Add DNS support
On 04 Oct 2008 Pieter posted a dns implementation for U-Boot.
http://www.mail-archive.com/u-boot-users@lists.sourceforge.net/msg10216.html
>
> DNS can be enabled by setting CFG_CMD_DNS. After performing a query,
> the serverip environment var is updated.
>
> Probably there are some cosmetic issues with the patch. Unfortunatly I
> do not have the time to correct these. So if anybody else likes DNS
> support in U-Boot and has the time, feel free to patch it in the main tree.
Here it is again - slightly modified & smaller:
- update to 2009-06 (Pieter's patch was for U-Boot 1.2.0)
- README.dns is added
- syntax is changed (now takes a third option, the env var to store
the result in)
- add a random port() function in net.c
- sort Makefile in ./net/Makefile
- dns just returns unless a env var is given
- run through checkpatch, and clean up style issues
- remove packet from stack
- cleaned up some comments
- failure returns much faster (if server responds, don't wait for
timeout)
- use built in functions (memcpy) rather than byte copy.
Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: Pieter Voorthuijsen <pieter.voorthuijsen@prodrive.nl>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
diff --git a/net/dns.c b/net/dns.c
new file mode 100644
index 0000000..f25c3f8
--- /dev/null
+++ b/net/dns.c
@@ -0,0 +1,211 @@
+/*
+ * DNS support driver
+ *
+ * Copyright (c) 2008 Pieter Voorthuijsen <pieter.voorthuijsen@prodrive.nl>
+ * Copyright (c) 2009 Robin Getz <rgetz@blackfin.uclinux.org>
+ *
+ * This is a simple DNS implementation for U-Boot. It will use the first IP
+ * in the DNS response as NetServerIP. This can then be used for any other
+ * network related activities.
+ *
+ * The packet handling is partly based on TADNS, original copyrights
+ * follow below.
+ *
+ */
+
+/*
+ * Copyright (c) 2004-2005 Sergey Lyubka <valenok@gmail.com>
+ *
+ * "THE BEER-WARE LICENSE" (Revision 42):
+ * Sergey Lyubka wrote this file. As long as you retain this notice you
+ * can do whatever you want with this stuff. If we meet some day, and you think
+ * this stuff is worth it, you can buy me a beer in return.
+ */
+
+#include <common.h>
+#include <command.h>
+#include <net.h>
+
+#include "dns.h"
+
+char *NetDNSResolve; /* The host to resolve */
+char *NetDNSenvvar; /* The envvar to store the answer in */
+
+static int DnsOurPort;
+
+static void
+DnsSend(void)
+{
+ struct header *header;
+ int n, name_len;
+ uchar *p, *pkt;
+ const char *s;
+ const char *name;
+ enum dns_query_type qtype = DNS_A_RECORD;
+
+ name = NetDNSResolve;
+ pkt = p = (uchar *)(NetTxPacket + NetEthHdrSize() + IP_HDR_SIZE);
+
+ /* Prepare DNS packet header */
+ header = (struct header *) pkt;
+ header->tid = 1;
+ header->flags = htons(0x100); /* standard query */
+ header->nqueries = htons(1); /* Just one query */
+ header->nanswers = 0;
+ header->nauth = 0;
+ header->nother = 0;
+
+ /* Encode DNS name */
+ name_len = strlen(name);
+ p = (uchar *) &header->data; /* For encoding host name into packet */
+
+ do {
+ s = strchr(name, '.');
+ if (!s)
+ s = name + name_len;
+
+ n = s - name; /* Chunk length */
+ *p++ = n; /* Copy length */
+ memcpy(p, name, n); /* Copy chunk */
+ p += n;
+
+ if (*s == '.')
+ n++;
+
+ name += n;
+ name_len -= n;
+ } while (*s != '\0');
+
+ *p++ = 0; /* Mark end of host name */
+ *p++ = 0; /* Some servers require double null */
+ *p++ = (unsigned char) qtype; /* Query Type */
+
+ *p++ = 0;
+ *p++ = 1; /* Class: inet, 0x0001 */
+
+ n = p - pkt; /* Total packet length */
+ debug("Packet size %d\n", n);
+
+ DnsOurPort = random_port();
+
+ NetSendUDPPacket(NetServerEther, NetOurDNSIP, DNS_SERVICE_PORT,
+ DnsOurPort, n);
+ debug("DNS packet sent\n");
+}
+
+static void
+DnsTimeout(void)
+{
+ puts("Timeout\n");
+ NetState = NETLOOP_FAIL;
+}
+
+static void
+DnsHandler(uchar *pkt, unsigned dest, unsigned src, unsigned len)
+{
+ struct header *header;
+ const unsigned char *p, *e, *s;
+ u16 type, i;
+ int found, stop, dlen;
+ char IPStr[22];
+ IPaddr_t IPAddress;
+ short tmp;
+
+
+ debug("%s\n", __func__);
+ if (dest != DnsOurPort)
+ return;
+
+ for (i = 0; i < len; i += 4)
+ debug("0x%p - 0x%.2x 0x%.2x 0x%.2x 0x%.2x\n",
+ pkt+i, pkt[i], pkt[i+1], pkt[i+2], pkt[i+3]);
+
+ /* We sent 1 query. We want to see more that 1 answer. */
+ header = (struct header *) pkt;
+ if (ntohs(header->nqueries) != 1)
+ return;
+
+ /* Received 0 answers */
+ if (header->nanswers == 0) {
+ puts("DNS server returned no answers\n");
+ NetState = NETLOOP_SUCCESS;
+ return;
+ }
+
+ /* Skip host name */
+ s = &header->data[0];
+ e = pkt + len;
+ for (p = s; p < e && *p != '\0'; p++)
+ continue;
+
+ /* We sent query class 1, query type 1 */
+ tmp = p[1] | (p[2] << 8);
+ if (&p[5] > e || ntohs(tmp) != DNS_A_RECORD) {
+ puts("DNS response was not A record\n");
+ NetState = NETLOOP_SUCCESS;
+ return;
+ }
+
+ /* Go to the first answer section */
+ p += 5;
+
+ /* Loop through the answers, we want A type answer */
+ for (found = stop = 0; !stop && &p[12] < e; ) {
+
+ /* Skip possible name in CNAME answer */
+ if (*p != 0xc0) {
+ while (*p && &p[12] < e)
+ p++;
+ p--;
+ }
+ debug("Name (Offset in header): %d\n", p[1]);
+
+ tmp = p[2] | (p[3] << 8);
+ type = ntohs(tmp);
+ debug("type = %d\n", type);
+ if (type == DNS_CNAME_RECORD) {
+ /* CNAME answer. shift to the next section */
+ debug("Found canonical name\n");
+ tmp = p[10] | (p[11] << 8);
+ dlen = ntohs(tmp);
+ debug("dlen = %d\n", dlen);
+ p += 12 + dlen;
+ } else if (type == DNS_A_RECORD) {
+ debug("Found A-record\n");
+ found = stop = 1;
+ } else {
+ debug("Unknown type\n");
+ stop = 1;
+ }
+ }
+
+ if (found && &p[12] < e) {
+
+ tmp = p[10] | (p[11] << 8);
+ dlen = ntohs(tmp);
+ p += 12;
+ memcpy(&IPAddress, p, 4);
+
+ if (p + dlen <= e) {
+ ip_to_string(IPAddress, IPStr);
+ printf("%s\n", IPStr);
+ if (NetDNSenvvar)
+ setenv(NetDNSenvvar, IPStr);
+ } else
+ puts("server responded with invalid IP number\n");
+ }
+
+ NetState = NETLOOP_SUCCESS;
+}
+
+void
+DnsStart(void)
+{
+ debug("%s\n", __func__);
+
+ NetSetTimeout(DNS_TIMEOUT, DnsTimeout);
+ NetSetHandler(DnsHandler);
+
+ DnsSend();
+}
+
