udhcpc6: new applet. Not yet functional.

It builds. It sends Solicit packets. Not sure these packets are well-formed.
I have no server to test it against.

function                                             old     new   delta
udhcpc6_main                                           -    2426   +2426
d6_send_raw_packet                                     -     428    +428
d6_send_kernel_packet                                  -     274    +274
d6_recv_raw_packet                                     -     248    +248
send_d6_discover                                       -     177    +177
packed_usage                                       28795   28966    +171
d6_run_script                                          -     156    +156
send_d6_renew                                          -     140    +140
send_d6_release                                        -     126    +126
d6_recv_kernel_packet                                  -     116    +116
send_d6_select                                         -      95     +95
perform_d6_release                                     -      78     +78
d6_find_option                                         -      74     +74
init_d6_packet                                         -      54     +54
d6_copy_option                                         -      48     +48
d6_mcast_from_client_config_ifindex                    -      42     +42
d6_dump_packet                                         -      24     +24
static.FF02__1_2                                       -      16     +16
d6_store_blob                                          -      13     +13
applet_names                                        2432    2440      +8
applet_main                                         1412    1416      +4
applet_nameofs                                       706     708      +2
add_d6_client_options                                  -       1      +1
------------------------------------------------------------------------------
(add/remove: 21/0 grow/shrink: 4/0 up/down: 4721/0)          Total: 4721 bytes
   text	   data	    bss	    dec	    hex	filename
 879080	    493	   7584	 887157	  d8975	busybox_old
 884585	    497	   7584	 892666	  d9efa	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 168 insertions, 0 deletions

diff --git a/networking/udhcp/d6_packet.c b/networking/udhcp/d6_packet.c
new file mode 100644
index 000000000..3a1bb3df1
--- /dev/null
+++ b/networking/udhcp/d6_packet.c
@@ -0,0 +1,168 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Copyright (C) 2011 Denys Vlasenko.
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
+ */
+#include "common.h"
+#include "d6_common.h"
+#include "dhcpd.h"
+#include <netinet/in.h>
+#include <netinet/if_ether.h>
+#include <netpacket/packet.h>
+
+#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2
+void FAST_FUNC d6_dump_packet(struct d6_packet *packet)
+{
+	if (dhcp_verbose < 2)
+		return;
+
+	bb_info_msg(
+		" xid %x"
+		, packet->d6_xid32
+	);
+	//*bin2hex(buf, (void *) packet->chaddr, sizeof(packet->chaddr)) = '\0';
+	//bb_info_msg(" chaddr %s", buf);
+}
+#endif
+
+int FAST_FUNC d6_recv_kernel_packet(struct in6_addr *peer_ipv6
+	UNUSED_PARAM
+	, struct d6_packet *packet, int fd)
+{
+	int bytes;
+
+	memset(packet, 0, sizeof(*packet));
+	bytes = safe_read(fd, packet, sizeof(*packet));
+	if (bytes < 0) {
+		log1("Packet read error, ignoring");
+		return bytes; /* returns -1 */
+	}
+
+	if (bytes < offsetof(struct d6_packet, d6_options)) {
+		bb_info_msg("Packet with bad magic, ignoring");
+		return -2;
+	}
+	log1("Received a packet");
+	d6_dump_packet(packet);
+
+	return bytes;
+}
+
+/* Construct a ipv6+udp header for a packet, send packet */
+int FAST_FUNC d6_send_raw_packet(
+		struct d6_packet *d6_pkt, unsigned d6_pkt_size,
+		struct in6_addr *src_ipv6, int source_port,
+		struct in6_addr *dst_ipv6, int dest_port, const uint8_t *dest_arp,
+		int ifindex)
+{
+	struct sockaddr_ll dest_sll;
+	struct ip6_udp_d6_packet packet;
+	int fd;
+	int result = -1;
+	const char *msg;
+
+	fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IPV6));
+	if (fd < 0) {
+		msg = "socket(%s)";
+		goto ret_msg;
+	}
+
+	memset(&dest_sll, 0, sizeof(dest_sll));
+	memset(&packet, 0, offsetof(struct ip6_udp_d6_packet, data));
+	packet.data = *d6_pkt; /* struct copy */
+
+	dest_sll.sll_family = AF_PACKET;
+	dest_sll.sll_protocol = htons(ETH_P_IPV6);
+	dest_sll.sll_ifindex = ifindex;
+	dest_sll.sll_halen = 6;
+	memcpy(dest_sll.sll_addr, dest_arp, 6);
+
+	if (bind(fd, (struct sockaddr *)&dest_sll, sizeof(dest_sll)) < 0) {
+		msg = "bind(%s)";
+		goto ret_close;
+	}
+
+	packet.ip6.ip6_vfc = (6 << 4); /* 4 bits version, top 4 bits of tclass */
+	if (src_ipv6)
+		packet.ip6.ip6_src = *src_ipv6; /* struct copy */
+	packet.ip6.ip6_dst = *dst_ipv6; /* struct copy */
+	packet.udp.source = htons(source_port);
+	packet.udp.dest = htons(dest_port);
+	/* size, excluding IP header: */
+	packet.udp.len = htons(sizeof(struct udphdr) + d6_pkt_size);
+	packet.ip6.ip6_plen = packet.udp.len;
+	/* UDP checksum skips first four bytes of IP header.
+	 * IPv6 'hop limit' field should be 0.
+	 * 'next header' field should be summed as if it is in a different
+	 * position, therefore we write its value into ip6_hlim:
+	 */
+	packet.ip6.ip6_hlim = IPPROTO_UDP;
+	packet.udp.check = inet_cksum((uint16_t *)&packet + 2,
+				offsetof(struct ip6_udp_d6_packet, data) - 4 + d6_pkt_size);
+	/* fix 'hop limit' and 'next header' after UDP checksumming */
+	packet.ip6.ip6_hlim = 8;
+	packet.ip6.ip6_nxt = IPPROTO_UDP;
+
+	d6_dump_packet(d6_pkt);
+	result = sendto(fd, &packet, offsetof(struct ip6_udp_d6_packet, data) + d6_pkt_size,
+			/*flags:*/ 0,
+			(struct sockaddr *) &dest_sll, sizeof(dest_sll)
+	);
+	msg = "sendto";
+ ret_close:
+	close(fd);
+	if (result < 0) {
+ ret_msg:
+		bb_perror_msg(msg, "PACKET");
+	}
+	return result;
+}
+
+/* Let the kernel do all the work for packet generation */
+int FAST_FUNC d6_send_kernel_packet(
+		struct d6_packet *d6_pkt, unsigned d6_pkt_size,
+		struct in6_addr *src_ipv6, int source_port,
+		struct in6_addr *dst_ipv6, int dest_port)
+{
+	struct sockaddr_in6 sa;
+	int fd;
+	int result = -1;
+	const char *msg;
+
+	fd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
+	if (fd < 0) {
+		msg = "socket(%s)";
+		goto ret_msg;
+	}
+	setsockopt_reuseaddr(fd);
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sin6_family = AF_INET6;
+	sa.sin6_port = htons(source_port);
+	sa.sin6_addr = *src_ipv6; /* struct copy */
+	if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
+		msg = "bind(%s)";
+		goto ret_close;
+	}
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sin6_family = AF_INET6;
+	sa.sin6_port = htons(dest_port);
+	sa.sin6_addr = *dst_ipv6; /* struct copy */
+	if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
+		msg = "connect";
+		goto ret_close;
+	}
+
+	d6_dump_packet(d6_pkt);
+	result = safe_write(fd, d6_pkt, d6_pkt_size);
+	msg = "write";
+ ret_close:
+	close(fd);
+	if (result < 0) {
+ ret_msg:
+		bb_perror_msg(msg, "UDP");
+	}
+	return result;
+}