应用层
NAME
getsockopt - get options on sockets
SYNOPSIS
#include <sys/types.h>
#include <sys/socket.h>
int getsockopt (int s, int level, int optname, void *optval, socklen_t *optlen);
调用关系
函数的调用关系图如下:
数据结构
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struct tcp_sock {
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...
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u32 mss_cache;
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u8 nonagle : 4,
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thin_lto : 1,
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thin_dupack : 1,
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unused : 2;
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unsigned int keepalive_time;
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unsigned int keepalive_intvl;
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u8 keepalive_probes;
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int linger2;
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u8 ecn_flags;
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u32 rcv_tstamp;
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u32 lsndtime;
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u32 window_clamp;
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u32 rcv_ssthresh;
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u16 advmss;
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u32 total_retrans;
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...
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}
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struct tcp_options_received {
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...
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u16 saw_tstamp : 1,
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tstamp_ok : 1,
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dsack : 1,
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wscale_ok : 1,
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sack_ok : 4,
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snd_wscale : 4,
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rcv_wscale : 4,
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...
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}
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#define TCPI_OPT_TIMESTAMPS 1
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#define TCPI_OPT_SACK 2
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#define TCPI_OPT_WSCALE 4
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#define TCPI_OPT_ECN 8
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struct tcp_info {
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__u8 tcpi_state;
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__u8 tcpi_ca_state;
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__u8 tcpi_retransmits;
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__u8 tcpi_probes;
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__u8 tcpi_backoff;
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__u8 tcpi_options;
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__u8 tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
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__u32 tcpi_rto;
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__u32 tcpi_ato;
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__u32 tcpi_snd_mss;
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__u32 tcpi_rcv_mss;
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__u32 tcpi_unacked;
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__u32 tcpi_sacked;
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__u32 tcpi_lost;
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__u32 tcpi_retrans;
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__u32 tcpi_fackets;
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-
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__u32 tcpi_last_data_sent;
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__u32 tcpi_last_ack_sent;
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__u32 tcpi_last_data_recv;
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__u32 tcpi_last_ack_recv;
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-
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__u32 tcpi_pmtu;
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__u32 tcpi_rcv_ssthresh;
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__u32 tcpi_rtt;
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__u32 tcpi_rttvar;
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__u32 tcpi_snd_ssthresh;
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__u32 tcpi_snd_cwnd;
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__u32 tcpi_advmss;
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__u32 tcpi_reordering;
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__u32 tcpi_rcv_rtt;
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__u32 tcpi_rcv_space;
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__u32 tcpi_total_retrans;
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};
函数实现
内核版本:2.6.37
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int tcp_getsockopt (struct sock *sk, int level, int optname, char __user *optval, int __user *optlen)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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if (level != SOL_TCP)
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return icsk->icsk_af_ops->getsockopt(sk, level, optname, optval, optlen);
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return do_tcp_getsockopt(sk, level, optname, optval, optlen);
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}
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static int do_tcp_getsockopt (struct sock *sk, int level, int optname, char __user *optval, int __user *optlen)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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struct tcp_sock *tp = tcp_sk(sk);
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int val, len;
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if (get_user(len, optlen))
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return -EFAULT;
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len = min_t(unsigned int, len, sizeof(int));
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if (len < 0)
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return -EINVAL;
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switch (optname) {
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case TCP_MAXSEG:
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val = tp->mss_cache;
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if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE) | TCPF_LISTEN))
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val = tp->rx_opt.user_mss;
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break;
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case TCP_NODELAY:
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val = !! (tp->nonagle & TCP_NAGLE_OFF);
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break;
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case TCP_CORK:
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val = !! (tp->nonagle & TCP_NAGLE_CORK);
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break;
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case TCP_KEEPIDLE:
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val = keepalive_time_when(tp) / HZ;
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break;
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case TCP_KEEPINTVL:
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val = keepalive_intvl_when(tp) / HZ;
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break;
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case TCP_KEEPCNT:
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val = keepalive_probes(tp);
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break;
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case TCP_SYNCNT:
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val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
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break;
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case TCP_LINGER2:
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val = tp->linger2;
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if (val >= 0)
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val = (val ? : sysctl_tcp_fin_timeout) / HZ;
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case TCP_DEFER_ACCEPT:
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...
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case TCP_WINDOW_CLAMP:
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val = tp->window_clamp;
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break;
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case TCP_INFO: {
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struct tcp_info info;
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if (get_user(len, optlen))
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return -EFAULT;
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tcp_get_info(sk, &info);
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len = min_t(unsigned int, len, sizeof(info));
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if (put_user(len, optlen))
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return -EFAULT;
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if (copy_to_user(optval, &info, len))
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return -EFAULT;
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return 0;
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}
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case TCP_QUICKACK:
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val = ! icsk->icsk_ack.pingpong;
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break;
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case TCP_CONGESTION:
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if (get_user(len, optlen))
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return -EFAULT;
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len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
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if (put_user(len, optlen)
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return -EFAULT;
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if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
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return -EFAULT;
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return 0;
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case TCP_COOKIE_TRANSACTIONS :
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...
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case TCP_THIN_LINEAR_TIMEOUTS:
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val = tp->thin_lto;
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break;
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case TCP_THIN_DUPACK:
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val = tp->thin_dupack;
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break;
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case TCP_USER_TIMEOUT:
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val = jiffies_to_msecs(icsk->icsk_user_timeout);
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break;
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default:
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return -ENOPROTOOPT;
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}
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if (put_user(len, optlen))
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return -EFAULT;
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if (copy_to_user(optval, &val, len))
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return -EFAULT;
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return 0;
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}
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static inline int keepalive_time_when(const struct tcp_sock *tp)
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{
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return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
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}
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static inline int keepalive_intvl_when(const struct tcp_sock *tp)
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{
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return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
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}
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static inline int keepalive_probes(const struct tcp_sock *tp)
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{
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return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
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}
TCP_INFO
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-
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void tcp_get_info(struct sock *sk, struct tcp_info *info)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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const struct inet_connection_sock *icsk = inet_csk(sk);
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u32 now = tcp_time_stamp;
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memset(info, 0, sizeof(*info));
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info->tcpi_state = sk->sk_state;
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info->tcpi_ca_state = icsk_ca_state;
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info->tcpi_retransmits = icsk->icsk_retransmits;
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info->tcpi_probes = icsk->icsk_probes_out;
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info->tcpi_backoff = icsk->icsk_backoff;
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if (tp->rx_opt.tstamp_ok)
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info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
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if (tcp_is_sack(tp))
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info->tcpi_options |= TCPI_OPT_SACK;
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if (tp->rx_opt.wscale_ok) {
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info->tcpi_options |= TCPI_OPT_WSCALE;
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info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
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info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
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}
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if (tp->ecn_flags & TCP_ECN_OK)
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info->tcpi_options |= TCPI_OPT_ECN;
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info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
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info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
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info->tcpi_snd_mss = tp->mss_cache;
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info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
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if (sk->sk_state == TCP_LISTEN) {
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info->tcpi_unacked = sk->sk_ack_backlog;
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info->tcpi_sacked = sk->sk_max_ack_backlog;
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} else {
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info->tcpi_unacked = tp->packets_out;
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info->tcpi_sacked = tp->sacked_out;
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}
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info->tcpi_lost = tp->lost_out;
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info->tcpi_retrans = tp->retrans_out;
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info->tcpi_fackets = tp->fackets_out;
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info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
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info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
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info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
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info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
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info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
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info->tcpi_rtt = jiffies_to_usecs(tp->srtt) >> 3;
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info->tcpi_rttvar = jiffies_to_usecs(tp->mdev) >> 2;
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info->tcpi_snd_ssthresh = tp->snd_ssthresh;
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info->tcpi_snd_cwnd = tp->snd_cwnd;
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info->tcpi_advmss = tp->advmss;
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info->tcpi_reordering = tp->reordering;
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info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt) >> 3;
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info->tcpi_rcv_space = tp->rcvq_space.space;
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info->tcpi_total_retrans = tp->total_retrans;
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}
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