Implement an option for setting static routes with gateway

[project/relayd.git] / dhcp.c

diff --git a/dhcp.c b/dhcp.c
index a144346..9dbea28 100644 (file)
--- a/dhcp.c
+++ b/dhcp.c
@@ -29,6 +29,19 @@ struct ip_packet {
        struct iphdr iph;
 } __packed;
 
+
+enum {
+       DHCP_OPTION_ROUTER = 0x03,
+       DHCP_OPTION_ROUTES = 0x79,
+       DHCP_OPTION_END = 0xff,
+};
+
+struct dhcp_option {
+       uint8_t code;
+       uint8_t len;
+       uint8_t data[];
+};
+
 struct dhcp_header {
        uint8_t op, htype, hlen, hops;
        uint32_t xit;
@@ -37,6 +50,8 @@ struct dhcp_header {
        unsigned char chaddr[16];
        unsigned char sname[64];
        unsigned char file[128];
+       uint32_t cookie;
+       uint8_t option_data[];
 } __packed;
 
 static uint16_t
@@ -65,11 +80,46 @@ chksum(uint16_t sum, const uint8_t *data, uint16_t len)
        return sum;
 }
 
+static void
+parse_dhcp_options(struct relayd_host *host, struct dhcp_header *dhcp, int len)
+{
+       uint8_t *end = (uint8_t *) dhcp + len;
+       struct dhcp_option *opt = (void *)dhcp->option_data;
+       static const uint8_t dest[4] = { 0, 0, 0, 0 };
+
+       while((uint8_t *) opt < end) {
+               if ((uint8_t *) opt + opt->len > end)
+                       break;
+
+               opt = (void *) &opt->data[opt->len];
+               switch(opt->code) {
+               case DHCP_OPTION_ROUTER:
+                       DPRINTF(2, "Found a DHCP router option, len=%d\n", opt->len);
+                       if (!memcmp(opt->data, host->ipaddr, 4))
+                               relayd_add_host_route(host, dest, 0);
+                       else
+                               relayd_add_pending_route(opt->data, dest, 0, 10000);
+                       break;
+               case DHCP_OPTION_ROUTES:
+                       DPRINTF(2, "Found a DHCP static routes option, len=%d\n", opt->len);
+                       break;
+               case DHCP_OPTION_END:
+                       opt = (void *) end;
+                       continue;
+               default:
+                       DPRINTF(3, "Skipping unknown DHCP option %02x\n", opt->code);
+                       continue;
+               }
+
+       }
+}
+
 bool relayd_handle_dhcp_packet(struct relayd_interface *rif, void *data, int len, bool forward)
 {
        struct ip_packet *pkt = data;
        struct udphdr *udp;
        struct dhcp_header *dhcp;
+       struct relayd_host *host;
        int udplen;
        uint16_t sum;
 
@@ -98,8 +148,11 @@ bool relayd_handle_dhcp_packet(struct relayd_interface *rif, void *data, int len
        if (!forward)
                return true;
 
-       if (dhcp->op == 2)
-               relayd_refresh_host(rif, pkt->eth.ether_shost, (void *) &pkt->iph.saddr);
+       if (dhcp->op == 2) {
+               host = relayd_refresh_host(rif, pkt->eth.ether_shost, (void *) &pkt->iph.saddr);
+               if (host)
+                       parse_dhcp_options(host, dhcp, udplen - sizeof(struct udphdr));
+       }
 
        DPRINTF(2, "%s: handling DHCP %s\n", rif->ifname, (dhcp->op == 1 ? "request" : "response"));