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Gracefully handle ACKs from the future

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This commit is contained in:
Joseph C. Lehner 2016-02-08 11:54:32 +01:00
parent 020c0c67f2
commit cac4275e60
1 changed files with 18 additions and 7 deletions
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21
tftp.c
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@ -222,9 +222,9 @@ inline void sock_perror(const char *msg)
int tftp_put(struct nmrpd_args *args) int tftp_put(struct nmrpd_args *args)
{ {
struct sockaddr_in addr; struct sockaddr_in addr;
uint16_t block, port; uint16_t block, ackblock, port;
ssize_t len, last_len; ssize_t len, last_len;
int fd, sock, ret, timeout; int fd, sock, ret, timeout, errors;
char rx[TFTP_PKT_SIZE], tx[TFTP_PKT_SIZE]; char rx[TFTP_PKT_SIZE], tx[TFTP_PKT_SIZE];
sock = -1; sock = -1;
@ -255,13 +255,16 @@ int tftp_put(struct nmrpd_args *args)
block = 0; block = 0;
last_len = -1; last_len = -1;
len = 0; len = 0;
errors = 0;
/* Not really, but this way the loop sends our WRQ before receiving */ /* Not really, but this way the loop sends our WRQ before receiving */
timeout = 1; timeout = 1;
pkt_mkwrq(tx, args->filename); pkt_mkwrq(tx, args->filename);
do { do {
if (timeout || (pkt_num(rx) == ACK && pkt_num(rx + 2) == block)) { ackblock = pkt_num(rx) == ACK ? pkt_num(rx + 2) : -1;
if (timeout || ackblock == block) {
if (!timeout) { if (!timeout) {
++block; ++block;
pkt_mknum(tx, DATA); pkt_mknum(tx, DATA);
@ -284,10 +287,18 @@ int tftp_put(struct nmrpd_args *args)
if (ret < 0) { if (ret < 0) {
goto cleanup; goto cleanup;
} }
} else if (pkt_num(rx) != ACK) { } else if (pkt_num(rx) != ACK || ackblock > block) {
if (verbosity) {
fprintf(stderr, "Expected ACK(%d), got ", block); fprintf(stderr, "Expected ACK(%d), got ", block);
pkt_print(rx, stderr); pkt_print(rx, stderr);
fprintf(stderr, "!\n"); fprintf(stderr, ".\n");
}
if (ackblock != -1 && ++errors > 5) {
fprintf(stderr, "Protocol error; bailing out.\n");
ret = -1;
goto cleanup;
}
} }
ret = tftp_recvfrom(sock, rx, &port, args->rx_timeout); ret = tftp_recvfrom(sock, rx, &port, args->rx_timeout);