From d3cdeebaf817a65f25772fd491e8c20556dd0f52 Mon Sep 17 00:00:00 2001 From: "Alex Xu (Hello71)" Date: Wed, 29 Jun 2016 21:42:36 -0400 Subject: Fix-ish timing out, add SYN retries. --- src/client.c | 165 ++++++++++++++++++++++++++++++++++------------------------- src/server.c | 10 ++-- 2 files changed, 101 insertions(+), 74 deletions(-) diff --git a/src/client.c b/src/client.c index 00f7a89..10ba78a 100644 --- a/src/client.c +++ b/src/client.c @@ -27,7 +27,6 @@ struct o_c_rsock { struct o_c_sock *o_socks_by_lport; struct c_data *c_data; ev_io io_w; - ev_timer tm_w; UT_hash_handle hh; int fd; socklen_t r_addrlen; @@ -43,8 +42,8 @@ struct o_c_sock { UT_hash_handle hh_ca; uint16_t seq_num; in_port_t l_port; - in_port_t r_port; uint8_t status; + int8_t syn_retries; }; #define PORTS_IN_INT sizeof(int) * CHAR_BIT @@ -58,10 +57,13 @@ struct c_data { socklen_t s_addrlen; unsigned int used_ports[32768 / PORTS_IN_INT]; int s_sock; + int i_sock; }; static struct c_data *global_c_data; +static const uint8_t tcp_syn_retry_timeouts[] = { 3, 6, 12, 24, 0 }; + /* reserve a local TCP port (local addr, remote addr, remote port are usually * fixed in the tuple) */ static uint16_t reserve_port(unsigned int *used_ports) { @@ -102,42 +104,68 @@ static void free_port(unsigned int *used_ports, uint16_t port_num) { used_ports[port_num / PORTS_IN_INT] ^= 1 << (port_num % PORTS_IN_INT); } -static void c_tm_cb(EV_P_ ev_timer *w, int revents __attribute__((unused))) { - struct o_c_sock *sock = w->data; - DBG("timing out socket @ %p", sock); - struct tcphdr buf = { - .th_sport = sock->l_port, - .th_dport = sock->r_port, - .th_seq = htonl(sock->seq_num), - .th_off = 5, - .th_flags = TH_FIN - }; - ssize_t sz = send(sock->rsock->c_data->s_sock, &buf, sizeof(buf), 0); - if (sz < 0) { - perror("send"); - ev_break(EV_A_ EVBREAK_ONE); - return; - } else if ((size_t)sz != sizeof(buf)) { - fprintf(stderr, "send %s our packet: tried %lu, sent %zd\n", (size_t)sz > sizeof(buf) ? "expanded" : "truncated", sizeof(buf), sz); +static void c_sock_cleanup(EV_P_ struct o_c_sock *sock, int stopping) { + if (sock->status != TCP_SYN_SENT) { + struct tcphdr buf = { + .th_sport = sock->l_port, + .th_dport = ((struct sockaddr_in *)sock->rsock->r_addr)->sin_port, + .th_seq = htonl(sock->seq_num), + .th_off = 5, + .th_flags = sock->status == TCP_ESTABLISHED ? TH_FIN : TH_RST + }; + + ssize_t sz = send(sock->rsock->c_data->s_sock, &buf, sizeof(buf), 0); + if (sz < 0) { + perror("send"); + ev_break(EV_A_ EVBREAK_ONE); + return; + } else if ((size_t)sz != sizeof(buf)) { + fprintf(stderr, "send %s our packet: tried %lu, sent %zd\n", (size_t)sz > sizeof(buf) ? "expanded" : "truncated", sizeof(buf), sz); + } } - free_port(sock->rsock->c_data->used_ports, sock->l_port); - ev_timer_stop(EV_A_ w); - HASH_DELETE(hh_lp, sock->rsock->o_socks_by_lport, sock); + if (!stopping) { + free_port(sock->rsock->c_data->used_ports, sock->l_port); + ev_timer_stop(EV_A_ &sock->tm_w); + + HASH_DELETE(hh_lp, sock->rsock->o_socks_by_lport, sock); + + if (!sock->rsock->o_socks_by_lport) { + close(sock->rsock->fd); + + ev_io_stop(EV_A_ &sock->rsock->io_w); + + HASH_DEL(sock->rsock->c_data->o_rsocks, sock->rsock); - if (!sock->rsock->o_socks_by_lport) { - close(sock->rsock->fd); + free(sock->rsock->r_addr); + free(sock->rsock); + } - ev_io_stop(EV_A_ &sock->rsock->io_w); - ev_timer_stop(EV_A_ &sock->rsock->tm_w); + free(sock); + } +} - HASH_DEL(sock->rsock->c_data->o_rsocks, sock->rsock); +static void c_tm_cb(EV_P_ ev_timer *w, int revents __attribute__((unused))) { + DBG("timing out socket %p", w->data); + c_sock_cleanup(EV_A_ w->data, 0); +} - free(sock->rsock->r_addr); - free(sock->rsock); +static int c_adv_syn_tm(EV_P_ struct o_c_sock *sock) { + uint8_t next_retr = tcp_syn_retry_timeouts[sock->syn_retries++]; + if (next_retr) { + ev_timer_set(&sock->tm_w, next_retr, 0.); + ev_timer_start(EV_A_ &sock->tm_w); } + return !!next_retr; +} - free(sock); +static void c_syn_tm_cb(EV_P_ ev_timer *w, int revents __attribute__((unused))) { + if (c_adv_syn_tm(EV_A_ w->data)) { + // resend SYN + } else { + DBG("connection timed out"); + c_sock_cleanup(EV_A_ w->data, 0); + } } static void cc_cb(struct ev_loop *loop __attribute__((unused)), ev_io *w, int revents __attribute__((unused))) { @@ -180,7 +208,7 @@ static void cc_cb(struct ev_loop *loop __attribute__((unused)), ev_io *w, int re struct tcphdr shdr = { .th_sport = sock->l_port, - .th_dport = sock->r_port, + .th_dport = ((struct sockaddr_in *)sock->rsock->r_addr)->sin_port, .th_seq = htonl(sock->seq_num), .th_ack = rhdr->th_seq, .th_win = 65535, @@ -214,6 +242,14 @@ static void cc_cb(struct ev_loop *loop __attribute__((unused)), ev_io *w, int re } free(sock->pending_data); + + ev_timer_stop(EV_A_ &sock->tm_w); + // 10 minutes. this is not very important because UDP packets will not + // be lost (any more), only delayed until a new connection is established. + // however, it is probably a good idea to set this higher than the UDP + // ping delay if you are using one. + ev_timer_init(&sock->tm_w, c_tm_cb, 10. * 60., 10. * 60.); + ev_timer_start(EV_A_ &sock->tm_w); } should_ssz = rsz - ntohs(rhdr->th_off) * 32 / CHAR_BIT; @@ -278,53 +314,47 @@ static void cs_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { sock->c_address = malloc(addresslen); memcpy(sock->c_address, &c_data->pkt_addr, addresslen); - struct o_c_rsock *rsock; - - HASH_FIND(hh, c_data->o_rsocks, res->ai_addr, res->ai_addrlen, rsock); + HASH_FIND(hh, c_data->o_rsocks, res->ai_addr, res->ai_addrlen, sock->rsock); - if (!rsock) { + if (!sock->rsock) { DBG("could not locate remote socket to host, initializing new raw socket"); - rsock = malloc(sizeof(*rsock)); - rsock->r_addr = malloc(res->ai_addrlen); + sock->rsock = malloc(sizeof(*sock->rsock)); + sock->rsock->r_addr = malloc(res->ai_addrlen); - memcpy(rsock->r_addr, res->ai_addr, res->ai_addrlen); - rsock->r_addrlen = res->ai_addrlen; + memcpy(sock->rsock->r_addr, res->ai_addr, res->ai_addrlen); + sock->rsock->r_addrlen = res->ai_addrlen; freeaddrinfo(res); - rsock->o_socks_by_lport = NULL; - rsock->c_data = c_data; + sock->rsock->o_socks_by_lport = NULL; + sock->rsock->c_data = c_data; - rsock->fd = socket(rsock->r_addr->sa_family, SOCK_RAW, IPPROTO_TCP); - if (!rsock->fd) { + sock->rsock->fd = socket(sock->rsock->r_addr->sa_family, SOCK_RAW, IPPROTO_TCP); + if (!sock->rsock->fd) { perror("socket"); ev_break(EV_A_ EVBREAK_ONE); return; } - if (connect(rsock->fd, rsock->r_addr, rsock->r_addrlen) == -1) { + if (connect(sock->rsock->fd, sock->rsock->r_addr, sock->rsock->r_addrlen) == -1) { perror("connect"); ev_break(EV_A_ EVBREAK_ONE); return; } - ev_io_init(&rsock->io_w, cc_cb, rsock->fd, EV_READ); - rsock->io_w.data = rsock; - ev_io_start(EV_A_ &rsock->io_w); + ev_io_init(&sock->rsock->io_w, cc_cb, sock->rsock->fd, EV_READ); + sock->rsock->io_w.data = sock->rsock; + ev_io_start(EV_A_ &sock->rsock->io_w); - HASH_ADD_KEYPTR(hh, c_data->o_rsocks, rsock->r_addr, rsock->r_addrlen, rsock); + HASH_ADD_KEYPTR(hh, c_data->o_rsocks, sock->rsock->r_addr, sock->rsock->r_addrlen, sock->rsock); } - sock->r_port = ((struct sockaddr_in *)rsock->r_addr)->sin_port; - HASH_ADD_KEYPTR(hh_ca, c_data->o_socks_by_caddr, sock->c_address, addresslen, sock); - HASH_ADD(hh_lp, rsock->o_socks_by_lport, l_port, sizeof(in_port_t), sock); - - sock->rsock = rsock; + HASH_ADD(hh_lp, sock->rsock->o_socks_by_lport, l_port, sizeof(in_port_t), sock); sock->seq_num = random(); struct tcphdr buf = { .th_sport = sock->l_port, - .th_dport = sock->r_port, + .th_dport = ((struct sockaddr_in *)sock->rsock->r_addr)->sin_port, .th_seq = htonl(sock->seq_num++), .th_flags = TH_SYN, .th_off = 5 @@ -335,7 +365,7 @@ static void cs_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { sock->pending_data_size = sz; DBG("sending SYN to remote"); - sz = send(rsock->fd, &buf, sizeof(buf), 0); + sz = send(sock->rsock->fd, &buf, sizeof(buf), 0); if (sz < 0) { perror("send"); ev_break(EV_A_ EVBREAK_ONE); @@ -346,9 +376,10 @@ static void cs_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { // resend SYN - //ev_timer_init(&sock->tm_w, c_tm_cb, 0., 60. * 60. * 3.); - //sock->tm_w.data = sock; - //ev_timer_start(EV_A_ &sock->tm_w); + ev_timer_init(&sock->tm_w, c_syn_tm_cb, 0., tcp_syn_retry_timeouts[0]); + sock->tm_w.data = sock; + sock->syn_retries = 0; + c_adv_syn_tm(EV_A_ sock); sock->status = TCP_SYN_SENT; @@ -357,7 +388,7 @@ static void cs_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { struct tcphdr tcp_hdr = { .th_sport = sock->l_port, - .th_dport = sock->r_port, + .th_dport = ((struct sockaddr_in *)sock->rsock->r_addr)->sin_port, .th_seq = htonl(sock->seq_num), .th_off = 5, .th_win = 65535, @@ -399,14 +430,10 @@ static void c_cleanup() { struct o_c_sock *sock; for (sock = global_c_data->o_socks_by_caddr; sock != NULL; sock = sock->hh_ca.next) { switch (sock->status) { - case TCP_ESTABLISHED: - // send TCP FIN - break; case TCP_CLOSE: break; default: - ; - // send TCP RST + c_sock_cleanup(EV_DEFAULT, sock, 1); } // don't bother freeing anything because we're about to exit anyways } @@ -422,7 +449,11 @@ int start_client(const char *s_host, const char *s_port, const char *r_host, con return 3; } - struct c_data c_data = { 0 }; + struct c_data c_data = { + .s_addrlen = res->ai_addrlen, + .r_host = r_host, + .r_port = r_port + }; c_data.s_sock = socket(res->ai_family, SOCK_DGRAM, 0); if (c_data.s_sock == -1) { @@ -435,10 +466,6 @@ int start_client(const char *s_host, const char *s_port, const char *r_host, con return 2; } - c_data.s_addrlen = res->ai_addrlen; - c_data.r_host = r_host; - c_data.r_port = r_port; - freeaddrinfo(res); global_c_data = &c_data; diff --git a/src/server.c b/src/server.c index d5332bc..f6714a2 100644 --- a/src/server.c +++ b/src/server.c @@ -43,7 +43,7 @@ static inline void s_prep_c_addr(struct o_s_sock *sock, struct tcphdr *hdr) { hdr->th_off = 5; } -static void s_s_cleanup(EV_P_ struct o_s_sock *sock) { +static void s_sock_cleanup(EV_P_ struct o_s_sock *sock) { DBG("cleaning up socket %p", sock); if (sock->status == TCP_ESTABLISHED) { @@ -75,7 +75,7 @@ static void s_s_cleanup(EV_P_ struct o_s_sock *sock) { static void s_tm_cb(EV_P_ ev_timer *w, int revents __attribute__((unused))) { DBG("timing out socket %p", w->data); - s_s_cleanup(EV_A_ w->data); + s_sock_cleanup(EV_A_ w->data); } static void sc_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { @@ -146,7 +146,7 @@ static void ss_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { #ifdef DEBUG char hbuf[NI_MAXHOST]; - r = getnameinfo(&s_data->pkt_addr, c_addrlen, hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST); + r = getnameinfo((struct sockaddr *)&s_data->pkt_addr, c_addrlen, hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST); if (r) { fprintf(stderr, "getnameinfo: %s\n", gai_strerror(r)); ev_break(EV_A_ EVBREAK_ONE); @@ -203,7 +203,7 @@ static void ss_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { ((struct sockaddr_in *)&s_data->pkt_addr)->sin_port = htons(0); DBG("sending SYN/ACK"); - if ((sz = sendto(w->fd, &buf, sizeof(buf), 0, &s_data->pkt_addr, s_data->s_addrlen)) == -1) { + if ((sz = sendto(w->fd, &buf, sizeof(buf), 0, (struct sockaddr *)&s_data->pkt_addr, s_data->s_addrlen)) == -1) { perror("sendto"); ev_break(EV_A_ EVBREAK_ONE); return; @@ -230,7 +230,7 @@ static void ss_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { if (th_flags == TH_RST) { DBG("RST received, cleaning up socket"); sock->status = TCP_CLOSE; - s_s_cleanup(EV_A_ sock); + s_sock_cleanup(EV_A_ sock); } if (th_flags & ~(TH_PUSH | TH_ACK)) { -- cgit v1.2.3-70-g09d2