ctdb-common: Factor out TCP packet marshalling code

This can be tested separately.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>

diff --git a/ctdb/common/system_socket.c b/ctdb/common/system_socket.c
index 838eb4ba9f6c374d70dd383ffdb6f3605b109bf6..7f08b817084bbc433d888fb0d72c6d0500f44d59 100644 (file)
--- a/ctdb/common/system_socket.c
+++ b/ctdb/common/system_socket.c
@@ -494,6 +494,121 @@ int ctdb_sys_send_arp(const ctdb_sock_addr *addr, const char *iface)
 
 #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
  * destination IP/port.
@@ -511,48 +626,29 @@ int ctdb_sys_send_tcp(const ctdb_sock_addr *dest,
                      uint32_t ack,
                      int rst)
 {
-       int s;
+       uint8_t buf[MAX(IP4_TCP_BUFFER_SIZE, IP6_TCP_BUFFER_SIZE)];
+       size_t len = 0;
        int ret;
+       int s;
        uint32_t one = 1;
        uint16_t tmpport;
        ctdb_sock_addr *tmpdest;
-       struct {
-               struct ip ip;
-               struct tcphdr tcp;
-       } ip4pkt;
-       struct {
-               struct ip6_hdr ip6;
-               struct tcphdr tcp;
-       } ip6pkt;
        int saved_errno;
 
        switch (src->ip.sin_family) {
        case AF_INET:
-               ZERO_STRUCT(ip4pkt);
-               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->ip.sin_addr.s_addr;
-               ip4pkt.ip.ip_dst.s_addr    = dest->ip.sin_addr.s_addr;
-               ip4pkt.ip.ip_sum   = 0;
-
-               ip4pkt.tcp.th_sport = src->ip.sin_port;
-               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;
+               ret = tcp4_build(buf,
+                                sizeof(buf),
+                                &src->ip,
+                                &dest->ip,
+                                seq,
+                                ack,
+                                rst,
+                                &len);
+               if (ret != 0) {
+                       DBG_ERR("Failed to build TCP packet (%d)\n", ret);
+                       return ret;
                }
-               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 */
                s = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
@@ -570,40 +666,33 @@ int ctdb_sys_send_tcp(const ctdb_sock_addr *dest,
                        return -1;
                }
 
-               ret = sendto(s, &ip4pkt, sizeof(ip4pkt), 0,
+               ret = sendto(s,
+                            buf,
+                            len,
+                            0,
                             (const struct sockaddr *)&dest->ip,
                             sizeof(dest->ip));
                saved_errno = errno;
                close(s);
-               if (ret != sizeof(ip4pkt)) {
+               if (ret != len) {
                        D_ERR("Failed sendto (%s)\n", strerror(saved_errno));
                        return -1;
                }
                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;
-               ip6pkt.tcp.th_dport = dest->ip6.sin6_port;
-               ip6pkt.tcp.th_seq   = seq;
-               ip6pkt.tcp.th_ack   = ack;
-               ip6pkt.tcp.th_flags = 0;
-               ip6pkt.tcp.th_flags |= TH_RST;
-               if (rst) {
-                       ip6pkt.tcp.th_flags |= TH_RST;
+               ret = tcp6_build(buf,
+                                sizeof(buf),
+                                &src->ip6,
+                                &dest->ip6,
+                                seq,
+                                ack,
+                                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);
                if (s == -1) {
@@ -618,14 +707,17 @@ int ctdb_sys_send_tcp(const ctdb_sock_addr *dest,
                tmpport = tmpdest->ip6.sin6_port;
 
                tmpdest->ip6.sin6_port = 0;
-               ret = sendto(s, &ip6pkt, sizeof(ip6pkt), 0,
+               ret = sendto(s,
+                            buf,
+                            len,
+                            0,
                             (const struct sockaddr *)&dest->ip6,
                             sizeof(dest->ip6));
                saved_errno = errno;
                tmpdest->ip6.sin6_port = tmpport;
                close(s);
 
-               if (ret != sizeof(ip6pkt)) {
+               if (ret != len) {
                        D_ERR("Failed sendto (%s)\n", strerror(saved_errno));
                        return -1;
                }