diff options
| -rw-r--r-- | networking/tftp.c | 31 |
1 files changed, 20 insertions, 11 deletions
diff --git a/networking/tftp.c b/networking/tftp.c index 6be265b..0b25f75 100644 --- a/networking/tftp.c +++ b/networking/tftp.c @@ -21,12 +21,12 @@ #include "libbb.h" - #if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT #define TFTP_BLOCKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */ -#define TFTP_TIMEOUT 5 /* seconds */ -#define TFTP_NUM_RETRIES 5 /* number of retries */ +#define TFTP_TIMEOUT 50000 /* 50ms, in microseconds */ +#define TFTP_MAXTIMEOUT 999000 /* about 1 second, in microseconds */ +#define TFTP_NUM_RETRIES 12 /* number of backed-off retries */ /* opcodes we support */ #define TFTP_RRQ 1 @@ -124,7 +124,7 @@ static int tftp( USE_GETPUT(const int cmd,) uint16_t opcode; uint16_t block_nr = 1; uint16_t recv_blk; - int timeout = TFTP_NUM_RETRIES; + int retries, waittime; char *cp; unsigned org_port; @@ -206,6 +206,10 @@ static int tftp( USE_GETPUT(const int cmd,) send_len = cp - xbuf; /* NB: send_len value is preserved in code below * for potential resend */ + + retries = TFTP_NUM_RETRIES; /* re-initialize */ + waittime = TFTP_TIMEOUT; + send_again: #if ENABLE_DEBUG_TFTP fprintf(stderr, "sending %u bytes\n", send_len); @@ -218,11 +222,10 @@ static int tftp( USE_GETPUT(const int cmd,) if (finished && (opcode == TFTP_ACK)) goto ret; - timeout = TFTP_NUM_RETRIES; /* re-initialize */ recv_again: /* Receive packet */ - tv.tv_sec = TFTP_TIMEOUT; - tv.tv_usec = 0; + tv.tv_sec = 0; + tv.tv_usec = waittime; FD_ZERO(&rfds); FD_SET(socketfd, &rfds); switch (select(socketfd + 1, &rfds, NULL, NULL, &tv)) { @@ -248,12 +251,18 @@ static int tftp( USE_GETPUT(const int cmd,) goto recv_again; goto process_pkt; case 0: - timeout--; - if (timeout == 0) { - bb_error_msg("last timeout"); + retries--; + if (retries == 0) { + bb_error_msg("timeout"); goto ret; } - bb_error_msg("last timeout" + 5); + + /* exponential backoff with limit */ + waittime += waittime/2; + if (waittime > TFTP_MAXTIMEOUT) { + waittime = TFTP_MAXTIMEOUT; + } + goto send_again; /* resend last sent pkt */ default: bb_perror_msg("select"); |