sendmail: use host rather than NIS domain name for HELO

According to RFC 5321 the argument to HELO "contains the fully-qualified
domain name of the SMTP client" or its IP address if no FQDN is available.
BusyBox sendmail uses the NIS domain name instead which, in many cases,
is likely to be the default "(none)". [vda: yes, I checked my machine
and its uts.domainname was indeed "(none)"]

Using the host name is more likely to satisfy the intent of the RFC while
allowing the otherwise unused safe_getdomainname function to be removed.

Signed-off-by: Ron Yorston <rmy@tigress.co.uk>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 4 insertions, 26 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 2cc1466..f12800f 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -795,7 +795,6 @@ void qsort_string_vector(char **sv, unsigned count) FAST_FUNC;
 int safe_poll(struct pollfd *ufds, nfds_t nfds, int timeout_ms) FAST_FUNC;
 
 char *safe_gethostname(void) FAST_FUNC;
-char *safe_getdomainname(void) FAST_FUNC;
 
 /* Convert each alpha char in str to lower-case */
 char* str_tolower(char *str) FAST_FUNC;
diff --git a/libbb/safe_gethostname.c b/libbb/safe_gethostname.c
index bdb9896..cac99ae 100644
--- a/libbb/safe_gethostname.c
+++ b/libbb/safe_gethostname.c
@@ -50,25 +50,3 @@ char* FAST_FUNC safe_gethostname(void)
 	uname(&uts);
 	return xstrndup(!uts.nodename[0] ? "?" : uts.nodename, sizeof(uts.nodename));
 }
-
-/*
- * On success return the current malloced and NUL terminated domainname.
- * On error return malloced and NUL terminated string "?".
- * This is an illegal first character for a domainname.
- * The returned malloced string must be freed by the caller.
- */
-char* FAST_FUNC safe_getdomainname(void)
-{
-#if defined(__linux__)
-/* The field domainname of struct utsname is Linux specific. */
-	struct utsname uts;
-	uname(&uts);
-	return xstrndup(!uts.domainname[0] ? "?" : uts.domainname, sizeof(uts.domainname));
-#else
-	/* We really don't care about people with domain names wider than most screens */
-	char buf[256];
-	int r = getdomainname(buf, sizeof(buf));
-	buf[sizeof(buf)-1] = '\0';
-	return xstrdup(r < 0 ? "?" : buf);
-#endif
-}
diff --git a/mailutils/sendmail.c b/mailutils/sendmail.c
index aa381c6..c426e9d 100644
--- a/mailutils/sendmail.c
+++ b/mailutils/sendmail.c
@@ -118,7 +118,7 @@ int sendmail_main(int argc UNUSED_PARAM, char **argv)
 	char *opt_from;
 	char *s;
 	llist_t *list = NULL;
-	char *domain = sane_address(safe_getdomainname());
+	char *host = sane_address(safe_gethostname());
 	unsigned nheaders = 0;
 	int code;
 
@@ -222,8 +222,9 @@ int sendmail_main(int argc UNUSED_PARAM, char **argv)
 	}
 
 	// we should start with modern EHLO
-	if (250 != smtp_checkp("EHLO %s", domain, -1))
-		smtp_checkp("HELO %s", domain, 250);
+	if (250 != smtp_checkp("EHLO %s", host, -1))
+		smtp_checkp("HELO %s", host, 250);
+	free(host);
 
 	// perform authentication
 	if (opts & OPT_a) {