Document resolve hostname API

3 files changed, 44 insertions, 2 deletions

diff --git a/comboot.doc b/comboot.doc
index a324cfcf..62b17db3 100644
--- a/comboot.doc
+++ b/comboot.doc
@@ -344,6 +344,13 @@ AX=0009h [2.00] Call PXE Stack [PXELINUX ONLY]
 	the status code in AX and in the first word of the data buffer
 	to determine if the PXE call succeeded or not.
 
+	The PXE stack will have the UDP stack OPEN; if you change that
+	you cannot call any of the file-related API functions, and
+	must restore UDP OPEN before returning to PXELINUX.
+
+	PXELINUX reserves UDP port numbers from 49152 to 65535 for its
+	own use; port numbers below that range is available.
+
 
 AX=000Ah [2.00]	Get Derivative-Specific Information
 
@@ -486,6 +493,7 @@ AX=000Eh [2.11]	Get configuration file name
 	Returns the name of the configuration file.  Note that it is
 	possible that the configuration file doesn't actually exist.
 
+
 AX=000Fh [3.00] Get IPAPPEND strings [PXELINUX]
 	Input:  AX	000Fh
 	Output:	CX	Number of strings (currently 2)
@@ -497,3 +505,22 @@ AX=000Fh [3.00] Get IPAPPEND strings [PXELINUX]
 	added to the command line, one for each bit of the "ipappend"
 	flag value, so entry 0 is the "ip=" string and entry 1 is the
 	"BOOTIF=" string.
+
+
+AX=0010h [3.00] Resolve hostname [PXELINUX]
+	Input:  ES:BX	Pointer to null-terminated hostname
+	Output:	EAX	IP address of hostname (zero if not found)
+
+	Queries the DNS server(s) for a specific hostname.  If the
+	hostname does not contain a dot (.), the local domain name
+	is automatically appended.
+
+	This function only return CF=1 if the function is not
+	supported.  If the function is supported, but the hostname did
+	not resolve, it returns with CF=0, EAX=0.
+
+	The IP address is returned in network byte order, i.e. if the
+	IP address is 1.2.3.4, EAX will contain 0x04030201.  Note that
+	all uses of IP addresses in PXE are also in network byte order.
+
+
diff --git a/comboot.inc b/comboot.inc
index 45233a84..3859998e 100644
--- a/comboot.inc
+++ b/comboot.inc
@@ -579,6 +579,20 @@ numIPAppends	equ ($-IPAppends)/2
 %else
 comapi_ipappend equ comapi_err
 %endif
+
+;
+; INT 22h AX=0010h	Resolve hostname
+;
+%if IS_PXELINUX
+comapi_dnsresolv:
+		mov ds,P_ES
+		mov si,P_BX
+		call dns_resolv
+		mov P_EAX,eax
+		ret
+%else
+comapi_dnsresolv equ comapi_err
+%endif
 		
 		section .data
 %macro 		int21 2
@@ -617,6 +631,7 @@ int22_table:
 		dw comapi_chainboot		; 000D clean up then bootstrap
 		dw comapi_configfile		; 000E get name of config file
 		dw comapi_ipappend		; 000F get ipappend strings
+		dw comapi_dnsresolv		; 0010 resolve hostname
 int22_count	equ ($-int22_table)/2
 
 APIKeyWait	db 0
diff --git a/dnsresolv.inc b/dnsresolv.inc
index d10c7d1d..3181c0db 100644
--- a/dnsresolv.inc
+++ b/dnsresolv.inc
@@ -20,8 +20,8 @@
 
 DNS_PORT	equ htons(53)		; Default DNS port 
 DNS_MAX_PACKET	equ 512			; Defined by protocol
-; TFTP uses the range 49152-57343; avoid that range
-DNS_LOCAL_PORT	equ htons(35000)	; All local DNS queries come from this port #
+; TFTP uses the range 49152-57343
+DNS_LOCAL_PORT	equ htons(60053)	; All local DNS queries come from this port #
 DNS_MAX_SERVERS equ 4			; Max no of DNS servers
 
 		section .text