Adds basic support for ProxyDHCP

- ProxyDHCP allows a second DHCP server to exist alongside your main
  DHCP server and supply additional BOOTP related options
- When u-boot sends out a DHCP request, the real DHCP server will
  respond with a normal response containing the new client IP address
  while simultaneously the ProxyDHCP server will respond with a blank
  client IP address and a `bootfile` option
- This patch adds CONFIG_SERVERIP_FROM_PROXYDHCP (default false) to
  enable this behavior and CONFIG_SERVERIP_FROM_PROXYDHCP_DELAY_MS
  (default 100) which tells u-boot to wait additional time after
  receiving the main DHCP response to give the ProxyDHCP response time
  to arrive
- The PXE spec for ProxyDHCP is more complicated than the solution
  added here as diagramed on page 16:
  http://www.pix.net/software/pxeboot/archive/pxespec.pdf:

```
DHCP Discover will be retried four times. The four timeouts are 4, 8, 16
and 32 seconds respectively. If a DHCPOFFER is received without an Option
timeouts in an attempt to receive a PXE response.
```

- Adding a simple delay worked for my purposes but let me know if a
  more robust solution is required

Signed-off-by: Lyle Franklin <lylejfranklin@gmail.com>

diff --git a/net/Kconfig b/net/Kconfig
index 1b3e420..c4b4dae 100644 (file)
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -74,4 +74,18 @@ config TFTP_WINDOWSIZE
          before an ack response is required.
          The default TFTP implementation implies a window size of 1.
 
+config SERVERIP_FROM_PROXYDHCP
+       bool "Get serverip value from Proxy DHCP response"
+       help
+         Allows bootfile config to be fetched from Proxy DHCP server
+               while IP is obtained from main DHCP server.
+
+config SERVERIP_FROM_PROXYDHCP_DELAY_MS
+       int "# of additional milliseconds to wait for ProxyDHCP response"
+       default 100
+       help
+         Amount of additional time to wait for ProxyDHCP response after
+               receiving response from main DHCP server. Has no effect if
+               SERVERIP_FROM_PROXYDHCP is false.
+
 endif   # if NET

diff --git a/net/bootp.c b/net/bootp.c
index de3dab4..163af41 100644 (file)
--- a/net/bootp.c
+++ b/net/bootp.c
@@ -146,10 +146,7 @@ static int check_reply_packet(uchar *pkt, unsigned dest, unsigned src,
        return retval;
 }
 
-/*
- * Copy parameters of interest from BOOTP_REPLY/DHCP_OFFER packet
- */
-static void store_net_params(struct bootp_hdr *bp)
+static void store_bootp_params(struct bootp_hdr *bp)
 {
 #if !defined(CONFIG_BOOTP_SERVERIP)
        struct in_addr tmp_ip;
@@ -183,6 +180,16 @@ static void store_net_params(struct bootp_hdr *bp)
        if (*net_boot_file_name)
                env_set("bootfile", net_boot_file_name);
 #endif
+}
+
+/*
+ * Copy parameters of interest from BOOTP_REPLY/DHCP_OFFER packet
+ */
+static void store_net_params(struct bootp_hdr *bp)
+{
+#if !defined(CONFIG_SERVERIP_FROM_PROXYDHCP)
+       store_bootp_params(bp);
+#endif
        net_copy_ip(&net_ip, &bp->bp_yiaddr);
 }
 
@@ -1055,8 +1062,12 @@ static void dhcp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
        debug("DHCPHandler: got DHCP packet: (src=%d, dst=%d, len=%d) state: "
              "%d\n", src, dest, len, dhcp_state);
 
-       if (net_read_ip(&bp->bp_yiaddr).s_addr == 0)
+       if (net_read_ip(&bp->bp_yiaddr).s_addr == 0) {
+#if defined(CONFIG_SERVERIP_FROM_PROXYDHCP)
+               store_bootp_params(bp);
+#endif
                return;
+       }
 
        switch (dhcp_state) {
        case SELECTING:
@@ -1075,6 +1086,12 @@ static void dhcp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
                        dhcp_packet_process_options(bp);
                        efi_net_set_dhcp_ack(pkt, len);
 
+#if defined(CONFIG_SERVERIP_FROM_PROXYDHCP)
+                       if (!net_server_ip.s_addr)
+                               udelay(CONFIG_SERVERIP_FROM_PROXYDHCP_DELAY_MS *
+                                       1000);
+#endif /* CONFIG_SERVERIP_FROM_PROXYDHCP */
+
                        debug("TRANSITIONING TO REQUESTING STATE\n");
                        dhcp_state = REQUESTING;