ftpd: simplify PORT check by assuming IP = peer's IP.
Should be as safe as before this change.
function old new delta
ftpd_main 2115 2025 -90
diff --git a/networking/ftpd.c b/networking/ftpd.c
index d63fd9b..6753248 100644
--- a/networking/ftpd.c
+++ b/networking/ftpd.c
@@ -422,21 +422,42 @@
free(response);
}
+/* libbb candidate */
+static
+len_and_sockaddr* get_peer_lsa(int fd)
+{
+ len_and_sockaddr *lsa;
+ socklen_t len = 0;
+
+ if (getpeername(fd, NULL, &len) != 0)
+ return NULL;
+ lsa = xzalloc(LSA_LEN_SIZE + len);
+ lsa->len = len;
+ getpeername(fd, &lsa->u.sa, &lsa->len);
+ return lsa;
+}
+
static void
handle_port(void)
{
unsigned port, port_hi;
char *raw, *comma;
+#ifdef WHY_BOTHER_WE_CAN_ASSUME_IP_MATCHES
socklen_t peer_ipv4_len;
struct sockaddr_in peer_ipv4;
struct in_addr port_ipv4_sin_addr;
+#endif
port_pasv_cleanup();
raw = G.ftp_arg;
/* PORT command format makes sense only over IPv4 */
- if (!raw || G.local_addr->u.sa.sa_family != AF_INET) {
+ if (!raw
+#ifdef WHY_BOTHER_WE_CAN_ASSUME_IP_MATCHES
+ || G.local_addr->u.sa.sa_family != AF_INET
+#endif
+ ) {
bail:
cmdio_write_error(FTP_BADCMD);
return;
@@ -459,6 +480,7 @@
goto bail;
port |= port_hi << 8;
+#ifdef WHY_BOTHER_WE_CAN_ASSUME_IP_MATCHES
replace_char(raw, ',', '.');
/* We are verifying that PORT's IP matches getpeername().
@@ -477,6 +499,10 @@
goto bail;
G.port_addr = xdotted2sockaddr(raw, port);
+#else
+ G.port_addr = get_peer_lsa(STDIN_FILENO);
+ set_nport(G.port_addr, port);
+#endif
cmdio_write_ok(FTP_PORTOK);
}