com32: add library function for DNS lookup

Add a library function for DNS lookup

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 70 insertions, 0 deletions

diff --git a/com32/lib/syslinux/pxe_dns.c b/com32/lib/syslinux/pxe_dns.c
new file mode 100644
index 00000000..9ab95137
--- /dev/null
+++ b/com32/lib/syslinux/pxe_dns.c
@@ -0,0 +1,70 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2010 Intel Corporation; author: H. Peter Anvin
+ *
+ *   Permission is hereby granted, free of charge, to any person
+ *   obtaining a copy of this software and associated documentation
+ *   files (the "Software"), to deal in the Software without
+ *   restriction, including without limitation the rights to use,
+ *   copy, modify, merge, publish, distribute, sublicense, and/or
+ *   sell copies of the Software, and to permit persons to whom
+ *   the Software is furnished to do so, subject to the following
+ *   conditions:
+ *
+ *   The above copyright notice and this permission notice shall
+ *   be included in all copies or substantial portions of the Software.
+ *
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ *   OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * pxe_dns.c
+ *
+ * Resolve a hostname via DNS
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <com32.h>
+
+#include <syslinux/pxe.h>
+
+/* Returns the status code from PXE (0 on success),
+   or -1 on invocation failure */
+uint32_t pxe_dns(const char *hostname)
+{
+    com32sys_t regs;
+    union {
+	unsigned char b[4];
+	uint32_t ip;
+    } q;
+
+    /* Is this a dot-quad? */
+    if (sscanf(hostname, "%hhu.%hhu.%hhu.%hhu",
+	       &q.b[0], &q.b[1], &q.b[2], &q.b[3]) == 4)
+	return q.ip;
+
+    memset(&regs, 0, sizeof regs);
+    regs.eax.w[0] = 0x0010;
+    regs.es = SEG(__com32.cs_bounce);
+    regs.ebx.w[0] = OFFS(__com32.cs_bounce);
+
+    strcpy((char *)__com32.cs_bounce, hostname);
+
+    __intcall(0x22, &regs, &regs);
+
+    if (regs.eflags.l & EFLAGS_CF)
+	return 0;
+
+    return regs.eax.l;
+}