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piggyback data on acks when making connections on linux

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This commit is contained in:
Matt Johnston 2015-02-13 22:49:15 +08:00
parent 8eb30c353a
commit 9aeda4c5bd
2 changed files with 40 additions and 9 deletions
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2
cli-main.c
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@ -73,7 +73,7 @@ int main(int argc, char ** argv) {
#endif
{
int sock = connect_remote(cli_opts.remotehost, cli_opts.remoteport,
0, &error);
1, &error);
sock_in = sock_out = sock;
}

47
dbutil.c
View File

@ -150,18 +150,31 @@ void dropbear_log(int priority, const char* format, ...) {
#ifdef DEBUG_TRACE
static double time_since_start()
{
static double start_time = -1;
double nowf;
struct timeval tv;
gettimeofday(&tv, NULL);
nowf = tv.tv_sec + (tv.tv_usec / 1000000.0);
if (start_time < 0)
{
start_time = nowf;
return 0;
}
return nowf - start_time;
}
void dropbear_trace(const char* format, ...) {
va_list param;
struct timeval tv;
if (!debug_trace) {
return;
}
gettimeofday(&tv, NULL);
va_start(param, format);
fprintf(stderr, "TRACE (%d) %d.%d: ", getpid(), (int)tv.tv_sec, (int)tv.tv_usec);
fprintf(stderr, "TRACE (%d) %f: ", getpid(), time_since_start());
vfprintf(stderr, format, param);
fprintf(stderr, "\n");
va_end(param);
@ -170,7 +183,6 @@ void dropbear_trace(const char* format, ...) {
void dropbear_trace2(const char* format, ...) {
static int trace_env = -1;
va_list param;
struct timeval tv;
if (trace_env == -1) {
trace_env = getenv("DROPBEAR_TRACE2") ? 1 : 0;
@ -180,10 +192,8 @@ void dropbear_trace2(const char* format, ...) {
return;
}
gettimeofday(&tv, NULL);
va_start(param, format);
fprintf(stderr, "TRACE2 (%d) %d.%d: ", getpid(), (int)tv.tv_sec, (int)tv.tv_usec);
fprintf(stderr, "TRACE2 (%d) %f: ", getpid(), time_since_start());
vfprintf(stderr, format, param);
fprintf(stderr, "\n");
va_end(param);
@ -390,6 +400,23 @@ int connect_unix(const char* path) {
}
#endif
#if defined(__linux__) && defined(TCP_DEFER_ACCEPT)
static void set_piggyback_ack(int sock) {
/* Undocumented Linux feature - set TCP_DEFER_ACCEPT and data will be piggybacked
on the 3rd packet (ack) of the TCP handshake. Saves a IP packet.
http://thread.gmane.org/gmane.linux.network/224627/focus=224727
"Piggyback the final ACK of the three way TCP connection establishment with the data" */
int val = 1;
/* No error checking, this is opportunistic */
int err = setsockopt(sock, IPPROTO_TCP, TCP_DEFER_ACCEPT, (void*)&val, sizeof(val));
if (err)
{
DEBUG_TRACE(("Failed setsockopt TCP_DEFER_ACCEPT: %s", strerror(errno)))
}
}
#endif
/* Connect via TCP to a host. Connection will try ipv4 or ipv6, will
* return immediately if nonblocking is set. On failure, if errstring
* wasn't null, it will be a newly malloced error message */
@ -437,6 +464,10 @@ int connect_remote(const char* remotehost, const char* remoteport,
if (nonblocking) {
setnonblocking(sock);
#if defined(__linux__) && defined(TCP_DEFER_ACCEPT)
set_piggyback_ack(sock);
#endif
}
if (connect(sock, res->ai_addr, res->ai_addrlen) < 0) {