From af421ceab33380c20fb0884ff79792538035a150 Mon Sep 17 00:00:00 2001
From: Michael Tuexen <tuexen@fh-muenster.de>
Date: Sat, 23 May 2015 20:45:42 +0200
Subject: [PATCH] Add support for RFC 4820 (Padding chunk and parameter)

This patch add support for the PAD chunk and PAD parameter defined
in https://tools.ietf.org/html/rfc4820
This fixes https://github.com/nplab/packetdrill/issues/16
---
 gtests/net/packetdrill/lexer.l                |  1 +
 .../net/packetdrill/packet_to_string_test.c   | 86 +++++++++++-------
 gtests/net/packetdrill/parser.y               | 26 +++++-
 gtests/net/packetdrill/run_packet.c           | 13 +++
 gtests/net/packetdrill/sctp.h                 | 15 ++++
 gtests/net/packetdrill/sctp_chunk_to_string.c | 41 ++++++++-
 gtests/net/packetdrill/sctp_packet.c          | 89 ++++++++++++++++++-
 gtests/net/packetdrill/sctp_packet.h          |  6 ++
 .../tests/bsd/sctp/sctp_active.pkt            |  2 +-
 .../tests/bsd/sctp/sctp_passive.pkt           |  4 +-
 10 files changed, 243 insertions(+), 40 deletions(-)

diff --git a/gtests/net/packetdrill/lexer.l b/gtests/net/packetdrill/lexer.l
index d5fb23b8..e462478e 100644
--- a/gtests/net/packetdrill/lexer.l
+++ b/gtests/net/packetdrill/lexer.l
@@ -227,6 +227,7 @@ COOKIE_ACK		return COOKIE_ACK;
 ECNE			return ECNE;
 CWR			return CWR;
 SHUTDOWN_COMPLETE	return SHUTDOWN_COMPLETE;
+PAD			return PAD;
 flgs			return FLAGS;
 len			return LEN;
 tag			return TAG;
diff --git a/gtests/net/packetdrill/packet_to_string_test.c b/gtests/net/packetdrill/packet_to_string_test.c
index b81befab..ae497533 100644
--- a/gtests/net/packetdrill/packet_to_string_test.c
+++ b/gtests/net/packetdrill/packet_to_string_test.c
@@ -102,7 +102,7 @@ static void test_sctp_ipv6_packet_to_string(void)
 	/* An IPv6/SCTP packet. */
 	u8 data[] = {
 		/* IPv6 Base Header: */
-		0x60, 0x00, 0x00, 0x00, 0x01, 0x80, 0x84, 0xff,
+		0x60, 0x00, 0x00, 0x00, 0x01, 0xa0, 0x84, 0xff,
 		0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x22, 0x22,
 		0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
@@ -110,7 +110,7 @@ static void test_sctp_ipv6_packet_to_string(void)
 		/* SCTP Common Header: */
 		0x04, 0xd2, 0x1f, 0x90,
 		0x01, 0x02, 0x03, 0x04,
-		0x22, 0x3e, 0x3f, 0x1c,
+		0x6e, 0xfc, 0x47, 0x17,
 		/* SCTP DATA Chunk */
 		0x00, 0x0f, 0x00, 0x13,
 		0x01, 0x02, 0x03, 0x04,
@@ -118,7 +118,7 @@ static void test_sctp_ipv6_packet_to_string(void)
 		0x00, 0x00, 0x00, 0x00,
 		0x00, 0x01, 0x02, 0x00,
 		/* SCTP INIT Chunk */
-		0x01, 0x00, 0x00, 0x50,
+		0x01, 0x00, 0x00, 0x60,
 		0x00, 0x00, 0x00, 0x01,
 		0x00, 0x01, 0x00, 0x00,
 		0x00, 0x0f, 0x00, 0x0f,
@@ -138,6 +138,10 @@ static void test_sctp_ipv6_packet_to_string(void)
 		0x00, 0x05, 0x00, 0x06,
 		0x00, 0x0b, 0x00, 0x00,
 		0x80, 0x00, 0x00, 0x04,
+		0x80, 0x05, 0x00, 0x10,
+		0x50, 0x50, 0x50, 0x50,
+		0x50, 0x50, 0x50, 0x50,
+		0x50, 0x50, 0x50, 0x50,
 		/* SCTP INIT_ACK Chunk */
 		0x02, 0x00, 0x00, 0x24,
 		0x00, 0x00, 0x00, 0x01,
@@ -219,7 +223,12 @@ static void test_sctp_ipv6_packet_to_string(void)
 		0x0d, 0x00, 0x00, 0x08,
 		0x01, 0x02, 0x03, 0x04,
 		/* SCTP SHUTDOWN_COMPLETE Chunk */
-		0x0e, 0x01, 0x00, 0x04
+		0x0e, 0x01, 0x00, 0x04,
+		/* SCTP PAD Chunk */
+		0x84, 0x00, 0x00, 0x10,
+		0x50, 0x50, 0x50, 0x50,
+		0x50, 0x50, 0x50, 0x50,
+		0x50, 0x50, 0x50, 0x50
 	};
 
 	struct packet *packet = packet_new(sizeof(data));
@@ -249,7 +258,8 @@ static void test_sctp_ipv6_packet_to_string(void)
 		     "COOKIE_PRESERVATIVE[incr=65536], "
 		     "HOSTNAME[addr=\"@A\"], "
 		     "SUPPORTED_ADDRESS_TYPES[types=[IPv4, IPv6, HOSTNAME]], "
-		     "ECN_CAPABLE[]]; "
+		     "ECN_CAPABLE[], "
+		     "PAD[len=16, val=...]]; "
 		"INIT_ACK[flgs=0x00, tag=1, a_rwnd=65536, os=15, is=15, tsn=16909060, "
 			 "STATE_COOKIE[len=7, val=...], "
 			 "UNRECOGNIZED_PARAMETER[params=["
@@ -265,7 +275,7 @@ static void test_sctp_ipv6_packet_to_string(void)
 		      "OUT_OF_RESOURCES[], "
 		      "UNRESOLVABLE_ADDRESS[HOSTNAME[addr=\"@A\"]], "
 		      "UNRECOGNIZED_CHUNK["
-			"CHUNK[type=0xfe, flags=0x05, value=[0x01]]], "
+			"CHUNK[type=0xfe, flgs=0x05, value=[0x01]]], "
 		      "INVALID_MANDATORY_PARAMETER[], "
 		      "UNRECOGNIZED_PARAMETERS["
 			"PARAMETER[type=0x800a, value=[]], "
@@ -283,7 +293,8 @@ static void test_sctp_ipv6_packet_to_string(void)
 		"COOKIE_ACK[flgs=0x00]; "
 		"ECNE[flgs=0x00, tsn=16909060]; "
 		"CWR[flgs=0x00, tsn=16909060]; "
-		"SHUTDOWN_COMPLETE[flgs=T]";
+		"SHUTDOWN_COMPLETE[flgs=T]; "
+		"PAD[flgs=0x00, len=16, val=...]";
 	assert(strcmp(dump, expected) == 0);
 	free(dump);
 
@@ -302,7 +313,8 @@ static void test_sctp_ipv6_packet_to_string(void)
 		     "COOKIE_PRESERVATIVE[incr=65536], "
 		     "HOSTNAME[addr=\"@A\"], "
 		     "SUPPORTED_ADDRESS_TYPES[types=[IPv4, IPv6, HOSTNAME]], "
-		     "ECN_CAPABLE[]]; "
+		     "ECN_CAPABLE[], "
+		     "PAD[len=16, val=...]]; "
 		"INIT_ACK[flgs=0x00, tag=1, a_rwnd=65536, os=15, is=15, tsn=16909060, "
 			 "STATE_COOKIE[len=7, val=...], "
 			 "UNRECOGNIZED_PARAMETER[params=["
@@ -318,7 +330,7 @@ static void test_sctp_ipv6_packet_to_string(void)
 		      "OUT_OF_RESOURCES[], "
 		      "UNRESOLVABLE_ADDRESS[HOSTNAME[addr=\"@A\"]], "
 		      "UNRECOGNIZED_CHUNK["
-			"CHUNK[type=0xfe, flags=0x05, value=[0x01]]], "
+			"CHUNK[type=0xfe, flgs=0x05, value=[0x01]]], "
 		      "INVALID_MANDATORY_PARAMETER[], "
 		      "UNRECOGNIZED_PARAMETERS["
 			"PARAMETER[type=0x800a, value=[]], "
@@ -336,7 +348,8 @@ static void test_sctp_ipv6_packet_to_string(void)
 		"COOKIE_ACK[flgs=0x00]; "
 		"ECNE[flgs=0x00, tsn=16909060]; "
 		"CWR[flgs=0x00, tsn=16909060]; "
-		"SHUTDOWN_COMPLETE[flgs=T]";
+		"SHUTDOWN_COMPLETE[flgs=T]; "
+		"PAD[flgs=0x00, len=16, val=...]";
 	assert(strcmp(dump, expected) == 0);
 	free(dump);
 
@@ -355,7 +368,8 @@ static void test_sctp_ipv6_packet_to_string(void)
 		     "COOKIE_PRESERVATIVE[incr=65536], "
 		     "HOSTNAME[addr=\"@A\"], "
 		     "SUPPORTED_ADDRESS_TYPES[types=[IPv4, IPv6, HOSTNAME]], "
-		     "ECN_CAPABLE[]]; "
+		     "ECN_CAPABLE[], "
+		     "PAD[len=16, val=...]]; "
 		"INIT_ACK[flgs=0x00, tag=1, a_rwnd=65536, os=15, is=15, tsn=16909060, "
 			 "STATE_COOKIE[len=7, val=...], "
 			 "UNRECOGNIZED_PARAMETER[params=["
@@ -371,7 +385,7 @@ static void test_sctp_ipv6_packet_to_string(void)
 		      "OUT_OF_RESOURCES[], "
 		      "UNRESOLVABLE_ADDRESS[HOSTNAME[addr=\"@A\"]], "
 		      "UNRECOGNIZED_CHUNK["
-			"CHUNK[type=0xfe, flags=0x05, value=[0x01]]], "
+			"CHUNK[type=0xfe, flgs=0x05, value=[0x01]]], "
 		      "INVALID_MANDATORY_PARAMETER[], "
 		      "UNRECOGNIZED_PARAMETERS["
 			"PARAMETER[type=0x800a, value=[]], "
@@ -389,35 +403,39 @@ static void test_sctp_ipv6_packet_to_string(void)
 		"COOKIE_ACK[flgs=0x00]; "
 		"ECNE[flgs=0x00, tsn=16909060]; "
 		"CWR[flgs=0x00, tsn=16909060]; "
-		"SHUTDOWN_COMPLETE[flgs=T]"
+		"SHUTDOWN_COMPLETE[flgs=T]; "
+		"PAD[flgs=0x00, len=16, val=...]"
 		"\n"
-		"0x0000: 60 00 00 00 01 80 84 ff 00 02 00 00 00 00 00 00 " "\n"
+		"0x0000: 60 00 00 00 01 a0 84 ff 00 02 00 00 00 00 00 00 " "\n"
 		"0x0010: 00 00 00 00 00 00 22 22 00 01 00 00 00 00 00 00 " "\n"
 		"0x0020: 00 00 00 00 00 00 11 11 04 d2 1f 90 01 02 03 04 " "\n"
-		"0x0030: 22 3e 3f 1c 00 0f 00 13 01 02 03 04 00 ff 01 00 " "\n"
-		"0x0040: 00 00 00 00 00 01 02 00 01 00 00 50 00 00 00 01 " "\n"
+		"0x0030: 6e fc 47 17 00 0f 00 13 01 02 03 04 00 ff 01 00 " "\n"
+		"0x0040: 00 00 00 00 00 01 02 00 01 00 00 60 00 00 00 01 " "\n"
 		"0x0050: 00 01 00 00 00 0f 00 0f 01 02 03 04 00 05 00 08 " "\n"
 		"0x0060: 01 02 03 04 00 06 00 14 00 00 00 00 00 00 00 00 " "\n"
 		"0x0070: 00 00 00 00 00 00 00 01 00 09 00 08 00 01 00 00 " "\n"
 		"0x0080: 00 0b 00 06 40 41 00 00 00 0c 00 0a 00 05 00 06 " "\n"
-		"0x0090: 00 0b 00 00 80 00 00 04 02 00 00 24 00 00 00 01 " "\n"
-		"0x00a0: 00 01 00 00 00 0f 00 0f 01 02 03 04 00 07 00 07 " "\n"
-		"0x00b0: 01 02 03 00 00 08 00 08 80 01 00 04 03 00 00 20 " "\n"
-		"0x00c0: 01 02 03 04 00 01 00 00 00 03 00 01 00 01 00 03 " "\n"
-		"0x00d0: 00 05 00 0f 10 00 10 14 01 02 03 04 04 00 00 0a " "\n"
-		"0x00e0: 00 01 00 06 01 02 00 00 05 00 00 0a 00 01 00 06 " "\n"
-		"0x00f0: 01 02 00 00 06 01 00 04 06 00 00 80 00 01 00 08 " "\n"
-		"0x0100: 00 ff 00 00 00 02 00 0a 00 00 00 01 00 07 00 00 " "\n"
-		"0x0110: 00 03 00 08 00 01 00 00 00 04 00 04 00 05 00 0c " "\n"
-		"0x0120: 00 0b 00 06 40 41 00 00 00 06 00 0c fe 05 00 05 " "\n"
-		"0x0130: 01 00 00 00 00 07 00 04 00 08 00 10 80 0a 00 04 " "\n"
-		"0x0140: 80 0b 00 05 01 00 00 00 00 09 00 08 01 02 03 04 " "\n"
-		"0x0150: 00 0a 00 04 00 0b 00 14 00 05 00 08 01 02 03 04 " "\n"
-		"0x0160: 00 05 00 08 02 03 04 05 00 0c 00 07 42 59 45 00 " "\n"
-		"0x0170: 00 0d 00 06 40 40 00 00 07 00 00 08 01 02 03 04 " "\n"
-		"0x0180: 08 00 00 04 09 00 00 04 0a 00 00 05 45 00 00 00 " "\n"
-		"0x0190: 0b 00 00 04 0c 00 00 08 01 02 03 04 0d 00 00 08 " "\n"
-		"0x01a0: 01 02 03 04 0e 01 00 04 " "\n";
+		"0x0090: 00 0b 00 00 80 00 00 04 80 05 00 10 50 50 50 50 " "\n"
+		"0x00a0: 50 50 50 50 50 50 50 50 02 00 00 24 00 00 00 01 " "\n"
+		"0x00b0: 00 01 00 00 00 0f 00 0f 01 02 03 04 00 07 00 07 " "\n"
+		"0x00c0: 01 02 03 00 00 08 00 08 80 01 00 04 03 00 00 20 " "\n"
+		"0x00d0: 01 02 03 04 00 01 00 00 00 03 00 01 00 01 00 03 " "\n"
+		"0x00e0: 00 05 00 0f 10 00 10 14 01 02 03 04 04 00 00 0a " "\n"
+		"0x00f0: 00 01 00 06 01 02 00 00 05 00 00 0a 00 01 00 06 " "\n"
+		"0x0100: 01 02 00 00 06 01 00 04 06 00 00 80 00 01 00 08 " "\n"
+		"0x0110: 00 ff 00 00 00 02 00 0a 00 00 00 01 00 07 00 00 " "\n"
+		"0x0120: 00 03 00 08 00 01 00 00 00 04 00 04 00 05 00 0c " "\n"
+		"0x0130: 00 0b 00 06 40 41 00 00 00 06 00 0c fe 05 00 05 " "\n"
+		"0x0140: 01 00 00 00 00 07 00 04 00 08 00 10 80 0a 00 04 " "\n"
+		"0x0150: 80 0b 00 05 01 00 00 00 00 09 00 08 01 02 03 04 " "\n"
+		"0x0160: 00 0a 00 04 00 0b 00 14 00 05 00 08 01 02 03 04 " "\n"
+		"0x0170: 00 05 00 08 02 03 04 05 00 0c 00 07 42 59 45 00 " "\n"
+		"0x0180: 00 0d 00 06 40 40 00 00 07 00 00 08 01 02 03 04 " "\n"
+		"0x0190: 08 00 00 04 09 00 00 04 0a 00 00 05 45 00 00 00 " "\n"
+		"0x01a0: 0b 00 00 04 0c 00 00 08 01 02 03 04 0d 00 00 08 " "\n"
+		"0x01b0: 01 02 03 04 0e 01 00 04 84 00 00 10 50 50 50 50 " "\n"
+		"0x01c0: 50 50 50 50 50 50 50 50 " "\n";
+	printf("expected = '%s'\n", expected);
 	assert(strcmp(dump, expected) == 0);
 	free(dump);
 	packet_free(packet);
diff --git a/gtests/net/packetdrill/parser.y b/gtests/net/packetdrill/parser.y
index 2e1d93f1..593603fa 100644
--- a/gtests/net/packetdrill/parser.y
+++ b/gtests/net/packetdrill/parser.y
@@ -503,7 +503,7 @@ static struct tcp_option *new_tcp_fast_open_option(const char *cookie_string,
 %token <reserved> SACK_DELAY SACK_FREQ
 %token <reserved> DATA INIT INIT_ACK HEARTBEAT HEARTBEAT_ACK ABORT
 %token <reserved> SHUTDOWN SHUTDOWN_ACK ERROR COOKIE_ECHO COOKIE_ACK ECNE CWR
-%token <reserved> SHUTDOWN_COMPLETE
+%token <reserved> SHUTDOWN_COMPLETE PAD
 %token <reserved> FLAGS LEN TAG A_RWND OS IS TSN SID SSN PPID CUM_TSN GAPS DUPS
 %token <reserved> HEARTBEAT_INFORMATION IPV4_ADDRESS IPV6_ADDRESS STATE_COOKIE
 %token <reserved> UNRECOGNIZED_PARAMETER COOKIE_PRESERVATIVE HOSTNAME_ADDRESS
@@ -561,6 +561,7 @@ static struct tcp_option *new_tcp_fast_open_option(const char *cookie_string,
 %type <chunk_list_item> sctp_cookie_echo_chunk_spec sctp_cookie_ack_chunk_spec
 %type <chunk_list_item> sctp_ecne_chunk_spec sctp_cwr_chunk_spec
 %type <chunk_list_item> sctp_shutdown_complete_chunk_spec
+%type <chunk_list_item> sctp_pad_chunk_spec
 %type <parameter_list> opt_parameter_list_spec sctp_parameter_list_spec
 %type <parameter_list_item> sctp_parameter_spec
 %type <parameter_list_item> sctp_heartbeat_information_parameter_spec
@@ -572,6 +573,7 @@ static struct tcp_option *new_tcp_fast_open_option(const char *cookie_string,
 %type <parameter_list_item> sctp_hostname_address_parameter_spec
 %type <parameter_list_item> sctp_supported_address_types_parameter_spec
 %type <parameter_list_item> sctp_ecn_capable_parameter_spec
+%type <parameter_list_item> sctp_pad_parameter_spec
 
 %type <integer> opt_flags opt_data_flags opt_abort_flags
 %type <integer> opt_shutdown_complete_flags opt_chunk_len
@@ -787,6 +789,7 @@ sctp_chunk_spec
 | sctp_ecne_chunk_spec              { $$ = $1; }
 | sctp_cwr_chunk_spec               { $$ = $1; }
 | sctp_shutdown_complete_chunk_spec { $$ = $1; }
+| sctp_pad_chunk_spec               { $$ = $1; }
 ;
 
 opt_chunk_len
@@ -1175,6 +1178,11 @@ sctp_shutdown_complete_chunk_spec
 	$$ = sctp_shutdown_complete_chunk_new($3);
 }
 
+sctp_pad_chunk_spec
+: PAD '[' opt_flags ',' opt_chunk_len ',' VAL '=' ELLIPSIS ']' {
+	$$ = sctp_pad_chunk_new($3, $5, NULL);
+}
+
 opt_parameter_list_spec
 : ',' ELLIPSIS                 { $$ = NULL; }
 |                              { $$ = sctp_parameter_list_new(); }
@@ -1198,6 +1206,7 @@ sctp_parameter_spec
 | sctp_hostname_address_parameter_spec        { $$ = $1; }
 | sctp_supported_address_types_parameter_spec { $$ = $1; }
 | sctp_ecn_capable_parameter_spec             { $$ = $1; }
+| sctp_pad_parameter_spec                     { $$ = $1; }
 ;
 
 sctp_heartbeat_information_parameter_spec
@@ -1315,6 +1324,21 @@ sctp_ecn_capable_parameter_spec
 	$$ = sctp_ecn_capable_parameter_new();
 }
 
+sctp_pad_parameter_spec
+: PAD '[' ELLIPSIS ']' {
+	$$ = sctp_pad_parameter_new(-1, NULL);
+}
+| PAD '[' LEN '=' ELLIPSIS ',' VAL '=' ELLIPSIS ']' {
+	$$ = sctp_pad_parameter_new(-1, NULL);
+}
+| PAD '[' LEN '=' INTEGER ',' VAL '=' ELLIPSIS ']' {
+	if (($5 < sizeof(struct sctp_pad_parameter)) ||
+	    !is_valid_u32($5)) {
+		semantic_error("len value out of range");
+	}
+	$$ = sctp_pad_parameter_new($5, NULL);
+}
+
 tcp_packet_spec
 : packet_prefix opt_ip_info flags seq opt_ack opt_window opt_tcp_options {
 	char *error = NULL;
diff --git a/gtests/net/packetdrill/run_packet.c b/gtests/net/packetdrill/run_packet.c
index 3eea2703..bf23e161 100644
--- a/gtests/net/packetdrill/run_packet.c
+++ b/gtests/net/packetdrill/run_packet.c
@@ -1426,6 +1426,14 @@ static int verify_shutdown_complete_chunk(struct sctp_shutdown_complete_chunk *a
 	return STATUS_OK;
 }
 
+static int verify_pad_chunk(struct sctp_pad_chunk *actual_chunk,
+                            struct sctp_pad_chunk *script_chunk,
+                            u32 flags, char **error)
+{
+	/* Nothing to check */
+	return STATUS_OK;
+}
+
 /* Verify that required actual SCTP packet fields are as the script expected. */
 static int verify_sctp(
 	const struct packet *actual_packet,
@@ -1559,6 +1567,11 @@ static int verify_sctp(
 			                                        (struct sctp_shutdown_complete_chunk *)script_chunk,
 			                                        flags, error);
 			break;
+		case SCTP_PAD_CHUNK_TYPE:
+			result = verify_pad_chunk((struct sctp_pad_chunk *)actual_chunk,
+			                          (struct sctp_pad_chunk *)script_chunk,
+			                          flags, error);
+			break;
 		default:
 			result = STATUS_ERR;
 			assert(!"unsupported SCTP chunk type");
diff --git a/gtests/net/packetdrill/sctp.h b/gtests/net/packetdrill/sctp.h
index 74ce79aa..b4e36e24 100644
--- a/gtests/net/packetdrill/sctp.h
+++ b/gtests/net/packetdrill/sctp.h
@@ -52,6 +52,7 @@ struct sctp_common_header {
 #define SCTP_ECNE_CHUNK_TYPE				0x0c
 #define SCTP_CWR_CHUNK_TYPE				0x0d
 #define SCTP_SHUTDOWN_COMPLETE_CHUNK_TYPE		0x0e
+#define SCTP_PAD_CHUNK_TYPE				0x84
 
 #define MAX_SCTP_CHUNK_BYTES	0xffff
 
@@ -204,6 +205,13 @@ struct sctp_shutdown_complete_chunk {
 	__be16 length;
 } __packed;
 
+struct sctp_pad_chunk {
+	__u8 type;
+	__u8 flags;
+	__be16 length;
+	__u8 padding_data[];
+} __packed;
+
 #define SCTP_HEARTBEAT_INFORMATION_PARAMETER_TYPE	0x0001
 #define SCTP_IPV4_ADDRESS_PARAMETER_TYPE		0x0005
 #define SCTP_IPV6_ADDRESS_PARAMETER_TYPE		0x0006
@@ -213,6 +221,7 @@ struct sctp_shutdown_complete_chunk {
 #define SCTP_HOSTNAME_ADDRESS_PARAMETER_TYPE		0x000b
 #define SCTP_SUPPORTED_ADDRESS_TYPES_PARAMETER_TYPE	0x000c
 #define SCTP_ECN_CAPABLE_PARAMETER_TYPE			0x8000
+#define SCTP_PAD_PARAMETER_TYPE				0x8005
 
 #define MAX_SCTP_PARAMETER_BYTES	0xffff
 
@@ -275,6 +284,12 @@ struct sctp_ecn_capable_parameter {
 	__be16 length;
 } __packed;
 
+struct sctp_pad_parameter {
+	__be16 type;
+	__be16 length;
+	__be16 padding_data[];
+} __packed;
+
 #define SCTP_INVALID_STREAM_IDENTIFIER_CAUSE_CODE	0x0001
 #define SCTP_MISSING_MADATORY_PARAMETER_CAUSE_CODE	0x0002
 #define SCTP_STALE_COOKIE_ERROR_CAUSE_CODE		0x0003
diff --git a/gtests/net/packetdrill/sctp_chunk_to_string.c b/gtests/net/packetdrill/sctp_chunk_to_string.c
index c365e7c3..e909bfc0 100644
--- a/gtests/net/packetdrill/sctp_chunk_to_string.c
+++ b/gtests/net/packetdrill/sctp_chunk_to_string.c
@@ -219,6 +219,20 @@ static int sctp_ecn_capable_parameter_to_string(
 	return STATUS_OK;
 }
 
+static int sctp_pad_parameter_to_string(
+	FILE *s,
+	struct sctp_pad_parameter *parameter,
+	char **error)
+{
+	u16 length;
+
+	length = ntohs(parameter->length);
+	fputs("PAD[", s);
+	fprintf(s, "len=%u, ", length);
+	fputs("val=...]", s);
+	return STATUS_OK;
+}
+
 static int sctp_unknown_parameter_to_string(
 	FILE *s,
 	struct sctp_parameter *parameter,
@@ -291,6 +305,10 @@ static int sctp_parameter_to_string(FILE *s,
 		result = sctp_ecn_capable_parameter_to_string(s,
 			(struct sctp_ecn_capable_parameter *)parameter, error);
 		break;
+	case SCTP_PAD_PARAMETER_TYPE:
+		result = sctp_pad_parameter_to_string(s,
+			(struct sctp_pad_parameter *)parameter, error);
+		break;
 	default:
 		result = sctp_unknown_parameter_to_string(s, parameter, error);
 		break;
@@ -1212,6 +1230,23 @@ static int sctp_shutdown_complete_chunk_to_string(
 	return STATUS_OK;
 }
 
+static int sctp_pad_chunk_to_string(
+	FILE *s,
+	struct sctp_pad_chunk *chunk,
+	char **error)
+{
+	u8 flags;
+	u16 length;
+
+	flags = chunk->flags;
+	length = ntohs(chunk->length);
+	fputs("PAD[", s);
+	fprintf(s, "flgs=0x%02x, ", chunk->flags);
+	fprintf(s, "len=%u, ", length);
+	fputs("val=...]", s);
+	return STATUS_OK;
+}
+
 static int sctp_unknown_chunk_to_string(FILE *s,
 					struct sctp_chunk *chunk,
 					char **error)
@@ -1221,7 +1256,7 @@ static int sctp_unknown_chunk_to_string(FILE *s,
 	length = ntohs(chunk->length);
 	fputs("CHUNK[", s);
 	fprintf(s, "type=0x%02x, ", chunk->type);
-	fprintf(s, "flags=0x%02x, ", chunk->flags);
+	fprintf(s, "flgs=0x%02x, ", chunk->flags);
 	fputs("value=[", s);
 	for (i = 0; i < length - sizeof(struct sctp_chunk); i++)
 		fprintf(s, "%s0x%02x",
@@ -1296,6 +1331,10 @@ int sctp_chunk_to_string(FILE *s, struct sctp_chunk *chunk, char **error)
 		result = sctp_shutdown_complete_chunk_to_string(s,
 			(struct sctp_shutdown_complete_chunk *)chunk, error);
 		break;
+	case SCTP_PAD_CHUNK_TYPE:
+		result = sctp_pad_chunk_to_string(s,
+			(struct sctp_pad_chunk *)chunk, error);
+		break;
 	default:
 		result = sctp_unknown_chunk_to_string(s, chunk, error);
 		break;
diff --git a/gtests/net/packetdrill/sctp_packet.c b/gtests/net/packetdrill/sctp_packet.c
index 886a921c..b1610938 100644
--- a/gtests/net/packetdrill/sctp_packet.c
+++ b/gtests/net/packetdrill/sctp_packet.c
@@ -808,6 +808,51 @@ sctp_shutdown_complete_chunk_new(s64 flgs)
 	                                flags, sctp_parameter_list_new());
 }
 
+struct sctp_chunk_list_item *
+sctp_pad_chunk_new(s64 flgs, s64 len, u8* padding)
+{
+	struct sctp_pad_chunk *chunk;
+	u32 flags;
+	u16 chunk_length, padding_length, chunk_padding_length;
+
+	assert((len == -1) || is_valid_u16(len));
+	assert((len != -1) || (padding == NULL));
+	flags = 0;
+	if (len == -1) {
+		padding_length = 0;
+		flags |= FLAG_CHUNK_LENGTH_NOCHECK;
+	} else {
+		assert(len <= MAX_SCTP_CHUNK_BYTES - sizeof(struct sctp_pad_chunk));
+		padding_length = len - sizeof(struct sctp_pad_chunk);
+	}
+	chunk_length = padding_length + sizeof(struct sctp_pad_chunk);
+	chunk_padding_length = chunk_length % 4;
+	if (chunk_padding_length > 0) {
+		chunk_padding_length = 4 - chunk_padding_length;
+	}
+	chunk = malloc(chunk_length + chunk_padding_length);
+	assert(chunk != NULL);
+	chunk->type = SCTP_PAD_CHUNK_TYPE;
+	if (flgs == -1) {
+		chunk->flags = 0;
+		flags |= FLAG_CHUNK_FLAGS_NOCHECK;
+	} else {
+		chunk->flags = (u8)flgs;
+	}
+	chunk->length = htons(chunk_length);
+	if (padding != NULL) {
+		memcpy(chunk->padding_data, padding, padding_length);
+	} else {
+		flags |= FLAG_CHUNK_VALUE_NOCHECK;
+		memset(chunk->padding_data, 'P', padding_length);
+	}
+	/* Clear the padding */
+	memset(chunk->padding_data + padding_length, 0, chunk_padding_length);
+	return sctp_chunk_list_item_new((struct sctp_chunk *)chunk,
+	                                chunk_length + chunk_padding_length,
+	                                flags, sctp_parameter_list_new());
+}
+
 struct sctp_chunk_list *
 sctp_chunk_list_new(void)
 {
@@ -1139,8 +1184,43 @@ sctp_supported_address_types_parameter_new(struct sctp_address_type_list *list)
 	                                    parameter_length, flags);
 }
 
+struct sctp_parameter_list_item *
+sctp_pad_parameter_new(s64 len, u8 *padding)
+{
+	struct sctp_pad_parameter *parameter;
+	u32 flags;
+	u16 parameter_length, padding_length, parameter_padding_length;
 
-/* SCTP_SUPPORTED_ADDRESS_TYPES_PARAMETER_TYPE	*/
+	assert((len == -1) || is_valid_u16(len));
+	assert((len != -1) || (padding == NULL));
+	flags = 0;
+	if (len == -1) {
+		padding_length = 0;
+		flags |= FLAG_PARAMETER_LENGTH_NOCHECK;
+	} else {
+		assert(len <= MAX_SCTP_PARAMETER_BYTES - sizeof(struct sctp_pad_parameter));
+		padding_length = len - sizeof(struct sctp_pad_parameter);
+	}
+	parameter_length = padding_length + sizeof(struct sctp_pad_parameter);
+	parameter_padding_length = parameter_length % 4;
+	if (parameter_padding_length > 0) {
+		parameter_padding_length = 4 - parameter_padding_length;
+	}
+	parameter = malloc(parameter_length + parameter_padding_length);
+	assert(parameter != NULL);
+	parameter->type = htons(SCTP_PAD_PARAMETER_TYPE);
+	parameter->length = htons(parameter_length);
+	if (padding != NULL) {
+		memcpy(parameter->padding_data, padding, padding_length);
+	} else {
+		/* flags |= FLAG_PARAMETER_VALUE_NOCHECK; */
+		memset(parameter->padding_data, 'P', padding_length);
+	}
+	/* Clear the padding */
+	memset(parameter->padding_data + padding_length, 0, parameter_padding_length);
+	return sctp_parameter_list_item_new((struct sctp_parameter *)parameter,
+	                                    parameter_length, flags);
+}
 
 struct sctp_parameter_list_item *
 sctp_ecn_capable_parameter_new(void)
@@ -1410,6 +1490,13 @@ new_sctp_packet(int address_family,
 				break;
 			case SCTP_SHUTDOWN_COMPLETE_CHUNK_TYPE:
 				break;
+			case SCTP_PAD_CHUNK_TYPE:
+				if (chunk_item->flags & FLAG_CHUNK_LENGTH_NOCHECK) {
+					asprintf(error,
+						 "chunk length must be specified for inbound packets");
+					return NULL;
+				}
+				break;
 			default:
 				asprintf(error, "Unknown chunk type 0x%02x", chunk_item->chunk->type);
 				return NULL;
diff --git a/gtests/net/packetdrill/sctp_packet.h b/gtests/net/packetdrill/sctp_packet.h
index eacbe555..36df5f54 100644
--- a/gtests/net/packetdrill/sctp_packet.h
+++ b/gtests/net/packetdrill/sctp_packet.h
@@ -197,6 +197,9 @@ sctp_cwr_chunk_new(s64 flgs, s64 lowest_tsn);
 struct sctp_chunk_list_item *
 sctp_shutdown_complete_chunk_new(s64 flgs);
 
+struct sctp_chunk_list_item *
+sctp_pad_chunk_new(s64 flgs, s64 len, u8* padding);
+
 struct sctp_chunk_list *
 sctp_chunk_list_new(void);
 
@@ -242,6 +245,9 @@ sctp_supported_address_types_parameter_new(struct sctp_address_type_list *list);
 struct sctp_parameter_list_item *
 sctp_ecn_capable_parameter_new(void);
 
+struct sctp_parameter_list_item *
+sctp_pad_parameter_new(s64 len, u8 *padding);
+
 struct sctp_parameter_list *
 sctp_parameter_list_new(void);
 
diff --git a/gtests/net/packetdrill/tests/bsd/sctp/sctp_active.pkt b/gtests/net/packetdrill/tests/bsd/sctp/sctp_active.pkt
index 87c7266d..c0c7d0c0 100644
--- a/gtests/net/packetdrill/tests/bsd/sctp/sctp_active.pkt
+++ b/gtests/net/packetdrill/tests/bsd/sctp/sctp_active.pkt
@@ -16,7 +16,7 @@
 +0.1 < sctp: COOKIE_ACK[flgs=0]
 +0.0 getsockopt(3, SOL_SOCKET, SO_ERROR, [0], [4]) = 0
 // Send some data
-+0.5 < sctp: HEARTBEAT[flgs=0, HEARTBEAT_INFORMATION[len=9, val=...]]
++0.5 < sctp: HEARTBEAT[flgs=0, HEARTBEAT_INFORMATION[len=9, val=...]]; PAD[flgs=0, len=1300, val=...]
 +0.0 > sctp: HEARTBEAT_ACK[flgs=0, HEARTBEAT_INFORMATION[len=9, val=...]]
 +1.0 write(3, ..., 1000) = 1000
 +0.0 > sctp: DATA[flgs=BE, len=1016, tsn=0, sid=0, ssn=0, ppid=0]
diff --git a/gtests/net/packetdrill/tests/bsd/sctp/sctp_passive.pkt b/gtests/net/packetdrill/tests/bsd/sctp/sctp_passive.pkt
index e8b517f5..5accc93c 100644
--- a/gtests/net/packetdrill/tests/bsd/sctp/sctp_passive.pkt
+++ b/gtests/net/packetdrill/tests/bsd/sctp/sctp_passive.pkt
@@ -9,9 +9,9 @@
 // Check the handshake with en empty(!) cookie
 +0.0 bind(3, ..., ...) = 0
 +0.0 listen(3, 1) = 0
-+0.0 < sctp: INIT[flgs=0, tag=1, a_rwnd=1500, os=1, is=1, tsn=0, ECN_CAPABLE[], COOKIE_PRESERVATIVE[incr=12345], SUPPORTED_ADDRESS_TYPES[types=[IPv4]]]
++0.0 < sctp: INIT[flgs=0, tag=1, a_rwnd=1500, os=1, is=1, tsn=0, ECN_CAPABLE[], COOKIE_PRESERVATIVE[incr=12345], SUPPORTED_ADDRESS_TYPES[types=[IPv4]], PAD[len=500, val=...], PAD[len=500, val=...]]
 +0.0 > sctp: INIT_ACK[flgs=0, tag=2, a_rwnd=..., os=..., is=..., tsn=10, STATE_COOKIE[len=..., val=...]]
-+0.1 < sctp: COOKIE_ECHO[flgs=0, len=..., val=...]; DATA[flgs=BE, len=1016, tsn=0, sid=0, ssn=0, ppid=0]
++0.1 < sctp: COOKIE_ECHO[flgs=0, len=..., val=...]; PAD[flgs=0, len=10, val=...]; DATA[flgs=BE, len=1016, tsn=0, sid=0, ssn=0, ppid=0]
 +0.0 > sctp: COOKIE_ACK[flgs=0]; SACK[flgs=0, cum_tsn=0, a_rwnd=..., gaps=..., dups=...]
 +0.0 accept(3, ..., ...) = 4
 +0.0 read(4, ..., 1000) = 1000
-- 
GitLab