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ctdb-common: Factor out TCP packet marshalling code

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This can be tested separately.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
This commit is contained in:
Martin Schwenke 2018-08-16 11:10:40 +10:00 committed by Amitay Isaacs
parent a67899573a
commit d7d23e78ed
1 changed files with 151 additions and 59 deletions
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210
ctdb/common/system_socket.c
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@ -494,6 +494,121 @@ int ctdb_sys_send_arp(const ctdb_sock_addr *addr, const char *iface)
#endif /* HAVE_PACKETSOCKET */ #endif /* HAVE_PACKETSOCKET */
#define IP4_TCP_BUFFER_SIZE sizeof(struct ip) + \
sizeof(struct tcphdr)
#define IP6_TCP_BUFFER_SIZE sizeof(struct ip6_hdr) + \
sizeof(struct tcphdr)
static int tcp4_build(uint8_t *buf,
size_t buflen,
const struct sockaddr_in *src,
const struct sockaddr_in *dst,
uint32_t seq,
uint32_t ack,
int rst,
size_t *len)
{
size_t l = IP4_TCP_BUFFER_SIZE;
struct {
struct ip ip;
struct tcphdr tcp;
} *ip4pkt;
if (l != sizeof(*ip4pkt)) {
return EMSGSIZE;
}
if (buflen < l) {
return EMSGSIZE;
}
ip4pkt = (void *)buf;
memset(ip4pkt, 0, l);
ip4pkt->ip.ip_v = 4;
ip4pkt->ip.ip_hl = sizeof(ip4pkt->ip)/4;
ip4pkt->ip.ip_len = htons(sizeof(ip4pkt));
ip4pkt->ip.ip_ttl = 255;
ip4pkt->ip.ip_p = IPPROTO_TCP;
ip4pkt->ip.ip_src.s_addr = src->sin_addr.s_addr;
ip4pkt->ip.ip_dst.s_addr = dst->sin_addr.s_addr;
ip4pkt->ip.ip_sum = 0;
ip4pkt->tcp.th_sport = src->sin_port;
ip4pkt->tcp.th_dport = dst->sin_port;
ip4pkt->tcp.th_seq = seq;
ip4pkt->tcp.th_ack = ack;
ip4pkt->tcp.th_flags = 0;
ip4pkt->tcp.th_flags |= TH_ACK;
if (rst) {
ip4pkt->tcp.th_flags |= TH_RST;
}
ip4pkt->tcp.th_off = sizeof(ip4pkt->tcp)/4;
/* this makes it easier to spot in a sniffer */
ip4pkt->tcp.th_win = htons(1234);
ip4pkt->tcp.th_sum = ip_checksum((uint16_t *)&ip4pkt->tcp,
sizeof(ip4pkt->tcp),
&ip4pkt->ip);
*len = l;
return 0;
}
static int tcp6_build(uint8_t *buf,
size_t buflen,
const struct sockaddr_in6 *src,
const struct sockaddr_in6 *dst,
uint32_t seq,
uint32_t ack,
int rst,
size_t *len)
{
size_t l = IP6_TCP_BUFFER_SIZE;
struct {
struct ip6_hdr ip6;
struct tcphdr tcp;
} *ip6pkt;
if (l != sizeof(*ip6pkt)) {
return EMSGSIZE;
}
if (buflen < l) {
return EMSGSIZE;
}
ip6pkt = (void *)buf;
memset(ip6pkt, 0, l);
ip6pkt->ip6.ip6_vfc = 0x60;
ip6pkt->ip6.ip6_plen = htons(20);
ip6pkt->ip6.ip6_nxt = IPPROTO_TCP;
ip6pkt->ip6.ip6_hlim = 64;
ip6pkt->ip6.ip6_src = src->sin6_addr;
ip6pkt->ip6.ip6_dst = dst->sin6_addr;
ip6pkt->tcp.th_sport = src->sin6_port;
ip6pkt->tcp.th_dport = dst->sin6_port;
ip6pkt->tcp.th_seq = seq;
ip6pkt->tcp.th_ack = ack;
ip6pkt->tcp.th_flags = 0;
ip6pkt->tcp.th_flags |= TH_ACK;
if (rst) {
ip6pkt->tcp.th_flags |= TH_RST;
}
ip6pkt->tcp.th_off = sizeof(ip6pkt->tcp)/4;
/* this makes it easier to spot in a sniffer */
ip6pkt->tcp.th_win = htons(1234);
ip6pkt->tcp.th_sum = ip6_checksum((uint16_t *)&ip6pkt->tcp,
sizeof(ip6pkt->tcp),
&ip6pkt->ip6);
*len = l;
return 0;
}
/* /*
* Send tcp segment from the specified IP/port to the specified * Send tcp segment from the specified IP/port to the specified
* destination IP/port. * destination IP/port.
@ -511,48 +626,29 @@ int ctdb_sys_send_tcp(const ctdb_sock_addr *dest,
uint32_t ack, uint32_t ack,
int rst) int rst)
{ {
int s; uint8_t buf[MAX(IP4_TCP_BUFFER_SIZE, IP6_TCP_BUFFER_SIZE)];
size_t len = 0;
int ret; int ret;
int s;
uint32_t one = 1; uint32_t one = 1;
uint16_t tmpport; uint16_t tmpport;
ctdb_sock_addr *tmpdest; ctdb_sock_addr *tmpdest;
struct {
struct ip ip;
struct tcphdr tcp;
} ip4pkt;
struct {
struct ip6_hdr ip6;
struct tcphdr tcp;
} ip6pkt;
int saved_errno; int saved_errno;
switch (src->ip.sin_family) { switch (src->ip.sin_family) {
case AF_INET: case AF_INET:
ZERO_STRUCT(ip4pkt); ret = tcp4_build(buf,
ip4pkt.ip.ip_v = 4; sizeof(buf),
ip4pkt.ip.ip_hl = sizeof(ip4pkt.ip)/4; &src->ip,
ip4pkt.ip.ip_len = htons(sizeof(ip4pkt)); &dest->ip,
ip4pkt.ip.ip_ttl = 255; seq,
ip4pkt.ip.ip_p = IPPROTO_TCP; ack,
ip4pkt.ip.ip_src.s_addr = src->ip.sin_addr.s_addr; rst,
ip4pkt.ip.ip_dst.s_addr = dest->ip.sin_addr.s_addr; &len);
ip4pkt.ip.ip_sum = 0; if (ret != 0) {
DBG_ERR("Failed to build TCP packet (%d)\n", ret);
ip4pkt.tcp.th_sport = src->ip.sin_port; return ret;
ip4pkt.tcp.th_dport = dest->ip.sin_port;
ip4pkt.tcp.th_seq = seq;
ip4pkt.tcp.th_ack = ack;
ip4pkt.tcp.th_flags = 0;
ip4pkt.tcp.th_flags |= TH_ACK;
if (rst) {
ip4pkt.tcp.th_flags |= TH_RST;
} }
ip4pkt.tcp.th_off = sizeof(ip4pkt.tcp)/4;
/* this makes it easier to spot in a sniffer */
ip4pkt.tcp.th_win = htons(1234);
ip4pkt.tcp.th_sum = ip_checksum((uint16_t *)&ip4pkt.tcp,
sizeof(ip4pkt.tcp),
&ip4pkt.ip);
/* open a raw socket to send this segment from */ /* open a raw socket to send this segment from */
s = socket(AF_INET, SOCK_RAW, IPPROTO_RAW); s = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
@ -570,40 +666,33 @@ int ctdb_sys_send_tcp(const ctdb_sock_addr *dest,
return -1; return -1;
} }
ret = sendto(s, &ip4pkt, sizeof(ip4pkt), 0, ret = sendto(s,
buf,
len,
0,
(const struct sockaddr *)&dest->ip, (const struct sockaddr *)&dest->ip,
sizeof(dest->ip)); sizeof(dest->ip));
saved_errno = errno; saved_errno = errno;
close(s); close(s);
if (ret != sizeof(ip4pkt)) { if (ret != len) {
D_ERR("Failed sendto (%s)\n", strerror(saved_errno)); D_ERR("Failed sendto (%s)\n", strerror(saved_errno));
return -1; return -1;
} }
break; break;
case AF_INET6:
ZERO_STRUCT(ip6pkt);
ip6pkt.ip6.ip6_vfc = 0x60;
ip6pkt.ip6.ip6_plen = htons(20);
ip6pkt.ip6.ip6_nxt = IPPROTO_TCP;
ip6pkt.ip6.ip6_hlim = 64;
ip6pkt.ip6.ip6_src = src->ip6.sin6_addr;
ip6pkt.ip6.ip6_dst = dest->ip6.sin6_addr;
ip6pkt.tcp.th_sport = src->ip6.sin6_port; case AF_INET6:
ip6pkt.tcp.th_dport = dest->ip6.sin6_port; ret = tcp6_build(buf,
ip6pkt.tcp.th_seq = seq; sizeof(buf),
ip6pkt.tcp.th_ack = ack; &src->ip6,
ip6pkt.tcp.th_flags = 0; &dest->ip6,
ip6pkt.tcp.th_flags |= TH_RST; seq,
if (rst) { ack,
ip6pkt.tcp.th_flags |= TH_RST; rst,
&len);
if (ret != 0) {
DBG_ERR("Failed to build TCP packet (%d)\n", ret);
return ret;
} }
ip6pkt.tcp.th_off = sizeof(ip6pkt.tcp)/4;
/* this makes it easier to spot in a sniffer */
ip6pkt.tcp.th_win = htons(1234);
ip6pkt.tcp.th_sum = ip6_checksum((uint16_t *)&ip6pkt.tcp,
sizeof(ip6pkt.tcp),
&ip6pkt.ip6);
s = socket(AF_INET6, SOCK_RAW, IPPROTO_RAW); s = socket(AF_INET6, SOCK_RAW, IPPROTO_RAW);
if (s == -1) { if (s == -1) {
@ -618,14 +707,17 @@ int ctdb_sys_send_tcp(const ctdb_sock_addr *dest,
tmpport = tmpdest->ip6.sin6_port; tmpport = tmpdest->ip6.sin6_port;
tmpdest->ip6.sin6_port = 0; tmpdest->ip6.sin6_port = 0;
ret = sendto(s, &ip6pkt, sizeof(ip6pkt), 0, ret = sendto(s,
buf,
len,
0,
(const struct sockaddr *)&dest->ip6, (const struct sockaddr *)&dest->ip6,
sizeof(dest->ip6)); sizeof(dest->ip6));
saved_errno = errno; saved_errno = errno;
tmpdest->ip6.sin6_port = tmpport; tmpdest->ip6.sin6_port = tmpport;
close(s); close(s);
if (ret != sizeof(ip6pkt)) { if (ret != len) {
D_ERR("Failed sendto (%s)\n", strerror(saved_errno)); D_ERR("Failed sendto (%s)\n", strerror(saved_errno));
return -1; return -1;
} }