tftpd: show requested file name in open error message

function                                             old     new   delta
tftp_protocol                                       1902    1949     +47

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/networking/tftp.c b/networking/tftp.c
index 04bfe844f..e74186884 100644
--- a/networking/tftp.c
+++ b/networking/tftp.c
@@ -402,9 +402,17 @@ static int tftp_protocol(
                 /* Open file (must be after changing user) */
                 local_fd = open(local_file, open_mode, 0666);
                 if (local_fd < 0) {
+                        /* sanitize name, it came from untrusted remote side */
+                        unsigned char *p = (void *) local_file;
+                        while (*p) {
+                                if (*p < ' ')
+                                        *p = '?';
+                                p++;
+                        }
+                        bb_perror_msg("can't open '%s'", local_file);
                         G_error_pkt_reason = ERR_NOFILE;
                         strcpy(G_error_pkt_str, "can't open file");
-                        goto send_err_pkt;
+                        goto send_err_pkt_nomsg;
                 }
 /* gcc 4.3.1 would NOT optimize it out as it should! */
 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
@@ -721,7 +729,7 @@ static int tftp_protocol(
                  *  must never resend the current DATA packet on receipt
                  *  of a duplicate ACK".
                  * DATA pkts are resent ONLY on timeout.
-                 * Thus "goto send_again" will ba a bad mistake above.
+                 * Thus "goto send_again" will be a bad mistake above.
                  * See:
                  * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
                  */
@@ -740,6 +748,7 @@ static int tftp_protocol(
  send_err_pkt:
         if (G_error_pkt_str[0])
                 bb_simple_error_msg(G_error_pkt_str);
+ send_err_pkt_nomsg:
         G.error_pkt[1] = TFTP_ERROR;
         xsendto(socket_fd, G.error_pkt, 4 + 1 + strlen(G_error_pkt_str),
                         &peer_lsa->u.sa, peer_lsa->len);