctl->server.authenticate != A_ANY)
break;
}
/* ordinary validation, no one-time password or RPA */
if ((ok = gen_transact(sock, "USER %s", ctl->remotename)))
break;
#ifdef OPIE_ENABLE
/* see RFC1938: A One-Time Password System */
if ((challenge = strstr(lastok, "otp-"))) {
char response[OPIE_RESPONSE_MAX+1];
int i;
char *n = xstrdup("");
i = opiegenerator(challenge, !strcmp(ctl->password, "opie") ? n : ctl->password, response);
free(n);
if ((i == -2) && !run.poll_interval) {
char secret[OPIE_SECRET_MAX+1];
fprintf(stderr, GT_("Secret pass phrase: "));
if (opiereadpass(secret, sizeof(secret), 0))
i = opiegenerator(challenge, secret, response);
memset(secret, 0, sizeof(secret));
};
if (i) {
ok = PS_ERROR;
break;
};
ok = gen_transact(sock, "PASS %s", response);
break;
}
#endif /* OPIE_ENABLE */
/* KPOP uses out-of-band authentication and does not check what
* we send here, so send some random fixed string, to avoid
* users switching *to* KPOP accidentally revealing their
* password */
if ((ctl->server.authenticate == A_ANY
|| ctl->server.authenticate == A_KERBEROS_V4
|| ctl->server.authenticate == A_KERBEROS_V5)
&& (ctl->server.service != NULL
&& strcmp(ctl->server.service, KPOP_PORT) == 0))
{
ok = gen_transact(sock, "PASS krb_ticket");
break;
}
/* check if we are actually allowed to send the password */
if (ctl->server.authenticate == A_ANY
|| ctl->server.authenticate == A_PASSWORD) {
strlcpy(shroud, ctl->password, sizeof(shroud));
ok = gen_transact(sock, "PASS %s", ctl->password);
} else {
report(stderr, GT_("We've run out of allowed authenticators and cannot continue.\n"));
ok = PS_AUTHFAIL;
}
memset(shroud, 0x55, sizeof(shroud));
shroud[0] = '\0';
break;
case P_APOP:
/* build MD5 digest from greeting timestamp + password */
/* find start of timestamp */
for (start = greeting; *start != 0 && *start != '<'; start++)
continue;
if (*start == 0) {
report(stderr,
GT_("Required APOP timestamp not found in greeting\n"));
return(PS_AUTHFAIL);
}
/* find end of timestamp */
for (end = start; *end != 0 && *end != '>'; end++)
continue;
if (*end == 0 || end == start + 1) {
report(stderr,
GT_("Timestamp syntax error in greeting\n"));
return(PS_AUTHFAIL);
}
else
*++end = '\0';
/* SECURITY: 2007-03-17
* Strictly validating the presented challenge for RFC-822
* conformity (it must be a msg-id in terms of that standard) is
* supposed to make attacks against the MD5 implementation
* harder[1]
*
* [1] "Security vulnerability in APOP authentication",
* Gaëtan Leurent, fetchmail-devel, 2007-03-17 */
if (!rfc822_valid_msgid((unsigned char *)start)) {
report(stderr,
GT_("Invalid APOP timestamp.\n"));
return PS_AUTHFAIL;
}
/* copy timestamp and password into digestion buffer */
msg = (char *)xmalloc((end-start+1) + strlen(ctl->password) + 1);
strcpy(msg,start);
strcat(msg,ctl->password);
strcpy((char *)ctl->digest, MD5Digest((unsigned char *)msg));
free(msg);
ok = gen_transact(sock, "APOP %s %s", ctl->remotename, (char *)ctl->digest);
break;
case P_RPOP:
if ((ok = gen_transact(sock,"USER %s", ctl->remotename)) == 0) {
strlcpy(shroud, ctl->password, sizeof(shroud));
ok = gen_transact(sock, "RPOP %s", ctl->password);
memset(shroud, 0x55, sizeof(shroud));
shroud[0] = '\0';
}
break;
default:
report(stderr, GT_("Undefined protocol request in POP3_auth\n"));
ok = PS_ERROR;
}
#ifdef SSL_ENABLE
/* this is for servers which claim to support TLS, but actually
* don't! */
if (connection_may_have_tls_errors
&& (ok == PS_SOCKET || ok == PS_PROTOCOL))
{
xfree(ctl->sslproto);
ctl->sslproto = xstrdup("");
/* repoll immediately without TLS */
ok = PS_REPOLL;
}
#endif
if (ok != 0)
{
/* maybe we detected a lock-busy condition? */
if (ok == PS_LOCKBUSY)
report(stderr, GT_("lock busy! Is another session active?\n"));
return(ok);
}
/* Disable the sleep. Based on patch by Brian Candler 2004-04-19/2004-11-08,
* accepted by Matthias Andree.
*
* Rationale: the server must have locked the spool before returning +OK;
* this sleep just wastes time and hence, for modem and GSM CSD users, money. */
#ifdef WANT_BOGUS
/*
* Empirical experience shows some server/OS combinations
* may need a brief pause even after any lockfiles on the
* server are released, to give the server time to finish
* copying back very large mailfolders from the temp-file...
* this is only ever an issue with extremely large mailboxes.
*/
sleep(3); /* to be _really_ safe, probably need sleep(5)! */
#endif
/* we're approved */
return(PS_SUCCESS);
}
static int capa_probe(int sock)
/* probe the capabilities of the remote server */
{
int ok;
if (done_capa) {
return PS_SUCCESS;
}
#if defined(GSSAPI)
has_gssapi = FALSE;
#endif /* defined(GSSAPI) */
#if defined(KERBEROS_V4) || defined(KERBEROS_V5)
has_kerberos = FALSE;
#endif /* defined(KERBEROS_V4) || defined(KERBEROS_V5) */
has_cram = FALSE;
#ifdef OPIE_ENABLE
has_otp = FALSE;
#endif /* OPIE_ENABLE */
#ifdef NTLM_ENABLE
has_ntlm = FALSE;
#endif /* NTLM_ENABLE */
ok = gen_transact(sock, "CAPA");
if (ok == PS_SUCCESS)
{
char buffer[64];
/* determine what authentication methods we have available */
while ((ok = gen_recv(sock, buffer, sizeof(buffer))) == 0)
{
if (DOTLINE(buffer))
break;
#ifdef SSL_ENABLE
if (strstr(buffer, "STLS"))
has_stls = TRUE;
#endif /* SSL_ENABLE */
#if defined(GSSAPI)
if (strstr(buffer, "GSSAPI"))
has_gssapi = TRUE;
#endif /* defined(GSSAPI) */
#if defined(KERBEROS_V4)
if (strstr(buffer, "KERBEROS_V4"))
has_kerberos = TRUE;
#endif /* defined(KERBEROS_V4) */
#ifdef OPIE_ENABLE
if (strstr(buffer, "X-OTP"))
has_otp = TRUE;
#endif /* OPIE_ENABLE */
#ifdef NTLM_ENABLE
if (strstr(buffer, "NTLM"))
has_ntlm = TRUE;
#endif /* NTLM_ENABLE */
if (strstr(buffer, "CRAM-MD5"))
has_cram = TRUE;
}
}
done_capa = TRUE;
return(ok);
}
