dhcpv4: use iovec for DNS search and MTU

Some more options converted.

Signed-off-by: David Härdeman <[email protected]>
Link: https://github.com/openwrt/odhcpd/pull/278
Signed-off-by: Álvaro Fernández Rojas <[email protected]>

diff --git a/src/dhcpv4.c b/src/dhcpv4.c
index 4909669c6e4232c4e3992b98f7763c9213df6f43..4b2073a0352e0879f26c71528a2f720ecd77afb5 100644 (file)
--- a/src/dhcpv4.c
+++ b/src/dhcpv4.c
@@ -624,12 +624,15 @@ enum {
        IOV_NETMASK,
        IOV_HOSTNAME,
        IOV_HOSTNAME_NAME,
+       IOV_MTU,
        IOV_BROADCAST,
        IOV_NTP,
        IOV_NTP_ADDR,
        IOV_LEASETIME,
        IOV_RENEW,
        IOV_REBIND,
+       IOV_SRCH_DOMAIN,
+       IOV_SRCH_DOMAIN_NAME,
        IOV_DNR,
        IOV_DNR_BODY,
        IOV_END,
@@ -682,6 +685,10 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
        struct dhcpv4_option reply_hostname = {
                .code = DHCPV4_OPT_HOSTNAME,
        };
+       struct dhcpv4_option_u16 reply_mtu = {
+               .code = DHCPV4_OPT_MTU,
+               .len = sizeof(uint16_t),
+       };
        struct dhcpv4_option_u32 reply_broadcast = {
                .code = DHCPV4_OPT_BROADCAST,
                .len = sizeof(uint32_t),
@@ -702,6 +709,9 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
                .code = DHCPV4_OPT_REBIND,
                .len = sizeof(uint32_t),
        };
+       struct dhcpv4_option reply_srch_domain = {
+               .code = DHCPV4_OPT_SEARCH_DOMAIN,
+       };
        struct dhcpv4_option reply_dnr = {
                .code = DHCPV4_OPT_DNR,
        };
@@ -716,12 +726,15 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
                [IOV_NETMASK]           = { &reply_netmask, 0 },
                [IOV_HOSTNAME]          = { &reply_hostname, 0 },
                [IOV_HOSTNAME_NAME]     = { NULL, 0 },
+               [IOV_MTU]               = { &reply_mtu, 0 },
                [IOV_BROADCAST]         = { &reply_broadcast, 0 },
                [IOV_NTP]               = { &reply_ntp, 0 },
                [IOV_NTP_ADDR]          = { iface->dhcpv4_ntp, 0 },
                [IOV_LEASETIME]         = { &reply_leasetime, 0 },
                [IOV_RENEW]             = { &reply_renew, 0 },
                [IOV_REBIND]            = { &reply_rebind, 0 },
+               [IOV_SRCH_DOMAIN]       = { &reply_srch_domain, 0 },
+               [IOV_SRCH_DOMAIN_NAME]  = { NULL, 0 },
                [IOV_DNR]               = { &reply_dnr, 0 },
                [IOV_DNR_BODY]          = { NULL, 0 },
                [IOV_END]               = { &reply_end, sizeof(reply_end) },
@@ -877,10 +890,12 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
 
        reply_opts[reply_opts_len++] = DHCPV4_OPT_NETMASK;
        reply_opts[reply_opts_len++] = DHCPV4_OPT_HOSTNAME;
+       reply_opts[reply_opts_len++] = DHCPV4_OPT_MTU;
        reply_opts[reply_opts_len++] = DHCPV4_OPT_BROADCAST;
        reply_opts[reply_opts_len++] = DHCPV4_OPT_LEASETIME;
        reply_opts[reply_opts_len++] = DHCPV4_OPT_RENEW;
        reply_opts[reply_opts_len++] = DHCPV4_OPT_REBIND;
+       reply_opts[reply_opts_len++] = DHCPV4_OPT_SEARCH_DOMAIN;
 
        if (a) {
                reply.yiaddr.s_addr = a->addr;
@@ -908,30 +923,6 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
                }
        }
 
-       struct ifreq ifr;
-
-       memset(&ifr, 0, sizeof(ifr));
-       strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name) - 1);
-
-       if (!ioctl(iface->dhcpv4_event.uloop.fd, SIOCGIFMTU, &ifr)) {
-               uint16_t mtu = htons(ifr.ifr_mtu);
-               dhcpv4_put(&reply, &cursor, DHCPV4_OPT_MTU, 2, &mtu);
-               reply_opts[reply_opts_len++] = DHCPV4_OPT_MTU;
-       }
-
-       if (iface->search && iface->search_len <= 255)
-               dhcpv4_put(&reply, &cursor, DHCPV4_OPT_SEARCH_DOMAIN,
-                               iface->search_len, iface->search);
-       else if (!res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
-               uint8_t search_buf[256];
-               int len = dn_comp(_res.dnsrch[0], search_buf,
-                                               sizeof(search_buf), NULL, NULL);
-               if (len > 0)
-                       dhcpv4_put(&reply, &cursor, DHCPV4_OPT_SEARCH_DOMAIN,
-                                       len, search_buf);
-       }
-       reply_opts[reply_opts_len++] = DHCPV4_OPT_SEARCH_DOMAIN;
-
        if (iface->dhcpv4_router_cnt == 0)
                dhcpv4_put(&reply, &cursor, DHCPV4_OPT_ROUTER, 4, &iface->dhcpv4_local);
        else
@@ -969,6 +960,19 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
                        iov[IOV_HOSTNAME_NAME].iov_len = reply_hostname.len;
                        break;
 
+               case DHCPV4_OPT_MTU:
+                       if (iov[IOV_MTU].iov_len)
+                               break;
+
+                       struct ifreq ifr = { .ifr_name = { 0x0, } };
+
+                       strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name) - 1);
+                       if (!ioctl(iface->dhcpv4_event.uloop.fd, SIOCGIFMTU, &ifr)) {
+                               reply_mtu.data = htons(ifr.ifr_mtu);
+                               iov[IOV_MTU].iov_len = sizeof(reply_mtu);
+                       }
+                       break;
+
                case DHCPV4_OPT_BROADCAST:
                        if (!a || iface->dhcpv4_bcast.s_addr == INADDR_ANY)
                                break;
@@ -1004,6 +1008,33 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
                        iov[IOV_REBIND].iov_len = sizeof(reply_rebind);
                        break;
 
+               case DHCPV4_OPT_SEARCH_DOMAIN:
+                       if (iov[IOV_SRCH_DOMAIN].iov_len || iface->search_len > UINT8_MAX)
+                               break;
+
+                       if (iface->search) {
+                               reply_srch_domain.len = iface->search_len;
+                               iov[IOV_SRCH_DOMAIN].iov_len = sizeof(reply_srch_domain);
+                               iov[IOV_SRCH_DOMAIN_NAME].iov_base = iface->search;
+                               iov[IOV_SRCH_DOMAIN_NAME].iov_len = iface->search_len;
+                       } else if (!res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
+                               int len;
+
+                               if (!iov[IOV_SRCH_DOMAIN_NAME].iov_base)
+                                       iov[IOV_SRCH_DOMAIN_NAME].iov_base = alloca(DNS_MAX_NAME_LEN);
+
+                               len = dn_comp(_res.dnsrch[0],
+                                             iov[IOV_SRCH_DOMAIN_NAME].iov_base,
+                                             DNS_MAX_NAME_LEN, NULL, NULL);
+                               if (len < 0)
+                                       break;
+
+                               reply_srch_domain.len = len;
+                               iov[IOV_SRCH_DOMAIN].iov_len = sizeof(reply_srch_domain);
+                               iov[IOV_SRCH_DOMAIN_NAME].iov_len = len;
+                       }
+                       break;
+
                case DHCPV4_OPT_DNR:
                        struct dhcpv4_dnr *dnrs;
                        size_t dnrs_len = 0;

diff --git a/src/dhcpv4.h b/src/dhcpv4.h
index c1dc136ee0090283426a08634ef9633fb1cb2946..4f4679fa5d924abc0c78d5765580ba7653e8335b 100644 (file)
--- a/src/dhcpv4.h
+++ b/src/dhcpv4.h
@@ -148,6 +148,12 @@ struct dhcpv4_option_u8 {
        uint8_t data;
 };
 
+struct dhcpv4_option_u16 {
+       uint8_t code;
+       uint8_t len;
+       uint16_t data;
+};
+
 struct dhcpv4_option_u32 {
        uint8_t code;
        uint8_t len;

diff --git a/src/odhcpd.h b/src/odhcpd.h
index 7d2636521499bb1891a1a207e44df317ea6ca4a8..ae0e6f5dc61be21dde462c852ce78654ae5e5fc4 100644 (file)
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -29,6 +29,10 @@
 #define min(a, b) (((a) < (b)) ? (a) : (b))
 #define max(a, b) (((a) > (b)) ? (a) : (b))
 
+/* RFC 1035, §2.3.4, with one extra byte for buffers */
+#define DNS_MAX_NAME_LEN 256
+#define DNS_MAX_LABEL_LEN 63
+
 // RFC 6106 defines this router advertisement option
 #define ND_OPT_ROUTE_INFO 24
 #define ND_OPT_RECURSIVE_DNS 25