/*
Copyright (C) 1999-2004 IC & S dbmail@ic-s.nl
Copyright (c) 2005-2006 NFG Net Facilities Group BV support@nfg.nl
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later
version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
*
* implementation for pop3 commands according to RFC 1081 */
#include "dbmail.h"
#define THIS_MODULE "pop3"
#define INCOMING_BUFFER_SIZE 512
#define APOP_STAMP_SIZE 255
#define MAX_USERID_SIZE 100
/* default timeout for server daemon */
#define DEFAULT_SERVER_TIMEOUT 300
/* max_errors defines the maximum number of allowed failures */
#define MAX_ERRORS 3
/* max_in_buffer defines the maximum number of bytes that are allowed to be
* in the incoming buffer */
#define MAX_IN_BUFFER 255
extern int pop_before_smtp;
extern volatile sig_atomic_t alarm_occured;
int pop3_error(PopSession_t * session, void *stream,
const char *formatstring, ...) PRINTF_ARGS(3, 4);
/* allowed pop3 commands */
const char *commands[] = {
"quit", /**< POP3_QUIT */
"user", /**< POP3_USER */
"pass", /**< POP3_PASS */
"stat", /**< POP3_STAT */
"list", /**< POP3_LIST */
"retr", /**< POP3_RETR */
"dele", /**< POP3_DELE */
"noop", /**< POP3_NOOP */
"last", /**< POP3_LAST */
"rset", /**< POP3_RSET */
"uidl", /**< POP3_UIDL */
"apop", /**< POP3_APOP */
"auth", /**< POP3_AUTH */
"top", /**< POP3_TOP */
"capa" /**< POP3_CAPA */
};
int pop3_handle_connection(clientinfo_t * ci)
{
/*
Handles connection and calls
pop command handler
*/
int done = 1; /* loop state */
char *buffer = NULL; /* connection buffer */
char myhostname[64];
int cnt; /* counter */
char unique_id[UID_SIZE];
PopSession_t session; /* current connection session */
/* setting Session variables */
memset(&session,0,sizeof(session));
/* clear the message list */
dm_list_init(&session.messagelst);
/* getting hostname */
gethostname(myhostname, 64);
myhostname[63] = '\0'; /* make sure string is terminated */
/* create an unique timestamp + processid for APOP authentication */
session.apop_stamp = g_new0(char,APOP_STAMP_SIZE);
create_unique_id(unique_id, 0);
snprintf(session.apop_stamp, APOP_STAMP_SIZE, "<%s@%s>", unique_id, myhostname);
if (ci->tx) {
/* sending greeting */
field_t banner;
GETCONFIGVALUE("banner", "POP", banner);
if (strlen(banner) > 0) {
ci_write(ci->tx, "+OK %s %s\r\n",
banner, session.apop_stamp);
} else {
ci_write(ci->tx, "+OK DBMAIL pop3 server ready to rock %s\r\n",
session.apop_stamp);
}
fflush(ci->tx);
} else {
TRACE(TRACE_MESSAGE, "TX stream is null!");
g_free(session.apop_stamp);
return 0;
}
/* set authorization state */
session.state = POP3_AUTHORIZATION_STATE;
/* setup the read buffer */
buffer = g_new0(char,INCOMING_BUFFER_SIZE);
/* lets start handling commands */
while (done > 0) {
if (db_check_connection())
break;
/* set the timeout counter */
if (session.state == POP3_AUTHORIZATION_STATE)
alarm(ci->login_timeout);
else
alarm(ci->timeout);
/* clear the buffer */
memset(buffer, 0, INCOMING_BUFFER_SIZE);
for (cnt = 0; cnt < INCOMING_BUFFER_SIZE - 1; cnt++) {
do {
clearerr(ci->rx);
fread(&buffer[cnt], 1, 1, ci->rx);
if (alarm_occured) {
alarm_occured = 0;
done = -2;
session.SessionResult = 1;
break;
}
} while (ferror(ci->rx) && errno == EINTR);
if (buffer[cnt] == '\n' || feof(ci->rx) || ferror(ci->rx)) {
buffer[cnt + 1] = '\0';
break;
}
}
if (done < 0) {
break;
} else if (feof(ci->rx) || ferror(ci->rx))
done = -1;
else {
/* reset function handle timeout */
alarm(0);
/* handle pop3 commands */
done = pop3(ci, buffer, &session);
}
fflush(ci->tx);
}
g_free(buffer);
buffer = NULL;
/* We're done with this client. The rest is cleanup */
session.state = POP3_UPDATE_STATE;
/* memory cleanup */
g_free(session.apop_stamp);
session.apop_stamp = NULL;
if (session.username != NULL && (session.was_apop || session.password != NULL)) {
switch (session.SessionResult) {
case 0:
TRACE(TRACE_MESSAGE, "user %s logging out [messages=%llu, octets=%llu]",
session.username,
session.virtual_totalmessages,
session.virtual_totalsize);
/* if everything went well, write down everything and do a cleanup */
if (db_update_pop(&session) == DM_SUCCESS)
ci_write(ci->tx, "+OK see ya later\r\n");
else
ci_write(ci->tx, "-ERR some deleted messages not removed\r\n");
fflush(ci->tx);
break;
case 1:
ci_write(ci->tx, "-ERR I'm leaving, you're too slow\r\n");
TRACE(TRACE_ERROR, "client timed out, connection closed");
break;
case 2:
TRACE(TRACE_ERROR, "alert! possible flood attempt, closing connection");
break;
case 3:
TRACE(TRACE_ERROR, "authorization layer failure");
break;
case 4:
TRACE(TRACE_ERROR, "storage layer failure");
break;
}
} else if (done==0) { // QUIT issued before AUTH phase completed
ci_write(ci->tx, "+OK see ya later\r\n");
fflush(ci->tx);
} else if (done==-2) {
ci_write(ci->tx, "-ERR I'm leaving, you're too slow\r\n");
TRACE(TRACE_ERROR, "client timed out before AUTH, connection closed");
} else {
TRACE(TRACE_ERROR, "error, incomplete session");
}
/* remove session info like messagelist etc. */
db_session_cleanup(&session);
/* username cleanup */
if (session.username != NULL) {
g_free(session.username);
session.username = NULL;
}
/* password cleanup */
if (session.password != NULL) {
g_free(session.password);
session.password = NULL;
}
/* reset timers */
alarm(0);
return 0;
}
int pop3_error(PopSession_t * session, void *stream,
const char *formatstring, ...)
{
va_list argp;
if (session->error_count >= MAX_ERRORS) {
TRACE(TRACE_MESSAGE, "too many errors (MAX_ERRORS is %d)",
MAX_ERRORS);
ci_write((FILE *) stream, "-ERR loser, go play somewhere else\r\n");
session->SessionResult = 2; /* possible flood */
return -3;
} else {
va_start(argp, formatstring);
vfprintf((FILE *) stream, formatstring, argp);
va_end(argp);
}
TRACE(TRACE_DEBUG, "an invalid command was issued");
session->error_count++;
return 1;
}
int pop3(clientinfo_t *ci, char *buffer, PopSession_t * session)
{
/* returns a 0 on a quit
* -1 on a failure
* 1 on a success
*/
char *command, *value;
Pop3Cmd_t cmdtype;
int found = 0;
int indx = 0;
u64_t result;
int validate_result;
u64_t top_lines, top_messageid;
struct element *tmpelement;
unsigned char *md5_apop_he;
char *searchptr;
u64_t user_idnr;
struct message *msg;
char *client_ip = ci->ip_src;
FILE *stream = ci->tx;
/* buffer overflow attempt */
if (strlen(buffer) > MAX_IN_BUFFER) {
TRACE(TRACE_DEBUG, "buffer overflow attempt");
return -3;
}
/* check for command issued */
while (strchr(ValidNetworkChars, buffer[indx]))
indx++;
/* end buffer */
buffer[indx] = '\0';
TRACE(TRACE_DEBUG, "incoming buffer: [%s]",
buffer);
command = buffer;
value = strstr(command, " "); /* look for the separator */
if (value != NULL) {
*value = '\0'; /* set a \0 on the command end */
value++; /* skip space */
if (strlen(value) == 0)
value = NULL; /* no value specified */
else {
TRACE(TRACE_DEBUG, "command issued :cmd [%s], value [%s]\n",
command, value);
}
}
/* find command that was issued */
for (cmdtype = POP3_QUIT; cmdtype <= POP3_CAPA; cmdtype++)
if (strcasecmp(command, commands[cmdtype]) == 0) {
session->was_apop = 1;
break;
}
TRACE(TRACE_DEBUG, "command looked up as commandtype %d",
cmdtype);
/* commands that are allowed to have no arguments */
if (value == NULL) {
switch (cmdtype) {
case POP3_QUIT:
case POP3_LIST:
case POP3_STAT:
case POP3_RSET:
case POP3_NOOP:
case POP3_LAST:
case POP3_UIDL:
case POP3_AUTH:
case POP3_CAPA:
break;
default:
return pop3_error(session, stream,
"-ERR your command does not compute\r\n");
break;
}
}
switch (cmdtype) {
case POP3_QUIT:
/* We return 0 here, and then pop3_handle_connection cleans up
* the connection, commits all changes, and sends the final
* "OK" message indicating that QUIT has completed. */
return 0;
case POP3_USER:
if (session->state != POP3_AUTHORIZATION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
if (session->username != NULL) {
/* reset username */
g_free(session->username);
session->username = NULL;
}
if (session->username == NULL) {
if (strlen(value) > MAX_USERID_SIZE)
return pop3_error(session, stream, "-ERR userid is too long\r\n");
/* create memspace for username */
session->username = g_new0(char,strlen(value) + 1);
strncpy(session->username, value, strlen(value) + 1);
}
ci_write((FILE *) stream, "+OK Password required for %s\r\n", session->username);
return 1;
case POP3_PASS:
if (session->state != POP3_AUTHORIZATION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
if (session->password != NULL) {
g_free(session->password);
session->password = NULL;
}
if (session->password == NULL) {
/* create memspace for password */
session->password = g_new0(char,strlen(value) + 1);
strncpy(session->password, value, strlen(value) + 1);
}
/* check in authorization layer if these credentials are correct */
validate_result = auth_validate(ci, session->username, session->password, &result);
switch (validate_result) {
case -1:
session->SessionResult = 3;
return -1;
case 0:
TRACE(TRACE_ERROR, "user [%s] coming from [%s] tried to login with wrong password",
session->username, ci->ip_src);
g_free(session->username);
session->username = NULL;
g_free(session->password);
session->password = NULL;
return pop3_error(session, stream, "-ERR username/password incorrect\r\n");
default:
/* user logged in OK */
session->state = POP3_TRANSACTION_STATE;
/* now we're going to build up a session for this user */
TRACE(TRACE_DEBUG, "validation OK, building a session for user [%s]",
session->username);
/* if pop_before_smtp is active, log this ip */
if (pop_before_smtp)
db_log_ip(client_ip);
child_reg_connected_user(session->username);
result = db_createsession(result, session);
if (result == 1) {
ci_write((FILE *) stream, "+OK %s has %llu messages (%llu octets)\r\n",
session->username,
session->virtual_totalmessages,
session->virtual_totalsize);
TRACE(TRACE_MESSAGE, "user %s logged in [messages=%llu, octets=%llu]",
session->username,
session->virtual_totalmessages,
session->virtual_totalsize);
} else
session->SessionResult = 4; /* Database error. */
return result;
}
return 1;
case POP3_LIST:
if (session->state != POP3_TRANSACTION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
tmpelement = dm_list_getstart(&session->messagelst);
if (value != NULL) {
/* they're asking for a specific message */
while (tmpelement != NULL) {
msg = (struct message *)tmpelement->data;
if (msg->messageid == strtoull(value,NULL, 10) && msg->virtual_messagestatus < MESSAGE_STATUS_DELETE) {
ci_write((FILE *) stream, "+OK %llu %llu\r\n", msg->messageid,msg->msize);
found = 1;
}
tmpelement = tmpelement->nextnode;
}
if (!found)
return pop3_error(session, stream, "-ERR [%s] no such message\r\n", value);
else
return 1;
}
/* just drop the list */
ci_write((FILE *) stream, "+OK %llu messages (%llu octets)\r\n",
session->virtual_totalmessages,
session->virtual_totalsize);
if (session->virtual_totalmessages > 0) {
/* traversing list */
while (tmpelement != NULL) {
msg = (struct message *)tmpelement->data;
if (msg->virtual_messagestatus < MESSAGE_STATUS_DELETE)
ci_write((FILE *) stream, "%llu %llu\r\n", msg->messageid,msg->msize);
tmpelement = tmpelement->nextnode;
}
}
ci_write((FILE *) stream, ".\r\n");
return 1;
case POP3_STAT:
if (session->state != POP3_TRANSACTION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
ci_write((FILE *) stream, "+OK %llu %llu\r\n",
session->virtual_totalmessages,
session->virtual_totalsize);
return 1;
case POP3_RETR:
TRACE(TRACE_DEBUG, "RETR command, retrieving message");
if (session->state != POP3_TRANSACTION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
tmpelement = dm_list_getstart(&(session->messagelst));
/* selecting a message */
TRACE(TRACE_DEBUG, "RETR command, selecting message");
while (tmpelement != NULL) {
msg = (struct message *) tmpelement->data;
if (msg->messageid == strtoull(value, NULL, 10) && msg->virtual_messagestatus < MESSAGE_STATUS_DELETE) { /* message is not deleted */
msg->virtual_messagestatus = MESSAGE_STATUS_SEEN;
ci_write((FILE *) stream, "+OK %llu octets\r\n", msg->msize);
return db_send_message_lines((void *) stream, msg->realmessageid, -2, 0);
}
tmpelement = tmpelement->nextnode;
}
return pop3_error(session, stream, "-ERR [%s] no such message\r\n", value);
case POP3_DELE:
if (session->state != POP3_TRANSACTION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
tmpelement = dm_list_getstart(&(session->messagelst));
/* selecting a message */
while (tmpelement != NULL) {
msg = (struct message *) tmpelement->data;
if (msg->messageid == strtoull(value, NULL, 10) && msg->virtual_messagestatus < MESSAGE_STATUS_DELETE) { /* message is not deleted */
msg->virtual_messagestatus = MESSAGE_STATUS_DELETE;
session->virtual_totalsize -= msg->msize;
session->virtual_totalmessages -= 1;
ci_write((FILE *) stream, "+OK message %llu deleted\r\n", msg->messageid);
return 1;
}
tmpelement = tmpelement->nextnode;
}
return pop3_error(session, stream, "-ERR [%s] no such message\r\n", value);
case POP3_RSET:
if (session->state != POP3_TRANSACTION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
tmpelement = dm_list_getstart(&(session->messagelst));
session->virtual_totalsize = session->totalsize;
session->virtual_totalmessages = session->totalmessages;
while (tmpelement != NULL) {
msg = (struct message *) tmpelement->data;
msg->virtual_messagestatus = msg->messagestatus;
tmpelement = tmpelement->nextnode;
}
ci_write((FILE *) stream, "+OK %llu messages (%llu octets)\r\n", session->virtual_totalmessages, session->virtual_totalsize);
return 1;
case POP3_LAST:
if (session->state != POP3_TRANSACTION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
tmpelement = dm_list_getstart(&(session->messagelst));
while (tmpelement != NULL) {
msg = (struct message *) tmpelement->data;
if (msg->virtual_messagestatus == MESSAGE_STATUS_NEW) {
/* we need the last message that has been accessed */
ci_write((FILE *) stream, "+OK %llu\r\n", msg->messageid - 1);
return 1;
}
tmpelement = tmpelement->nextnode;
}
/* all old messages */
ci_write((FILE *) stream, "+OK %llu\r\n", session->virtual_totalmessages);
return 1;
case POP3_NOOP:
if (session->state != POP3_TRANSACTION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
ci_write((FILE *) stream, "+OK\r\n");
return 1;
case POP3_UIDL:
if (session->state != POP3_TRANSACTION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
tmpelement = dm_list_getstart(&(session->messagelst));
if (value != NULL) {
/* they're asking for a specific message */
while (tmpelement != NULL) {
msg = (struct message *)tmpelement->data;
if (msg->messageid == strtoull(value,NULL, 10) && msg->virtual_messagestatus < MESSAGE_STATUS_DELETE) {
ci_write((FILE *) stream, "+OK %llu %s\r\n", msg->messageid,msg->uidl);
found = 1;
}
tmpelement = tmpelement->nextnode;
}
if (!found)
return pop3_error(session, stream, "-ERR [%s] no such message\r\n", value);
else
return 1;
}
/* just drop the list */
ci_write((FILE *) stream, "+OK Some very unique numbers for you\r\n");
if (session->virtual_totalmessages > 0) {
/* traversing list */
while (tmpelement != NULL) {
msg = (struct message *)tmpelement->data;
if (msg->virtual_messagestatus < MESSAGE_STATUS_DELETE)
ci_write((FILE *) stream, "%llu %s\r\n", msg->messageid, msg->uidl);
tmpelement = tmpelement->nextnode;
}
}
ci_write((FILE *) stream, ".\r\n");
return 1;
case POP3_APOP:
if (session->state != POP3_AUTHORIZATION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
/* find out where the md5 hash starts */
searchptr = strstr(value, " ");
if (searchptr == NULL)
return pop3_error(session, stream, "-ERR your command does not compute\r\n");
/* skip the space */
searchptr = searchptr + 1;
/* value should now be the username */
value[searchptr - value - 1] = '\0';
if (strlen(searchptr) != 32)
return pop3_error(session, stream, "-ERR not a valid md5 hash\r\n");
if (strlen(value) > MAX_USERID_SIZE)
return pop3_error(session, stream, "-ERR userid is too long\r\n");
md5_apop_he = g_new0(unsigned char,strlen(searchptr) + 1);
session->username = g_new0(char,strlen(value) + 1);
strncpy((char *)md5_apop_he, searchptr, strlen(searchptr) + 1);
strncpy(session->username, value, strlen(value) + 1);
/*
* check the encryption used for this user
* note that if the user does not exist it is not noted
* by db_getencryption()
*/
if (auth_user_exists(session->username, &user_idnr) == -1) {
TRACE(TRACE_ERROR, "error finding if user exists. username = [%s]",
session->username);
return -1;
}
if (strcasecmp(auth_getencryption(user_idnr), "") != 0) {
/* it should be clear text */
g_free(md5_apop_he);
g_free(session->username);
session->username = NULL;
md5_apop_he = NULL;
return pop3_error(session, stream, "-ERR APOP command is not supported for this user\r\n");
}
TRACE(TRACE_DEBUG, "APOP auth, username [%s], md5_hash [%s]", session->username, md5_apop_he);
result = auth_md5_validate(ci,session->username, md5_apop_he, session->apop_stamp);
g_free(md5_apop_he);
md5_apop_he = 0;
switch (result) {
case -1:
session->SessionResult = 3;
return -1;
case 0:
TRACE(TRACE_ERROR, "user [%s] tried to login with wrong password", session->username);
g_free(session->username);
session->username = NULL;
g_free(session->password);
session->password = NULL;
return pop3_error(session, stream, "-ERR authentication attempt is invalid\r\n");
default:
/* user logged in OK */
session->state = POP3_TRANSACTION_STATE;
/* user seems to be valid, let's build a session */
TRACE(TRACE_DEBUG, "validation OK, building a session for user [%s]",
session->username);
/* if pop_before_smtp is active, log this ip */
if (pop_before_smtp)
db_log_ip(client_ip);
child_reg_connected_user(session->username);
result = db_createsession(result, session);
if (result == 1) {
ci_write((FILE *) stream, "+OK %s has %llu messages (%llu octets)\r\n",
session->username,
session->virtual_totalmessages,
session->virtual_totalsize);
TRACE(TRACE_MESSAGE, "user %s logged in [messages=%llu, octets=%llu]",
session->username,
session->virtual_totalmessages,
session->virtual_totalsize);
} else
session->SessionResult = 4; /* Database error. */
return result;
}
return 1;
case POP3_AUTH:
if (session->state != POP3_AUTHORIZATION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
return pop3_error(session, stream, "-ERR no AUTH mechanisms supported\r\n");
case POP3_TOP:
if (session->state != POP3_TRANSACTION_STATE)
return pop3_error(session, stream, "-ERR wrong command mode\r\n");
/* find out how many lines they want */
searchptr = strstr(value, " ");
/* insufficient parameters */
if (searchptr == NULL)
return pop3_error(session, stream, "-ERR your command does not compute\r\n");
/* skip the space */
searchptr = searchptr + 1;
/* value should now be the the message that needs to be retrieved */
value[searchptr - value - 1] = '\0';
/* check if searchptr or value are negative. If so return an
error. This is done by only letting the strings contain
digits (0-9) */
if (strspn(searchptr, "0123456789") != strlen(searchptr))
return pop3_error(session, stream, "-ERR wrong parameter\r\n");
if (strspn(value, "0123456789") != strlen(value))
return pop3_error(session, stream, "-ERR wrong parameter\r\n");
top_lines = strtoull(searchptr, NULL, 10);
top_messageid = strtoull(value, NULL, 10);
if (top_messageid < 1)
return pop3_error(session, stream, "-ERR wrong parameter\r\n");
TRACE(TRACE_DEBUG, "TOP command (partially) retrieving message");
tmpelement = dm_list_getstart(&(session->messagelst));
/* selecting a message */
TRACE(TRACE_DEBUG, "TOP command, selecting message");
while (tmpelement != NULL) {
msg = (struct message *) tmpelement->data;
if (msg->messageid == top_messageid && msg->virtual_messagestatus < MESSAGE_STATUS_DELETE) { /* message is not deleted */
ci_write((FILE *) stream, "+OK %llu lines of message %llu\r\n", top_lines, top_messageid);
return db_send_message_lines(stream, msg->realmessageid, top_lines, 0);
}
tmpelement = tmpelement->nextnode;
}
return pop3_error(session, stream, "-ERR no such message\r\n");
case POP3_CAPA:
ci_write((FILE *) stream, "+OK Capability list follows\r\nTOP\r\nUSER\r\nUIDL\r\n.\r\n");
return 1;
default:
return pop3_error(session, stream, "-ERR command not understood\r\n");
}
return 1;
}
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