/*
* Parse all the " by MTA ..." parts in received headers to guess the
* email address that this was originally delivered to.
*
* Extract just the MTA here by removing leading whitespace and
* assuming that the MTA name ends at the next whitespace. Test for
* *(by+4) to be non-'\0' to make sure there's something there at all
* - and then assume that the first whitespace delimited token that
* follows is the receiving system in this step of the receive chain.
*
* Return the address that was found, if any, and NULL otherwise.
*/
static const char *
guess_from_in_received_by (notmuch_config_t *config, const char *received)
{
const char *addr;
const char *by = received;
char *domain, *tld, *mta, *ptr, *token;
while ((by = strstr (by, " by ")) != NULL) {
by += 4;
if (*by == '\0')
break;
mta = xstrdup (by);
token = strtok(mta," \t");
if (token == NULL) {
free (mta);
break;
}
/*
* Now extract the last two components of the MTA host name as
* domain and tld.
*/
domain = tld = NULL;
while ((ptr = strsep (&token, ". \t")) != NULL) {
if (*ptr == '\0')
continue;
domain = tld;
tld = ptr;
}
if (domain) {
/*
* Recombine domain and tld and look for it among the
* configured email addresses. This time we have a known
* domain name and nothing else - so the test is the other
* way around: we check if this is a substring of one of
* the email addresses.
*/
*(tld - 1) = '.';
addr = string_in_user_address (domain, config);
if (addr) {
free (mta);
return addr;
}
}
free (mta);
}
return NULL;
}
static const char *
guess_from_received_header (notmuch_config_t *config, notmuch_message_t *message)
{
const char *addr, *received, *by;
char *mta,*ptr,*token;
char *domain=NULL;
char *tld=NULL;
const char *delim=". \t";
size_t i;
const char *to_headers[] = {
"Envelope-to",
"X-Original-To",
"Delivered-To",
};
/* sadly, there is no standard way to find out to which email
* address a mail was delivered - what is in the headers depends
* on the MTAs used along the way. So we are trying a number of
* heuristics which hopefully will answer this question.
* We only got here if none of the users email addresses are in
* the To: or Cc: header. From here we try the following in order:
* 1) check for an Envelope-to: header
* 2) check for an X-Original-To: header
* 3) check for a Delivered-To: header
* 4) check for a (for <*****@*****.**>) clause in Received: headers
* 5) check for the domain part of known email addresses in the
* 'by' part of Received headers
* If none of these work, we give up and return NULL
*/
for (i = 0; i < ARRAY_SIZE (to_headers); i++) {
const char *tohdr = notmuch_message_get_header (message, to_headers[i]);
/* Note: tohdr potentially contains a list of email addresses. */
addr = user_address_in_string (tohdr, config);
if (addr)
return addr;
}
/* We get the concatenated Received: headers and search from the
* front (last Received: header added) and try to extract from
* them indications to which email address this message was
* delivered.
* The Received: header is special in our get_header function
* and is always concatenated.
*/
received = notmuch_message_get_header (message, "received");
if (received == NULL)
return NULL;
/* First we look for a " for <*****@*****.**>" in the received
* header
*/
ptr = strstr (received, " for ");
/* Note: ptr potentially contains a list of email addresses. */
addr = user_address_in_string (ptr, config);
if (addr)
return addr;
/* Finally, we parse all the " by MTA ..." headers to guess the
* email address that this was originally delivered to.
* We extract just the MTA here by removing leading whitespace and
* assuming that the MTA name ends at the next whitespace.
* We test for *(by+4) to be non-'\0' to make sure there's
* something there at all - and then assume that the first
* whitespace delimited token that follows is the receiving
* system in this step of the receive chain
*/
by = received;
while((by = strstr (by, " by ")) != NULL) {
by += 4;
if (*by == '\0')
break;
mta = xstrdup (by);
token = strtok(mta," \t");
if (token == NULL) {
free (mta);
break;
}
/* Now extract the last two components of the MTA host name
* as domain and tld.
*/
domain = tld = NULL;
while ((ptr = strsep (&token, delim)) != NULL) {
if (*ptr == '\0')
continue;
domain = tld;
tld = ptr;
}
if (domain) {
/* Recombine domain and tld and look for it among the configured
* email addresses.
* This time we have a known domain name and nothing else - so
* the test is the other way around: we check if this is a
* substring of one of the email addresses.
*/
*(tld-1) = '.';
addr = string_in_user_address (domain, config);
if (addr) {
free (mta);
return addr;
}
}
free (mta);
}
return NULL;
}
