Separate out DHCP processing

So we can later call it on UDP datagrams obtained from UDP socket.

dhcp6.c

@@ -29,7 +29,7 @@ static struct dhcp6_in_option list_option;
 
 static int dhcpv6_format_dns_search_name(const char *strdns, uint8_t *buffer);
 
-static void dhcp6_send_reply(sessionidt s, tunnelidt t, struct in6_addr *ip6_src)
+static void dhcp6_send_reply(sessionidt s, tunnelidt t, const struct in6_addr *ip6_src)
 {
 	struct ip6_hdr *p_ip6_hdr;
 	struct udphdr *p_udp;
@@ -309,26 +309,22 @@ static char * get_msg_type(uint8_t type)
 	}
 }
 
-void dhcpv6_process(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
+void dhcpv6_process(sessionidt s, tunnelidt t, const struct in6_addr *addr, uint8_t *p, uint16_t l)
 {
-	struct ip6_hdr *p_ip6_hdr_in;
+	struct dhcp6_mess_hdr *p_mess_hdr = (struct dhcp6_mess_hdr *) p;
-	struct dhcp6_mess_hdr *p_mess_hdr;
 	struct dhcp6_opt_h *p_opt;
 	uint8_t *p_end;
 	uint16_t len;
 
 	CSTAT(dhcpv6_process);
 
-	p_ip6_hdr_in = (struct ip6_hdr *) p;
-	p_mess_hdr = (struct dhcp6_mess_hdr *) (p + 48);
-
 	LOG(3, s, t, "Got DHCPv6 message Type: %s(%d)\n", get_msg_type(p_mess_hdr->type), p_mess_hdr->type);
 
 	if (!session[s].route6[0].ipv6route.s6_addr[0] || !session[s].route6[0].ipv6prefixlen)
 		return;
 
 	p_opt = (struct dhcp6_opt_h *) &p_mess_hdr[1];
-	p_end = ((uint8_t *)p_ip6_hdr_in) + ntohs(p_ip6_hdr_in->ip6_plen) + sizeof(*p_ip6_hdr_in);
+	p_end = p + l;
 	memset(&list_option, 0, sizeof(list_option));
 	list_option.p_mess_hdr = p_mess_hdr;
 	while (((uint8_t *)p_opt) < p_end)
@@ -413,7 +409,7 @@ void dhcpv6_process(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 				return;
 			}
 
-			dhcp6_send_reply(s, t, &p_ip6_hdr_in->ip6_src);
+			dhcp6_send_reply(s, t, addr);
 		}
 		break;
 
@@ -458,8 +454,8 @@ void dhcpv6_process(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 				return;
 			}
 
-			dhcp6_send_reply(s, t, &p_ip6_hdr_in->ip6_src);
+			dhcp6_send_reply(s, t, addr);
-			send_ipv6_ra(s, t, &p_ip6_hdr_in->ip6_src); // send a RA
+			send_ipv6_ra(s, t, addr); // send a RA
 		}
 		break;
 
@@ -489,7 +485,7 @@ void dhcpv6_process(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 				return;
 			}
 
-			dhcp6_send_reply(s, t, &p_ip6_hdr_in->ip6_src);
+			dhcp6_send_reply(s, t, addr);
 		}
 		break;
 
@@ -501,7 +497,7 @@ void dhcpv6_process(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 				return;
 			}
 
-			dhcp6_send_reply(s, t, &p_ip6_hdr_in->ip6_src);
+			dhcp6_send_reply(s, t, addr);
 		}
 		break;
 
@@ -527,6 +523,37 @@ void dhcpv6_process(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 	return;
 }
 
+void dhcpv6_process_from_ipv6(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
+{
+	struct ip6_hdr *p_ip6_hdr_in = (struct ip6_hdr *) p;
+	struct in6_addr *addr = &p_ip6_hdr_in->ip6_src;
+	uint16_t ipv6_len = ntohs(p_ip6_hdr_in->ip6_plen);
+
+	l -= sizeof(*p_ip6_hdr_in);
+	p += sizeof(*p_ip6_hdr_in);
+
+	if (ipv6_len > l)
+	{
+		LOG(5, 0, 0, "bogus IPv6 packet size??\n");
+		return;
+	}
+
+	if (p_ip6_hdr_in->ip6_nxt != 17)
+	{
+		LOG(5, 0, 0, "not UDP DHCP packet??\n");
+		return;
+	}
+	if (ipv6_len < sizeof(struct udphdr))
+	{
+		LOG(5, 0, 0, "bogus IPv6 packet size for UDP??\n");
+		return;
+	}
+	ipv6_len -= sizeof(struct udphdr);
+	p += sizeof(struct udphdr);
+
+	dhcpv6_process(s, t, addr, p, ipv6_len);
+}
+
 static int dhcpv6_format_dns_search_name(const char *strdns, uint8_t *buffer)
 {
 	int n = strlen(strdns);

dhcp6.h

@@ -212,7 +212,7 @@ struct dhcp6_opt_ia_prefix {
 } __attribute__((packed));
 
 // dhcp6.c
-void dhcpv6_process(uint16_t s, uint16_t t, uint8_t *p, uint16_t l);
+void dhcpv6_process_from_ipv6(uint16_t s, uint16_t t, uint8_t *p, uint16_t l);
 void dhcpv6_init(void);
 
 #endif /* __DHCP6_H__ */

icmp.c

@@ -96,7 +96,7 @@ struct nd_opt_rdnss_info_l2tpns
 	struct in6_addr nd_opt_rdnssi[0];
 };
 
-void send_ipv6_ra(sessionidt s, tunnelidt t, struct in6_addr *ip)
+void send_ipv6_ra(sessionidt s, tunnelidt t, const struct in6_addr *ip)
 {
 	struct nd_opt_prefix_info *pinfo;
 	struct ip6_hdr *p_ip6_hdr;

l2tpns.h

@@ -960,7 +960,7 @@ int rad_tunnel_pwdecode(uint8_t *pl2tpsecret, size_t *pl2tpsecretlen, const char
 
 // l2tpns.c
 clockt backoff(uint8_t try);
-void send_ipv6_ra(sessionidt s, tunnelidt t, struct in6_addr *ip);
+void send_ipv6_ra(sessionidt s, tunnelidt t, const struct in6_addr *ip);
 void route6set(sessionidt s, struct in6_addr ip, int prefixlen, int add);
 void routes6set(sessionidt s, sessiont *sp, int add);
 sessionidt sessionbyip(in_addr_t ip);

ppp.c

@@ -2286,7 +2286,7 @@ void processipv6in(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
 			*(uint16_t *)(p + 34) == 0 && *(p + 36) == 0 && *(p + 37) == 1 && *(p + 38) == 0 && *(p + 39) == 2 &&
 			*(p + 40) == 2 && *(p + 41) == 0x22 && *(p + 42) == 2 && *(p + 43) == 0x23)
 	{
-		dhcpv6_process(s, t, p, l);
+		dhcpv6_process_from_ipv6(s, t, p, l);
 		return;
 	}