[PATCHv2] networking: consolidate the IP checksum code
Baruch Siach
baruch at tkos.co.il
Mon Sep 5 12:15:11 UTC 2011
Use a single IP checksum routine for ping, traceroute and udhcp.
Signed-off-by: Baruch Siach <baruch at tkos.co.il>
---
Changes from v1:
Fix inet_cksum() with odd length on big endian systems
Remove declaration of removed udhcp_checksum()
include/libbb.h | 1 +
libbb/Kbuild.src | 6 ++++++
libbb/inet_cksum.c | 41 +++++++++++++++++++++++++++++++++++++++++
networking/ping.c | 31 +++----------------------------
networking/traceroute.c | 35 +----------------------------------
networking/udhcp/common.h | 2 --
networking/udhcp/dhcpc.c | 4 ++--
networking/udhcp/packet.c | 34 +++-------------------------------
8 files changed, 57 insertions(+), 97 deletions(-)
create mode 100644 libbb/inet_cksum.c
diff --git a/include/libbb.h b/include/libbb.h
index 1ca4489..f60f427 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -640,6 +640,7 @@ ssize_t recv_from_to(int fd, void *buf, size_t len, int flags,
struct sockaddr *to,
socklen_t sa_size) FAST_FUNC;
+uint16_t inet_cksum(uint16_t *addr, int len) FAST_FUNC;
char *xstrdup(const char *s) FAST_FUNC RETURNS_MALLOC;
char *xstrndup(const char *s, int n) FAST_FUNC RETURNS_MALLOC;
diff --git a/libbb/Kbuild.src b/libbb/Kbuild.src
index 875d024..335b341 100644
--- a/libbb/Kbuild.src
+++ b/libbb/Kbuild.src
@@ -166,6 +166,12 @@ lib-$(CONFIG_IOSTAT) += get_cpu_count.o
lib-$(CONFIG_MPSTAT) += get_cpu_count.o
lib-$(CONFIG_POWERTOP) += get_cpu_count.o
+lib-$(CONFIG_PING) += inet_cksum.o
+lib-$(CONFIG_TRACEROUTE) += inet_cksum.o
+lib-$(CONFIG_TRACEROUTE6) += inet_cksum.o
+lib-$(CONFIG_UDHCPC) += inet_cksum.o
+lib-$(CONFIG_UDHCPD) += inet_cksum.o
+
# We shouldn't build xregcomp.c if we don't need it - this ensures we don't
# require regex.h to be in the include dir even if we don't need it thereby
# allowing us to build busybox even if uclibc regex support is disabled.
diff --git a/libbb/inet_cksum.c b/libbb/inet_cksum.c
new file mode 100644
index 0000000..79b7f2c
--- /dev/null
+++ b/libbb/inet_cksum.c
@@ -0,0 +1,41 @@
+/*
+ * Checksum routine for Internet Protocol family headers (C Version)
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
+ */
+
+#include "libbb.h"
+
+uint16_t FAST_FUNC inet_cksum(uint16_t *addr, int len)
+{
+ int nleft = len;
+ uint16_t *w = addr;
+ uint16_t answer;
+ int sum = 0;
+
+ /*
+ * Our algorithm is simple, using a 32 bit accumulator (sum),
+ * we add sequential 16 bit words to it, and at the end, fold
+ * back all the carry bits from the top 16 bits into the lower
+ * 16 bits.
+ */
+ while (nleft > 1) {
+ sum += *w++;
+ nleft -= 2;
+ }
+
+ /* mop up an odd byte, if necessary */
+ if (nleft == 1) {
+ /* Make sure that the left-over byte is added correctly both
+ * with little and big endian hosts */
+ uint16_t tmp = 0;
+ *(uint8_t*)&tmp = *(uint8_t*)w;
+ sum += tmp;
+ }
+
+ /* add back carry outs from top 16 bits to low 16 bits */
+ sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
+ sum += (sum >> 16); /* add carry */
+ answer = ~sum; /* truncate to 16 bits */
+ return answer;
+}
diff --git a/networking/ping.c b/networking/ping.c
index efd4f21..a1fd9df 100644
--- a/networking/ping.c
+++ b/networking/ping.c
@@ -149,31 +149,6 @@ enum {
PINGINTERVAL = 1, /* 1 second */
};
-/* Common routines */
-
-static int in_cksum(unsigned short *buf, int sz)
-{
- int nleft = sz;
- int sum = 0;
- unsigned short *w = buf;
- unsigned short ans = 0;
-
- while (nleft > 1) {
- sum += *w++;
- nleft -= 2;
- }
-
- if (nleft == 1) {
- *(unsigned char *) (&ans) = *(unsigned char *) w;
- sum += ans;
- }
-
- sum = (sum >> 16) + (sum & 0xFFFF);
- sum += (sum >> 16);
- ans = ~sum;
- return ans;
-}
-
#if !ENABLE_FEATURE_FANCY_PING
/* Simple version */
@@ -201,7 +176,7 @@ static void ping4(len_and_sockaddr *lsa)
pkt = (struct icmp *) G.packet;
memset(pkt, 0, sizeof(G.packet));
pkt->icmp_type = ICMP_ECHO;
- pkt->icmp_cksum = in_cksum((unsigned short *) pkt, sizeof(G.packet));
+ pkt->icmp_cksum = inet_cksum((uint16_t *) pkt, sizeof(G.packet));
xsendto(pingsock, G.packet, DEFDATALEN + ICMP_MINLEN, &lsa->u.sa, lsa->len);
@@ -493,7 +468,7 @@ static void sendping4(int junk UNUSED_PARAM)
/* No hton: we'll read it back on the same machine */
*(uint32_t*)&pkt->icmp_dun = monotonic_us();
- pkt->icmp_cksum = in_cksum((unsigned short *) pkt, datalen + ICMP_MINLEN);
+ pkt->icmp_cksum = inet_cksum((uint16_t *) pkt, datalen + ICMP_MINLEN);
sendping_tail(sendping4, ICMP_MINLEN);
}
@@ -512,7 +487,7 @@ static void sendping6(int junk UNUSED_PARAM)
/*if (datalen >= 4)*/
*(uint32_t*)(&pkt->icmp6_data8[4]) = monotonic_us();
- //TODO? pkt->icmp_cksum = in_cksum(...);
+ //TODO? pkt->icmp_cksum = inet_cksum(...);
sendping_tail(sendping6, sizeof(struct icmp6_hdr));
}
diff --git a/networking/traceroute.c b/networking/traceroute.c
index c321035..d197e54 100644
--- a/networking/traceroute.c
+++ b/networking/traceroute.c
@@ -418,39 +418,6 @@ wait_for_reply(len_and_sockaddr *from_lsa, struct sockaddr *to, unsigned *timest
return read_len;
}
-/*
- * Checksum routine for Internet Protocol family headers (C Version)
- */
-static uint16_t
-in_cksum(uint16_t *addr, int len)
-{
- int nleft = len;
- uint16_t *w = addr;
- uint16_t answer;
- int sum = 0;
-
- /*
- * Our algorithm is simple, using a 32 bit accumulator (sum),
- * we add sequential 16 bit words to it, and at the end, fold
- * back all the carry bits from the top 16 bits into the lower
- * 16 bits.
- */
- while (nleft > 1) {
- sum += *w++;
- nleft -= 2;
- }
-
- /* mop up an odd byte, if necessary */
- if (nleft == 1)
- sum += *(unsigned char *)w;
-
- /* add back carry outs from top 16 bits to low 16 bits */
- sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
- sum += (sum >> 16); /* add carry */
- answer = ~sum; /* truncate to 16 bits */
- return answer;
-}
-
static void
send_probe(int seq, int ttl)
{
@@ -477,7 +444,7 @@ send_probe(int seq, int ttl)
/* Always calculate checksum for icmp packets */
outicmp->icmp_cksum = 0;
- outicmp->icmp_cksum = in_cksum((uint16_t *)outicmp,
+ outicmp->icmp_cksum = inet_cksum((uint16_t *)outicmp,
packlen - (sizeof(*outip) + optlen));
if (outicmp->icmp_cksum == 0)
outicmp->icmp_cksum = 0xffff;
diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index ad6991c..80d97e8 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -277,8 +277,6 @@ int FAST_FUNC udhcp_str2nip(const char *str, void *arg);
/* 2nd param is "struct option_set**" */
int FAST_FUNC udhcp_str2optset(const char *str, void *arg);
-uint16_t udhcp_checksum(void *addr, int count) FAST_FUNC;
-
void udhcp_init_header(struct dhcp_packet *packet, char type) FAST_FUNC;
int udhcp_recv_kernel_packet(struct dhcp_packet *packet, int fd) FAST_FUNC;
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 4d755e6..3be09f4 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -739,7 +739,7 @@ static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
/* verify IP checksum */
check = packet.ip.check;
packet.ip.check = 0;
- if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
+ if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
log1("Bad IP header checksum, ignoring");
return -2;
}
@@ -750,7 +750,7 @@ static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
check = packet.udp.check;
packet.udp.check = 0;
- if (check && check != udhcp_checksum(&packet, bytes)) {
+ if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
log1("Packet with bad UDP checksum received, ignoring");
return -2;
}
diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c
index 66b42c5..4d5ff06 100644
--- a/networking/udhcp/packet.c
+++ b/networking/udhcp/packet.c
@@ -129,35 +129,6 @@ int FAST_FUNC udhcp_recv_kernel_packet(struct dhcp_packet *packet, int fd)
return bytes;
}
-uint16_t FAST_FUNC udhcp_checksum(void *addr, int count)
-{
- /* Compute Internet Checksum for "count" bytes
- * beginning at location "addr".
- */
- int32_t sum = 0;
- uint16_t *source = (uint16_t *) addr;
-
- while (count > 1) {
- /* This is the inner loop */
- sum += *source++;
- count -= 2;
- }
-
- /* Add left-over byte, if any */
- if (count > 0) {
- /* Make sure that the left-over byte is added correctly both
- * with little and big endian hosts */
- uint16_t tmp = 0;
- *(uint8_t*)&tmp = *(uint8_t*)source;
- sum += tmp;
- }
- /* Fold 32-bit sum to 16 bits */
- while (sum >> 16)
- sum = (sum & 0xffff) + (sum >> 16);
-
- return ~sum;
-}
-
/* Construct a ip/udp header for a packet, send packet */
int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
uint32_t source_nip, int source_port,
@@ -212,13 +183,14 @@ int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
packet.udp.len = htons(UDP_DHCP_SIZE - padding);
/* for UDP checksumming, ip.len is set to UDP packet len */
packet.ip.tot_len = packet.udp.len;
- packet.udp.check = udhcp_checksum(&packet, IP_UDP_DHCP_SIZE - padding);
+ packet.udp.check = inet_cksum((uint16_t *)&packet,
+ IP_UDP_DHCP_SIZE - padding);
/* but for sending, it is set to IP packet len */
packet.ip.tot_len = htons(IP_UDP_DHCP_SIZE - padding);
packet.ip.ihl = sizeof(packet.ip) >> 2;
packet.ip.version = IPVERSION;
packet.ip.ttl = IPDEFTTL;
- packet.ip.check = udhcp_checksum(&packet.ip, sizeof(packet.ip));
+ packet.ip.check = inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip));
udhcp_dump_packet(dhcp_pkt);
result = sendto(fd, &packet, IP_UDP_DHCP_SIZE - padding, /*flags:*/ 0,
--
1.7.5.4
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