diff options
Diffstat (limited to 'dnsresolv.inc')
| -rw-r--r-- | dnsresolv.inc | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/dnsresolv.inc b/dnsresolv.inc index 3181c0db..05d0fff3 100644 --- a/dnsresolv.inc +++ b/dnsresolv.inc @@ -31,9 +31,6 @@ DNS_MAX_SERVERS equ 4 ; Max no of DNS servers ; On return, DI points to the first byte after the label set, ; and SI to the terminating byte. ; -; Assumes DS == ES. Change references to [bx] to [es:bx] to remove -; that assumption. -; ; On return, DX contains the number of dots encountered. ; dns_mangle: @@ -53,13 +50,13 @@ dns_mangle: jz .endstring cmp al,'.' je .isdot - inc byte [bx] + inc byte [es:bx] stosb jmp .getbyte .endstring: dec si dec dx ; We always counted one high - cmp byte [bx],0 + cmp byte [es:bx],0 jz .done xor al,al stosb @@ -128,11 +125,6 @@ dns_skiplabel: pop ax ret -; Actual resolver function -; Points to a null-terminated or :-terminated string in DS:SI -; and returns the name in EAX if it exists and can be found. -; If EAX = 0 on exit, the lookup failed. - ; DNS header format struc dnshdr .id: resw 1 @@ -186,19 +178,25 @@ pxe_udp_read_pkt_dns: LastDNSServer dw DNSServers +; Actual resolver function +; Points to a null-terminated or :-terminated string in DS:SI +; and returns the name in EAX if it exists and can be found. +; If EAX = 0 on exit, the lookup failed. + section .text dns_resolv: + push ds + push es push di push cx push dx - ; Initialize... - mov eax,[MyIP] - mov [pxe_udp_read_pkt_dns.dip],eax + push cs + pop es ; ES <- CS ; First, build query packet mov di,DNSSendBuf+dnshdr.flags - inc word [di-2] ; New query ID + inc word [es:di-2] ; New query ID mov ax,htons(0100h) ; Recursion requested stosw mov ax,htons(1) ; One question @@ -209,8 +207,16 @@ dns_resolv: stosw call dns_mangle ; Convert name to DNS labels + + push cs ; DS <- CS + pop ds + push si ; Save pointer to after DNS string + ; Initialize... + mov eax,[MyIP] + mov [pxe_udp_read_pkt_dns.dip],eax + and dx,dx jnz .fqdn ; If we have dots, assume it's FQDN dec di ; Remove final null @@ -247,6 +253,8 @@ dns_resolv: pop dx pop cx pop di + pop es + pop ds ret .moreservers: |