tpws: segmentation failure warning and fix

tpws/helpers.c

@@ -11,6 +11,10 @@
 #include <sys/stat.h>
 #include <libgen.h>
 
+#ifdef __linux__
+#include <linux/tcp.h>
+#endif
+
 #ifdef __ANDROID__
 #include "andr/ifaddrs.h"
 #else
@@ -461,3 +465,55 @@ bool parse_cidr6(char *s, struct cidr6 *cidr)
 	if (p) *p = d; // restore char
 	return b;
 }
+
+
+void msleep(unsigned int ms)
+{
+	struct timespec time = {
+		 .tv_nsec = (ms % 1000) * 1000000,
+		 .tv_sec = ms / 1000
+	};
+	nanosleep(&time, 0);
+}
+
+#ifdef __linux__
+bool socket_has_notsent(int sfd)
+{
+	struct tcp_info tcpi;
+	socklen_t ts = sizeof(tcpi);
+
+	if (getsockopt(sfd, IPPROTO_TCP, TCP_INFO, (char *)&tcpi, &ts) < 0)
+		return false;
+	if (tcpi.tcpi_state != 1)
+		return false;
+	size_t s = (char *)&tcpi.tcpi_notsent_bytes - (char *)&tcpi.tcpi_state;
+	if (ts < s)
+		return false;
+	return !!tcpi.tcpi_notsent_bytes;
+}
+bool socket_wait_notsent(int sfd, unsigned int delay_ms, unsigned int *wasted_ms)
+{
+	struct timespec tres;
+	unsigned int mtick;
+
+	if (wasted_ms) *wasted_ms=0;
+	if (!socket_has_notsent(sfd)) return true;
+
+	if (clock_getres(CLOCK_MONOTONIC,&tres))
+	{
+		tres.tv_nsec = 10000000;
+		tres.tv_sec = 0;
+	}
+	mtick = (unsigned int)(tres.tv_sec*1000) + (unsigned int)(tres.tv_nsec/1000000);
+	if (mtick<1) mtick=1;
+	for(;;)
+	{
+		msleep(mtick);
+		if (wasted_ms) *wasted_ms+=mtick;
+		if (!socket_has_notsent(sfd)) return true;
+		if (delay_ms<=mtick) break;
+		delay_ms-=mtick;
+	}
+	return false;
+}
+#endif

tpws/helpers.h

@@ -117,3 +117,9 @@ static inline const struct in6_addr *mask_from_preflen6(uint8_t preflen)
 {
 	return ip6_mask+preflen;
 }
+
+void msleep(unsigned int ms);
+#ifdef __linux__
+bool socket_has_notsent(int sfd);
+bool socket_wait_notsent(int sfd, unsigned int delay_ms, unsigned int *wasted_ms);
+#endif

tpws/params.h

@@ -104,6 +104,7 @@ struct params_s
 	uint8_t proxy_type;
 	bool no_resolve;
 	bool skip_nodelay;
+	bool fix_seg;
 	bool droproot;
 	uid_t uid;
 	gid_t gid;

tpws/tpws.c

@@ -169,6 +169,9 @@ static void exithelp(void)
 		" --uid=uid[:gid]\t\t\t; drop root privs\n"
 #if defined(__FreeBSD__)
 		" --enable-pf\t\t\t\t; enable PF redirector support. required in FreeBSD when used with PF firewall.\n"
+#endif
+#if defined(__linux__)
+		" --fix-seg\t\t\t\t; fix segmentation failures at the cost of possible slowdown\n"
 #endif
 		" --debug=0|1|2|syslog|@<filename>\t; 1 and 2 means log to console and set debug level. for other targets use --debug-level.\n"
 		" --debug-level=0|1|2\t\t\t; specify debug level\n"
@@ -635,8 +638,9 @@ void parse_params(int argc, char *argv[])
 		{ "local-tcp-user-timeout",required_argument,0,0 },	// optidx=62
 		{ "remote-tcp-user-timeout",required_argument,0,0 },	// optidx=63
 		{ "mss",required_argument,0,0 },			// optidx=64
+		{ "fix-seg",no_argument,0,0 },				// optidx=65
 #ifdef SPLICE_PRESENT
-		{ "nosplice",no_argument,0,0 },				// optidx=65
+		{ "nosplice",no_argument,0,0 },				// optidx=66
 #endif
 #endif
 		{ "hostlist-auto-retrans-threshold",optional_argument,0,0}, // ignored. for nfqws command line compatibility
@@ -1228,8 +1232,11 @@ void parse_params(int argc, char *argv[])
 				exit_clean(1);
 			}
 			break;
+		case 65: /* fix-seg */
+			params.fix_seg = true;
+			break;
 #ifdef SPLICE_PRESENT
-		case 65: /* nosplice */
+		case 66: /* nosplice */
 			params.nosplice = true;
 			break;
 #endif

tpws/tpws_conn.c

@@ -1244,7 +1244,21 @@ static bool handle_epoll(tproxy_conn_t *conn, struct tailhead *conn_list, uint32
 							if (wr>0) conn->partner->twr += wr;
 							break;
 						}
-
+#ifdef __linux__
+						if (params.fix_seg)
+						{
+							unsigned int wasted;
+							if (!socket_wait_notsent(conn->partner->fd, 20, &wasted))
+								DLOG_ERR("WARNING ! segmentation failed\n");
+							if (wasted)
+								VPRINT("WARNING ! wasted %u ms to fix segmenation\n", wasted);
+						}
+						else
+						{
+							if (socket_has_notsent(conn->partner->fd))
+								DLOG_ERR("WARNING ! segmentation failed\n");
+						}
+#endif
 						from = to;
 					}
 				}