From 6dc809f40721e5424367b09c8dbfe07da50b8ca9 Mon Sep 17 00:00:00 2001 From: Bernhard Kaindl Date: Sat, 15 Oct 2011 23:59:22 +0000 Subject: [PATCH] net/dns.c: Fix endian conversion for big-endian in dns command net/dns.c used endian conversion macros wrongly (shorts in reply were put swapped into CPU, and then ntohs() was used to swap it back, which broke on big-endian). Fix this by using the correct linux conversion macro for reading a unaligned short in network byte order: get_unaligned_be16() Thanks to Mike Frysinger pointing at the best macro to use. Tested on big and little endian qemu boards (mips and versatile) Signed-off-by: Bernhard Kaindl Cc: Pieter Voorthuijsen Cc: Robin Getz Acked-by: Mike Frysinger --- net/dns.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) diff --git a/net/dns.c b/net/dns.c index b51d1bd982..7a3f1f9768 100644 --- a/net/dns.c +++ b/net/dns.c @@ -25,6 +25,7 @@ #include #include #include +#include #include "dns.h" @@ -109,7 +110,6 @@ DnsHandler(uchar *pkt, unsigned dest, IPaddr_t sip, unsigned src, unsigned len) int found, stop, dlen; char IPStr[22]; IPaddr_t IPAddress; - short tmp; debug("%s\n", __func__); @@ -120,14 +120,14 @@ DnsHandler(uchar *pkt, unsigned dest, IPaddr_t sip, unsigned src, unsigned len) 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. */ + /* We sent one query. We want to have a single 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"); + puts("DNS: host not found\n"); NetState = NETLOOP_SUCCESS; return; } @@ -139,9 +139,8 @@ DnsHandler(uchar *pkt, unsigned dest, IPaddr_t sip, unsigned src, unsigned len) 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"); + if (&p[5] > e || get_unaligned_be16(p+1) != DNS_A_RECORD) { + puts("DNS: response was not an A record\n"); NetState = NETLOOP_SUCCESS; return; } @@ -160,14 +159,12 @@ DnsHandler(uchar *pkt, unsigned dest, IPaddr_t sip, unsigned src, unsigned len) } debug("Name (Offset in header): %d\n", p[1]); - tmp = p[2] | (p[3] << 8); - type = ntohs(tmp); + type = get_unaligned_be16(p+2); 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); + dlen = get_unaligned_be16(p+10); debug("dlen = %d\n", dlen); p += 12 + dlen; } else if (type == DNS_A_RECORD) { @@ -181,8 +178,7 @@ DnsHandler(uchar *pkt, unsigned dest, IPaddr_t sip, unsigned src, unsigned len) if (found && &p[12] < e) { - tmp = p[10] | (p[11] << 8); - dlen = ntohs(tmp); + dlen = get_unaligned_be16(p+10); p += 12; memcpy(&IPAddress, p, 4);