task #14270: DHCP should support user-defined additional options: added two hooks for adding and parsing user defined DHCP options

src/core/ipv4/dhcp.c

@@ -78,6 +78,16 @@
 
 #include <string.h>
 
+#ifdef LWIP_HOOK_FILENAME
+#include LWIP_HOOK_FILENAME
+#endif
+#ifndef LWIP_HOOK_DHCP_APPEND_OPTIONS
+#define LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, dhcp, state, msg, msg_type)
+#endif
+#ifndef LWIP_HOOK_DHCP_PARSE_OPTION
+#define LWIP_HOOK_DHCP_PARSE_OPTION(netif, dhcp, state, msg, msg_type, option, len, pbuf, offset)
+#endif
+
 /** DHCP_CREATE_RAND_XID: if this is set to 1, the xid is created using
  * LWIP_RAND() (this overrides DHCP_GLOBAL_XID)
  */
@@ -381,6 +391,7 @@ dhcp_select(struct netif *netif)
     dhcp_option_hostname(dhcp, netif);
 #endif /* LWIP_NETIF_HOSTNAME */
 
+    LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, dhcp, DHCP_STATE_REQUESTING, dhcp->msg_out, DHCP_REQUEST);
     dhcp_option_trailer(dhcp);
     /* shrink the pbuf to the actual content length */
     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
@@ -815,6 +826,7 @@ dhcp_inform(struct netif *netif)
     dhcp_option(&dhcp, DHCP_OPTION_MAX_MSG_SIZE, DHCP_OPTION_MAX_MSG_SIZE_LEN);
     dhcp_option_short(&dhcp, DHCP_MAX_MSG_LEN(netif));
 
+    LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, &dhcp, DHCP_STATE_INFORMING, dhcp.msg_out, DHCP_INFORM);
     dhcp_option_trailer(&dhcp);
 
     pbuf_realloc(dhcp.p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp.options_out_len);
@@ -927,6 +939,7 @@ dhcp_decline(struct netif *netif)
     dhcp_option(dhcp, DHCP_OPTION_REQUESTED_IP, 4);
     dhcp_option_long(dhcp, lwip_ntohl(ip4_addr_get_u32(&dhcp->offered_ip_addr)));
 
+    LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, dhcp, DHCP_STATE_BACKING_OFF, dhcp->msg_out, DHCP_DECLINE);
     dhcp_option_trailer(dhcp);
     /* resize pbuf to reflect true size of options */
     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
@@ -977,6 +990,7 @@ dhcp_discover(struct netif *netif)
     for (i = 0; i < LWIP_ARRAYSIZE(dhcp_discover_request_options); i++) {
       dhcp_option_byte(dhcp, dhcp_discover_request_options[i]);
     }
+    LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, dhcp, DHCP_STATE_SELECTING, dhcp->msg_out, DHCP_DISCOVER);
     dhcp_option_trailer(dhcp);
 
     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_discover: realloc()ing\n"));
@@ -1146,6 +1160,7 @@ dhcp_renew(struct netif *netif)
     dhcp_option_hostname(dhcp, netif);
 #endif /* LWIP_NETIF_HOSTNAME */
 
+    LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, dhcp, DHCP_STATE_RENEWING, dhcp->msg_out, DHCP_REQUEST);
     /* append DHCP message trailer */
     dhcp_option_trailer(dhcp);
 
@@ -1198,6 +1213,7 @@ dhcp_rebind(struct netif *netif)
     dhcp_option_hostname(dhcp, netif);
 #endif /* LWIP_NETIF_HOSTNAME */
 
+    LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, dhcp, DHCP_STATE_REBINDING, dhcp->msg_out, DHCP_DISCOVER);
     dhcp_option_trailer(dhcp);
 
     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
@@ -1246,7 +1262,7 @@ dhcp_reboot(struct netif *netif)
     for (i = 0; i < LWIP_ARRAYSIZE(dhcp_discover_request_options); i++) {
       dhcp_option_byte(dhcp, dhcp_discover_request_options[i]);
     }
-
+    LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, dhcp, DHCP_STATE_REBOOTING, dhcp->msg_out, DHCP_REQUEST);
     dhcp_option_trailer(dhcp);
 
     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
@@ -1309,11 +1325,12 @@ dhcp_release_and_stop(struct netif *netif)
     if (result == ERR_OK) {
       dhcp_option(dhcp, DHCP_OPTION_SERVER_ID, 4);
       dhcp_option_long(dhcp, lwip_ntohl(ip4_addr_get_u32(ip_2_ip4(&server_ip_addr))));
-  
+
+      LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, dhcp, dhcp->state, dhcp->msg_out, DHCP_RELEASE);
       dhcp_option_trailer(dhcp);
-  
+
       pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
-  
+
       udp_sendto_if(dhcp_pcb, dhcp->p_out, &server_ip_addr, DHCP_SERVER_PORT, netif);
       dhcp_delete_msg(dhcp);
       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_release: RELEASED, DHCP_STATE_OFF\n"));
@@ -1579,6 +1596,9 @@ again:
       default:
         decode_len = 0;
         LWIP_DEBUGF(DHCP_DEBUG, ("skipping option %"U16_F" in options\n", (u16_t)op));
+        LWIP_HOOK_DHCP_PARSE_OPTION(ip_current_netif(), dhcp, dhcp->state, dhcp->msg_in,
+          dhcp_option_given(dhcp, DHCP_OPTION_IDX_MSG_TYPE) ? (u8_t)dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_MSG_TYPE) : 0,
+          op, len, q, val_offset);
         break;
     }
     offset += len + 2;

src/include/lwip/opt.h

@@ -2717,6 +2717,55 @@
 #ifdef __DOXYGEN__
 #define LWIP_HOOK_UNKNOWN_ETH_PROTOCOL(pbuf, netif)
 #endif
+
+/**
+ * LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, dhcp, state, msg, msg_type):
+ * Called from various dhcp functions when sending a DHCP message.
+ * This hook is called just before the DHCP message trailer is added, so the
+ * options are at the end of a DHCP message.
+ * Arguments:
+ * - netif: struct netif that the packet will be sent through
+ * - dhcp: struct dhcp on that netif
+ * - state: current dhcp state (dhcp_state_enum_t as an u8_t)
+ * - msg: struct dhcp_msg that will be sent
+ * - msg_type: dhcp message type to be sent (u8_t)
+ * Returns void
+ *
+ * Options need to appended like this:
+ *   LWIP_ASSERT("dhcp option overflow", dhcp->options_out_len + option_len + 2 <= DHCP_OPTIONS_LEN);
+ *   dhcp->msg_out->options[dhcp->options_out_len++] = <option_number>;
+ *   dhcp->msg_out->options[dhcp->options_out_len++] = <option_len>;
+ *   dhcp->msg_out->options[dhcp->options_out_len++] = <option_bytes>;
+ *   [...]
+ */
+#ifdef __DOXYGEN__
+#define LWIP_HOOK_DHCP_APPEND_OPTIONS(netif, dhcp, state, msg, msg_type)
+#endif
+
+/**
+ * LWIP_HOOK_DHCP_PARSE_OPTION(netif, dhcp, state, msg, msg_type, option, len, pbuf, offset):
+ * Called from dhcp_parse_reply when receiving a DHCP message.
+ * This hook is called for every option in the received message that is not handled internally.
+ * Arguments:
+ * - netif: struct netif that the packet will be sent through
+ * - dhcp: struct dhcp on that netif
+ * - state: current dhcp state (dhcp_state_enum_t as an u8_t)
+ * - msg: struct dhcp_msg that was received
+ * - msg_type: dhcp message type received (u8_t, ATTENTION: only valid after
+ *             the message type option has been parsed!)
+ * - option: option value (u8_t)
+ * - len: option data length (u8_t)
+ * - pbuf: pbuf where option data is contained
+ * - offset: offset in pbuf where option *data* begins
+ * Returns void
+ *
+ * A nice way to get the option contents is @ref pbuf_get_contiguous:
+ *  u8_t buf[32];
+ *  u8_t *ptr = (u8_t*)pbuf_get_contiguous(p, buf, sizeof(buf), LWIP_MIN(option_len, sizeof(buf)), offset);
+ */
+#ifdef __DOXYGEN__
+#define LWIP_HOOK_DHCP_PARSE_OPTION(netif, dhcp, state, msg, msg_type, option, len, pbuf, offset)
+#endif
 /**
  * @}
  */