/* * pop3.c -- POP3 protocol methods * * Copyright 1998 by Eric S. Raymond. * For license terms, see the file COPYING in this directory. */ #include "config.h" #ifdef POP3_ENABLE #include #include #include #if defined(HAVE_UNISTD_H) #include #endif #if defined(STDC_HEADERS) #include #endif #include #include "fetchmail.h" #include "socket.h" #include "i18n.h" #include "uid_db.h" #ifdef OPIE_ENABLE #ifdef __cplusplus extern "C" { #endif #include #ifdef __cplusplus } #endif #endif /* OPIE_ENABLE */ /* global variables: please reinitialize them explicitly for proper * working in daemon mode */ /* TODO: session variables to be initialized before server greeting */ #ifdef OPIE_ENABLE static char lastok[POPBUFSIZE+1]; #endif /* OPIE_ENABLE */ /* session variables initialized in capa_probe() or pop3_getauth() */ flag done_capa = FALSE; #if defined(GSSAPI) flag has_gssapi = FALSE; #endif /* defined(GSSAPI) */ #if defined(KERBEROS_V4) || defined(KERBEROS_V5) flag has_kerberos = FALSE; #endif /* defined(KERBEROS_V4) || defined(KERBEROS_V5) */ static flag has_cram = FALSE; #ifdef OPIE_ENABLE flag has_otp = FALSE; #endif /* OPIE_ENABLE */ #ifdef NTLM_ENABLE flag has_ntlm = FALSE; #endif /* NTLM_ENABLE */ #ifdef SSL_ENABLE static flag has_stls = FALSE; #endif /* SSL_ENABLE */ /* mailbox variables initialized in pop3_getrange() */ static int last; /* mail variables initialized in pop3_fetch() */ #ifdef SDPS_ENABLE char *sdps_envfrom; char *sdps_envto; #endif /* SDPS_ENABLE */ #ifdef NTLM_ENABLE #include "ntlm.h" /* * NTLM support by Grant Edwards. * * Handle MS-Exchange NTLM authentication method. This is the same * as the NTLM auth used by Samba for SMB related services. We just * encode the packets in base64 instead of sending them out via a * network interface. * * Much source (ntlm.h, smb*.c smb*.h) was borrowed from Samba. */ static int do_pop3_ntlm(int sock, struct query *ctl, int msn_instead /** if true, send AUTH MSN, else send AUTH NTLM */) { char msgbuf[POPBUFSIZE+1]; int result; gen_send(sock, msn_instead ? "AUTH MSN" : "AUTH NTLM"); if ((result = ntlm_helper(sock, ctl, "POP3"))) return result; if ((result = gen_recv (sock, msgbuf, sizeof msgbuf))) return result; if (strstr (msgbuf, "OK")) return PS_SUCCESS; else return PS_AUTHFAIL; } #endif /* NTLM */ #define DOTLINE(s) (s[0] == '.' && (s[1]=='\r'||s[1]=='\n'||s[1]=='\0')) static int pop3_ok (int sock, char *argbuf) /* parse command response */ { int ok; char buf [POPBUFSIZE+1]; char *bufp; if ((ok = gen_recv(sock, buf, sizeof(buf))) == 0) { bufp = buf; if (*bufp == '+' || *bufp == '-') bufp++; else return(PS_PROTOCOL); while (isalpha((unsigned char)*bufp)) bufp++; if (*bufp) *(bufp++) = '\0'; if (strcmp(buf,"+OK") == 0) { #ifdef OPIE_ENABLE strcpy(lastok, bufp); #endif /* OPIE_ENABLE */ ok = 0; } else if (strncmp(buf,"-ERR", 4) == 0) { if (stage == STAGE_FETCH) ok = PS_TRANSIENT; else if (stage > STAGE_GETAUTH) ok = PS_PROTOCOL; /* * We're checking for "lock busy", "unable to lock", * "already locked", "wait a few minutes" etc. here. * This indicates that we have to wait for the server to * unwedge itself before we can poll again. * * PS_LOCKBUSY check empirically verified with two recent * versions of the Berkeley popper; QPOP (version 2.2) and * QUALCOMM Pop server derived from UCB (version 2.1.4-R3) * These are caught by the case-indifferent "lock" check. * The "wait" catches "mail storage services unavailable, * wait a few minutes and try again" on the InterMail server. * * If these aren't picked up on correctly, fetchmail will * think there is an authentication failure and wedge the * connection in order to prevent futile polls. * * Gad, what a kluge. */ else if (strstr(bufp,"lock") || strstr(bufp,"Lock") || strstr(bufp,"LOCK") || strstr(bufp,"wait") /* these are blessed by RFC 2449 */ || strstr(bufp,"[IN-USE]")||strstr(bufp,"[LOGIN-DELAY]")) ok = PS_LOCKBUSY; else if ((strstr(bufp,"Service") || strstr(bufp,"service")) && (strstr(bufp,"unavailable"))) ok = PS_SERVBUSY; else ok = PS_AUTHFAIL; /* * We always want to pass the user lock-busy messages, because * they're red flags. Other stuff (like AUTH failures on non- * RFC1734 servers) only if we're debugging. */ if (*bufp && (ok == PS_LOCKBUSY || outlevel >= O_MONITOR)) report(stderr, "%s\n", bufp); } else ok = PS_PROTOCOL; #if POPBUFSIZE > MSGBUFSIZE #error "POPBUFSIZE must not be larger than MSGBUFSIZE" #endif if (argbuf != NULL) strcpy(argbuf,bufp); } return(ok); } 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); } static void set_peek_capable(struct query *ctl) { /* we're peek-capable means that the use of TOP is enabled, * see pop3_fetch for details - short story, we can use TOP if * we have a means of reliably tracking which mail we need to * refetch should the connection abort in the middle. * fetchall forces RETR, as does keep without UIDL */ peek_capable = !ctl->fetchall && (!ctl->keep || ctl->server.uidl); } 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; char *commonname; #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. * * (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")) { if ((ctl->server.workarounds & WKA_TOP) == 0) { report(stdout, GT_("Warning: \"Maillennium POP3\" 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_starttls(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_starttls(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_starttls(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 commonname = ctl->server.pollname; if (ctl->server.via) commonname = ctl->server.via; if (ctl->sslcommonname) commonname = ctl->sslcommonname; if (maybe_starttls(ctl)) { if (has_stls || must_starttls(ctl)) /* if TLS is mandatory, ignore capabilities */ { /* Don't need to worry whether TLS is mandatory or * opportunistic unless SSLOpen() fails (see below). */ if (gen_transact(sock, "STLS") == PS_SUCCESS && (set_timeout(mytimeout), SSLOpen(sock, ctl->sslcert, ctl->sslkey, ctl->sslproto, 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. */ set_timeout(0); 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); } } else if (must_starttls(ctl)) { /* Config required TLS but we couldn't guarantee it, so we must * stop. */ set_timeout(0); 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. */ set_timeout(0); connection_may_have_tls_errors = TRUE; if (outlevel >= O_VERBOSE) { report(stdout, GT_("%s: opportunistic upgrade to TLS failed, trying to continue.\n"), commonname); } } } } else { /* maybe_starttls() */ if (has_stls && outlevel >= O_VERBOSE) { report(stdout, GT_("%s: WARNING: server offered STLS, but sslproto '' given.\n"), commonname); } } /* maybe_starttls() */ #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); } /* cut off C string at first POSIX space */ static void trim(char *s) { s += strcspn(s, POSIX_space); s[0] = '\0'; } /* 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; } /** Parse the UID response (leading +OK must have been * stripped off) in buf, store the number in gotnum, and store the ID * into the caller-provided buffer "id" of size "idsize". * Returns PS_SUCCESS or PS_PROTOCOL for failure. */ static int parseuid(const char *buf, unsigned long *gotnum, char *id, size_t idsize) { const char *i; char *j; /* skip leading blanks ourselves */ i = buf; i += strspn(i, POSIX_space); errno = 0; *gotnum = strtoul(i, &j, 10); if (j == i || !*j || errno || NULL == strchr(POSIX_space, *j)) { report(stderr, GT_("Cannot handle UIDL response from upstream server.\n")); return PS_PROTOCOL; } j += strspn(j, POSIX_space); strlcpy(id, j, idsize); trim(id); return PS_SUCCESS; } /** request UIDL for single message \a num and stuff the result into the * buffer \a id which can hold \a idsize bytes */ static int pop3_getuidl(int sock, int num, char *id /** output */, size_t idsize) { int ok; char buf [POPBUFSIZE+1]; unsigned long gotnum; gen_send(sock, "UIDL %d", num); if ((ok = pop3_ok(sock, buf)) != 0) return(ok); if ((ok = parseuid(buf, &gotnum, id, idsize))) return ok; if (gotnum != (unsigned long)num) { report(stderr, GT_("Server responded with UID for wrong message.\n")); return PS_PROTOCOL; } return(PS_SUCCESS); } /** Do a binary search with single UIDL commands to find the first * unseen message. */ static int pop3_fastuidl( int sock, struct query *ctl, unsigned int count, int *newp) { int ok; unsigned int first_nr, last_nr, try_nr; char id [IDLEN+1]; first_nr = 0; last_nr = count + 1; while (first_nr < last_nr - 1) { struct uid_db_record *rec; try_nr = (first_nr + last_nr) / 2; if ((ok = pop3_getuidl(sock, try_nr, id, sizeof(id))) != 0) return ok; if ((rec = find_uid_by_id(&ctl->oldsaved, id))) { flag mark = rec->status; if (mark == UID_DELETED || mark == UID_EXPUNGED) { if (outlevel >= O_VERBOSE) report(stderr, GT_("id=%s (num=%u) was deleted, but is still present!\n"), id, try_nr); /* just mark it as seen now! */ rec->status = mark = UID_SEEN; } /* narrow the search region! */ if (mark == UID_UNSEEN) { if (outlevel >= O_DEBUG) report(stdout, GT_("%u is unseen\n"), try_nr); last_nr = try_nr; } else first_nr = try_nr; /* save the number */ set_uid_db_num(&ctl->oldsaved, rec, try_nr); } else { if (outlevel >= O_DEBUG) report(stdout, GT_("%u is unseen\n"), try_nr); last_nr = try_nr; /* save it */ rec = uid_db_insert(&ctl->oldsaved, id, UID_UNSEEN); set_uid_db_num(&ctl->oldsaved, rec, try_nr); } } if (outlevel >= O_DEBUG && last_nr <= count) report(stdout, GT_("%u is first unseen\n"), last_nr); /* update last! */ *newp = count - first_nr; last = first_nr; return 0; } static int pop3_slowuidl( int sock, struct query *ctl, int *countp, int *newp) { /* XXX FIXME: this code is severely broken. A Cc:d mailing list * message will arrive twice with the same Message-ID, so this * slowuidl code will break. Same goes for messages without * Message-ID headers at all. This code would best be removed. */ /* This approach tries to get the message headers from the * remote hosts and compares the message-id to the already known * ones: * + if the first message containes a new id, all messages on * the server will be new * + if the first is known, try to estimate the last known message * on the server and check. If this works you know the total number * of messages to get. * + Otherwise run a binary search to determine the last known message */ struct uid_db_record *rec; int ok, nolinear = 0; int first_nr, n_recs, try_id, try_nr, add_id; int num; char id [IDLEN+1]; if ((ok = pop3_gettopid(sock, 1, id, sizeof(id))) != 0) return ok; rec = first_uid_in_db(&ctl->oldsaved, id); if (!rec) { /* the first message is unknown -> all messages are new */ *newp = *countp; return 0; } first_nr = rec->pos; /* check where we expect the latest known message */ n_recs = uid_db_n_records(&ctl->oldsaved); try_id = n_recs - first_nr; /* -1 + 1 */ if( try_id > 1 ) { if( try_id <= *countp ) { if ((ok = pop3_gettopid(sock, try_id, id, sizeof(id))) != 0) return ok; rec = last_uid_in_db(&ctl->oldsaved, id); try_nr = rec ? rec->pos : -1; } else { try_id = *countp+1; try_nr = -1; } if( try_nr != n_recs -1 ) { /* some messages inbetween have been deleted... */ if( try_nr == -1 ) { nolinear = 1; for( add_id = 1<<30; add_id > try_id-1; add_id >>= 1 ) ; for( ; add_id; add_id >>= 1 ) { if( try_nr == -1 ) { if( try_id - add_id <= 1 ) { continue; } try_id -= add_id; } else try_id += add_id; if ((ok = pop3_gettopid(sock, try_id, id, sizeof(id))) != 0) return ok; rec = find_uid_by_id(&ctl->oldsaved, id); try_nr = rec ? rec->pos : -1; } if( try_nr == -1 ) { try_id--; } } else { report(stderr, GT_("Messages inserted into list on server. Cannot handle this.\n")); return -1; } } } /* the first try_id messages are known -> copy them to the newsaved list */ for( num = first_nr; num < n_recs; num++ ) { rec = find_uid_by_pos(&ctl->oldsaved, num); rec = uid_db_insert(&ctl->newsaved, rec->id, rec->status); set_uid_db_num(&ctl->newsaved, rec, num - first_nr + 1); } if( nolinear ) { clear_uid_db(&ctl->oldsaved); last = try_id; } *newp = *countp - try_id; return 0; } static int pop3_getrange(int sock, struct query *ctl, const char *folder, int *countp, int *newp, int *bytes) /* get range of messages to be fetched */ { int ok; char buf [POPBUFSIZE+1]; (void)folder; /* Ensure that the new list is properly empty */ clear_uid_db(&ctl->newsaved); #ifdef MBOX /* Alain Knaff suggests this, but it's not RFC standard */ if (folder) if ((ok = gen_transact(sock, "MBOX %s", folder))) return ok; #endif /* MBOX */ /* get the total message count */ gen_send(sock, "STAT"); ok = pop3_ok(sock, buf); if (ok == 0) { int asgn; asgn = sscanf(buf,"%d %d", countp, bytes); if (asgn != 2) return PS_PROTOCOL; } else return(ok); /* * Newer, RFC-1725/1939-conformant POP servers may not have the LAST * command. We work as hard as possible to hide this, but it makes * counting new messages intrinsically quadratic in the worst case. */ last = 0; *newp = -1; /* if there are messages, and UIDL is desired, use UIDL * also use UIDL if fetchall is unset */ if (*countp > 0 && (!ctl->fetchall || ctl->server.uidl)) { int fastuidl; char id [IDLEN+1]; set_uid_db_num_pos_0(&ctl->oldsaved, *countp); set_uid_db_num_pos_0(&ctl->newsaved, *countp); /* should we do fast uidl this time? */ fastuidl = ctl->fastuidl; if (*countp > 7 && /* linear search is better if there are few mails! */ !ctl->fetchall && /* with fetchall, all uids are required */ !ctl->flush && /* with flush, it is safer to disable fastuidl */ NUM_NONZERO (fastuidl)) { if (fastuidl == 1) dofastuidl = 1; else dofastuidl = ctl->fastuidlcount != 0; } else dofastuidl = 0; if (!ctl->server.uidl) { gen_send(sock, "LAST"); ok = pop3_ok(sock, buf); } else ok = 1; if (ok == 0) { /* scan LAST reply */ if (sscanf(buf, "%d", &last) == 0) { report(stderr, GT_("protocol error\n")); return(PS_ERROR); } *newp = (*countp - last); } else { /* do UIDL */ if (dofastuidl) return(pop3_fastuidl( sock, ctl, *countp, newp)); /* grab the mailbox's UID list */ if (gen_transact(sock, "UIDL") != 0) { /* don't worry, yet! do it the slow way */ if (pop3_slowuidl(sock, ctl, countp, newp)) { report(stderr, GT_("protocol error while fetching UIDLs\n")); return(PS_ERROR); } } else { /* UIDL worked - parse reply */ unsigned long unum; *newp = 0; while (gen_recv(sock, buf, sizeof(buf)) == PS_SUCCESS) { if (DOTLINE(buf)) break; if (parseuid(buf, &unum, id, sizeof(id)) == PS_SUCCESS) { struct uid_db_record *old_rec, *new_rec; new_rec = uid_db_insert(&ctl->newsaved, id, UID_UNSEEN); if ((old_rec = find_uid_by_id(&ctl->oldsaved, id))) { flag mark = old_rec->status; if (mark == UID_DELETED || mark == UID_EXPUNGED) { /* XXX FIXME: switch 3 occurrences from * (int)unum or (unsigned int)unum to * remove the cast and use %lu - not now * though, time for new release */ if (outlevel >= O_VERBOSE) report(stderr, GT_("id=%s (num=%d) was deleted, but is still present!\n"), id, (int)unum); /* just mark it as seen now! */ old_rec->status = mark = UID_SEEN; } new_rec->status = mark; if (mark == UID_UNSEEN) { (*newp)++; if (outlevel >= O_DEBUG) report(stdout, GT_("%u is unseen\n"), (unsigned int)unum); } } else { (*newp)++; if (outlevel >= O_DEBUG) report(stdout, GT_("%u is unseen\n"), (unsigned int)unum); /* add it to oldsaved also! In case, we do not * swap the lists (say, due to socket error), * the same mail will not be downloaded again. */ old_rec = uid_db_insert(&ctl->oldsaved, id, UID_UNSEEN); } /* * save the number if it will be needed later on * (messsage will either be fetched or deleted) */ if (new_rec->status == UID_UNSEEN || ctl->flush) { set_uid_db_num(&ctl->oldsaved, old_rec, unum); set_uid_db_num(&ctl->newsaved, new_rec, unum); } } else return PS_ERROR; } /* multi-line loop for UIDL reply */ } /* UIDL parser */ } /* do UIDL */ } return(PS_SUCCESS); } static int pop3_getpartialsizes(int sock, int first, int last, int *sizes) /* capture the size of message #first */ { int ok = 0, i, num; char buf [POPBUFSIZE+1]; unsigned int size; for (i = first; i <= last; i++) { gen_send(sock, "LIST %d", i); if ((ok = pop3_ok(sock, buf)) != 0) return(ok); if (sscanf(buf, "%d %u", &num, &size) == 2) { if (num == i) sizes[i - first] = size; else /* warn about possible attempt to induce buffer overrun * * we expect server reply message number and requested * message number to match */ report(stderr, "Warning: ignoring bogus data for message sizes returned by server.\n"); } } return(ok); } static int pop3_getsizes(int sock, int count, int *sizes) /* capture the sizes of all messages */ { int ok; if ((ok = gen_transact(sock, "LIST")) != 0) return(ok); else { char buf [POPBUFSIZE+1]; while ((ok = gen_recv(sock, buf, sizeof(buf))) == 0) { unsigned int num, size; if (DOTLINE(buf)) break; else if (sscanf(buf, "%u %u", &num, &size) == 2) { if (num > 0 && num <= (unsigned)count) sizes[num - 1] = size; else /* warn about possible attempt to induce buffer overrun */ report(stderr, "Warning: ignoring bogus data for message sizes returned by server.\n"); } } return(ok); } } static int pop3_is_old(int sock, struct query *ctl, int num) /* is the given message old? */ { struct uid_db_record *rec; if (!uid_db_n_records(&ctl->oldsaved)) return (num <= last); else if (dofastuidl) { char id [IDLEN+1]; if (num <= last) return(TRUE); /* in fast uidl, we manipulate the old list only! */ if ((rec = find_uid_by_num(&ctl->oldsaved, num))) { /* we already have the id! */ return(rec->status != UID_UNSEEN); } /* get the uidl first! */ if (pop3_getuidl(sock, num, id, sizeof(id)) != PS_SUCCESS) return(TRUE); if ((rec = find_uid_by_id(&ctl->oldsaved, id))) { /* we already have the id! */ set_uid_db_num(&ctl->oldsaved, rec, num); return(rec->status != UID_UNSEEN); } /* save it */ rec = uid_db_insert(&ctl->oldsaved, id, UID_UNSEEN); set_uid_db_num(&ctl->oldsaved, rec, num); return(FALSE); } else { rec = find_uid_by_num(&ctl->newsaved, num); return !rec || rec->status != UID_UNSEEN; } } #ifdef UNUSED /* * We could use this to fetch headers only as we do for IMAP. The trouble * is that there's no way to fetch the body only. So the following RETR * would have to re-fetch the header. Enough messages have longer headers * than bodies to make this a net loss. */ static int pop_fetch_headers(int sock, struct query *ctl,int number,int *lenp) /* request headers of nth message */ { int ok; char buf[POPBUFSIZE+1]; gen_send(sock, "TOP %d 0", number); if ((ok = pop3_ok(sock, buf)) != 0) return(ok); *lenp = -1; /* we got sizes from the LIST response */ return(PS_SUCCESS); } #endif /* UNUSED */ static int pop3_fetch(int sock, struct query *ctl, int number, int *lenp) /* request nth message */ { int ok; char buf[POPBUFSIZE+1]; #ifdef SDPS_ENABLE /* * See http://www.demon.net/helpdesk/producthelp/mail/sdps-tech.html/ * for a description of what we're parsing here. * -- updated 2006-02-22 */ if (ctl->server.sdps) { int linecount = 0; sdps_envfrom = (char *)NULL; sdps_envto = (char *)NULL; gen_send(sock, "*ENV %d", number); do { if (gen_recv(sock, buf, sizeof(buf))) { break; } linecount++; switch (linecount) { case 4: /* No need to wrap envelope from address */ /* FIXME: some parts of fetchmail don't handle null * envelope senders, so use <> to mark null sender * as a workaround. */ if (strspn(buf, " \t") == strlen(buf)) strcpy(buf, "<>"); sdps_envfrom = (char *)xmalloc(strlen(buf)+1); strcpy(sdps_envfrom,buf); break; case 5: /* Wrap address with To: <> so nxtaddr() likes it */ sdps_envto = (char *)xmalloc(strlen(buf)+7); sprintf(sdps_envto,"To: <%s>",buf); break; } } while (!(buf[0] == '.' && (buf[1] == '\r' || buf[1] == '\n' || buf[1] == '\0'))); } #else (void)ctl; #endif /* SDPS_ENABLE */ /* * Though the POP RFCs don't document this fact, on almost every * POP3 server I know of messages are marked "seen" only at the * time the OK response to a RETR is issued. * * This means we can use TOP to fetch the message without setting its * seen flag. This is good! It means that if the protocol exchange * craps out during the message, it will still be marked `unseen' on * the server. (Exception: in early 1999 SpryNet's POP3 servers were * reported to mark messages seen on a TOP fetch.) * * However...*don't* do this if we're using keep to suppress deletion! * In that case, marking the seen flag is the only way to prevent the * message from being re-fetched on subsequent runs. * * Also use RETR (that means no TOP, no peek) if fetchall is on. * This gives us a workaround for servers like usa.net's that bungle * TOP. It's pretty harmless because fetchall guarantees that any * message dropped by an interrupted RETR will be picked up on the * next poll of the site. * * We take advantage here of the fact that, according to all the * POP RFCs, "if the number of lines requested by the POP3 client * is greater than than the number of lines in the body, then the * POP3 server sends the entire message."). * * The line count passed (99999999) is the maximum value CompuServe will * accept; it's much lower than the natural value 2147483646 (the maximum * twos-complement signed 32-bit integer minus 1) */ if (!peek_capable) gen_send(sock, "RETR %d", number); else gen_send(sock, "TOP %d 99999999", number); if ((ok = pop3_ok(sock, buf)) != 0) return(ok); *lenp = -1; /* we got sizes from the LIST response */ return(PS_SUCCESS); } static void mark_uid_seen(struct query *ctl, int number) /* Tell the UID code we've seen this. */ { struct uid_db_record *rec; if ((rec = find_uid_by_num(&ctl->newsaved, number))) rec->status = UID_SEEN; /* mark it as seen in oldsaved also! In case, we do not swap the lists * (say, due to socket error), the same mail will not be downloaded * again. */ if ((rec = find_uid_by_num(&ctl->oldsaved, number))) rec->status = UID_SEEN; } static int pop3_delete(int sock, struct query *ctl, int number) /* delete a given message */ { struct uid_db_record *rec; int ok; mark_uid_seen(ctl, number); /* actually, mark for deletion -- doesn't happen until QUIT time */ ok = gen_transact(sock, "DELE %d", number); if (ok != PS_SUCCESS) return(ok); rec = find_uid_by_num(dofastuidl ? &ctl->oldsaved : &ctl->newsaved, number); rec->status = UID_DELETED; return(PS_SUCCESS); } static int pop3_mark_seen(int sock, struct query *ctl, int number) /* mark a given message as seen */ { (void)sock; mark_uid_seen(ctl, number); return(PS_SUCCESS); } static int pop3_logout(int sock, struct query *ctl) /* send logout command */ { int ok; #ifdef __UNUSED__ /* * We used to do this in case the server marks messages deleted when seen. * (Yes, this has been reported, in the MercuryP/NLM server. * It's even legal under RFC 1939 (section 8) as a site policy.) * It interacted badly with UIDL, though. Thomas Zajic wrote: * "Running 'fetchmail -F -v' and checking the logs, I found out * that fetchmail did in fact flush my mailbox properly, but sent * a RSET just before sending QUIT to log off. This caused the * POP3 server to undo/forget about the previous DELEs, resetting * my mailbox to its original (ie. unflushed) state. The * ~/.fetchids file did get flushed though, so the next time * fetchmail was run it saw all the old messages as new ones ..." */ if (ctl->keep) gen_transact(sock, "RSET"); #endif /* __UNUSED__ */ ok = gen_transact(sock, "QUIT"); if (!ok) expunge_uids(ctl); return(ok); } static const struct method pop3 = { "POP3", /* Post Office Protocol v3 */ "pop3", /* port for plain and TLS POP3 */ "pop3s", /* port for SSL POP3 */ FALSE, /* this is not a tagged protocol */ TRUE, /* this uses a message delimiter */ pop3_ok, /* parse command response */ pop3_getauth, /* get authorization */ pop3_getrange, /* query range of messages */ pop3_getsizes, /* we can get a list of sizes */ pop3_getpartialsizes, /* we can get the size of 1 mail */ pop3_is_old, /* how do we tell a message is old? */ pop3_fetch, /* request given message */ NULL, /* no way to fetch body alone */ NULL, /* no message trailer */ pop3_delete, /* how to delete a message */ pop3_mark_seen, /* how to mark a message as seen */ NULL, /* no action at end of mailbox */ pop3_logout, /* log out, we're done */ FALSE, /* no, we can't re-poll */ }; int doPOP3 (struct query *ctl) /* retrieve messages using POP3 */ { #ifndef MBOX if (ctl->mailboxes->id) { fprintf(stderr,GT_("Option --folder is not supported with POP3\n")); return(PS_SYNTAX); } #endif /* MBOX */ return(do_protocol(ctl, &pop3)); } #endif /* POP3_ENABLE */ /* pop3.c ends here */