utility function for parsing and validating SMTP response lines

ok gilles@

3 files changed, 51 insertions, 44 deletions

diff --git a/usr.sbin/smtpd/client.c b/usr.sbin/smtpd/client.c
index f3807210dfc..6d1a45d1199 100644
--- a/usr.sbin/smtpd/client.c
+++ b/usr.sbin/smtpd/client.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: client.c,v 1.38 2011/11/03 14:34:13 chl Exp $	*/
+/*	$OpenBSD: client.c,v 1.39 2011/12/11 19:58:09 eric Exp $	*/
 
 /*
  * Copyright (c) 2009 Jacek Masiulaniec <jacekm@dobremiasto.net>
@@ -44,6 +44,8 @@ SSL		*ssl_client_init(int, char *, size_t, char *, size_t);
 int		 ssl_buf_read(SSL *, struct ibuf_read *);
 int		 ssl_buf_write(SSL *, struct msgbuf *);
 
+const char *parse_smtp_response(char *, size_t, char **, int *);
+
 /*
  * Initialize SMTP session.
  */
@@ -630,17 +632,19 @@ client_status(struct smtp_client *sp, char *fmt, ...)
 int
 client_getln(struct smtp_client *sp, int type)
 {
-	char	*ln = NULL, *cause = "";
-	int	 i, rv = -1;
+	const char	*e;
+	char		*ln = NULL, *msg, cause[1024];
+	int		 cont, rv = -1;
 
 	sp->reply[0] = '\0';
 
 	/* get a reply, dealing with multiline responses */
-	for (;;) {
+	for (cont = 1; cont;) {
+		free(ln);
 		errno = 0;
 		if ((ln = buf_getln(&sp->r)) == NULL) {
 			if (errno)
-				cause = "150 buf_getln error";
+				strlcpy(cause, "150 buf_getln error", sizeof(cause));
 			else
 				rv = 0;
 			goto done;
@@ -648,51 +652,19 @@ client_getln(struct smtp_client *sp, int type)
 
 		fprintf(sp->verbose, "<<< %s\n", ln);
 
-		/* 3-char replies are invalid on their own, append space */
-		if (strlen(ln) == 3) {
-			char buf[5];
-
-			strlcpy(buf, ln, sizeof(buf));
-			strlcat(buf, " ", sizeof(buf));
-			free(ln);
-			if ((ln = strdup(buf)) == NULL) {
-				cause = "150 strdup error";
-				goto done;
-			}
-		}
-
-		if (strlen(ln) < 4 || (ln[3] != ' ' && ln[3] != '-')) {
-			cause = "150 garbled smtp reply";
+		if ((e = parse_smtp_response(ln, strlen(ln), &msg, &cont))) {
+			snprintf(cause, sizeof(cause), "150 %s", e);
 			goto done;
 		}
 
 		if (type == CLIENT_EHLO) {
-			if (strcmp(ln + 4, "STARTTLS") == 0)
+			if (strcmp(msg, "STARTTLS") == 0)
 				sp->exts[CLIENT_EXT_STARTTLS].have = 1;
-			else if (strncmp(ln + 4, "AUTH", 4) == 0)
+			else if (strncmp(msg, "AUTH", 4) == 0)
 				sp->exts[CLIENT_EXT_AUTH].have = 1;
-			else if (strcmp(ln + 4, "PIPELINING") == 0)
+			else if (strcmp(msg, "PIPELINING") == 0)
 				sp->exts[CLIENT_EXT_PIPELINING].have = 1;
 		}
-
-		if (ln[3] == ' ')
-			break;
-
-		free(ln);
-	}
-
-	/* validate reply code */
-	if (ln[0] < '2' || ln[0] > '5' || !isdigit(ln[1]) || !isdigit(ln[2])) {
-		cause = "150 reply code out of range";
-		goto done;
-	}
-
-	/* validate reply message */
-	for (i = 0; ln[i] != '\0'; i++) {
-		if (!isprint(ln[i])) {
-			cause = "150 non-printable character in reply";
-			goto done;
-		}
 	}
 
 	strlcpy(sp->reply, ln, sizeof(sp->reply));
diff --git a/usr.sbin/smtpd/smtpd.h b/usr.sbin/smtpd/smtpd.h
index 6ffafc74186..f8aa32952fc 100644
--- a/usr.sbin/smtpd/smtpd.h
+++ b/usr.sbin/smtpd/smtpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: smtpd.h,v 1.257 2011/12/11 17:02:10 eric Exp $	*/
+/*	$OpenBSD: smtpd.h,v 1.258 2011/12/11 19:58:09 eric Exp $	*/
 
 /*
  * Copyright (c) 2008 Gilles Chehade <gilles@openbsd.org>
@@ -1220,3 +1220,4 @@ u_int32_t evpid_to_msgid(u_int64_t);
 u_int64_t msgid_to_evpid(u_int32_t);
 void log_imsg(int, int, struct imsg*);
 int ckdir(const char *, mode_t, uid_t, gid_t, int);
+const char *parse_smtp_response(char *, size_t, char **, int *);
diff --git a/usr.sbin/smtpd/util.c b/usr.sbin/smtpd/util.c
index e1e0c95a87d..a36eda191d6 100644
--- a/usr.sbin/smtpd/util.c
+++ b/usr.sbin/smtpd/util.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.c,v 1.51 2011/11/16 19:38:56 eric Exp $	*/
+/*	$OpenBSD: util.c,v 1.52 2011/12/11 19:58:09 eric Exp $	*/
 
 /*
  * Copyright (c) 2000,2001 Markus Friedl.  All rights reserved.
@@ -591,3 +591,37 @@ msgid_to_evpid(u_int32_t msgid)
 {
 	return ((u_int64_t)msgid << 32);
 }
+
+const char *
+parse_smtp_response(char *line, size_t len, char **msg, int *cont)
+{
+	size_t	 i;
+
+	if (len >= SMTP_LINE_MAX)
+		return "line too long";
+
+	if (len > 3) {
+		if (msg)
+			*msg = line + 4;
+		if (cont)
+			*cont = (line[3] == '-');
+	} else if (len == 3) {
+		if (msg)
+			*msg = line + 3;
+		if (cont)
+			*cont = 0;
+	} else
+		return "line too short";
+
+	/* validate reply code */
+	if (line[0] < '2' || line[0] > '5' || !isdigit(line[1]) ||
+	    !isdigit(line[2]))
+		return "reply code out of range";
+
+	/* validate reply message */
+	for (i = 0; i < len; i++)
+		if (!isprint(line[i]))
+			return "non-printable character in reply";
+
+	return NULL;
+}