diff options
Diffstat (limited to 'third-party/libuv/samples/socks5-proxy/client.c')
| -rw-r--r-- | third-party/libuv/samples/socks5-proxy/client.c | 737 |
1 files changed, 737 insertions, 0 deletions
diff --git a/third-party/libuv/samples/socks5-proxy/client.c b/third-party/libuv/samples/socks5-proxy/client.c new file mode 100644 index 0000000000..ae9913a1c6 --- /dev/null +++ b/third-party/libuv/samples/socks5-proxy/client.c @@ -0,0 +1,737 @@ +/* Copyright StrongLoop, Inc. All rights reserved. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to + * deal in the Software without restriction, including without limitation the + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + */ + +#include "defs.h" +#include <errno.h> +#include <stdlib.h> +#include <string.h> + +/* A connection is modeled as an abstraction on top of two simple state + * machines, one for reading and one for writing. Either state machine + * is, when active, in one of three states: busy, done or stop; the fourth + * and final state, dead, is an end state and only relevant when shutting + * down the connection. A short overview: + * + * busy done stop + * ----------|---------------------------|--------------------|------| + * readable | waiting for incoming data | have incoming data | idle | + * writable | busy writing out data | completed write | idle | + * + * We could remove the done state from the writable state machine. For our + * purposes, it's functionally equivalent to the stop state. + * + * When the connection with upstream has been established, the client_ctx + * moves into a state where incoming data from the client is sent upstream + * and vice versa, incoming data from upstream is sent to the client. In + * other words, we're just piping data back and forth. See conn_cycle() + * for details. + * + * An interesting deviation from libuv's I/O model is that reads are discrete + * rather than continuous events. In layman's terms, when a read operation + * completes, the connection stops reading until further notice. + * + * The rationale for this approach is that we have to wait until the data + * has been sent out again before we can reuse the read buffer. + * + * It also pleasingly unifies with the request model that libuv uses for + * writes and everything else; libuv may switch to a request model for + * reads in the future. + */ +enum conn_state { + c_busy, /* Busy; waiting for incoming data or for a write to complete. */ + c_done, /* Done; read incoming data or write finished. */ + c_stop, /* Stopped. */ + c_dead +}; + +/* Session states. */ +enum sess_state { + s_handshake, /* Wait for client handshake. */ + s_handshake_auth, /* Wait for client authentication data. */ + s_req_start, /* Start waiting for request data. */ + s_req_parse, /* Wait for request data. */ + s_req_lookup, /* Wait for upstream hostname DNS lookup to complete. */ + s_req_connect, /* Wait for uv_tcp_connect() to complete. */ + s_proxy_start, /* Connected. Start piping data. */ + s_proxy, /* Connected. Pipe data back and forth. */ + s_kill, /* Tear down session. */ + s_almost_dead_0, /* Waiting for finalizers to complete. */ + s_almost_dead_1, /* Waiting for finalizers to complete. */ + s_almost_dead_2, /* Waiting for finalizers to complete. */ + s_almost_dead_3, /* Waiting for finalizers to complete. */ + s_almost_dead_4, /* Waiting for finalizers to complete. */ + s_dead /* Dead. Safe to free now. */ +}; + +static void do_next(client_ctx *cx); +static int do_handshake(client_ctx *cx); +static int do_handshake_auth(client_ctx *cx); +static int do_req_start(client_ctx *cx); +static int do_req_parse(client_ctx *cx); +static int do_req_lookup(client_ctx *cx); +static int do_req_connect_start(client_ctx *cx); +static int do_req_connect(client_ctx *cx); +static int do_proxy_start(client_ctx *cx); +static int do_proxy(client_ctx *cx); +static int do_kill(client_ctx *cx); +static int do_almost_dead(client_ctx *cx); +static int conn_cycle(const char *who, conn *a, conn *b); +static void conn_timer_reset(conn *c); +static void conn_timer_expire(uv_timer_t *handle, int status); +static void conn_getaddrinfo(conn *c, const char *hostname); +static void conn_getaddrinfo_done(uv_getaddrinfo_t *req, + int status, + struct addrinfo *ai); +static int conn_connect(conn *c); +static void conn_connect_done(uv_connect_t *req, int status); +static void conn_read(conn *c); +static void conn_read_done(uv_stream_t *handle, + ssize_t nread, + const uv_buf_t *buf); +static void conn_alloc(uv_handle_t *handle, size_t size, uv_buf_t *buf); +static void conn_write(conn *c, const void *data, unsigned int len); +static void conn_write_done(uv_write_t *req, int status); +static void conn_close(conn *c); +static void conn_close_done(uv_handle_t *handle); + +/* |incoming| has been initialized by server.c when this is called. */ +void client_finish_init(server_ctx *sx, client_ctx *cx) { + conn *incoming; + conn *outgoing; + + cx->sx = sx; + cx->state = s_handshake; + s5_init(&cx->parser); + + incoming = &cx->incoming; + incoming->client = cx; + incoming->result = 0; + incoming->rdstate = c_stop; + incoming->wrstate = c_stop; + incoming->idle_timeout = sx->idle_timeout; + CHECK(0 == uv_timer_init(sx->loop, &incoming->timer_handle)); + + outgoing = &cx->outgoing; + outgoing->client = cx; + outgoing->result = 0; + outgoing->rdstate = c_stop; + outgoing->wrstate = c_stop; + outgoing->idle_timeout = sx->idle_timeout; + CHECK(0 == uv_tcp_init(cx->sx->loop, &outgoing->handle.tcp)); + CHECK(0 == uv_timer_init(cx->sx->loop, &outgoing->timer_handle)); + + /* Wait for the initial packet. */ + conn_read(incoming); +} + +/* This is the core state machine that drives the client <-> upstream proxy. + * We move through the initial handshake and authentication steps first and + * end up (if all goes well) in the proxy state where we're just proxying + * data between the client and upstream. + */ +static void do_next(client_ctx *cx) { + int new_state; + + ASSERT(cx->state != s_dead); + switch (cx->state) { + case s_handshake: + new_state = do_handshake(cx); + break; + case s_handshake_auth: + new_state = do_handshake_auth(cx); + break; + case s_req_start: + new_state = do_req_start(cx); + break; + case s_req_parse: + new_state = do_req_parse(cx); + break; + case s_req_lookup: + new_state = do_req_lookup(cx); + break; + case s_req_connect: + new_state = do_req_connect(cx); + break; + case s_proxy_start: + new_state = do_proxy_start(cx); + break; + case s_proxy: + new_state = do_proxy(cx); + break; + case s_kill: + new_state = do_kill(cx); + break; + case s_almost_dead_0: + case s_almost_dead_1: + case s_almost_dead_2: + case s_almost_dead_3: + case s_almost_dead_4: + new_state = do_almost_dead(cx); + break; + default: + UNREACHABLE(); + } + cx->state = new_state; + + if (cx->state == s_dead) { + if (DEBUG_CHECKS) { + memset(cx, -1, sizeof(*cx)); + } + free(cx); + } +} + +static int do_handshake(client_ctx *cx) { + unsigned int methods; + conn *incoming; + s5_ctx *parser; + uint8_t *data; + size_t size; + int err; + + parser = &cx->parser; + incoming = &cx->incoming; + ASSERT(incoming->rdstate == c_done); + ASSERT(incoming->wrstate == c_stop); + incoming->rdstate = c_stop; + + if (incoming->result < 0) { + pr_err("read error: %s", uv_strerror(incoming->result)); + return do_kill(cx); + } + + data = (uint8_t *) incoming->t.buf; + size = (size_t) incoming->result; + err = s5_parse(parser, &data, &size); + if (err == s5_ok) { + conn_read(incoming); + return s_handshake; /* Need more data. */ + } + + if (size != 0) { + /* Could allow a round-trip saving shortcut here if the requested auth + * method is S5_AUTH_NONE (provided unauthenticated traffic is allowed.) + * Requires client support however. + */ + pr_err("junk in handshake"); + return do_kill(cx); + } + + if (err != s5_auth_select) { + pr_err("handshake error: %s", s5_strerror(err)); + return do_kill(cx); + } + + methods = s5_auth_methods(parser); + if ((methods & S5_AUTH_NONE) && can_auth_none(cx->sx, cx)) { + s5_select_auth(parser, S5_AUTH_NONE); + conn_write(incoming, "\5\0", 2); /* No auth required. */ + return s_req_start; + } + + if ((methods & S5_AUTH_PASSWD) && can_auth_passwd(cx->sx, cx)) { + /* TODO(bnoordhuis) Implement username/password auth. */ + } + + conn_write(incoming, "\5\377", 2); /* No acceptable auth. */ + return s_kill; +} + +/* TODO(bnoordhuis) Implement username/password auth. */ +static int do_handshake_auth(client_ctx *cx) { + UNREACHABLE(); + return do_kill(cx); +} + +static int do_req_start(client_ctx *cx) { + conn *incoming; + + incoming = &cx->incoming; + ASSERT(incoming->rdstate == c_stop); + ASSERT(incoming->wrstate == c_done); + incoming->wrstate = c_stop; + + if (incoming->result < 0) { + pr_err("write error: %s", uv_strerror(incoming->result)); + return do_kill(cx); + } + + conn_read(incoming); + return s_req_parse; +} + +static int do_req_parse(client_ctx *cx) { + conn *incoming; + conn *outgoing; + s5_ctx *parser; + uint8_t *data; + size_t size; + int err; + + parser = &cx->parser; + incoming = &cx->incoming; + outgoing = &cx->outgoing; + ASSERT(incoming->rdstate == c_done); + ASSERT(incoming->wrstate == c_stop); + ASSERT(outgoing->rdstate == c_stop); + ASSERT(outgoing->wrstate == c_stop); + incoming->rdstate = c_stop; + + if (incoming->result < 0) { + pr_err("read error: %s", uv_strerror(incoming->result)); + return do_kill(cx); + } + + data = (uint8_t *) incoming->t.buf; + size = (size_t) incoming->result; + err = s5_parse(parser, &data, &size); + if (err == s5_ok) { + conn_read(incoming); + return s_req_parse; /* Need more data. */ + } + + if (size != 0) { + pr_err("junk in request %u", (unsigned) size); + return do_kill(cx); + } + + if (err != s5_exec_cmd) { + pr_err("request error: %s", s5_strerror(err)); + return do_kill(cx); + } + + if (parser->cmd == s5_cmd_tcp_bind) { + /* Not supported but relatively straightforward to implement. */ + pr_warn("BIND requests are not supported."); + return do_kill(cx); + } + + if (parser->cmd == s5_cmd_udp_assoc) { + /* Not supported. Might be hard to implement because libuv has no + * functionality for detecting the MTU size which the RFC mandates. + */ + pr_warn("UDP ASSOC requests are not supported."); + return do_kill(cx); + } + ASSERT(parser->cmd == s5_cmd_tcp_connect); + + if (parser->atyp == s5_atyp_host) { + conn_getaddrinfo(outgoing, (const char *) parser->daddr); + return s_req_lookup; + } + + if (parser->atyp == s5_atyp_ipv4) { + memset(&outgoing->t.addr4, 0, sizeof(outgoing->t.addr4)); + outgoing->t.addr4.sin_family = AF_INET; + outgoing->t.addr4.sin_port = htons(parser->dport); + memcpy(&outgoing->t.addr4.sin_addr, + parser->daddr, + sizeof(outgoing->t.addr4.sin_addr)); + } else if (parser->atyp == s5_atyp_ipv6) { + memset(&outgoing->t.addr6, 0, sizeof(outgoing->t.addr6)); + outgoing->t.addr6.sin6_family = AF_INET6; + outgoing->t.addr6.sin6_port = htons(parser->dport); + memcpy(&outgoing->t.addr6.sin6_addr, + parser->daddr, + sizeof(outgoing->t.addr6.sin6_addr)); + } else { + UNREACHABLE(); + } + + return do_req_connect_start(cx); +} + +static int do_req_lookup(client_ctx *cx) { + s5_ctx *parser; + conn *incoming; + conn *outgoing; + + parser = &cx->parser; + incoming = &cx->incoming; + outgoing = &cx->outgoing; + ASSERT(incoming->rdstate == c_stop); + ASSERT(incoming->wrstate == c_stop); + ASSERT(outgoing->rdstate == c_stop); + ASSERT(outgoing->wrstate == c_stop); + + if (outgoing->result < 0) { + /* TODO(bnoordhuis) Escape control characters in parser->daddr. */ + pr_err("lookup error for \"%s\": %s", + parser->daddr, + uv_strerror(outgoing->result)); + /* Send back a 'Host unreachable' reply. */ + conn_write(incoming, "\5\4\0\1\0\0\0\0\0\0", 10); + return s_kill; + } + + /* Don't make assumptions about the offset of sin_port/sin6_port. */ + switch (outgoing->t.addr.sa_family) { + case AF_INET: + outgoing->t.addr4.sin_port = htons(parser->dport); + break; + case AF_INET6: + outgoing->t.addr6.sin6_port = htons(parser->dport); + break; + default: + UNREACHABLE(); + } + + return do_req_connect_start(cx); +} + +/* Assumes that cx->outgoing.t.sa contains a valid AF_INET/AF_INET6 address. */ +static int do_req_connect_start(client_ctx *cx) { + conn *incoming; + conn *outgoing; + int err; + + incoming = &cx->incoming; + outgoing = &cx->outgoing; + ASSERT(incoming->rdstate == c_stop); + ASSERT(incoming->wrstate == c_stop); + ASSERT(outgoing->rdstate == c_stop); + ASSERT(outgoing->wrstate == c_stop); + + if (!can_access(cx->sx, cx, &outgoing->t.addr)) { + pr_warn("connection not allowed by ruleset"); + /* Send a 'Connection not allowed by ruleset' reply. */ + conn_write(incoming, "\5\2\0\1\0\0\0\0\0\0", 10); + return s_kill; + } + + err = conn_connect(outgoing); + if (err != 0) { + pr_err("connect error: %s\n", uv_strerror(err)); + return do_kill(cx); + } + + return s_req_connect; +} + +static int do_req_connect(client_ctx *cx) { + const struct sockaddr_in6 *in6; + const struct sockaddr_in *in; + char addr_storage[sizeof(*in6)]; + conn *incoming; + conn *outgoing; + uint8_t *buf; + int addrlen; + + incoming = &cx->incoming; + outgoing = &cx->outgoing; + ASSERT(incoming->rdstate == c_stop); + ASSERT(incoming->wrstate == c_stop); + ASSERT(outgoing->rdstate == c_stop); + ASSERT(outgoing->wrstate == c_stop); + + /* Build and send the reply. Not very pretty but gets the job done. */ + buf = (uint8_t *) incoming->t.buf; + if (outgoing->result == 0) { + /* The RFC mandates that the SOCKS server must include the local port + * and address in the reply. So that's what we do. + */ + addrlen = sizeof(addr_storage); + CHECK(0 == uv_tcp_getsockname(&outgoing->handle.tcp, + (struct sockaddr *) addr_storage, + &addrlen)); + buf[0] = 5; /* Version. */ + buf[1] = 0; /* Success. */ + buf[2] = 0; /* Reserved. */ + if (addrlen == sizeof(*in)) { + buf[3] = 1; /* IPv4. */ + in = (const struct sockaddr_in *) &addr_storage; + memcpy(buf + 4, &in->sin_addr, 4); + memcpy(buf + 8, &in->sin_port, 2); + conn_write(incoming, buf, 10); + } else if (addrlen == sizeof(*in6)) { + buf[3] = 4; /* IPv6. */ + in6 = (const struct sockaddr_in6 *) &addr_storage; + memcpy(buf + 4, &in6->sin6_addr, 16); + memcpy(buf + 20, &in6->sin6_port, 2); + conn_write(incoming, buf, 22); + } else { + UNREACHABLE(); + } + return s_proxy_start; + } else { + pr_err("upstream connection error: %s\n", uv_strerror(outgoing->result)); + /* Send a 'Connection refused' reply. */ + conn_write(incoming, "\5\5\0\1\0\0\0\0\0\0", 10); + return s_kill; + } + + UNREACHABLE(); + return s_kill; +} + +static int do_proxy_start(client_ctx *cx) { + conn *incoming; + conn *outgoing; + + incoming = &cx->incoming; + outgoing = &cx->outgoing; + ASSERT(incoming->rdstate == c_stop); + ASSERT(incoming->wrstate == c_done); + ASSERT(outgoing->rdstate == c_stop); + ASSERT(outgoing->wrstate == c_stop); + incoming->wrstate = c_stop; + + if (incoming->result < 0) { + pr_err("write error: %s", uv_strerror(incoming->result)); + return do_kill(cx); + } + + conn_read(incoming); + conn_read(outgoing); + return s_proxy; +} + +/* Proxy incoming data back and forth. */ +static int do_proxy(client_ctx *cx) { + if (conn_cycle("client", &cx->incoming, &cx->outgoing)) { + return do_kill(cx); + } + + if (conn_cycle("upstream", &cx->outgoing, &cx->incoming)) { + return do_kill(cx); + } + + return s_proxy; +} + +static int do_kill(client_ctx *cx) { + int new_state; + + if (cx->state >= s_almost_dead_0) { + return cx->state; + } + + /* Try to cancel the request. The callback still runs but if the + * cancellation succeeded, it gets called with status=UV_ECANCELED. + */ + new_state = s_almost_dead_1; + if (cx->state == s_req_lookup) { + new_state = s_almost_dead_0; + uv_cancel(&cx->outgoing.t.req); + } + + conn_close(&cx->incoming); + conn_close(&cx->outgoing); + return new_state; +} + +static int do_almost_dead(client_ctx *cx) { + ASSERT(cx->state >= s_almost_dead_0); + return cx->state + 1; /* Another finalizer completed. */ +} + +static int conn_cycle(const char *who, conn *a, conn *b) { + if (a->result < 0) { + if (a->result != UV_EOF) { + pr_err("%s error: %s", who, uv_strerror(a->result)); + } + return -1; + } + + if (b->result < 0) { + return -1; + } + + if (a->wrstate == c_done) { + a->wrstate = c_stop; + } + + /* The logic is as follows: read when we don't write and write when we don't + * read. That gives us back-pressure handling for free because if the peer + * sends data faster than we consume it, TCP congestion control kicks in. + */ + if (a->wrstate == c_stop) { + if (b->rdstate == c_stop) { + conn_read(b); + } else if (b->rdstate == c_done) { + conn_write(a, b->t.buf, b->result); + b->rdstate = c_stop; /* Triggers the call to conn_read() above. */ + } + } + + return 0; +} + +static void conn_timer_reset(conn *c) { + CHECK(0 == uv_timer_start(&c->timer_handle, + conn_timer_expire, + c->idle_timeout, + 0)); +} + +static void conn_timer_expire(uv_timer_t *handle, int status) { + conn *c; + + CHECK(0 == status); + c = CONTAINER_OF(handle, conn, timer_handle); + c->result = UV_ETIMEDOUT; + do_next(c->client); +} + +static void conn_getaddrinfo(conn *c, const char *hostname) { + struct addrinfo hints; + + memset(&hints, 0, sizeof(hints)); + hints.ai_family = AF_UNSPEC; + hints.ai_socktype = SOCK_STREAM; + hints.ai_protocol = IPPROTO_TCP; + CHECK(0 == uv_getaddrinfo(c->client->sx->loop, + &c->t.addrinfo_req, + conn_getaddrinfo_done, + hostname, + NULL, + &hints)); + conn_timer_reset(c); +} + +static void conn_getaddrinfo_done(uv_getaddrinfo_t *req, + int status, + struct addrinfo *ai) { + conn *c; + + c = CONTAINER_OF(req, conn, t.addrinfo_req); + c->result = status; + + if (status == 0) { + /* FIXME(bnoordhuis) Should try all addresses. */ + if (ai->ai_family == AF_INET) { + c->t.addr4 = *(const struct sockaddr_in *) ai->ai_addr; + } else if (ai->ai_family == AF_INET6) { + c->t.addr6 = *(const struct sockaddr_in6 *) ai->ai_addr; + } else { + UNREACHABLE(); + } + } + + uv_freeaddrinfo(ai); + do_next(c->client); +} + +/* Assumes that c->t.sa contains a valid AF_INET or AF_INET6 address. */ +static int conn_connect(conn *c) { + ASSERT(c->t.addr.sa_family == AF_INET || + c->t.addr.sa_family == AF_INET6); + conn_timer_reset(c); + return uv_tcp_connect(&c->t.connect_req, + &c->handle.tcp, + &c->t.addr, + conn_connect_done); +} + +static void conn_connect_done(uv_connect_t *req, int status) { + conn *c; + + if (status == UV_ECANCELED) { + return; /* Handle has been closed. */ + } + + c = CONTAINER_OF(req, conn, t.connect_req); + c->result = status; + do_next(c->client); +} + +static void conn_read(conn *c) { + ASSERT(c->rdstate == c_stop); + CHECK(0 == uv_read_start(&c->handle.stream, conn_alloc, conn_read_done)); + c->rdstate = c_busy; + conn_timer_reset(c); +} + +static void conn_read_done(uv_stream_t *handle, + ssize_t nread, + const uv_buf_t *buf) { + conn *c; + + c = CONTAINER_OF(handle, conn, handle); + ASSERT(c->t.buf == buf->base); + ASSERT(c->rdstate == c_busy); + c->rdstate = c_done; + c->result = nread; + + uv_read_stop(&c->handle.stream); + do_next(c->client); +} + +static void conn_alloc(uv_handle_t *handle, size_t size, uv_buf_t *buf) { + conn *c; + + c = CONTAINER_OF(handle, conn, handle); + ASSERT(c->rdstate == c_busy); + buf->base = c->t.buf; + buf->len = sizeof(c->t.buf); +} + +static void conn_write(conn *c, const void *data, unsigned int len) { + uv_buf_t buf; + + ASSERT(c->wrstate == c_stop || c->wrstate == c_done); + c->wrstate = c_busy; + + /* It's okay to cast away constness here, uv_write() won't modify the + * memory. + */ + buf.base = (char *) data; + buf.len = len; + + CHECK(0 == uv_write(&c->write_req, + &c->handle.stream, + &buf, + 1, + conn_write_done)); + conn_timer_reset(c); +} + +static void conn_write_done(uv_write_t *req, int status) { + conn *c; + + if (status == UV_ECANCELED) { + return; /* Handle has been closed. */ + } + + c = CONTAINER_OF(req, conn, write_req); + ASSERT(c->wrstate == c_busy); + c->wrstate = c_done; + c->result = status; + do_next(c->client); +} + +static void conn_close(conn *c) { + ASSERT(c->rdstate != c_dead); + ASSERT(c->wrstate != c_dead); + c->rdstate = c_dead; + c->wrstate = c_dead; + c->timer_handle.data = c; + c->handle.handle.data = c; + uv_close(&c->handle.handle, conn_close_done); + uv_close((uv_handle_t *) &c->timer_handle, conn_close_done); +} + +static void conn_close_done(uv_handle_t *handle) { + conn *c; + + c = handle->data; + do_next(c->client); +} |