/* * 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 "fetchmail.h" #include "socket.h" #include "i18n.h" #if OPIE_ENABLE #include #endif /* OPIE_ENABLE */ #ifndef strstr /* glibc-2.1 declares this as a macro */ extern char *strstr(); /* needed on sysV68 R3V7.1. */ #endif /* strstr */ static int last; #ifdef SDPS_ENABLE char *sdps_envfrom; char *sdps_envto; #endif /* SDPS_ENABLE */ #if OPIE_ENABLE static char lastok[POPBUFSIZE+1]; #endif /* OPIE_ENABLE */ #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(*bufp)) bufp++; if (*bufp) *(bufp++) = '\0'; if (strcmp(buf,"+OK") == 0) { #if OPIE_ENABLE strcpy(lastok, bufp); #endif /* OPIE_ENABLE */ ok = 0; } else if (strncmp(buf,"-ERR", 4) == 0) { 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 (argbuf != NULL) strcpy(argbuf,bufp); } return(ok); } static int pop3_getauth(int sock, struct query *ctl, char *greeting) /* apply for connection authorization */ { int ok; char *start,*end; char *msg; #if OPIE_ENABLE char *challenge; #endif /* OPIE_ENABLE */ #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) */ flag has_cram = FALSE; #ifdef OPIE_ENABLE flag has_otp = FALSE; #endif /* OPIE_ENABLE */ #ifdef SSL_ENABLE flag has_ssl = FALSE; #endif /* SSL_ENABLE */ #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 /* 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. if it doesn't, no harm done, we * just fall back to a plain login. 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. * * APOP was introduced in RFC 1450, and CAPA not until * RFC2449. So the < check is an easy way to prevent CAPA from * being sent to the more primitive POP3 servers dating from * RFC 1081 and RFC 1225, which seem more likely to choke on * it. This certainly catches IMAP-2000's POP3 gateway. * * These authentication methods are blessed by RFC1734, * describing the POP3 AUTHentication command. */ if (ctl->server.authenticate == A_ANY && strchr(greeting, '<') && gen_transact(sock, "CAPA") == 0) { 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_ssl = 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 */ if (strstr(buffer, "CRAM-MD5")) has_cram = TRUE; } } #ifdef SSL_ENABLE if (has_ssl && !ctl->use_ssl && #if INET6_ENABLE ctl->server.service && (strcmp(ctl->server.service, "pop3s")) #else /* INET6_ENABLE */ ctl->server.port != 995 #endif /* INET6_ENABLE */ ) { char *realhost; realhost = ctl->server.via ? ctl->server.via : ctl->server.pollname; gen_transact(sock, "STLS"); if (SSLOpen(sock,ctl->sslcert,ctl->sslkey,ctl->sslproto,ctl->sslcertck, ctl->sslcertpath,ctl->sslfingerprint,realhost,ctl->server.pollname) == -1) { report(stderr, GT_("SSL connection failed.\n")); return(PS_AUTHFAIL); } } #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 && #if INET6_ENABLE ctl->server.service && (strcmp(ctl->server.service, KPOP_PORT)!=0) #else /* INET6_ENABLE */ ctl->server.port != KPOP_PORT #endif /* INET6_ENABLE */ && (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)) { ok = do_gssauth(sock,"AUTH",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 */ if (has_cram && (ctl->server.authenticate == A_CRAM_MD5 || 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 */ gen_transact(sock, "USER %s", ctl->remotename); strcpy(shroud, ctl->password); ok = gen_transact(sock, "PASS %s", ctl->password); 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'; /* copy timestamp and password into digestion buffer */ xalloca(msg, char *, (end-start+1) + strlen(ctl->password) + 1); strcpy(msg,start); strcat(msg,ctl->password); strcpy(ctl->digest, MD5Digest((unsigned char *)msg)); ok = gen_transact(sock, "APOP %s %s", ctl->remotename, ctl->digest); break; case P_RPOP: if ((ok = gen_transact(sock,"USER %s", ctl->remotename)) == 0) ok = gen_transact(sock, "RPOP %s", ctl->password); break; default: report(stderr, GT_("Undefined protocol request in POP3_auth\n")); ok = PS_ERROR; } 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); } /* * 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)! */ /* we're peek-capable if use of TOP is enabled */ peek_capable = !(ctl->fetchall || ctl->keep); /* we're approved */ return(PS_SUCCESS); } static int pop3_gettopid( int sock, int num , char *id) { int ok; int got_it; char buf [POPBUFSIZE+1]; sprintf( buf, "TOP %d 1", num ); if ((ok = gen_transact(sock, buf )) != 0) return ok; got_it = 0; while ((ok = gen_recv(sock, buf, sizeof(buf))) == 0) { if (DOTLINE(buf)) break; if ( ! got_it && ! strncasecmp("Message-Id:", buf, 11 )) { got_it = 1; /* prevent stack overflows */ buf[IDLEN+12] = 0; sscanf( buf+12, "%s", id); } } return 0; } static int pop3_slowuidl( int sock, struct query *ctl, int *countp, int *newp) { /* 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 */ int ok, nolinear = 0; int first_nr, list_len, try_id, try_nr, add_id; int num; char id [IDLEN+1]; if( (ok = pop3_gettopid( sock, 1, id )) != 0 ) return ok; if( ( first_nr = str_nr_in_list(&ctl->oldsaved, id) ) == -1 ) { /* the first message is unknown -> all messages are new */ *newp = *countp; return 0; } /* check where we expect the latest known message */ list_len = count_list( &ctl->oldsaved ); try_id = list_len - first_nr; /* -1 + 1 */ if( try_id > 1 ) { if( try_id <= *countp ) { if( (ok = pop3_gettopid( sock, try_id, id )) != 0 ) return ok; try_nr = str_nr_last_in_list(&ctl->oldsaved, id); } else { try_id = *countp+1; try_nr = -1; } if( try_nr != list_len -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 )) != 0 ) return ok; try_nr = str_nr_in_list(&ctl->oldsaved, id); } 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 < list_len; num++ ) { struct idlist *new = save_str(&ctl->newsaved, str_from_nr_list(&ctl->oldsaved, num), UID_UNSEEN); new->val.status.num = num - first_nr + 1; } if( nolinear ) { free_str_list(&ctl->oldsaved); ctl->oldsaved = 0; 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]; /* Ensure that the new list is properly empty */ ctl->newsaved = (struct idlist *)NULL; #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) sscanf(buf,"%d %d", countp, bytes); else return(ok); /* * Newer, RFC-1725-conformant POP servers may not have the LAST command. * We work as hard as possible to hide this ugliness, but it makes * counting new messages intrinsically quadratic in the worst case. */ last = 0; *newp = -1; if (*countp > 0 && !ctl->fetchall) { char id [IDLEN+1]; if (!ctl->server.uidl) { gen_send(sock, "LAST"); ok = pop3_ok(sock, buf); } else ok = 1; if (ok == 0) { if (sscanf(buf, "%d", &last) == 0) { report(stderr, GT_("protocol error\n")); return(PS_ERROR); } *newp = (*countp - last); } else { /* grab the mailbox's UID list */ if ((ok = gen_transact(sock, "UIDL")) != 0) { /* don't worry, yet! do it the slow way */ if((ok = pop3_slowuidl( sock, ctl, countp, newp))!=0) { report(stderr, GT_("protocol error while fetching UIDLs\n")); return(PS_ERROR); } } else { int num; *newp = 0; while ((ok = gen_recv(sock, buf, sizeof(buf))) == 0) { if (DOTLINE(buf)) break; else if (sscanf(buf, "%d %s", &num, id) == 2) { struct idlist *new; new = save_str(&ctl->newsaved, id, UID_UNSEEN); new->val.status.num = num; if (str_in_list(&ctl->oldsaved, id, FALSE)) { new->val.status.mark = UID_SEEN; str_set_mark(&ctl->oldsaved, id, UID_SEEN); } else (*newp)++; } } } } } return(PS_SUCCESS); } 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 <= 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? */ { if (!ctl->oldsaved) return (num <= last); else return (str_in_list(&ctl->oldsaved, str_find(&ctl->newsaved, num), FALSE)); } #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/services/mail/sdps-tech.html * for a description of what we're parsing here. */ 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 */ sdps_envfrom = xmalloc(strlen(buf)+1); strcpy(sdps_envfrom,buf); break; case 5: /* Wrap address with To: <> so nxtaddr() likes it */ sdps_envto = xmalloc(strlen(buf)+7); sprintf(sdps_envto,"To: <%s>",buf); break; } } while (!(buf[0] == '.' && (buf[1] == '\r' || buf[1] == '\n' || buf[1] == '\0'))); } #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 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 (ctl->keep || ctl->fetchall) 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 int pop3_delete(int sock, struct query *ctl, int number) /* delete a given message */ { /* actually, mark for deletion -- doesn't happen until QUIT time */ return(gen_transact(sock, "DELE %d", number)); } 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); if (ctl->lastid) { free(ctl->lastid); ctl->lastid = NULL; } return(ok); } const static struct method pop3 = { "POP3", /* Post Office Protocol v3 */ #if INET6_ENABLE "pop3", /* standard POP3 port */ "pop3s", /* ssl POP3 port */ #else /* INET6_ENABLE */ 110, /* standard POP3 port */ 995, /* ssl POP3 port */ #endif /* INET6_ENABLE */ 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_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_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 --remote is not supported with POP3\n")); return(PS_SYNTAX); } #endif /* MBOX */ peek_capable = !ctl->fetchall; return(do_protocol(ctl, &pop3)); } #endif /* POP3_ENABLE */ /* pop3.c ends here */