/* 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); }