/* * imap.c -- IMAP2bis/IMAP4 protocol methods * * Copyright 1997 by Eric S. Raymond * For license terms, see the file COPYING in this directory. */ #include "config.h" #include #include #include #if defined(STDC_HEADERS) #include #endif #include "fetchmail.h" #include "socket.h" #include "i18n.h" #if OPIE_ENABLE #endif /* OPIE_ENABLE */ #ifndef strstr /* glibc-2.1 declares this as a macro */ extern char *strstr(); /* needed on sysV68 R3V7.1. */ #endif /* strstr */ /* imap_version values */ #define IMAP2 -1 /* IMAP2 or IMAP2BIS, RFC1176 */ #define IMAP4 0 /* IMAP4 rev 0, RFC1730 */ #define IMAP4rev1 1 /* IMAP4 rev 1, RFC2060 */ static int count, unseen, deletions, imap_version, preauth; static int expunged, expunge_period, saved_timeout; static flag do_idle; static char capabilities[MSGBUFSIZE+1]; static unsigned int *unseen_messages; static int imap_ok(int sock, char *argbuf) /* parse command response */ { char buf[MSGBUFSIZE+1]; do { int ok; char *cp; if ((ok = gen_recv(sock, buf, sizeof(buf)))) return(ok); /* all tokens in responses are caseblind */ for (cp = buf; *cp; cp++) if (islower(*cp)) *cp = toupper(*cp); /* interpret untagged status responses */ if (strstr(buf, "* CAPABILITY")) strncpy(capabilities, buf + 12, sizeof(capabilities)); else if (strstr(buf, "EXISTS")) { count = atoi(buf+2); /* * Nasty kluge to handle RFC2177 IDLE. If we know we're idling * we can't wait for the tag matching the IDLE; we have to tell the * server the IDLE is finished by shipping back a DONE when we * see an EXISTS. Only after that will a tagged response be * shipped. The idling flag also gets cleared on a timeout. */ if (stage == STAGE_IDLE) { /* we do our own write and report here to disable tagging */ SockWrite(sock, "DONE\r\n", 6); if (outlevel >= O_MONITOR) report(stdout, "IMAP> DONE\n"); mytimeout = saved_timeout; stage = STAGE_FETCH; } } else if (strstr(buf, "PREAUTH")) preauth = TRUE; /* * The server may decide to make the mailbox read-only, * which causes fetchmail to go into a endless loop * fetching the same message over and over again. * * However, for check_only, we use EXAMINE which will * mark the mailbox read-only as per the RFC. * * This checks for the condition and aborts if * the mailbox is read-only. * * See RFC 2060 section 6.3.1 (SELECT). * See RFC 2060 section 6.3.2 (EXAMINE). */ else if (!check_only && strstr(buf, "[READ-ONLY]")) return(PS_LOCKBUSY); } while (tag[0] != '\0' && strncmp(buf, tag, strlen(tag))); if (tag[0] == '\0') { if (argbuf) strcpy(argbuf, buf); return(PS_SUCCESS); } else { char *cp; /* skip the tag */ for (cp = buf; !isspace(*cp); cp++) continue; while (isspace(*cp)) cp++; if (strncmp(cp, "OK", 2) == 0) { if (argbuf) strcpy(argbuf, cp); return(PS_SUCCESS); } else if (strncmp(cp, "BAD", 3) == 0) return(PS_ERROR); else if (strncmp(cp, "NO", 2) == 0) { if (stage == STAGE_GETAUTH) return(PS_AUTHFAIL); /* RFC2060, 6.2.2 */ else return(PS_ERROR); } else return(PS_PROTOCOL); } } #if NTLM_ENABLE #include "ntlm.h" static tSmbNtlmAuthRequest request; static tSmbNtlmAuthChallenge challenge; static tSmbNtlmAuthResponse response; /* * 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_imap_ntlm(int sock, struct query *ctl) { char msgbuf[2048]; int result,len; gen_send(sock, "AUTHENTICATE NTLM"); if ((result = gen_recv(sock, msgbuf, sizeof msgbuf))) return result; if (msgbuf[0] != '+') return PS_AUTHFAIL; buildSmbNtlmAuthRequest(&request,ctl->remotename,NULL); if (outlevel >= O_DEBUG) dumpSmbNtlmAuthRequest(stdout, &request); memset(msgbuf,0,sizeof msgbuf); to64frombits (msgbuf, (unsigned char*)&request, SmbLength(&request)); if (outlevel >= O_MONITOR) report(stdout, "IMAP> %s\n", msgbuf); strcat(msgbuf,"\r\n"); SockWrite (sock, msgbuf, strlen (msgbuf)); if ((gen_recv(sock, msgbuf, sizeof msgbuf))) return result; len = from64tobits ((unsigned char*)&challenge, msgbuf); if (outlevel >= O_DEBUG) dumpSmbNtlmAuthChallenge(stdout, &challenge); buildSmbNtlmAuthResponse(&challenge, &response,ctl->remotename,ctl->password); if (outlevel >= O_DEBUG) dumpSmbNtlmAuthResponse(stdout, &response); memset(msgbuf,0,sizeof msgbuf); to64frombits (msgbuf, (unsigned char*)&response, SmbLength(&response)); if (outlevel >= O_MONITOR) report(stdout, "IMAP> %s\n", msgbuf); strcat(msgbuf,"\r\n"); SockWrite (sock, msgbuf, strlen (msgbuf)); if ((result = gen_recv (sock, msgbuf, sizeof msgbuf))) return result; if (strstr (msgbuf, "OK")) return PS_SUCCESS; else return PS_AUTHFAIL; } #endif /* NTLM */ static int imap_canonicalize(char *result, char *raw, int maxlen) /* encode an IMAP password as per RFC1730's quoting conventions */ { int i, j; j = 0; for (i = 0; i < strlen(raw) && i < maxlen; i++) { if ((raw[i] == '\\') || (raw[i] == '"')) result[j++] = '\\'; result[j++] = raw[i]; } result[j] = '\0'; return(i); } static int imap_getauth(int sock, struct query *ctl, char *greeting) /* apply for connection authorization */ { int ok = 0; /* probe to see if we're running IMAP4 and can use RFC822.PEEK */ capabilities[0] = '\0'; if ((ok = gen_transact(sock, "CAPABILITY")) == PS_SUCCESS) { /* UW-IMAP server 10.173 notifies in all caps, but RFC2060 says we should expect a response in mixed-case */ if (strstr(capabilities, "IMAP4REV1") || strstr(capabilities, "IMAP4rev1")) { imap_version = IMAP4rev1; if (outlevel >= O_DEBUG) report(stdout, _("Protocol identified as IMAP4 rev 1\n")); } else { imap_version = IMAP4; if (outlevel >= O_DEBUG) report(stdout, _("Protocol identified as IMAP4 rev 0\n")); } } else if (ok == PS_ERROR) { imap_version = IMAP2; if (outlevel >= O_DEBUG) report(stdout, _("Protocol identified as IMAP2 or IMAP2BIS\n")); } else return(ok); peek_capable = (imap_version >= IMAP4); /* * Assumption: expunges are cheap, so we want to do them * after every message unless user said otherwise. */ if (NUM_SPECIFIED(ctl->expunge)) expunge_period = NUM_VALUE_OUT(ctl->expunge); else expunge_period = 1; /* * Handle idling. We depend on coming through here on startup * and after each timeout (including timeouts during idles). */ if (strstr(capabilities, "IDLE") && ctl->idle) { do_idle = TRUE; if (outlevel >= O_VERBOSE) report(stdout, _("will idle after poll\n")); } /* * If either (a) we saw a PREAUTH token in the greeting, or * (b) the user specified ssh preauthentication, then we're done. */ if (preauth || ctl->server.authenticate == A_SSH) { preauth = FALSE; /* reset for the next session */ return(PS_SUCCESS); } /* * Time to authenticate the user. * Try the protocol variants that don't require passwords first. */ ok = PS_AUTHFAIL; #ifdef GSSAPI if ((ctl->server.authenticate == A_ANY || ctl->server.authenticate == A_GSSAPI) && strstr(capabilities, "AUTH=GSSAPI")) if(ok = do_gssauth(sock, "AUTHENTICATE", ctl->server.truename, ctl->remotename)) { /* SASL cancellation of authentication */ gen_send(sock, "*"); if(ctl->server.authenticate != A_ANY) return ok; } else return ok; #endif /* GSSAPI */ #ifdef KERBEROS_V4 if ((ctl->server.authenticate == A_ANY || ctl->server.authenticate == A_KERBEROS_V4 || ctl->server.authenticate == A_KERBEROS_V5) && strstr(capabilities, "AUTH=KERBEROS_V4")) { if ((ok = do_rfc1731(sock, "AUTHENTICATE", ctl->server.truename))) { /* SASL cancellation of authentication */ gen_send(sock, "*"); if(ctl->server.authenticate != A_ANY) return ok; } else return ok; } #endif /* KERBEROS_V4 */ /* * No such luck. OK, now try the variants that mask your password * in a challenge-response. */ if ((ctl->server.authenticate == A_ANY || ctl->server.authenticate == A_CRAM_MD5) && strstr(capabilities, "AUTH=CRAM-MD5")) { if ((ok = do_cram_md5 (sock, "AUTHENTICATE", ctl, NULL))) { /* SASL cancellation of authentication */ gen_send(sock, "*"); if(ctl->server.authenticate != A_ANY) return ok; } else return ok; } #if OPIE_ENABLE if ((ctl->server.authenticate == A_ANY || ctl->server.authenticate == A_OTP) && strstr(capabilities, "AUTH=X-OTP")) if ((ok = do_otp(sock, "AUTHENTICATE", ctl))) { /* SASL cancellation of authentication */ gen_send(sock, "*"); if(ctl->server.authenticate != A_ANY) return ok; } else return ok; #else if (ctl->server.authenticate == A_NTLM) { report(stderr, _("Required OTP capability not compiled into fetchmail\n")); } #endif /* OPIE_ENABLE */ #ifdef NTLM_ENABLE if ((ctl->server.authenticate == A_ANY || ctl->server.authenticate == A_NTLM) && strstr (capabilities, "AUTH=NTLM")) { if ((ok = do_imap_ntlm(sock, ctl))) { /* SASL cancellation of authentication */ gen_send(sock, "*"); if(ctl->server.authenticate != A_ANY) return ok; } else return(ok); } #else if (ctl->server.authenticate == A_NTLM) { report(stderr, _("Required NTLM capability not compiled into fetchmail\n")); } #endif /* NTLM_ENABLE */ #ifdef __UNUSED__ /* The Cyrus IMAP4rev1 server chokes on this */ /* this handles either AUTH=LOGIN or AUTH-LOGIN */ if ((imap_version >= IMAP4rev1) && (!strstr(capabilities, "LOGIN"))) { report(stderr, _("Required LOGIN capability not supported by server\n")); } #endif /* __UNUSED__ */ /* we're stuck with sending the password en clair */ if ((ctl->server.authenticate == A_ANY || ctl->server.authenticate == A_PASSWORD) && !strstr (capabilities, "LOGINDISABLED")) { /* these sizes guarantee no buffer overflow */ char remotename[NAMELEN*2+1], password[PASSWORDLEN*2+1]; imap_canonicalize(remotename, ctl->remotename, NAMELEN); imap_canonicalize(password, ctl->password, PASSWORDLEN); strcpy(shroud, ctl->password); ok = gen_transact(sock, "LOGIN \"%s\" \"%s\"", remotename, password); shroud[0] = '\0'; if (ok) { /* SASL cancellation of authentication */ gen_send(sock, "*"); if(ctl->server.authenticate != A_ANY) return ok; } else return(ok); } return(ok); } static int internal_expunge(int sock) /* ship an expunge, resetting associated counters */ { int ok; if ((ok = gen_transact(sock, "EXPUNGE"))) return(ok); expunged += deletions; deletions = 0; #ifdef IMAP_UID /* not used */ expunge_uids(ctl); #endif /* IMAP_UID */ return(PS_SUCCESS); } static int imap_idle(int sock) /* start an RFC2177 IDLE */ { stage = STAGE_IDLE; saved_timeout = mytimeout; mytimeout = 0; return (gen_transact(sock, "IDLE")); } static int imap_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[MSGBUFSIZE+1], *cp; /* find out how many messages are waiting */ *bytes = -1; if (pass > 1) { /* * We have to have an expunge here, otherwise the re-poll will * infinite-loop picking up un-expunged messages -- unless the * expunge period is one and we've been nuking each message * just after deletion. */ ok = 0; if (deletions && expunge_period != 1) ok = internal_expunge(sock); count = -1; if (do_idle) ok = imap_idle(sock); if (ok || gen_transact(sock, "NOOP")) { report(stderr, _("re-poll failed\n")); return(ok); } else if (count == -1) /* no EXISTS response to NOOP/IDLE */ { count = 0; } if (outlevel >= O_DEBUG) report(stdout, _("%d messages waiting after re-poll\n"), count); } else { ok = gen_transact(sock, check_only ? "EXAMINE \"%s\"" : "SELECT \"%s\"", folder ? folder : "INBOX"); if (ok != 0) { report(stderr, _("mailbox selection failed\n")); return(ok); } else if (outlevel >= O_DEBUG) report(stdout, _("%d messages waiting after first poll\n"), count); /* no messages? then we may need to idle until we get some */ if (count == 0 && do_idle) imap_idle(sock); } *countp = count; /* OK, now get a count of unseen messages and their indices */ if (!ctl->fetchall && count > 0) { if (unseen_messages) free(unseen_messages); unseen_messages = xmalloc(count * sizeof(unsigned int)); memset(unseen_messages, 0, count * sizeof(unsigned int)); unseen = 0; gen_send(sock, "SEARCH UNSEEN"); do { ok = gen_recv(sock, buf, sizeof(buf)); if (ok != 0) { report(stderr, _("search for unseen messages failed\n")); return(PS_PROTOCOL); } else if ((cp = strstr(buf, "* SEARCH"))) { char *ep; cp += 8; /* skip "* SEARCH" */ while (*cp && unseen < count) { /* skip whitespace */ while (*cp && isspace(*cp)) cp++; if (*cp) { /* * Message numbers are between 1 and 2^32 inclusive, * so unsigned int is large enough. */ unseen_messages[unseen]=(unsigned int)strtol(cp,&ep,10); if (outlevel >= O_DEBUG) report(stdout, _("%u is unseen\n"), unseen_messages[unseen]); unseen++; cp = ep; } } } } while (tag[0] != '\0' && strncmp(buf, tag, strlen(tag))); } else unseen = -1; *newp = unseen; expunged = 0; return(PS_SUCCESS); } static int imap_getsizes(int sock, int count, int *sizes) /* capture the sizes of all messages */ { char buf [MSGBUFSIZE+1]; /* * Some servers (as in, PMDF5.1-9.1 under OpenVMS 6.1) * won't accept 1:1 as valid set syntax. Some implementors * should be taken out and shot for excessive anality. * * Microsoft Exchange (brain-dead piece of crap that it is) * sometimes gets its knickers in a knot about bodiless messages. * You may see responses like this: * * fetchmail: IMAP> A0004 FETCH 1:9 RFC822.SIZE * fetchmail: IMAP< * 2 FETCH (RFC822.SIZE 1187) * fetchmail: IMAP< * 3 FETCH (RFC822.SIZE 3954) * fetchmail: IMAP< * 4 FETCH (RFC822.SIZE 1944) * fetchmail: IMAP< * 5 FETCH (RFC822.SIZE 2933) * fetchmail: IMAP< * 6 FETCH (RFC822.SIZE 1854) * fetchmail: IMAP< * 7 FETCH (RFC822.SIZE 34054) * fetchmail: IMAP< * 8 FETCH (RFC822.SIZE 5561) * fetchmail: IMAP< * 9 FETCH (RFC822.SIZE 1101) * fetchmail: IMAP< A0004 NO The requested item could not be found. * * This means message 1 has only headers. For kicks and grins * you can telnet in and look: * A003 FETCH 1 FULL * A003 NO The requested item could not be found. * A004 fetch 1 rfc822.header * A004 NO The requested item could not be found. * A006 FETCH 1 BODY * * 1 FETCH (BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 35 3)) * A006 OK FETCH completed. * * To get around this, we terminate the read loop on a NO and count * on the fact that the sizes array has been preinitialized with a * known-bad size value. */ if (count == 1) gen_send(sock, "FETCH 1 RFC822.SIZE", count); else gen_send(sock, "FETCH 1:%d RFC822.SIZE", count); for (;;) { int num, size, ok; if ((ok = gen_recv(sock, buf, sizeof(buf)))) return(ok); else if (strstr(buf, "OK") || strstr(buf, "NO")) break; else if (sscanf(buf, "* %d FETCH (RFC822.SIZE %d)", &num, &size) == 2) sizes[num - 1] = size; } return(PS_SUCCESS); } static int imap_is_old(int sock, struct query *ctl, int number) /* is the given message old? */ { flag seen = TRUE; int i; /* * Expunges change the fetch numbers, but unseen_messages contains * indices from before any expungees were done. So neither the * argument nor the values in message_sequence need to be decremented. */ seen = TRUE; for (i = 0; i < unseen; i++) if (unseen_messages[i] == number) { seen = FALSE; break; } return(seen); } static char *skip_token(char *ptr) { while(isspace(*ptr)) ptr++; while(!isspace(*ptr) && !iscntrl(*ptr)) ptr++; while(isspace(*ptr)) ptr++; return(ptr); } static int imap_fetch_headers(int sock, struct query *ctl,int number,int *lenp) /* request headers of nth message */ { char buf [MSGBUFSIZE+1]; int num; /* expunges change the fetch numbers */ number -= expunged; /* * This is blessed by RFC1176, RFC1730, RFC2060. * According to the RFCs, it should *not* set the \Seen flag. */ gen_send(sock, "FETCH %d RFC822.HEADER", number); /* looking for FETCH response */ for (;;) { int ok; char *ptr; if ((ok = gen_recv(sock, buf, sizeof(buf)))) return(ok); ptr = skip_token(buf); /* either "* " or "AXXXX " */ if (sscanf(ptr, "%d FETCH (%*s {%d}", &num, lenp) == 2) break; /* try to recover from chronically fucked-up M$ Exchange servers */ else if (!strncmp(ptr, "NO", 2)) return(PS_TRANSIENT); else if (!strncmp(ptr, "BAD", 3)) return(PS_TRANSIENT); } if (num != number) return(PS_ERROR); else return(PS_SUCCESS); } static int imap_fetch_body(int sock, struct query *ctl, int number, int *lenp) /* request body of nth message */ { char buf [MSGBUFSIZE+1], *cp; int num; /* expunges change the fetch numbers */ number -= expunged; /* * If we're using IMAP4, we can 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. * * 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 (and according * to RFC2060 p.43 this fetch should set Seen as a side effect). * * According to RFC2060, and Mark Crispin the IMAP maintainer, * FETCH %d BODY[TEXT] and RFC822.TEXT are "functionally * equivalent". However, we know of at least one server that * treats them differently in the presence of MIME attachments; * the latter form downloads the attachment, the former does not. * The server is InterChange, and the fool who implemented this * misfeature ought to be strung up by his thumbs. * * When I tried working around this by disabling use of the 4rev1 form, * I found that doing this breaks operation with M$ Exchange. * Annoyingly enough, Exchange's refusal to cope is technically legal * under RFC2062. Trust Microsoft, the Great Enemy of interoperability * standards, to find a way to make standards compliance irritating.... */ switch (imap_version) { case IMAP4rev1: /* RFC 2060 */ if (!ctl->keep) gen_send(sock, "FETCH %d BODY.PEEK[TEXT]", number); else gen_send(sock, "FETCH %d BODY[TEXT]", number); break; case IMAP4: /* RFC 1730 */ if (!ctl->keep) gen_send(sock, "FETCH %d RFC822.TEXT.PEEK", number); else gen_send(sock, "FETCH %d RFC822.TEXT", number); break; default: /* RFC 1176 */ gen_send(sock, "FETCH %d RFC822.TEXT", number); break; } /* looking for FETCH response */ do { int ok; if ((ok = gen_recv(sock, buf, sizeof(buf)))) return(ok); } while (!strstr(buf+4, "FETCH") || sscanf(buf+2, "%d", &num) != 1); if (num != number) return(PS_ERROR); /* * Try to extract a length from the FETCH response. RFC2060 requires * it to be present, but at least one IMAP server (Novell GroupWise) * botches this. */ if ((cp = strchr(buf, '{'))) *lenp = atoi(cp + 1); else *lenp = -1; /* missing length part in FETCH reponse */ return(PS_SUCCESS); } static int imap_trail(int sock, struct query *ctl, int number) /* discard tail of FETCH response after reading message text */ { /* expunges change the fetch numbers */ /* number -= expunged; */ for (;;) { char buf[MSGBUFSIZE+1]; int ok; if ((ok = gen_recv(sock, buf, sizeof(buf)))) return(ok); /* UW IMAP returns "OK FETCH", Cyrus returns "OK Completed" */ if (strstr(buf, "OK")) break; #ifdef __UNUSED__ /* * Any IMAP server that fails to set Seen on a BODY[TEXT] * fetch violates RFC2060 p.43 (top). This becomes an issue * when keep is on, because seen messages aren't deleted and * get refetched on each poll. As a workaround, if keep is on * we can set the Seen flag explicitly. * * This code isn't used yet because we don't know of any IMAP * servers broken in this way. */ if (ctl->keep) if ((ok = gen_transact(sock, imap_version == IMAP4 ? "STORE %d +FLAGS.SILENT (\\Seen)" : "STORE %d +FLAGS (\\Seen)", number))) return(ok); #endif /* __UNUSED__ */ } return(PS_SUCCESS); } static int imap_delete(int sock, struct query *ctl, int number) /* set delete flag for given message */ { int ok; /* expunges change the fetch numbers */ number -= expunged; /* * Use SILENT if possible as a minor throughput optimization. * Note: this has been dropped from IMAP4rev1. * * We set Seen because there are some IMAP servers (notably HP * OpenMail) that do message-receipt DSNs, but only when the seen * bit is set. This is the appropriate time -- we get here right * after the local SMTP response that says delivery was * successful. */ if ((ok = gen_transact(sock, imap_version == IMAP4 ? "STORE %d +FLAGS.SILENT (\\Seen \\Deleted)" : "STORE %d +FLAGS (\\Seen \\Deleted)", number))) return(ok); else deletions++; /* * We do an expunge after expunge_period messages, rather than * just before quit, so that a line hit during a long session * won't result in lots of messages being fetched again during * the next session. */ if (NUM_NONZERO(expunge_period) && (deletions % expunge_period) == 0) internal_expunge(sock); return(PS_SUCCESS); } static int imap_logout(int sock, struct query *ctl) /* send logout command */ { /* if any un-expunged deletions remain, ship an expunge now */ if (deletions) internal_expunge(sock); #ifdef USE_SEARCH /* Memory clean-up */ if (unseen_messages) free(unseen_messages); #endif /* USE_SEARCH */ return(gen_transact(sock, "LOGOUT")); } const static struct method imap = { "IMAP", /* Internet Message Access Protocol */ #if INET6_ENABLE "imap", "imaps", #else /* INET6_ENABLE */ 143, /* standard IMAP2bis/IMAP4 port */ 993, /* ssl IMAP2bis/IMAP4 port */ #endif /* INET6_ENABLE */ TRUE, /* this is a tagged protocol */ FALSE, /* no message delimiter */ imap_ok, /* parse command response */ imap_getauth, /* get authorization */ imap_getrange, /* query range of messages */ imap_getsizes, /* get sizes of messages (used for ESMTP SIZE option) */ imap_is_old, /* no UID check */ imap_fetch_headers, /* request given message headers */ imap_fetch_body, /* request given message body */ imap_trail, /* eat message trailer */ imap_delete, /* delete the message */ imap_logout, /* expunge and exit */ TRUE, /* yes, we can re-poll */ }; int doIMAP(struct query *ctl) /* retrieve messages using IMAP Version 2bis or Version 4 */ { return(do_protocol(ctl, &imap)); } /* imap.c ends here */