+/*************************************************
+* Verify HELO argument *
+*************************************************/
+
+/* This function is called if helo_verify_hosts or helo_try_verify_hosts is
+matched. It is also called from ACL processing if verify = helo is used and
+verification was not previously tried (i.e. helo_try_verify_hosts was not
+matched). The result of its processing is to set helo_verified and
+helo_verify_failed. These variables should both be FALSE for this function to
+be called.
+
+Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
+for IPv6 ::ffff: literals.
+
+Argument: none
+Returns: TRUE if testing was completed;
+ FALSE on a temporary failure
+*/
+
+BOOL
+smtp_verify_helo(void)
+{
+BOOL yield = TRUE;
+
+HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
+ sender_helo_name);
+
+if (sender_helo_name == NULL)
+ {
+ HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
+ }
+
+else if (sender_helo_name[0] == '[')
+ {
+ helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
+ Ustrlen(sender_host_address)) == 0;
+
+ #if HAVE_IPV6
+ if (!helo_verified)
+ {
+ if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
+ helo_verified = Ustrncmp(sender_helo_name + 1,
+ sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
+ }
+ #endif
+
+ HDEBUG(D_receive)
+ { if (helo_verified) debug_printf("matched host address\n"); }
+ }
+
+/* Do a reverse lookup if one hasn't already given a positive or negative
+response. If that fails, or the name doesn't match, try checking with a forward
+lookup. */
+
+else
+ {
+ if (sender_host_name == NULL && !host_lookup_failed)
+ yield = host_name_lookup() != DEFER;
+
+ /* If a host name is known, check it and all its aliases. */
+
+ if (sender_host_name != NULL)
+ {
+ helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0;
+
+ if (helo_verified)
+ {
+ HDEBUG(D_receive) debug_printf("matched host name\n");
+ }
+ else
+ {
+ uschar **aliases = sender_host_aliases;
+ while (*aliases != NULL)
+ {
+ helo_verified = strcmpic(*aliases++, sender_helo_name) == 0;
+ if (helo_verified) break;
+ }
+ HDEBUG(D_receive)
+ {
+ if (helo_verified)
+ debug_printf("matched alias %s\n", *(--aliases));
+ }
+ }
+ }
+
+ /* Final attempt: try a forward lookup of the helo name */
+
+ if (!helo_verified)
+ {
+ int rc;
+ host_item h;
+ h.name = sender_helo_name;
+ h.address = NULL;
+ h.mx = MX_NONE;
+ h.next = NULL;
+ HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
+ sender_helo_name);
+ rc = host_find_byname(&h, NULL, NULL, TRUE);
+ if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
+ {
+ host_item *hh = &h;
+ while (hh != NULL)
+ {
+ if (Ustrcmp(hh->address, sender_host_address) == 0)
+ {
+ helo_verified = TRUE;
+ HDEBUG(D_receive)
+ debug_printf("IP address for %s matches calling address\n",
+ sender_helo_name);
+ break;
+ }
+ hh = hh->next;
+ }
+ }
+ }
+ }
+
+if (!helo_verified) helo_verify_failed = FALSE; /* We've tried ... */
+return yield;
+}
+
+
+
+
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