dhcpv6: server unicast option support

Add server unicast option support according rfc3315

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

diff --git a/src/dhcpv6.c b/src/dhcpv6.c
index 2a9f8a2f56b7d5bd3fdb059a517732a271feeaec..63890526e9045fb2a5604698c2ac4de07b491a59 100644 (file)
--- a/src/dhcpv6.c
+++ b/src/dhcpv6.c
@@ -27,6 +27,7 @@
 #include <sys/time.h>
 #include <sys/ioctl.h>
 #include <sys/socket.h>
+#include <arpa/inet.h>
 #include <netinet/in.h>
 
 #include <net/if.h>
@@ -106,6 +107,8 @@ static int64_t t1 = 0, t2 = 0, t3 = 0;
 static int request_prefix = -1;
 static enum odhcp6c_ia_mode na_mode = IA_MODE_NONE, pd_mode = IA_MODE_NONE;
 static bool accept_reconfig = false;
+// Server unicast address
+static struct in6_addr server_addr = IN6ADDR_ANY_INIT;
 
 // Reconfigure key
 static uint8_t reconf_key[16];
@@ -180,6 +183,7 @@ int init_dhcpv6(const char *ifname, unsigned int options, int sol_timeout)
                        htons(DHCPV6_OPT_SIP_SERVER_A),
                        htons(DHCPV6_OPT_DNS_SERVERS),
                        htons(DHCPV6_OPT_DNS_DOMAIN),
+                       htons(DHCPV6_OPT_UNICAST),
                        htons(DHCPV6_OPT_SNTP_SERVERS),
                        htons(DHCPV6_OPT_NTP_SERVER),
                        htons(DHCPV6_OPT_AFTR_NAME),
@@ -501,7 +505,29 @@ static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
        struct msghdr msg = {.msg_name = &srv, .msg_namelen = sizeof(srv),
                        .msg_iov = iov, .msg_iovlen = cnt};
 
-       sendmsg(sock, &msg, 0);
+       switch (type) {
+       case DHCPV6_MSG_REQUEST:
+       case DHCPV6_MSG_RENEW:
+       case DHCPV6_MSG_RELEASE:
+       case DHCPV6_MSG_DECLINE:
+               if (!IN6_IS_ADDR_UNSPECIFIED(&server_addr) &&
+                       odhcp6c_addr_in_scope(&server_addr)) {
+                       srv.sin6_addr = server_addr;
+                       if (!IN6_IS_ADDR_LINKLOCAL(&server_addr))
+                               srv.sin6_scope_id = 0;
+               }
+               break;
+       default:
+               break;
+       }
+
+       if (sendmsg(sock, &msg, 0) < 0) {
+               char in6_str[INET6_ADDRSTRLEN];
+
+               syslog(LOG_ERR, "Failed to send DHCPV6 message to %s (%s)",
+                       inet_ntop(AF_INET6, (const void *)&srv.sin6_addr,
+                               in6_str, sizeof(in6_str)), strerror(errno));
+       }
 }
 
 
@@ -799,7 +825,7 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
        uint16_t olen, otype;
        uint8_t *odata, pref = 0;
        struct dhcpv6_server_cand cand = {false, false, 0, 0, {0},
-                                       DHCPV6_SOL_MAX_RT,
+                                       IN6ADDR_ANY_INIT, DHCPV6_SOL_MAX_RT,
                                        DHCPV6_INF_MAX_RT, NULL, NULL, 0, 0};
        bool have_na = false;
        int have_pd = 0;
@@ -818,6 +844,8 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
                } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
                                cand.preference >= 0) {
                        cand.preference = pref = odata[0];
+               } else if (otype == DHCPV6_OPT_UNICAST && olen == sizeof(cand.server_addr)) {
+                       cand.server_addr = *(struct in6_addr *)odata;
                } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
                        cand.wants_reconfigure = true;
                } else if (otype == DHCPV6_OPT_SOL_MAX_RT && olen == 4) {
@@ -1008,6 +1036,9 @@ static int dhcpv6_handle_reply(enum dhcpv6_msg orig, _unused const int rc,
 
                                dhcpv6_parse_ia(ia_hdr, odata + olen);
                                passthru = false;
+                       } else if (otype == DHCPV6_OPT_UNICAST && olen == sizeof(server_addr)) {
+                               server_addr = *(struct in6_addr *)odata;
+                               passthru = false;
                        } else if (otype == DHCPV6_OPT_STATUS && olen >= 2) {
                                uint8_t *mdata = (olen > 2) ? &odata[2] : NULL;
                                uint16_t mlen = (olen > 2) ? olen - 2 : 0;
@@ -1015,8 +1046,7 @@ static int dhcpv6_handle_reply(enum dhcpv6_msg orig, _unused const int rc,
 
                                dhcpv6_handle_status_code(orig, code, mdata, mlen, &ret);
                                passthru = false;
-                       }
-                       else if (otype == DHCPV6_OPT_DNS_SERVERS) {
+                       } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
                                if (olen % 16 == 0)
                                        odhcp6c_add_state(STATE_DNS, odata, olen);
                        } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
@@ -1345,7 +1375,18 @@ static void dhcpv6_handle_status_code(const enum dhcpv6_msg orig,
                break;
 
        case DHCPV6_UseMulticast:
-               // TODO handle multicast status code
+               switch(orig) {
+               case DHCPV6_MSG_REQUEST:
+               case DHCPV6_MSG_RENEW:
+               case DHCPV6_MSG_RELEASE:
+               case DHCPV6_MSG_DECLINE:
+                       // Message needs to be retransmitted according to RFC3315 chapter 18.1.8
+                       server_addr = in6addr_any;
+                       *ret = 0;
+                       break;
+               default:
+                       break;
+               }
                break;
 
        case DHCPV6_NoAddrsAvail:

diff --git a/src/odhcp6c.c b/src/odhcp6c.c
index e97ad267f192e5b6e421658f8dae2e92eea61d46..2fe41e5160158ed8501863e23a130a640b285034 100644 (file)
--- a/src/odhcp6c.c
+++ b/src/odhcp6c.c
@@ -14,6 +14,7 @@
 
 #include <time.h>
 #include <errno.h>
+#include <ctype.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -22,16 +23,23 @@
 #include <syslog.h>
 #include <signal.h>
 #include <string.h>
+#include <strings.h>
 #include <stdbool.h>
 
 #include <net/if.h>
 #include <sys/syscall.h>
 #include <arpa/inet.h>
+#include <linux/if_addr.h>
 
 #include "odhcp6c.h"
 #include "ra.h"
 
 
+#ifndef IN6_IS_ADDR_UNIQUELOCAL
+#define IN6_IS_ADDR_UNIQUELOCAL(a) \
+       ((((__const uint32_t *) (a))[0] & htonl (0xfe000000)) \
+        == htonl (0xfc000000))
+#endif
 
 static void sighandler(int signal);
 static int usage(void);
@@ -47,6 +55,7 @@ static volatile bool signal_term = false;
 static int urandom_fd = -1, allow_slaac_only = 0;
 static bool bound = false, release = true, ra = false;
 static time_t last_update = 0;
+static char *ifname = NULL;
 
 static unsigned int min_update_interval = DEFAULT_MIN_UPDATE_INTERVAL;
 static unsigned int script_sync_delay = 10;
@@ -235,7 +244,7 @@ int main(_unused int argc, char* const argv[])
        if (!verbosity)
                setlogmask(LOG_UPTO(LOG_WARNING));
 
-       const char *ifname = argv[optind];
+       ifname = argv[optind];
 
        if (help || !ifname)
                return usage();
@@ -690,6 +699,57 @@ bool odhcp6c_is_bound(void)
        return bound;
 }
 
+bool odhcp6c_addr_in_scope(const struct in6_addr *addr)
+{
+       FILE *fd = fopen("/proc/net/if_inet6", "r");
+       int len;
+       char buf[256];
+
+       if (fd == NULL)
+               return false;
+
+       while (fgets(buf, sizeof(buf), fd)) {
+               struct in6_addr inet6_addr;
+               uint32_t flags, dummy;
+               unsigned int i;
+               char name[8], addr_buf[32];
+
+               len = strlen(buf);
+
+               if ((len <= 0) || buf[len - 1] != '\n')
+                       return false;
+
+               buf[--len] = '\0';
+
+               if (sscanf(buf, "%s %x %x %x %x %s",
+                               addr_buf, &dummy, &dummy, &dummy, &flags, name) != 6)
+                       return false;
+
+               if (strcmp(name, ifname) ||
+                       (flags & (IFA_F_DADFAILED | IFA_F_TENTATIVE | IFA_F_DEPRECATED)))
+                       continue;
+
+               for (i = 0; i < sizeof(addr_buf); i++) {
+                       if (!isxdigit(addr_buf[i]) || isupper(addr_buf[i]))
+                               return false;
+               }
+
+               memset(&inet6_addr, 0, sizeof(inet6_addr));
+               for (i = 0; i < (sizeof(addr_buf) / 2); i++) {
+                       unsigned char byte;
+                       static const char hex[] = "0123456789abcdef";
+                       byte = ((index(hex, addr_buf[i * 2]) - hex) << 4) |
+                               (index(hex, addr_buf[i * 2 + 1]) - hex);
+                       inet6_addr.s6_addr[i] = byte;
+               }
+
+               if ((IN6_IS_ADDR_LINKLOCAL(&inet6_addr) == IN6_IS_ADDR_LINKLOCAL(addr)) &&
+                       (IN6_IS_ADDR_UNIQUELOCAL(&inet6_addr) == IN6_IS_ADDR_UNIQUELOCAL(addr)))
+                       return true;
+       }
+       return false;
+}
+
 static void sighandler(int signal)
 {
        if (signal == SIGUSR1)

diff --git a/src/odhcp6c.h b/src/odhcp6c.h
index 2a10113852481a209d5e039ee041c020afc2f118..e55d3c1a988d2622fbe26fb6b66132b9e9d89ae2 100644 (file)
--- a/src/odhcp6c.h
+++ b/src/odhcp6c.h
@@ -227,6 +227,7 @@ struct dhcpv6_server_cand {
        int16_t preference;
        uint8_t duid_len;
        uint8_t duid[130];
+       struct in6_addr server_addr;
        uint32_t sol_max_rt;
        uint32_t inf_max_rt;
        void *ia_na;
@@ -343,6 +344,7 @@ bool odhcp6c_signal_process(void);
 uint64_t odhcp6c_get_milli_time(void);
 int odhcp6c_random(void *buf, size_t len);
 bool odhcp6c_is_bound(void);
+bool odhcp6c_addr_in_scope(const struct in6_addr *addr);
 
 // State manipulation
 void odhcp6c_clear_state(enum odhcp6c_state state);