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ctdb-common: Factor out TCP packet parsing code
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
Amitay Isaacs
parent
028fdc12e7
commit
e2ac36867d
@ -736,6 +736,116 @@ int ctdb_sys_send_tcp(const ctdb_sock_addr *dest,
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* wscript has checked to make sure that pcap is available if needed.
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*/
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static int tcp4_extract(const uint8_t *ip_pkt,
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size_t pktlen,
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struct sockaddr_in *src,
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struct sockaddr_in *dst,
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uint32_t *ack_seq,
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uint32_t *seq,
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int *rst,
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uint16_t *window)
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{
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const struct ip *ip;
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const struct tcphdr *tcp;
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if (pktlen < sizeof(struct ip)) {
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return EMSGSIZE;
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}
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/* IP */
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ip = (const struct ip *)ip_pkt;
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/* We only want IPv4 packets */
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if (ip->ip_v != 4) {
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return ENOMSG;
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}
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/* Dont look at fragments */
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if ((ntohs(ip->ip_off)&0x1fff) != 0) {
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return ENOMSG;
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}
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/* we only want TCP */
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if (ip->ip_p != IPPROTO_TCP) {
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return ENOMSG;
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}
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/* make sure its not a short packet */
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if (offsetof(struct tcphdr, th_ack) + 4 + (ip->ip_hl*4) > pktlen) {
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return EMSGSIZE;
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}
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/* TCP */
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tcp = (const struct tcphdr *)((ip->ip_hl*4) + (const char *)ip);
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/* tell the caller which one we've found */
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src->sin_family = AF_INET;
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src->sin_addr.s_addr = ip->ip_src.s_addr;
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src->sin_port = tcp->th_sport;
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dst->sin_family = AF_INET;
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dst->sin_addr.s_addr = ip->ip_dst.s_addr;
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dst->sin_port = tcp->th_dport;
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*ack_seq = tcp->th_ack;
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*seq = tcp->th_seq;
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if (window != NULL) {
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*window = tcp->th_win;
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}
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if (rst != NULL) {
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*rst = tcp->th_flags & TH_RST;
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}
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return 0;
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}
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static int tcp6_extract(const uint8_t *ip_pkt,
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size_t pktlen,
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struct sockaddr_in6 *src,
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struct sockaddr_in6 *dst,
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uint32_t *ack_seq,
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uint32_t *seq,
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int *rst,
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uint16_t *window)
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{
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const struct ip6_hdr *ip6;
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const struct tcphdr *tcp;
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if (pktlen < sizeof(struct ip6_hdr)) {
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return EMSGSIZE;
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}
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/* IP6 */
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ip6 = (const struct ip6_hdr *)ip_pkt;
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/* we only want TCP */
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if (ip6->ip6_nxt != IPPROTO_TCP) {
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return ENOMSG;
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}
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/* TCP */
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tcp = (const struct tcphdr *)(ip6+1);
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/* tell the caller which one we've found */
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src->sin6_family = AF_INET6;
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src->sin6_port = tcp->th_sport;
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src->sin6_addr = ip6->ip6_src;
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dst->sin6_family = AF_INET6;
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dst->sin6_port = tcp->th_dport;
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dst->sin6_addr = ip6->ip6_dst;
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*ack_seq = tcp->th_ack;
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*seq = tcp->th_seq;
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if (window != NULL) {
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*window = tcp->th_win;
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}
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if (rst != NULL) {
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*rst = tcp->th_flags & TH_RST;
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}
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return 0;
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}
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#ifdef HAVE_AF_PACKET
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/*
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@ -792,13 +902,10 @@ int ctdb_sys_read_tcp_packet(int s, void *private_data,
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ssize_t nread;
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uint8_t pkt[100]; /* Large enough for simple ACK/RST packets */
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struct ether_header *eth;
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struct iphdr *ip;
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struct ip6_hdr *ip6;
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struct tcphdr *tcp;
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int ret;
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nread = recv(s, pkt, sizeof(pkt), MSG_TRUNC);
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if (nread < sizeof(*eth)+sizeof(*ip)) {
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if (nread < sizeof(*eth)) {
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return EMSGSIZE;
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}
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@ -810,78 +917,26 @@ int ctdb_sys_read_tcp_packet(int s, void *private_data,
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/* we want either IPv4 or IPv6 */
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if (ntohs(eth->ether_type) == ETHERTYPE_IP) {
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/* IP */
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ip = (struct iphdr *)(eth+1);
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ret = tcp4_extract(pkt + sizeof(struct ether_header),
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(size_t)nread - sizeof(struct ether_header),
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&src->ip,
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&dst->ip,
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ack_seq,
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seq,
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rst,
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window);
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return ret;
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/* We only want IPv4 packets */
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if (ip->version != 4) {
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return ENOMSG;
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}
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/* Dont look at fragments */
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if ((ntohs(ip->frag_off)&0x1fff) != 0) {
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return ENOMSG;
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}
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/* we only want TCP */
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if (ip->protocol != IPPROTO_TCP) {
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return ENOMSG;
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}
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/* make sure its not a short packet */
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if (offsetof(struct tcphdr, th_ack) + 4 +
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(ip->ihl*4) + sizeof(*eth) > nread) {
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return EMSGSIZE;
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}
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/* TCP */
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tcp = (struct tcphdr *)((ip->ihl*4) + (char *)ip);
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/* tell the caller which one we've found */
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src->ip.sin_family = AF_INET;
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src->ip.sin_addr.s_addr = ip->saddr;
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src->ip.sin_port = tcp->th_sport;
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dst->ip.sin_family = AF_INET;
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dst->ip.sin_addr.s_addr = ip->daddr;
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dst->ip.sin_port = tcp->th_dport;
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*ack_seq = tcp->th_ack;
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*seq = tcp->th_seq;
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if (window != NULL) {
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*window = tcp->th_win;
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}
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if (rst != NULL) {
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*rst = tcp->th_flags & TH_RST;
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}
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return 0;
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} else if (ntohs(eth->ether_type) == ETHERTYPE_IP6) {
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/* IP6 */
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ip6 = (struct ip6_hdr *)(eth+1);
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/* we only want TCP */
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if (ip6->ip6_nxt != IPPROTO_TCP) {
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return ENOMSG;
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}
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/* TCP */
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tcp = (struct tcphdr *)(ip6+1);
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/* tell the caller which one we've found */
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src->ip6.sin6_family = AF_INET6;
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src->ip6.sin6_port = tcp->th_sport;
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src->ip6.sin6_addr = ip6->ip6_src;
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dst->ip6.sin6_family = AF_INET6;
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dst->ip6.sin6_port = tcp->th_dport;
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dst->ip6.sin6_addr = ip6->ip6_dst;
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*ack_seq = tcp->th_ack;
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*seq = tcp->th_seq;
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if (window != NULL) {
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*window = tcp->th_win;
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}
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if (rst != NULL) {
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*rst = tcp->th_flags & TH_RST;
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}
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return 0;
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ret = tcp6_extract(pkt + sizeof(struct ether_header),
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(size_t)nread - sizeof(struct ether_header),
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&src->ip6,
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&dst->ip6,
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ack_seq,
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seq,
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rst,
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window);
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return ret;
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}
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return ENOMSG;
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@ -923,9 +978,6 @@ int ctdb_sys_read_tcp_packet(int s,
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{
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int ret;
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struct ether_header *eth;
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struct ip *ip;
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struct ip6_hdr *ip6;
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struct tcphdr *tcp;
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struct pcap_pkthdr pkthdr;
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const u_char *buffer;
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pcap_t *pt = (pcap_t *)private_data;
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@ -943,78 +995,28 @@ int ctdb_sys_read_tcp_packet(int s,
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/* we want either IPv4 or IPv6 */
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if (eth->ether_type == htons(ETHERTYPE_IP)) {
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/* IP */
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ip = (struct ip *)(eth+1);
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ret = tcp4_extract(buffer + sizeof(struct ether_header),
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(size_t)(pkthdr.caplen -
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sizeof(struct ether_header)),
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&src->ip,
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&dst->ip,
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ack_seq,
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seq,
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rst,
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window);
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return ret;
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/* We only want IPv4 packets */
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if (ip->ip_v != 4) {
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return ENOMSG;
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}
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/* Dont look at fragments */
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if ((ntohs(ip->ip_off)&0x1fff) != 0) {
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return ENOMSG;
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}
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/* we only want TCP */
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if (ip->ip_p != IPPROTO_TCP) {
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return ENOMSG;
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}
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/* make sure its not a short packet */
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if (offsetof(struct tcphdr, th_ack) + 4 +
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(ip->ip_hl*4) + sizeof(*eth) > pkthdr.caplen) {
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return EMSGSIZE;
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}
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/* TCP */
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tcp = (struct tcphdr *)((ip->ip_hl*4) + (char *)ip);
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/* tell the caller which one we've found */
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src->ip.sin_family = AF_INET;
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src->ip.sin_addr.s_addr = ip->ip_src.s_addr;
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src->ip.sin_port = tcp->th_sport;
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dst->ip.sin_family = AF_INET;
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dst->ip.sin_addr.s_addr = ip->ip_dst.s_addr;
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dst->ip.sin_port = tcp->th_dport;
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*ack_seq = tcp->th_ack;
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*seq = tcp->th_seq;
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if (window != NULL) {
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*window = tcp->th_win;
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}
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if (rst != NULL) {
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*rst = tcp->th_flags & TH_RST;
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}
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return 0;
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} else if (eth->ether_type == htons(ETHERTYPE_IP6)) {
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/* IP6 */
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ip6 = (struct ip6_hdr *)(eth+1);
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/* we only want TCP */
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if (ip6->ip6_nxt != IPPROTO_TCP) {
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return ENOMSG;
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}
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/* TCP */
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tcp = (struct tcphdr *)(ip6+1);
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/* tell the caller which one we've found */
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src->ip6.sin6_family = AF_INET6;
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src->ip6.sin6_port = tcp->th_sport;
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src->ip6.sin6_addr = ip6->ip6_src;
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dst->ip6.sin6_family = AF_INET6;
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dst->ip6.sin6_port = tcp->th_dport;
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dst->ip6.sin6_addr = ip6->ip6_dst;
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*ack_seq = tcp->th_ack;
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*seq = tcp->th_seq;
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if (window != NULL) {
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*window = tcp->th_win;
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}
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if (rst != NULL) {
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*rst = tcp->th_flags & TH_RST;
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}
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return 0;
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ret = tcp6_extract(buffer + sizeof(struct ether_header),
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(size_t)(pkthdr.caplen -
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sizeof(struct ether_header)),
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&src->ip6,
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&dst->ip6,
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ack_seq,
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seq,
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rst,
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window);
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return ret;
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}
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return ENOMSG;
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