tcp: Better helpers for converting between connection pointer and index
The macro CONN_OR_NULL() is used to look up connections by index with
bounds checking. Replace it with an inline function, which means:
- Better type checking
- No danger of multiple evaluation of an @index with side effects
Also add a helper to perform the reverse translation: from connection
pointer to index. Introduce a macro for this which will make later
cleanups easier and safer.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson
Stefano Brivio
parent
46b78ce96a
commit
60be7438fa
1 changed files with 45 additions and 38 deletions
83
tcp.c
83
tcp.c
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@ -518,14 +518,6 @@ struct tcp_conn {
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(conn->events & (SOCK_FIN_RCVD | TAP_FIN_RCVD)))
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#define CONN_HAS(conn, set) ((conn->events & (set)) == (set))
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#define CONN(index) (tc + (index))
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/* We probably don't want to use gcc statement expressions (for portability), so
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* use this only after well-defined sequence points (no pre-/post-increments).
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*/
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#define CONN_OR_NULL(index) \
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(((int)(index) >= 0 && (index) < TCP_MAX_CONNS) ? (tc + (index)) : NULL)
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static const char *tcp_event_str[] __attribute((__unused__)) = {
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"SOCK_ACCEPTED", "TAP_SYN_RCVD", "ESTABLISHED", "TAP_SYN_ACK_SENT",
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@ -705,6 +697,21 @@ static size_t tcp6_l2_flags_buf_bytes;
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/* TCP connections */
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static struct tcp_conn tc[TCP_MAX_CONNS];
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#define CONN(index) (tc + (index))
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#define CONN_IDX(conn) ((conn) - tc)
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/** conn_at_idx() - Find a connection by index, if present
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* @index: Index of connection to lookup
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*
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* Return: pointer to connection, or NULL if @index is out of bounds
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*/
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static inline struct tcp_conn *conn_at_idx(int index)
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{
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if ((index < 0) || (index >= TCP_MAX_CONNS))
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return NULL;
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return CONN(index);
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}
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/* Table for lookup from remote address, local port, remote port */
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static struct tcp_conn *tc_hash[TCP_HASH_TABLE_SIZE];
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@ -761,7 +768,7 @@ static int tcp_epoll_ctl(const struct ctx *c, struct tcp_conn *conn)
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{
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int m = (conn->flags & IN_EPOLL) ? EPOLL_CTL_MOD : EPOLL_CTL_ADD;
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union epoll_ref ref = { .r.proto = IPPROTO_TCP, .r.s = conn->sock,
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.r.p.tcp.tcp.index = conn - tc,
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.r.p.tcp.tcp.index = CONN_IDX(conn),
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.r.p.tcp.tcp.v6 = CONN_V6(conn) };
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struct epoll_event ev = { .data.u64 = ref.u64 };
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@ -784,7 +791,7 @@ static int tcp_epoll_ctl(const struct ctx *c, struct tcp_conn *conn)
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union epoll_ref ref_t = { .r.proto = IPPROTO_TCP,
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.r.s = conn->sock,
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.r.p.tcp.tcp.timer = 1,
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.r.p.tcp.tcp.index = conn - tc };
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.r.p.tcp.tcp.index = CONN_IDX(conn) };
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struct epoll_event ev_t = { .data.u64 = ref_t.u64,
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.events = EPOLLIN | EPOLLET };
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@ -813,7 +820,7 @@ static void tcp_timer_ctl(const struct ctx *c, struct tcp_conn *conn)
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union epoll_ref ref = { .r.proto = IPPROTO_TCP,
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.r.s = conn->sock,
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.r.p.tcp.tcp.timer = 1,
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.r.p.tcp.tcp.index = conn - tc };
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.r.p.tcp.tcp.index = CONN_IDX(conn) };
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struct epoll_event ev = { .data.u64 = ref.u64,
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.events = EPOLLIN | EPOLLET };
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int fd;
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@ -846,7 +853,7 @@ static void tcp_timer_ctl(const struct ctx *c, struct tcp_conn *conn)
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it.it_value.tv_sec = ACT_TIMEOUT;
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}
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debug("TCP: index %li, timer expires in %lu.%03lus", conn - tc,
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debug("TCP: index %li, timer expires in %lu.%03lus", CONN_IDX(conn),
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it.it_value.tv_sec, it.it_value.tv_nsec / 1000 / 1000);
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timerfd_settime(conn->timer, 0, &it, NULL);
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@ -867,7 +874,7 @@ static void conn_flag_do(const struct ctx *c, struct tcp_conn *conn,
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conn->flags &= flag;
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if (fls(~flag) >= 0) {
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debug("TCP: index %li: %s dropped", conn - tc,
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debug("TCP: index %li: %s dropped", CONN_IDX(conn),
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tcp_flag_str[fls(~flag)]);
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}
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} else {
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@ -876,7 +883,7 @@ static void conn_flag_do(const struct ctx *c, struct tcp_conn *conn,
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conn->flags |= flag;
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if (fls(flag) >= 0) {
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debug("TCP: index %li: %s", conn - tc,
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debug("TCP: index %li: %s", CONN_IDX(conn),
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tcp_flag_str[fls(flag)]);
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}
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}
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@ -926,12 +933,12 @@ static void conn_event_do(const struct ctx *c, struct tcp_conn *conn,
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new += 5;
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if (prev != new) {
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debug("TCP: index %li, %s: %s -> %s", conn - tc,
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debug("TCP: index %li, %s: %s -> %s", CONN_IDX(conn),
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num == -1 ? "CLOSED" : tcp_event_str[num],
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prev == -1 ? "CLOSED" : tcp_state_str[prev],
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(new == -1 || num == -1) ? "CLOSED" : tcp_state_str[new]);
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} else {
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debug("TCP: index %li, %s", conn - tc,
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debug("TCP: index %li, %s", CONN_IDX(conn),
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num == -1 ? "CLOSED" : tcp_event_str[num]);
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}
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@ -1355,12 +1362,12 @@ static void tcp_hash_insert(const struct ctx *c, struct tcp_conn *conn,
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int b;
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b = tcp_hash(c, af, addr, conn->tap_port, conn->sock_port);
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conn->next_index = tc_hash[b] ? tc_hash[b] - tc : -1;
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conn->next_index = tc_hash[b] ? CONN_IDX(tc_hash[b]) : -1;
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tc_hash[b] = conn;
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conn->hash_bucket = b;
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debug("TCP: hash table insert: index %li, sock %i, bucket: %i, next: "
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"%p", conn - tc, conn->sock, b, CONN_OR_NULL(conn->next_index));
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"%p", CONN_IDX(conn), conn->sock, b, conn_at_idx(conn->next_index));
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}
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/**
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@ -1373,19 +1380,19 @@ static void tcp_hash_remove(const struct tcp_conn *conn)
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int b = conn->hash_bucket;
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for (entry = tc_hash[b]; entry;
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prev = entry, entry = CONN_OR_NULL(entry->next_index)) {
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prev = entry, entry = conn_at_idx(entry->next_index)) {
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if (entry == conn) {
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if (prev)
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prev->next_index = conn->next_index;
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else
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tc_hash[b] = CONN_OR_NULL(conn->next_index);
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tc_hash[b] = conn_at_idx(conn->next_index);
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break;
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}
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}
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debug("TCP: hash table remove: index %li, sock %i, bucket: %i, new: %p",
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conn - tc, conn->sock, b,
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prev ? CONN_OR_NULL(prev->next_index) : tc_hash[b]);
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CONN_IDX(conn), conn->sock, b,
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prev ? conn_at_idx(prev->next_index) : tc_hash[b]);
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}
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/**
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@ -1399,10 +1406,10 @@ static void tcp_hash_update(struct tcp_conn *old, struct tcp_conn *new)
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int b = old->hash_bucket;
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for (entry = tc_hash[b]; entry;
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prev = entry, entry = CONN_OR_NULL(entry->next_index)) {
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prev = entry, entry = conn_at_idx(entry->next_index)) {
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if (entry == old) {
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if (prev)
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prev->next_index = new - tc;
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prev->next_index = CONN_IDX(new);
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else
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tc_hash[b] = new;
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break;
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@ -1411,7 +1418,7 @@ static void tcp_hash_update(struct tcp_conn *old, struct tcp_conn *new)
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debug("TCP: hash table update: old index %li, new index %li, sock %i, "
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"bucket: %i, old: %p, new: %p",
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old - tc, new - tc, new->sock, b, old, new);
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CONN_IDX(old), CONN_IDX(new), new->sock, b, old, new);
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}
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/**
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@ -1431,7 +1438,7 @@ static struct tcp_conn *tcp_hash_lookup(const struct ctx *c, int af,
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int b = tcp_hash(c, af, addr, tap_port, sock_port);
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struct tcp_conn *conn;
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for (conn = tc_hash[b]; conn; conn = CONN_OR_NULL(conn->next_index)) {
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for (conn = tc_hash[b]; conn; conn = conn_at_idx(conn->next_index)) {
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if (tcp_hash_match(conn, af, addr, tap_port, sock_port))
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return conn;
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}
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@ -1448,9 +1455,9 @@ static void tcp_table_compact(struct ctx *c, struct tcp_conn *hole)
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{
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struct tcp_conn *from, *to;
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if ((hole - tc) == --c->tcp.conn_count) {
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if (CONN_IDX(hole) == --c->tcp.conn_count) {
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debug("TCP: hash table compaction: maximum index was %li (%p)",
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hole - tc, hole);
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CONN_IDX(hole), hole);
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memset(hole, 0, sizeof(*hole));
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return;
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}
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@ -1465,7 +1472,7 @@ static void tcp_table_compact(struct ctx *c, struct tcp_conn *hole)
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debug("TCP: hash table compaction: old index %li, new index %li, "
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"sock %i, from: %p, to: %p",
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from - tc, to - tc, from->sock, from, to);
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CONN_IDX(from), CONN_IDX(to), from->sock, from, to);
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memset(from, 0, sizeof(*from));
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}
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@ -1488,7 +1495,7 @@ static void tcp_conn_destroy(struct ctx *c, struct tcp_conn *conn)
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static void tcp_rst_do(struct ctx *c, struct tcp_conn *conn);
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#define tcp_rst(c, conn) \
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do { \
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debug("TCP: index %li, reset at %s:%i", conn - tc, \
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debug("TCP: index %li, reset at %s:%i", CONN_IDX(conn), \
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__func__, __LINE__); \
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tcp_rst_do(c, conn); \
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} while (0)
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@ -2734,7 +2741,7 @@ int tcp_tap_handler(struct ctx *c, int af, const void *addr,
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return 1;
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}
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trace("TCP: packet length %lu from tap for index %lu", len, conn - tc);
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trace("TCP: packet length %lu from tap for index %lu", len, CONN_IDX(conn));
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if (th->rst) {
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conn_event(c, conn, CLOSED);
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@ -2942,7 +2949,7 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
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*/
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static void tcp_timer_handler(struct ctx *c, union epoll_ref ref)
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{
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struct tcp_conn *conn = CONN_OR_NULL(ref.r.p.tcp.tcp.index);
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struct tcp_conn *conn = conn_at_idx(ref.r.p.tcp.tcp.index);
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struct itimerspec check_armed = { { 0 }, { 0 } };
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if (!conn)
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@ -2961,17 +2968,17 @@ static void tcp_timer_handler(struct ctx *c, union epoll_ref ref)
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conn_flag(c, conn, ~ACK_TO_TAP_DUE);
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} else if (conn->flags & ACK_FROM_TAP_DUE) {
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if (!(conn->events & ESTABLISHED)) {
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debug("TCP: index %li, handshake timeout", conn - tc);
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debug("TCP: index %li, handshake timeout", CONN_IDX(conn));
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tcp_rst(c, conn);
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} else if (CONN_HAS(conn, SOCK_FIN_SENT | TAP_FIN_ACKED)) {
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debug("TCP: index %li, FIN timeout", conn - tc);
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debug("TCP: index %li, FIN timeout", CONN_IDX(conn));
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tcp_rst(c, conn);
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} else if (conn->retrans == TCP_MAX_RETRANS) {
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debug("TCP: index %li, retransmissions count exceeded",
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conn - tc);
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CONN_IDX(conn));
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tcp_rst(c, conn);
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} else {
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debug("TCP: index %li, ACK timeout, retry", conn - tc);
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debug("TCP: index %li, ACK timeout, retry", CONN_IDX(conn));
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conn->retrans++;
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conn->seq_to_tap = conn->seq_ack_from_tap;
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tcp_data_from_sock(c, conn);
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@ -2989,7 +2996,7 @@ static void tcp_timer_handler(struct ctx *c, union epoll_ref ref)
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*/
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timerfd_settime(conn->timer, 0, &new, &old);
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if (old.it_value.tv_sec == ACT_TIMEOUT) {
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debug("TCP: index %li, activity timeout", conn - tc);
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debug("TCP: index %li, activity timeout", CONN_IDX(conn));
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tcp_rst(c, conn);
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}
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}
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@ -3022,7 +3029,7 @@ void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
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return;
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}
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if (!(conn = CONN_OR_NULL(ref.r.p.tcp.tcp.index)))
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if (!(conn = conn_at_idx(ref.r.p.tcp.tcp.index)))
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return;
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if (conn->events == CLOSED)
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