> From: Baruch Siach <[email protected]>
>
> Use a single IP checksum routine for ping, traceroute and udhcp.
>
> Signed-off-by: Baruch Siach <[email protected]>
> ---
>
> Changes from v1:
> Fix inet_cksum() with odd length on big endian systems
> Remove declaration of removed udhcp_checksum()
This looks like it is from quagga. I cleaned that up/optimized it
some years ago into this(you might want to fix the types):
int /* return checksum in low-order 16 bits */
in_cksum(void *parg, int nbytes)
{
u_short *ptr = parg;
register long sum; /* assumes long == 32 bits */
register u_short answer; /* assumes u_short == 16 bits */
register int count;
/*
* 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.
*/
sum = 0;
count = nbytes >> 1; /* div by 2 */
for(ptr--; count; --count)
sum += *++ptr;
if (nbytes & 1) /* Odd */
sum += *(u_char *)(++ptr); /* one byte only */
/*
* Add back carry outs from top 16 bits to low 16 bits.
*/
sum = (sum >> 16) + (sum & 0xffff); /* add high-16 to low-16 */
sum += (sum >> 16); /* add carry */
answer = ~sum; /* ones-complement, then truncate to 16 bits */
return(answer);
}
>
> 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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