6 files changed, 76 insertions, 15 deletions

diff --git a/networking/udhcp/Config.src b/networking/udhcp/Config.src
index 7ba7f48fc..d9c501c18 100644
--- a/networking/udhcp/Config.src
+++ b/networking/udhcp/Config.src
@@ -10,6 +10,13 @@ config UDHCPD
         udhcpd is a DHCP server geared primarily toward embedded systems,
         while striving to be fully functional and RFC compliant.
 
+config FEATURE_UDHCPD_BOOTP
+        bool "Answer to BOOTP requests as well"
+        default y
+        depends on UDHCPD
+        help
+        Support old BOOTP protocol too.
+
 config FEATURE_UDHCPD_BASE_IP_ON_MAC
         bool "Select IP address based on client MAC"
         default n
diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
index ae818db05..ad580f38d 100644
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -252,6 +252,14 @@ uint8_t* FAST_FUNC udhcp_scan_options(struct dhcp_packet *packet, struct dhcp_sc
         /* option bytes: [code][len][data1][data2]..[dataLEN] */
         while (1) {
                 if (scan_state->rem <= 0) {
+                        if (ENABLE_FEATURE_UDHCPD_BOOTP && scan_state->rem == 0) {
+                                /* DHCP requires END option to be present.
+                                 * We are here if packet fails this condition
+                                 * (options[] are zero-padded to the end).
+                                 * Assume BOOTP packet without further checks.
+                                 */
+                                break; /* return NULL */
+                        }
  complain:
                         bb_simple_error_msg("bad packet, malformed option field");
                         return NULL;
@@ -278,7 +286,7 @@ uint8_t* FAST_FUNC udhcp_scan_options(struct dhcp_packet *packet, struct dhcp_sc
                                 scan_state->rem = sizeof(packet->sname);
                                 continue;
                         }
-                        break;
+                        break; /* return NULL */
                 }
 
                 if (scan_state->rem <= OPT_LEN) /* [len] byte exists? */
diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index 49a0b593d..3ef371a7c 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -20,8 +20,11 @@ extern const uint8_t MAC_BCAST_ADDR[6] ALIGN2; /* six all-ones */
 
 /*** DHCP packet ***/
 
+#define RFC1048_MAGIC           0x63825363
+/* RFC 1048 still uses BOOTP's small buffer (4 byte cookie + 60 the rest) */
+#define RFC1048_OPTIONS_BUFSIZE 60
+
 /* DHCP protocol. See RFC 2131 */
-#define DHCP_MAGIC              0x63825363
 #define DHCP_OPTIONS_BUFSIZE    308
 #define BOOTREQUEST             1
 #define BOOTREPLY               2
@@ -57,8 +60,10 @@ struct dhcp_packet {
          * such as 'unix' or 'gateway'; this means 'boot the named program
          * configured for my machine'"
          */
-        /* BOOTP fields end here, BOOTP says optional uint8_t vend[64] follows */
-        uint32_t cookie;      /* DHCP magic bytes: 99,130,83,99 decimal */
+        /* BOOTP fields end here, BOOTP says optional uint8_t vend[64] follows. */
+        /* RFC 1048 defined this cookie value and options 0-12 and 255. */
+        /* DHCP extended it and required option 255 (END) to be always present. */
+        uint32_t cookie;      /* RFC 1048 magic bytes: 99,130,83,99 decimal */
         uint8_t options[DHCP_OPTIONS_BUFSIZE + CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS];
 };
 #define DHCP_PKT_SNAME_LEN      64
@@ -200,6 +205,9 @@ struct dhcp_scan_state {
 #define SNAME_FIELD             2
 
 /* DHCP_MESSAGE_TYPE values */
+#if ENABLE_FEATURE_UDHCPD_BOOTP
+#define MSGTYPE_BOOTP           0 /* there was no TYPE option in client's packet, assuming BOOTP */
+#endif
 #define DHCPDISCOVER            1 /* client -> server */
 #define DHCPOFFER               2 /* client <- server */
 #define DHCPREQUEST             3 /* client -> server */
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index c757fb37c..200a2fb8a 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -971,7 +971,7 @@ static NOINLINE int d4_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
         }
  skip_udp_sum_check:
 
-        if (packet.data.cookie != htonl(DHCP_MAGIC)) {
+        if (packet.data.cookie != htonl(RFC1048_MAGIC)) {
                 log1s("packet with bad magic, ignoring");
                 return -2;
         }
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index 66750e2e6..2904119e5 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -649,7 +649,8 @@ static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacke
         packet->flags = oldpacket->flags;
         packet->gateway_nip = oldpacket->gateway_nip;
         packet->ciaddr = oldpacket->ciaddr;
-        udhcp_add_simple_option(packet, DHCP_SERVER_ID, server_data.server_nip);
+        IF_FEATURE_UDHCPD_BOOTP(if (type != MSGTYPE_BOOTP))
+                udhcp_add_simple_option(packet, DHCP_SERVER_ID, server_data.server_nip);
 }
 
 /* Fill options field, siaddr_nip, and sname and boot_file fields.
@@ -725,7 +726,12 @@ static uint32_t select_lease_time(struct dhcp_packet *packet)
 
 /* We got a DHCP DISCOVER. Send an OFFER. */
 /* NOINLINE: limit stack usage in caller */
-static NOINLINE void send_offer(struct dhcp_packet *oldpacket,
+#if !ENABLE_FEATURE_UDHCPD_BOOTP
+#define send_offer(is_dhcp_client, ...) \
+        send_offer(__VA_ARGS__)
+#endif
+static NOINLINE void send_offer(void *is_dhcp_client,
+                struct dhcp_packet *oldpacket,
                 uint32_t static_lease_nip,
                 struct dyn_lease *lease,
                 uint32_t requested_nip,
@@ -734,7 +740,12 @@ static NOINLINE void send_offer(struct dhcp_packet *oldpacket,
         struct dhcp_packet packet;
         uint32_t lease_time_sec;
 
+#if ENABLE_FEATURE_UDHCPD_BOOTP
+        init_packet(&packet, oldpacket, is_dhcp_client ? DHCPOFFER : MSGTYPE_BOOTP);
+#else
+        enum { is_dhcp_client = 1 };
         init_packet(&packet, oldpacket, DHCPOFFER);
+#endif
 
         /* If it is a static lease, use its IP */
         packet.yiaddr = static_lease_nip;
@@ -784,9 +795,16 @@ static NOINLINE void send_offer(struct dhcp_packet *oldpacket,
                 }
         }
 
-        lease_time_sec = select_lease_time(oldpacket);
-        udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
+        if (is_dhcp_client) {
+                lease_time_sec = select_lease_time(oldpacket);
+                udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
+        }
+/* TODO: pass "is_dhcp_client" to add_server_options(), avoid adding confusing options to BOOTP clients? */
         add_server_options(&packet);
+        if (!is_dhcp_client && udhcp_end_option(packet.options) >= RFC1048_OPTIONS_BUFSIZE) {
+                bb_simple_error_msg("BOOTP reply too large, not sending");
+                return;
+        }
 
         /* send_packet emits error message itself if it detects failure */
         send_packet_verbose(&packet, "sending OFFER to %s");
@@ -1050,8 +1068,12 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
                         continue;
                 }
                 msg_type = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
-                if (!msg_type || msg_type[0] < DHCP_MINTYPE || msg_type[0] > DHCP_MAXTYPE) {
-                        bb_info_msg("no or bad message type option%s", ", ignoring packet");
+                if (
+                        IF_FEATURE_UDHCPD_BOOTP( msg_type && )
+                        IF_NOT_FEATURE_UDHCPD_BOOTP( !msg_type || )
+                        (msg_type[0] < DHCP_MINTYPE || msg_type[0] > DHCP_MAXTYPE)
+                ) {
+                        bb_info_msg("bad message type option%s", ", ignoring packet");
                         continue;
                 }
 
@@ -1086,12 +1108,25 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
                         move_from_unaligned32(requested_nip, requested_ip_opt);
                 }
 
+#if ENABLE_FEATURE_UDHCPD_BOOTP
+                /* Handle old BOOTP clients */
+                if (!msg_type) {
+                        log1("received %s", "BOOTP BOOTREQUEST");
+                        if (!static_lease_nip) {
+                                bb_info_msg("no static lease for BOOTP client%s", ", ignoring packet");
+                                continue;
+                        }
+                        send_offer(msg_type, &packet, static_lease_nip, lease, requested_nip, arpping_ms);
+                        continue;
+                }
+#endif
+
                 switch (msg_type[0]) {
 
                 case DHCPDISCOVER:
                         log1("received %s", "DISCOVER");
 
-                        send_offer(&packet, static_lease_nip, lease, requested_nip, arpping_ms);
+                        send_offer(msg_type, &packet, static_lease_nip, lease, requested_nip, arpping_ms);
                         break;
 
                 case DHCPREQUEST:
diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c
index 529978189..f9dc11d01 100644
--- a/networking/udhcp/packet.c
+++ b/networking/udhcp/packet.c
@@ -18,6 +18,8 @@ void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type)
         memset(packet, 0, sizeof(*packet));
         packet->op = BOOTREQUEST; /* if client to a server */
         switch (type) {
+        IF_FEATURE_UDHCPD_BOOTP(case MSGTYPE_BOOTP:)
+                /* reply to a BOOTP (not DHCP) client */
         case DHCPOFFER:
         case DHCPACK:
         case DHCPNAK:
@@ -25,10 +27,11 @@ void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type)
         }
         packet->htype = 1; /* ethernet */
         packet->hlen = 6;
-        packet->cookie = htonl(DHCP_MAGIC);
+        packet->cookie = htonl(RFC1048_MAGIC);
         if (DHCP_END != 0)
                 packet->options[0] = DHCP_END;
-        udhcp_add_simple_option(packet, DHCP_MESSAGE_TYPE, type);
+        IF_FEATURE_UDHCPD_BOOTP(if (type != MSGTYPE_BOOTP))
+                udhcp_add_simple_option(packet, DHCP_MESSAGE_TYPE, type);
 }
 #endif
 
@@ -90,7 +93,7 @@ int FAST_FUNC udhcp_recv_kernel_packet(struct dhcp_packet *packet, int fd)
         }
 
         if (bytes < offsetof(struct dhcp_packet, options)
-         || packet->cookie != htonl(DHCP_MAGIC)
+         || packet->cookie != htonl(RFC1048_MAGIC)
         ) {
                 bb_simple_info_msg("packet with bad magic, ignoring");
                 return -2;