socket_wrapper.c

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	SWRAP_ACCEPT_ACK,
	SWRAP_RECVFROM,
	SWRAP_SENDTO,
	SWRAP_SENDTO_UNREACH,
	SWRAP_PENDING_RST,
	SWRAP_RECV,
	SWRAP_RECV_RST,
	SWRAP_SEND,
	SWRAP_SEND_RST,
	SWRAP_CLOSE_SEND,
	SWRAP_CLOSE_RECV,
	SWRAP_CLOSE_ACK
};

struct swrap_file_hdr {
	uint32_t	magic;
	uint16_t	version_major;
	uint16_t	version_minor;
	int32_t		timezone;
	uint32_t	sigfigs;
	uint32_t	frame_max_len;
#define SWRAP_FRAME_LENGTH_MAX 0xFFFF
	uint32_t	link_type;
};
#define SWRAP_FILE_HDR_SIZE 24

struct swrap_packet {
	struct {
		uint32_t seconds;
		uint32_t micro_seconds;
		uint32_t recorded_length;
		uint32_t full_length;
	} frame;
#define SWRAP_PACKET__FRAME_SIZE 16

	struct {
		struct {
			uint8_t		ver_hdrlen;
			uint8_t		tos;
			uint16_t	packet_length;
			uint16_t	identification;
			uint8_t		flags;
			uint8_t		fragment;
			uint8_t		ttl;
			uint8_t		protocol;
			uint16_t	hdr_checksum;
			uint32_t	src_addr;
			uint32_t	dest_addr;
		} hdr;
#define SWRAP_PACKET__IP_HDR_SIZE 20

		union {
			struct {
				uint16_t	source_port;
				uint16_t	dest_port;
				uint32_t	seq_num;
				uint32_t	ack_num;
				uint8_t		hdr_length;
				uint8_t		control;
				uint16_t	window;
				uint16_t	checksum;
				uint16_t	urg;
			} tcp;
#define SWRAP_PACKET__IP_P_TCP_SIZE 20
			struct {
				uint16_t	source_port;
				uint16_t	dest_port;
				uint16_t	length;
				uint16_t	checksum;
			} udp;
#define SWRAP_PACKET__IP_P_UDP_SIZE 8
			struct {
				uint8_t		type;
				uint8_t		code;
				uint16_t	checksum;
				uint32_t	unused;
			} icmp;
#define SWRAP_PACKET__IP_P_ICMP_SIZE 8
		} p;
	} ip;
};
#define SWRAP_PACKET_SIZE 56

static const char *socket_wrapper_pcap_file(void)
{
	static int initialized = 0;
	static const char *s = NULL;
	static const struct swrap_file_hdr h;
	static const struct swrap_packet p;

	if (initialized == 1) {
		return s;
	}
	initialized = 1;

	/*
	 * TODO: don't use the structs use plain buffer offsets
	 *       and PUSH_U8(), PUSH_U16() and PUSH_U32()
	 * 
	 * for now make sure we disable PCAP support
	 * if the struct has alignment!
	 */
	if (sizeof(h) != SWRAP_FILE_HDR_SIZE) {
		return NULL;
	}
	if (sizeof(p) != SWRAP_PACKET_SIZE) {
		return NULL;
	}
	if (sizeof(p.frame) != SWRAP_PACKET__FRAME_SIZE) {
		return NULL;
	}
	if (sizeof(p.ip.hdr) != SWRAP_PACKET__IP_HDR_SIZE) {
		return NULL;
	}
	if (sizeof(p.ip.p.tcp) != SWRAP_PACKET__IP_P_TCP_SIZE) {
		return NULL;
	}
	if (sizeof(p.ip.p.udp) != SWRAP_PACKET__IP_P_UDP_SIZE) {
		return NULL;
	}
	if (sizeof(p.ip.p.icmp) != SWRAP_PACKET__IP_P_ICMP_SIZE) {
		return NULL;
	}

	s = getenv("SOCKET_WRAPPER_PCAP_FILE");
	if (s == NULL) {
		return NULL;
	}
	if (strncmp(s, "./", 2) == 0) {
		s += 2;
	}
	return s;
}

static struct swrap_packet *swrap_packet_init(struct timeval *tval,
					      const struct sockaddr_in *src_addr,
					      const struct sockaddr_in *dest_addr,
					      int socket_type,
					      const unsigned char *payload,
					      size_t payload_len,
					      unsigned long tcp_seq,
					      unsigned long tcp_ack,
					      unsigned char tcp_ctl,
					      int unreachable,
					      size_t *_packet_len)
{
	struct swrap_packet *ret;
	struct swrap_packet *packet;
	size_t packet_len;
	size_t alloc_len;
	size_t nonwire_len = sizeof(packet->frame);
	size_t wire_hdr_len = 0;
	size_t wire_len = 0;
	size_t icmp_hdr_len = 0;
	size_t icmp_truncate_len = 0;
	unsigned char protocol = 0, icmp_protocol = 0;
	unsigned short src_port = src_addr->sin_port;
	unsigned short dest_port = dest_addr->sin_port;

	switch (socket_type) {
	case SOCK_STREAM:
		protocol = 0x06; /* TCP */
		wire_hdr_len = sizeof(packet->ip.hdr) + sizeof(packet->ip.p.tcp);
		wire_len = wire_hdr_len + payload_len;
		break;

	case SOCK_DGRAM:
		protocol = 0x11; /* UDP */
		wire_hdr_len = sizeof(packet->ip.hdr) + sizeof(packet->ip.p.udp);
		wire_len = wire_hdr_len + payload_len;
		break;

	default:
		return NULL;
	}

	if (unreachable) {
		icmp_protocol = protocol;
		protocol = 0x01; /* ICMP */
		if (wire_len > 64 ) {
			icmp_truncate_len = wire_len - 64;
		}
		icmp_hdr_len = sizeof(packet->ip.hdr) + sizeof(packet->ip.p.icmp);
		wire_hdr_len += icmp_hdr_len;
		wire_len += icmp_hdr_len;
	}

	packet_len = nonwire_len + wire_len;
	alloc_len = packet_len;
	if (alloc_len < sizeof(struct swrap_packet)) {
		alloc_len = sizeof(struct swrap_packet);
	}
	ret = (struct swrap_packet *)malloc(alloc_len);
	if (!ret) return NULL;

	packet = ret;

	packet->frame.seconds		= tval->tv_sec;
	packet->frame.micro_seconds	= tval->tv_usec;
	packet->frame.recorded_length	= wire_len - icmp_truncate_len;
	packet->frame.full_length	= wire_len - icmp_truncate_len;

	packet->ip.hdr.ver_hdrlen	= 0x45; /* version 4 and 5 * 32 bit words */
	packet->ip.hdr.tos		= 0x00;
	packet->ip.hdr.packet_length	= htons(wire_len - icmp_truncate_len);
	packet->ip.hdr.identification	= htons(0xFFFF);
	packet->ip.hdr.flags		= 0x40; /* BIT 1 set - means don't fraqment */
	packet->ip.hdr.fragment		= htons(0x0000);
	packet->ip.hdr.ttl		= 0xFF;
	packet->ip.hdr.protocol		= protocol;
	packet->ip.hdr.hdr_checksum	= htons(0x0000);
	packet->ip.hdr.src_addr		= src_addr->sin_addr.s_addr;
	packet->ip.hdr.dest_addr	= dest_addr->sin_addr.s_addr;

	if (unreachable) {
		packet->ip.p.icmp.type		= 0x03; /* destination unreachable */
		packet->ip.p.icmp.code		= 0x01; /* host unreachable */
		packet->ip.p.icmp.checksum	= htons(0x0000);
		packet->ip.p.icmp.unused	= htonl(0x00000000);

		/* set the ip header in the ICMP payload */
		packet = (struct swrap_packet *)(((unsigned char *)ret) + icmp_hdr_len);
		packet->ip.hdr.ver_hdrlen	= 0x45; /* version 4 and 5 * 32 bit words */
		packet->ip.hdr.tos		= 0x00;
		packet->ip.hdr.packet_length	= htons(wire_len - icmp_hdr_len);
		packet->ip.hdr.identification	= htons(0xFFFF);
		packet->ip.hdr.flags		= 0x40; /* BIT 1 set - means don't fraqment */
		packet->ip.hdr.fragment		= htons(0x0000);
		packet->ip.hdr.ttl		= 0xFF;
		packet->ip.hdr.protocol		= icmp_protocol;
		packet->ip.hdr.hdr_checksum	= htons(0x0000);
		packet->ip.hdr.src_addr		= dest_addr->sin_addr.s_addr;
		packet->ip.hdr.dest_addr	= src_addr->sin_addr.s_addr;

		src_port = dest_addr->sin_port;
		dest_port = src_addr->sin_port;
	}

	switch (socket_type) {
	case SOCK_STREAM:
		packet->ip.p.tcp.source_port	= src_port;
		packet->ip.p.tcp.dest_port	= dest_port;
		packet->ip.p.tcp.seq_num	= htonl(tcp_seq);
		packet->ip.p.tcp.ack_num	= htonl(tcp_ack);
		packet->ip.p.tcp.hdr_length	= 0x50; /* 5 * 32 bit words */
		packet->ip.p.tcp.control	= tcp_ctl;
		packet->ip.p.tcp.window		= htons(0x7FFF);
		packet->ip.p.tcp.checksum	= htons(0x0000);
		packet->ip.p.tcp.urg		= htons(0x0000);

		break;

	case SOCK_DGRAM:
		packet->ip.p.udp.source_port	= src_addr->sin_port;
		packet->ip.p.udp.dest_port	= dest_addr->sin_port;
		packet->ip.p.udp.length		= htons(8 + payload_len);
		packet->ip.p.udp.checksum	= htons(0x0000);

		break;
	}

	if (payload && payload_len > 0) {
		unsigned char *p = (unsigned char *)ret;
		p += nonwire_len;
		p += wire_hdr_len;
		memcpy(p, payload, payload_len);
	}

	*_packet_len = packet_len - icmp_truncate_len;
	return ret;
}

static int swrap_get_pcap_fd(const char *fname)
{
	static int fd = -1;

	if (fd != -1) return fd;

	fd = open(fname, O_WRONLY|O_CREAT|O_EXCL|O_APPEND, 0644);
	if (fd != -1) {
		struct swrap_file_hdr file_hdr;
		file_hdr.magic		= 0xA1B2C3D4;
		file_hdr.version_major	= 0x0002;	
		file_hdr.version_minor	= 0x0004;
		file_hdr.timezone	= 0x00000000;
		file_hdr.sigfigs	= 0x00000000;
		file_hdr.frame_max_len	= SWRAP_FRAME_LENGTH_MAX;
		file_hdr.link_type	= 0x0065; /* 101 RAW IP */

		write(fd, &file_hdr, sizeof(file_hdr));
		return fd;
	}

	fd = open(fname, O_WRONLY|O_APPEND, 0644);

	return fd;
}

static struct swrap_packet *swrap_marshall_packet(struct socket_info *si,
								  const struct sockaddr *addr,
								  enum swrap_packet_type type,
								  const void *buf, size_t len,
								  size_t *packet_len)
{
	const struct sockaddr_in *src_addr;
	const struct sockaddr_in *dest_addr;
	unsigned long tcp_seq = 0;
	unsigned long tcp_ack = 0;
	unsigned char tcp_ctl = 0;
	int unreachable = 0;

	struct timeval tv;

	switch (si->family) {
	case AF_INET:
		break;
	default:
		return NULL;
	}

	switch (type) {
	case SWRAP_CONNECT_SEND:
		if (si->type != SOCK_STREAM) return NULL;

		src_addr = (const struct sockaddr_in *)si->myname;
		dest_addr = (const struct sockaddr_in *)addr;

		tcp_seq = si->io.pck_snd;
		tcp_ack = si->io.pck_rcv;
		tcp_ctl = 0x02; /* SYN */

		si->io.pck_snd += 1;

		break;

	case SWRAP_CONNECT_RECV:
		if (si->type != SOCK_STREAM) return NULL;

		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)addr;

		tcp_seq = si->io.pck_rcv;
		tcp_ack = si->io.pck_snd;
		tcp_ctl = 0x12; /** SYN,ACK */

		si->io.pck_rcv += 1;

		break;

	case SWRAP_CONNECT_UNREACH:
		if (si->type != SOCK_STREAM) return NULL;

		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)addr;

		/* Unreachable: resend the data of SWRAP_CONNECT_SEND */
		tcp_seq = si->io.pck_snd - 1;
		tcp_ack = si->io.pck_rcv;
		tcp_ctl = 0x02; /* SYN */
		unreachable = 1;

		break;

	case SWRAP_CONNECT_ACK:
		if (si->type != SOCK_STREAM) return NULL;

		src_addr = (const struct sockaddr_in *)si->myname;
		dest_addr = (const struct sockaddr_in *)addr;

		tcp_seq = si->io.pck_snd;
		tcp_ack = si->io.pck_rcv;
		tcp_ctl = 0x10; /* ACK */

		break;

	case SWRAP_ACCEPT_SEND:
		if (si->type != SOCK_STREAM) return NULL;

		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)addr;

		tcp_seq = si->io.pck_rcv;
		tcp_ack = si->io.pck_snd;
		tcp_ctl = 0x02; /* SYN */

		si->io.pck_rcv += 1;

		break;

	case SWRAP_ACCEPT_RECV:
		if (si->type != SOCK_STREAM) return NULL;

		src_addr = (const struct sockaddr_in *)si->myname;
		dest_addr = (const struct sockaddr_in *)addr;

		tcp_seq = si->io.pck_snd;
		tcp_ack = si->io.pck_rcv;
		tcp_ctl = 0x12; /* SYN,ACK */

		si->io.pck_snd += 1;

		break;

	case SWRAP_ACCEPT_ACK:
		if (si->type != SOCK_STREAM) return NULL;

		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)addr;

		tcp_seq = si->io.pck_rcv;
		tcp_ack = si->io.pck_snd;
		tcp_ctl = 0x10; /* ACK */

		break;

	case SWRAP_SEND:
		src_addr = (const struct sockaddr_in *)si->myname;
		dest_addr = (const struct sockaddr_in *)si->peername;

		tcp_seq = si->io.pck_snd;
		tcp_ack = si->io.pck_rcv;
		tcp_ctl = 0x18; /* PSH,ACK */

		si->io.pck_snd += len;

		break;

	case SWRAP_SEND_RST:
		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)si->peername;

		if (si->type == SOCK_DGRAM) {
			return swrap_marshall_packet(si, si->peername,
					  SWRAP_SENDTO_UNREACH,
			      		  buf, len, packet_len);
		}

		tcp_seq = si->io.pck_rcv;
		tcp_ack = si->io.pck_snd;
		tcp_ctl = 0x14; /** RST,ACK */

		break;

	case SWRAP_PENDING_RST:
		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)si->peername;

		if (si->type == SOCK_DGRAM) {
			return NULL;
		}

		tcp_seq = si->io.pck_rcv;
		tcp_ack = si->io.pck_snd;
		tcp_ctl = 0x14; /* RST,ACK */

		break;

	case SWRAP_RECV:
		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)si->peername;

		tcp_seq = si->io.pck_rcv;
		tcp_ack = si->io.pck_snd;
		tcp_ctl = 0x18; /* PSH,ACK */

		si->io.pck_rcv += len;

		break;

	case SWRAP_RECV_RST:
		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)si->peername;

		if (si->type == SOCK_DGRAM) {
			return NULL;
		}

		tcp_seq = si->io.pck_rcv;
		tcp_ack = si->io.pck_snd;
		tcp_ctl = 0x14; /* RST,ACK */

		break;

	case SWRAP_SENDTO:
		src_addr = (const struct sockaddr_in *)si->myname;
		dest_addr = (const struct sockaddr_in *)addr;

		si->io.pck_snd += len;

		break;

	case SWRAP_SENDTO_UNREACH:
		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)addr;

		unreachable = 1;

		break;

	case SWRAP_RECVFROM:
		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)addr;

		si->io.pck_rcv += len;

		break;

	case SWRAP_CLOSE_SEND:
		if (si->type != SOCK_STREAM) return NULL;

		src_addr = (const struct sockaddr_in *)si->myname;
		dest_addr = (const struct sockaddr_in *)si->peername;

		tcp_seq = si->io.pck_snd;
		tcp_ack = si->io.pck_rcv;
		tcp_ctl = 0x11; /* FIN, ACK */

		si->io.pck_snd += 1;

		break;

	case SWRAP_CLOSE_RECV:
		if (si->type != SOCK_STREAM) return NULL;

		dest_addr = (const struct sockaddr_in *)si->myname;
		src_addr = (const struct sockaddr_in *)si->peername;

		tcp_seq = si->io.pck_rcv;
		tcp_ack = si->io.pck_snd;
		tcp_ctl = 0x11; /* FIN,ACK */

		si->io.pck_rcv += 1;

		break;

	case SWRAP_CLOSE_ACK:
		if (si->type != SOCK_STREAM) return NULL;

		src_addr = (const struct sockaddr_in *)si->myname;
		dest_addr = (const struct sockaddr_in *)si->peername;

		tcp_seq = si->io.pck_snd;
		tcp_ack = si->io.pck_rcv;
		tcp_ctl = 0x10; /* ACK */

		break;
	default:
		return NULL;
	}

	swrapGetTimeOfDay(&tv);

	return swrap_packet_init(&tv, src_addr, dest_addr, si->type,
				   (const unsigned char *)buf, len,
				   tcp_seq, tcp_ack, tcp_ctl, unreachable,
				   packet_len);
}

static void swrap_dump_packet(struct socket_info *si, 
							  const struct sockaddr *addr,
							  enum swrap_packet_type type,
							  const void *buf, size_t len)
{
	const char *file_name;
	struct swrap_packet *packet;
	size_t packet_len = 0;
	int fd;

	file_name = socket_wrapper_pcap_file();
	if (!file_name) {
		return;
	}

	packet = swrap_marshall_packet(si, addr, type, buf, len, &packet_len);
	if (!packet) {
		return;
	}

	fd = swrap_get_pcap_fd(file_name);
	if (fd != -1) {
		write(fd, packet, packet_len);
	}

	free(packet);
}

_PUBLIC_ int swrap_socket(int family, int type, int protocol)
{
	struct socket_info *si;
	int fd;

	if (!socket_wrapper_dir()) {
		return real_socket(family, type, protocol);
	}

	switch (family) {
	case AF_INET:
#ifdef HAVE_IPV6
	case AF_INET6:
#endif
		break;
	case AF_UNIX:
		return real_socket(family, type, protocol);
	default:
		errno = EAFNOSUPPORT;
		return -1;
	}

	switch (type) {
	case SOCK_STREAM:
		break;
	case SOCK_DGRAM: