From e454a7edb591d95156b0082a18969257cc66d61c Mon Sep 17 00:00:00 2001
From: frekky <frekky@frekkworks.com>
Date: Mon, 28 Sep 2015 20:06:23 +0800
Subject: [PATCH] Modified options packet to change more than 1 option at a
 time

---
 doc/proto_00000800.txt |   8 +-
 src/client.c           | 229 ++++++++---------------------------------
 src/client.h           |   2 +-
 src/server.c           | 118 ++++++++++++---------
 4 files changed, 119 insertions(+), 238 deletions(-)

diff --git a/doc/proto_00000800.txt b/doc/proto_00000800.txt
index c6a56f8..75eff72 100644
--- a/doc/proto_00000800.txt
+++ b/doc/proto_00000800.txt
@@ -111,12 +111,14 @@ Options:
 Client sends:
 	First byte o or O
 	5 bits coded as Base32 char, meaning userid
-	1 char, meaning option
+	number of options (n) as decimal digit
+	n chars, each a valid option (to be processed in order)
 	CMC as 3 Base32 chars
 Server sends:
-	Full name of option if accepted. After this, option immediately takes
-	effect in server.
+	Option chars in the same order as request, indicating that options were
+	accepted by the server.
 	BADCODEC if not accepted. Previous situation remains.
+	BADLEN if number of options doesn't match length of query.
 	All options affect only the requesting client.
 
 	Option chars:
diff --git a/src/client.c b/src/client.c
index 02146cc..1b263d6 100644
--- a/src/client.c
+++ b/src/client.c
@@ -474,7 +474,7 @@ send_query(int fd, uint8_t *hostname)
 					" always work any more. Start with -L0 next time on this network.");
 				lazymode = 0;
 				server_timeout_ms = 0;
-				handshake_lazyoff(fd);
+				handshake_switch_options(fd, 0, compression_down, downenc);
 			}
 		}
 	}
@@ -1455,51 +1455,21 @@ send_codec_switch(int fd, int userid, int bits)
 }
 
 static void
-send_compression_switch(int fd, int userid)
+send_server_options(int fd, int userid, int lazy, int compression, char denc, char *options)
+/* Options must be length >=4 */
 {
-	char buf[512] = "o_____.";
-	buf[1] = b32_5to8(userid);
-	buf[2] = compression_down ? 'c' : 'd';
-
-	buf[3] = b32_5to8((rand_seed >> 10) & 0x1f);
-	buf[4] = b32_5to8((rand_seed >> 5) & 0x1f);
-	buf[5] = b32_5to8((rand_seed) & 0x1f);
-	rand_seed++;
-
-	strncat(buf, topdomain, 512 - strlen(buf));
-	send_query(fd, (uint8_t *)buf);
-}
-
-static void
-send_downenc_switch(int fd, int userid)
-{
-	char buf[512] = "o_____.";
-	buf[1] = b32_5to8(userid);
-	buf[2] = tolower(downenc);
-
-	buf[3] = b32_5to8((rand_seed >> 10) & 0x1f);
-	buf[4] = b32_5to8((rand_seed >> 5) & 0x1f);
-	buf[5] = b32_5to8((rand_seed) & 0x1f);
-	rand_seed++;
-
-	strncat(buf, topdomain, 512 - strlen(buf));
-	send_query(fd, (uint8_t *)buf);
-}
-
-static void
-send_lazy_switch(int fd, int userid)
-{
-	char buf[512] = "o_____.";
+	char buf[512] = "oU3___CMC.";
 	buf[1] = b32_5to8(userid);
 
-	if (lazymode)
-		buf[2] = 'l';
-	else
-		buf[2] = 'i';
+	options[0] = tolower(denc);
+	options[1] = lazy ? 'l' : 'i';
+	options[2] = compression ? 'c' : 'd';
+	options[3] = 0;
+	strncpy(buf + 3, options, 3);
 
-	buf[3] = b32_5to8((rand_seed >> 10) & 0x1f);
-	buf[4] = b32_5to8((rand_seed >> 5) & 0x1f);
-	buf[5] = b32_5to8((rand_seed ) & 0x1f);
+	buf[6] = b32_5to8((rand_seed >> 10) & 0x1f);
+	buf[7] = b32_5to8((rand_seed >> 5) & 0x1f);
+	buf[8] = b32_5to8((rand_seed) & 0x1f);
 	rand_seed++;
 
 	strncat(buf, topdomain, 512 - strlen(buf));
@@ -2185,87 +2155,54 @@ codec_revert:
 	fprintf(stderr, "Falling back to upstream codec %s\n", dataenc->name);
 }
 
-static void
-handshake_switch_downcompression(int dns_fd)
+void
+handshake_switch_options(int dns_fd, int lazy, int compression, char denc)
 {
 	char in[4096];
-	int i;
 	int read;
-	char *status;
+	char *dname, *comp_status, *lazy_status;
+	char opts[4];
 
-	status = compression_down ? "on" : "off";
-	fprintf(stderr, "Switching %s downstream data compression\n", status);
-	for (i = 0; running && i < 5; i++) {
-
-		send_compression_switch(dns_fd, userid);
-
-		read = handshake_waitdns(dns_fd, in, sizeof(in), 'O', i+1);
-
-		if (read > 0) {
-			if (strncmp("BADLEN", in, 6) == 0) {
-				fprintf(stderr, "Server got bad message length.\n");
-				goto fail;
-			} else if (strncmp("BADIP", in, 5) == 0) {
-				fprintf(stderr, "Server rejected sender IP address.\n");
-				goto fail;
-			} else if (strncmp("BADCODEC", in, 8) == 0) {
-				fprintf(stderr, "Server rejected the compression option.\n");
-				goto fail;
-			}
-			in[read] = 0; /* zero terminate */
-			fprintf(stderr, "Server %s downstream compression\n", in);
-			return;
-		}
-
-		fprintf(stderr, "Retrying downstream compression switch...\n");
-	}
-	if (!running)
-		return;
-
-	fprintf(stderr, "No reply from server on downstream compression switch.\n");
-
-fail:
-	fprintf(stderr, "Failed to switch %s downstream data compression\n", status);
-}
-
-static void
-handshake_switch_downenc(int dns_fd)
-{
-	char in[4096];
-	int i;
-	int read;
-	char *dname;
+	comp_status = compression ? "enabled" : "disabled";
 
 	dname = "Base32";
-	if (downenc == 'S')
+	if (denc == 'S')
 		dname = "Base64";
-	else if (downenc == 'U')
+	else if (denc == 'U')
 		dname = "Base64u";
-	else if (downenc == 'V')
+	else if (denc == 'V')
 		dname = "Base128";
-	else if (downenc == 'R')
+	else if (denc == 'R')
 		dname = "Raw";
 
-	fprintf(stderr, "Switching downstream to codec %s\n", dname);
-	for (i=0; running && i<5 ;i++) {
+	lazy_status = lazy ? "lazy" : "immediate";
 
-		send_downenc_switch(dns_fd, userid);
+	fprintf(stderr, "Switching server options: %s mode, downstream codec %s, compression %s...\n",
+			lazy_status, dname, comp_status);
+	for (int i = 0; running && i < 5; i++) {
 
-		read = handshake_waitdns(dns_fd, in, sizeof(in), 'O', i+1);
+		send_server_options(dns_fd, userid, lazy, compression, denc, opts);
+
+		read = handshake_waitdns(dns_fd, in, sizeof(in) - 1, 'O', i + 1);
 
 		if (read > 0) {
 			if (strncmp("BADLEN", in, 6) == 0) {
 				fprintf(stderr, "Server got bad message length.\n");
-				goto codec_revert;
+				goto opt_revert;
 			} else if (strncmp("BADIP", in, 5) == 0) {
 				fprintf(stderr, "Server rejected sender IP address.\n");
-				goto codec_revert;
+				goto opt_revert;
 			} else if (strncmp("BADCODEC", in, 8) == 0) {
-				fprintf(stderr, "Server rejected the selected codec.\n");
-				goto codec_revert;
+				fprintf(stderr, "Server rejected the selected options.\n");
+				goto opt_revert;
+			} else if (strncasecmp(opts, in + 3, 3) != 0) {
+				fprintf(stderr, "Server failed to change options.\n");
+				goto opt_revert;
 			}
-			in[read] = 0; /* zero terminate */
-			fprintf(stderr, "Server switched downstream to codec %s\n", in);
+			fprintf(stderr, "Switched server options successfully. (%s)\n", opts);
+			lazymode = lazy;
+			compression_down = compression;
+			downenc = denc;
 			return;
 		}
 
@@ -2276,79 +2213,9 @@ handshake_switch_downenc(int dns_fd)
 
 	fprintf(stderr, "No reply from server on codec switch.\n");
 
-codec_revert:
-	fprintf(stderr, "Falling back to downstream codec Base32\n");
-}
-
-static void
-handshake_try_lazy(int dns_fd)
-{
-	char in[4096];
-	int i;
-	int read;
-
-	fprintf(stderr, "Switching to lazy mode for low-latency\n");
-	for (i=0; running && i<5; i++) {
-
-		send_lazy_switch(dns_fd, userid);
-
-		read = handshake_waitdns(dns_fd, in, sizeof(in), 'O', i+1);
-
-		if (read > 0) {
-			if (strncmp("BADLEN", in, 6) == 0) {
-				fprintf(stderr, "Server got bad message length.\n");
-				goto codec_revert;
-			} else if (strncmp("BADIP", in, 5) == 0) {
-				fprintf(stderr, "Server rejected sender IP address.\n");
-				goto codec_revert;
-			} else if (strncmp("BADCODEC", in, 8) == 0) {
-				fprintf(stderr, "Server rejected lazy mode.\n");
-				goto codec_revert;
-			} else if (strncmp("Lazy", in, 4) == 0) {
-				fprintf(stderr, "Server switched to lazy mode\n");
-				lazymode = 1;
-				return;
-			}
-		}
-
-		fprintf(stderr, "Retrying lazy mode switch...\n");
-	}
-	if (!running)
-		return;
-
-	fprintf(stderr, "No reply from server on lazy switch.\n");
-
-codec_revert:
-	fprintf(stderr, "Falling back to legacy mode\n");
-	lazymode = 0;
-	max_timeout_ms = 1000;
-}
-
-void
-handshake_lazyoff(int dns_fd)
-/* Used in the middle of data transfer, timing is different and no error msgs */
-{
-	char in[4096];
-	int i;
-	int read;
-
-	for (i=0; running && i<5; i++) {
-
-		send_lazy_switch(dns_fd, userid);
-
-		read = handshake_waitdns(dns_fd, in, sizeof(in), 'O', 1);
-
-		if (read == 9 && strncmp("Immediate", in, 9) == 0) {
-			warnx("Server switched back to legacy mode.");
-			lazymode = 0;
-			max_timeout_ms = 1000;
-			return;
-		}
-	}
-	if (!running)
-		return;
-
-	warnx("No reply from server on legacy mode switch.");
+opt_revert:
+	fprintf(stderr, "Falling back to previous configuration, downstream codec %s.\n",
+			dataenc->name);
 }
 
 static int
@@ -2600,16 +2467,8 @@ client_handshake(int dns_fd, int raw_mode, int autodetect_frag_size, int fragsiz
 		if (!running)
 			return -1;
 
-		handshake_switch_downenc(dns_fd);
-		if (!running)
-			return -1;
-
-		if (!compression_down)
-			handshake_switch_downcompression(dns_fd);
-
-		if (lazymode) {
-			handshake_try_lazy(dns_fd);
-		}
+		/* Set options for compression, lazymode and downstream codec */
+		handshake_switch_options(dns_fd, lazymode, compression_down, downenc);
 		if (!running)
 			return -1;
 
diff --git a/src/client.h b/src/client.h
index ee43a52..bdb8a1c 100644
--- a/src/client.h
+++ b/src/client.h
@@ -49,7 +49,7 @@ void client_set_hostname_maxlen(size_t i);
 int client_handshake(int dns_fd, int raw_mode, int autodetect_frag_size, int fragsize);
 int client_tunnel(int tun_fd, int dns_fd);
 
-void handshake_lazyoff(int dns_fd);
+void handshake_switch_options(int dns_fd, int lazy, int compression, char denc);
 void send_ping(int fd, int ping_response, int ack);
 
 #endif
diff --git a/src/server.c b/src/server.c
index f6fd8b7..f26e076 100644
--- a/src/server.c
+++ b/src/server.c
@@ -1388,7 +1388,12 @@ handle_null_request(int tun_fd, int dns_fd, struct dnsfd *dns_fds, struct query
 		}
 		return;
 	} else if(in[0] == 'O' || in[0] == 'o') { /* Protocol options */
-		if (domain_len < 3) { /* len at least 3, example: "O1T" */
+		int bits = 0;
+		int numopts;
+		char num[2], *opts;
+
+		int tmp_lazy, tmp_downenc, tmp_comp;
+		if (domain_len < 7) { /* len at least 7, example: "oa1tcmc" */
 			write_dns(dns_fd, q, "BADLEN", 6, 'T');
 			return;
 		}
@@ -1400,59 +1405,67 @@ handle_null_request(int tun_fd, int dns_fd, struct dnsfd *dns_fds, struct query
 			return; /* illegal id */
 		}
 
-		int bits = 0;
-		switch (toupper(in[2])) {
-		case 'T':
-			users[userid].downenc = 'T';
-			write_dns(dns_fd, q, "Base32", 6, users[userid].downenc);
-			bits = 5;
-			break;
-		case 'S':
-			users[userid].downenc = 'S';
-			write_dns(dns_fd, q, "Base64", 6, users[userid].downenc);
-			bits = 6;
-			break;
-		case 'U':
-			users[userid].downenc = 'U';
-			write_dns(dns_fd, q, "Base64u", 7, users[userid].downenc);
-			bits = 6;
-			break;
-		case 'V':
-			users[userid].downenc = 'V';
-			write_dns(dns_fd, q, "Base128", 7, users[userid].downenc);
-			bits = 7;
-			break;
-		case 'R':
-			users[userid].downenc = 'R';
-			write_dns(dns_fd, q, "Raw", 3, users[userid].downenc);
-			bits = 8;
-			break;
-		case 'L':
-			users[userid].lazy = 1;
-			write_dns(dns_fd, q, "Lazy", 4, users[userid].downenc);
-			break;
-		case 'I':
-			users[userid].lazy = 0;
-			write_dns(dns_fd, q, "Immediate", 9, users[userid].downenc);
-			break;
-		case 'C':
-			users[userid].down_compression = 1;
-			write_dns(dns_fd, q, "Enabled", 7, users[userid].downenc);
-			break;
-		case 'D':
-			users[userid].down_compression = 0;
-			write_dns(dns_fd, q, "Disabled", 8, users[userid].downenc);
-			break;
-		default:
-			write_dns(dns_fd, q, "BADCODEC", 8, users[userid].downenc);
-			break;
+		num[0] = in[2];
+		num[1] = 0;
+		numopts = atoi(num);
+
+		if (domain_len != numopts + 6 || numopts == 0) {
+			write_dns(dns_fd, q, "BADLEN", 6, 'T');
 		}
+
+		/* Temporary variables: don't change anything until all options parsed */
+		tmp_lazy = users[userid].lazy;
+		tmp_comp = users[userid].down_compression;
+		tmp_downenc = users[userid].downenc;
+
+		opts = (char *) in + 3;
+
+		for (int i = 0; i < numopts; i++) {
+			switch (toupper(opts[i])) {
+			case 'T':
+				tmp_downenc = 'T';
+				bits = 5;
+				break;
+			case 'S':
+				tmp_downenc = 'S';
+				bits = 6;
+				break;
+			case 'U':
+				tmp_downenc = 'U';
+				bits = 6;
+				break;
+			case 'V':
+				tmp_downenc = 'V';
+				bits = 7;
+				break;
+			case 'R':
+				tmp_downenc = 'R';
+				bits = 8;
+				break;
+			case 'L':
+				tmp_lazy = 1;
+				break;
+			case 'I':
+				tmp_lazy = 0;
+				break;
+			case 'C':
+				tmp_comp = 1;
+				break;
+			case 'D':
+				tmp_comp = 0;
+				break;
+			default:
+				write_dns(dns_fd, q, "BADCODEC", 8, users[userid].downenc);
+				return;
+			}
+		}
+
 		/* Automatically switch to raw encoding if PRIVATE or NULL request */
-		if (q->type == T_NULL || q->type == T_PRIVATE) {
+		if ((q->type == T_NULL || q->type == T_PRIVATE) && !bits) {
 			users[userid].downenc = 'R';
 			bits = 8;
 			if (debug >= 3)
-				warnx("Assuming raw data encoding due to NULL/PRIVATE requests for user %d.", userid);
+				warnx("Assuming raw data encoding with NULL/PRIVATE requests for user %d.", userid);
 		}
 		if (bits) {
 			int f = users[userid].fragsize;
@@ -1462,6 +1475,13 @@ handle_null_request(int tun_fd, int dns_fd, struct dnsfd *dns_fds, struct query
 					  users[userid].outgoing->maxfraglen, userid, bits, users[userid].downenc);
 			users[userid].downenc_bits = bits;
 		}
+
+		/* Store any changes */
+		users[userid].down_compression = tmp_comp;
+		users[userid].downenc = tmp_downenc;
+		users[userid].lazy = tmp_lazy;
+
+		write_dns(dns_fd, q, opts, numopts, users[userid].downenc);
 		return;
 	} else if(in[0] == 'Y' || in[0] == 'y') { /* Downstream codec check */
 		int i;