tftp: corrupted input packets were killing retransmits - fixed

diff --git a/networking/tftp.c b/networking/tftp.c
index a62c5d8..2d28973 100644 (file)
--- a/networking/tftp.c
+++ b/networking/tftp.c
@@ -144,7 +144,10 @@ static int tftp(const int cmd, const struct hostent *host,
 
        /* Can't use RESERVE_CONFIG_BUFFER here since the allocation
         * size varies meaning BUFFERS_GO_ON_STACK would fail */
-       char *buf=xmalloc(tftp_bufsize += 4);
+       /* We must keep the transmit and receive buffers seperate */
+       /* In case we rcv a garbage pkt and we need to rexmit the last pkt */
+       char *xbuf = xmalloc(tftp_bufsize += 4);
+       char *rbuf = xmalloc(tftp_bufsize);
 
        if ((socketfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
                /* need to unlink the localfile, so don't use xsocket here. */
@@ -172,7 +175,7 @@ static int tftp(const int cmd, const struct hostent *host,
 
        while (1) {
 
-               cp = buf;
+               cp = xbuf;
 
                /* first create the opcode part */
                *((unsigned short *) cp) = htons(opcode);
@@ -184,18 +187,18 @@ static int tftp(const int cmd, const struct hostent *host,
                {
                        int too_long = 0;
 
-                       /* see if the filename fits into buf
+                       /* see if the filename fits into xbuf
                         * and fill in packet.  */
                        len = strlen(remotefile) + 1;
 
-                       if ((cp + len) >= &buf[tftp_bufsize - 1]) {
+                       if ((cp + len) >= &xbuf[tftp_bufsize - 1]) {
                                too_long = 1;
                        } else {
                                safe_strncpy(cp, remotefile, len);
                                cp += len;
                        }
 
-                       if (too_long || ((&buf[tftp_bufsize - 1] - cp) < MODE_OCTET_LEN)) {
+                       if (too_long || ((&xbuf[tftp_bufsize - 1] - cp) < MODE_OCTET_LEN)) {
                                bb_error_msg("remote filename too long");
                                break;
                        }
@@ -210,7 +213,7 @@ static int tftp(const int cmd, const struct hostent *host,
 
                        if (len != TFTP_BLOCKSIZE_DEFAULT) {
 
-                               if ((&buf[tftp_bufsize - 1] - cp) < 15) {
+                               if ((&xbuf[tftp_bufsize - 1] - cp) < 15) {
                                        bb_error_msg("remote filename too long");
                                        break;
                                }
@@ -259,15 +262,15 @@ static int tftp(const int cmd, const struct hostent *host,
                timeout = TFTP_NUM_RETRIES;     /* re-initialize */
                do {
 
-                       len = cp - buf;
+                       len = cp - xbuf;
 
 #if ENABLE_DEBUG_TFTP
                        fprintf(stderr, "sending %u bytes\n", len);
-                       for (cp = buf; cp < &buf[len]; cp++)
+                       for (cp = xbuf; cp < &xbuf[len]; cp++)
                                fprintf(stderr, "%02x ", (unsigned char) *cp);
                        fprintf(stderr, "\n");
 #endif
-                       if (sendto(socketfd, buf, len, 0,
+                       if (sendto(socketfd, xbuf, len, 0,
                                           (struct sockaddr *) &sa, sizeof(sa)) < 0) {
                                bb_perror_msg("send");
                                len = -1;
@@ -292,7 +295,7 @@ static int tftp(const int cmd, const struct hostent *host,
 
                        switch (select(socketfd + 1, &rfds, NULL, NULL, &tv)) {
                        case 1:
-                               len = recvfrom(socketfd, buf, tftp_bufsize, 0,
+                               len = recvfrom(socketfd, rbuf, tftp_bufsize, 0,
                                                           (struct sockaddr *) &from, &fromlen);
 
                                if (len < 0) {
@@ -334,8 +337,8 @@ static int tftp(const int cmd, const struct hostent *host,
 
                /* process received packet */
 
-               opcode = ntohs(*((unsigned short *) buf));
-               tmp = ntohs(*((unsigned short *) &buf[2]));
+               opcode = ntohs(*((unsigned short *) rbuf));
+               tmp = ntohs(*((unsigned short *) &rbuf[2]));
 
 #if ENABLE_DEBUG_TFTP
                fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, tmp);
@@ -344,9 +347,9 @@ static int tftp(const int cmd, const struct hostent *host,
                if (opcode == TFTP_ERROR) {
                        const char *msg = NULL;
 
-                       if (buf[4] != '\0') {
-                               msg = &buf[4];
-                               buf[tftp_bufsize - 1] = '\0';
+                       if (rbuf[4] != '\0') {
+                               msg = &rbuf[4];
+                               rbuf[tftp_bufsize - 1] = '\0';
                        } else if (tmp < (sizeof(tftp_bb_error_msg)
                                                          / sizeof(char *))) {
 
@@ -370,7 +373,7 @@ static int tftp(const int cmd, const struct hostent *host,
 
                                char *res;
 
-                               res = tftp_option_get(&buf[2], len - 2, OPTION_BLOCKSIZE);
+                               res = tftp_option_get(&rbuf[2], len - 2, OPTION_BLOCKSIZE);
 
                                if (res) {
                                        int blksize = xatoi_u(res);
@@ -408,7 +411,7 @@ static int tftp(const int cmd, const struct hostent *host,
 
                        if (tmp == block_nr) {
 
-                               len = full_write(localfd, &buf[4], len - 4);
+                               len = full_write(localfd, &rbuf[4], len - 4);
 
                                if (len < 0) {
                                        bb_perror_msg(bb_msg_write_error);
@@ -450,7 +453,8 @@ static int tftp(const int cmd, const struct hostent *host,
 
 #if ENABLE_FEATURE_CLEAN_UP
        close(socketfd);
-       free(buf);
+       free(xbuf);
+       free(rbuf);
 #endif
 
        return finished ? EXIT_SUCCESS : EXIT_FAILURE;