/* $Id: reqs.c,v 1.45 2001-12-18 05:01:03 rjkaes Exp $ * * This is where all the work in tinyproxy is actually done. Incoming * connections have a new thread created for them. The thread then * processes the headers from the client, the response from the server, * and then relays the bytes between the two. * If TUNNEL_SUPPORT is enabled, then tinyproxy will actually work * as a simple buffering TCP tunnel. Very cool! (Robert actually uses * this feature for a buffering NNTP tunnel.) * * Copyright (C) 1998 Steven Young * Copyright (C) 1999,2000 Robert James Kaes (rjkaes@flarenet.com) * Copyright (C) 2000 Chris Lightfoot (chris@ex-parrot.com) * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2, or (at your option) any * later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. */ #include "tinyproxy.h" #include "acl.h" #include "anonymous.h" #include "buffer.h" #include "conns.h" #include "filter.h" #include "log.h" #include "regexp.h" #include "reqs.h" #include "sock.h" #include "stats.h" #include "utils.h" #define HTTP400ERROR "Unrecognizable request. Only HTTP is allowed." #define HTTP500ERROR "Unable to connect to remote server." #define HTTP503ERROR "Internal server error." /* * Maximum length of a HTTP line */ #define HTTP_LINE_LENGTH (1024 * 16) /* * Macro to help test if the Upstream proxy supported is compiled in and * enabled. */ #ifdef UPSTREAM_SUPPORT # define UPSTREAM_CONFIGURED() (config.upstream_name && config.upstream_port != -1) #else # define UPSTREAM_CONFIGURED() (0) #endif /* * Read in the first line from the client (the request line for HTTP * connections. The request line is allocated from the heap, but it must * be freed in another function. */ static char * read_request_line(struct conn_s *connptr) { char *request_buffer; size_t len; retry: len = readline(connptr->client_fd, &request_buffer); if (len <= 0) { log_message(LOG_ERR, "read_request_line: Client (file descriptor: %d) closed socket before read.", connptr->client_fd); safefree(request_buffer); return NULL; } /* * Strip the new line and character return from the string. */ if (chomp(request_buffer, len) == len) { /* * If the number of characters removed is the same as the * length then it was a blank line. Free the buffer and * try again (since we're looking for a request line.) */ safefree(request_buffer); goto retry; } log_message(LOG_CONN, "Request (file descriptor %d): %s", connptr->client_fd, request_buffer); return request_buffer; } /* * This structure holds the information pulled from a URL request. */ struct request_s { char *method; char *protocol; char *host; char *path; int port; }; static void free_request_struct(struct request_s *request) { if (!request) return; safefree(request->method); safefree(request->protocol); safefree(request->host); safefree(request->path); safefree(request); } /* * Pull the information out of the URL line. */ static int extract_http_url(const char *url, struct request_s *request) { request->host = safemalloc(strlen(url) + 1); request->path = safemalloc(strlen(url) + 1); if (!request->host || !request->path) { safefree(request->host); safefree(request->path); return -1; } if (sscanf (url, "http://%[^:/]:%d%s", request->host, &request->port, request->path) == 3) ; else if (sscanf(url, "http://%[^/]%s", request->host, request->path) == 2) request->port = 80; else if (sscanf(url, "http://%[^:/]:%d", request->host, &request->port) == 2) strcpy(request->path, "/"); else if (sscanf(url, "http://%[^/]", request->host) == 1) { request->port = 80; strcpy(request->path, "/"); } else { log_message(LOG_ERR, "extract_http_url: Can't parse URL."); safefree(request->host); safefree(request->path); return -1; } return 0; } /* * Extract the URL from a SSL connection. */ static int extract_ssl_url(const char *url, struct request_s *request) { request->host = safemalloc(strlen(url) + 1); if (!request->host) return -1; if (sscanf(url, "%[^:]:%d", request->host, &request->port) == 2) ; else if (sscanf(url, "%s", request->host) == 1) request->port = 443; else { log_message(LOG_ERR, "extract_ssl_url: Can't parse URL."); safefree(request->host); return -1; } return 0; } /* * Create a connection for HTTP connections. */ static int establish_http_connection(struct conn_s *connptr, struct request_s *request) { char *buffer; buffer = safemalloc(HTTP_LINE_LENGTH); if (!buffer) return -1; if (snprintf(buffer, HTTP_LINE_LENGTH, "%s %s HTTP/1.0\r\n", request->method, request->path) < 0) goto error; if (safe_write(connptr->server_fd, buffer, strlen(buffer)) < 0) goto error; /* * Send headers */ if (snprintf(buffer, HTTP_LINE_LENGTH, "Host: %s\r\n", request->host) < 0) goto error; if (safe_write(connptr->server_fd, buffer, strlen(buffer)) < 0) goto error; /* * Send the Connection header since we don't support persistant * connections. */ if (safe_write(connptr->server_fd, "Connection: close\r\n", 19) < 0) goto error; safefree(buffer); return 0; error: safefree(buffer); return -1; } /* * These two defines are for the SSL tunnelling. */ #define SSL_CONNECTION_RESPONSE "HTTP/1.0 200 Connection established\r\n" #define PROXY_AGENT "Proxy-agent: " PACKAGE "/" VERSION "\r\n" /* * Send the appropriate response to the client to establish a SSL * connection. */ static inline int send_ssl_response(struct conn_s *connptr) { if (safe_write (connptr->client_fd, SSL_CONNECTION_RESPONSE, strlen(SSL_CONNECTION_RESPONSE)) < 0) return -1; if (safe_write(connptr->client_fd, PROXY_AGENT, strlen(PROXY_AGENT)) < 0) return -1; if (safe_write(connptr->client_fd, "\r\n", 2) < 0) return -1; return 0; } /* * Break the request line apart and figure out where to connect and * build a new request line. Finally connect to the remote server. */ static struct request_s * process_request(struct conn_s *connptr, char *request_line) { char *url; struct request_s *request; int ret; size_t request_len; /* NULL out all the fields so free's don't cause segfaults. */ request = safecalloc(1, sizeof(struct request_s)); if (!request) return NULL; request_len = strlen(request_line) + 1; request->method = safemalloc(request_len); url = safemalloc(request_len); request->protocol = safemalloc(request_len); if (!request->method || !url || !request->protocol) { safefree(url); free_request_struct(request); return NULL; } ret = sscanf(request_line, "%[^ ] %[^ ] %[^ ]", request->method, url, request->protocol); if (ret < 2) { log_message(LOG_ERR, "process_request: Bad Request on file descriptor %d", connptr->client_fd); httperr(connptr, 400, "Bad Request. No request found."); safefree(url); free_request_struct(request); return NULL; } /* * NOTE: We need to add code for the simple HTTP/0.9 style GET * request. */ if (!url) { log_message(LOG_ERR, "process_request: Null URL on file descriptor %d", connptr->client_fd); httperr(connptr, 400, "Bad Request. Null URL."); safefree(url); free_request_struct(request); return NULL; } if (strncasecmp(url, "http://", 7) == 0) { /* Make sure the first four characters are lowercase */ memcpy(url, "http", 4); if (extract_http_url(url, request) < 0) { httperr(connptr, 400, "Bad Request. Could not parse URL."); safefree(url); free_request_struct(request); return NULL; } } else if (strcmp(request->method, "CONNECT") == 0) { if (extract_ssl_url(url, request) < 0) { httperr(connptr, 400, "Bad Request. Could not parse URL."); safefree(url); free_request_struct(request); return NULL; } connptr->connect_method = TRUE; } else { log_message(LOG_ERR, "process_request: Unknown URL type on file descriptor %d", connptr->client_fd); httperr(connptr, 400, "Bad Request. Unknown URL type."); safefree(url); free_request_struct(request); return NULL; } safefree(url); #ifdef FILTER_ENABLE /* * Filter restricted domains */ if (config.filter) { if (filter_url(request->host)) { update_stats(STAT_DENIED); log_message(LOG_NOTICE, "Proxying refused on filtered domain \"%s\"", request->host); httperr(connptr, 404, "Connection to filtered domain is now allowed."); free_request_struct(request); return NULL; } } #endif /* * Check to see if they're requesting the stat host */ if (config.stathost && strcmp(config.stathost, request->host) == 0) { log_message(LOG_NOTICE, "Request for the stathost."); free_request_struct(request); showstats(connptr); return NULL; } /* * Break apart the protocol and update the connection structure. */ if (strncasecmp(request->protocol, "http", 4) == 0) { memcpy(request->protocol, "HTTP", 4); sscanf(request->protocol, "HTTP/%u.%u", &connptr->protocol.major, &connptr->protocol.minor); } return request; } /* * Check to see if the line is allowed or not depending on the anonymous * headers which are to be allowed. If the header is found in the * anonymous list return 0, otherwise return -1. */ static int compare_header(char *line) { char *buffer; char *ptr; int ret; if ((ptr = strstr(line, ":")) == NULL) return -1; if ((buffer = safemalloc(ptr - line + 1)) == NULL) return -1; memcpy(buffer, line, (size_t) (ptr - line)); buffer[ptr - line] = '\0'; ret = anonymous_search(buffer); safefree(buffer); return ret; } /* * pull_client_data is used to pull across any client data (like in a * POST) which needs to be handled before an error can be reported, or * server headers can be processed. * - rjkaes */ static int pull_client_data(struct conn_s *connptr, unsigned long int length) { char *buffer; ssize_t len; buffer = safemalloc(MAXBUFFSIZE); if (!buffer) return -1; do { len = safe_read(connptr->client_fd, buffer, min(MAXBUFFSIZE, length)); if (len <= 0) { safefree(buffer); return -1; } if (!connptr->send_response_message) { if (safe_write(connptr->server_fd, buffer, len) < 0) { safefree(buffer); return -1; } } length -= len; } while (length > 0); safefree(buffer); return 0; } #ifdef XTINYPROXY_ENABLE /* * Add the X-Tinyproxy header to the collection of headers being sent to * the server. * -rjkaes */ static int add_xtinyproxy_header(struct conn_s *connptr) { char ipaddr[PEER_IP_LENGTH]; char xtinyproxy[32]; int length; /* * Don't try to send if we have an invalid server handle. */ if (connptr->server_fd == -1) return 0; length = snprintf(xtinyproxy, sizeof(xtinyproxy), "X-Tinyproxy: %s\r\n", getpeer_ip(connptr->client_fd, ipaddr)); if (safe_write(connptr->server_fd, xtinyproxy, length) < 0) return -1; return 0; } #endif /* XTINYPROXY */ /* * Here we loop through all the headers the client is sending. If we * are running in anonymous mode, we will _only_ send the headers listed * (plus a few which are required for various methods). * - rjkaes */ static int process_client_headers(struct conn_s *connptr) { char *header; long content_length = -1; short int sent_via_header = 0; ssize_t len; static char *skipheaders[] = { "host", "connection", "keep-alive", "proxy-authenticate", "proxy-authorization", "te", "trailers", "transfer-encoding", "upgrade" }; int i; for (;;) { if ((len = readline(connptr->client_fd, &header)) <= 0) { DEBUG2("Client (file descriptor %d) closed connection.", connptr->client_fd); return -1; } /* * If we receive a CR LF (or just a LF) on a line by itself, * the headers are finished. */ if ((len == 1 && header[0] == '\n') || (len == 2 && header[0] == '\r' && header[1] == '\n')) { break; } /* * Don't send headers if there's already an error, or if * this was a CONNECT method (unless upstream proxy is in * use.) */ if (connptr->server_fd == -1 || (connptr->connect_method && !UPSTREAM_CONFIGURED())) { safefree(header); continue; } /* * If we find a Via header we need to append our information * to the end of it. */ if (strncasecmp(header, "via", 3) == 0) { char hostname[128]; char via_header_buffer[256]; char *new_header; sent_via_header = 1; gethostname(hostname, sizeof(hostname)); snprintf(via_header_buffer, sizeof(via_header_buffer), ", %hu.%hu %s (%s/%s)\r\n", connptr->protocol.major, connptr->protocol.minor, hostname, PACKAGE, VERSION); chomp(header, strlen(header)); new_header = safemalloc(strlen(header) + strlen(via_header_buffer) + 1); strcpy(new_header, header); strcat(new_header, via_header_buffer); safefree(header); header = new_header; } /* * Don't send certain headers. */ for (i = 0; i < (sizeof(skipheaders) / sizeof(char *)); i++) { if (strncasecmp (header, skipheaders[i], strlen(skipheaders[i])) == 0) { break; } } if (i != (sizeof(skipheaders) / sizeof(char *))) { safefree(header); continue; } if (is_anonymous_enabled() && compare_header(header) < 0) { safefree(header); continue; } if (content_length == -1 && strncasecmp(header, "content-length", 14) == 0) { char *content_ptr = strchr(header, ':') + 1; content_length = atol(content_ptr); } if (safe_write(connptr->server_fd, header, strlen(header)) < 0) { safefree(header); return -1; } safefree(header); } if (!connptr->send_response_message && (!connptr->connect_method || UPSTREAM_CONFIGURED())) { #ifdef XTINYPROXY_ENABLE if (config.my_domain && add_xtinyproxy_header(connptr) < 0) { safefree(header); return -1; } #endif /* XTINYPROXY */ if (sent_via_header == 0) { /* * We're the first proxy so send the first Via header. */ char via_header_buffer[256]; char hostname[128]; gethostname(hostname, sizeof(hostname)); snprintf(via_header_buffer, sizeof(via_header_buffer), "Via: %hu.%hu %s (%s/%s)\r\n", connptr->protocol.major, connptr->protocol.minor, hostname, PACKAGE, VERSION); safe_write(connptr->server_fd, via_header_buffer, strlen(via_header_buffer)); } if ((connptr->server_fd != -1) && safe_write(connptr->server_fd, header, strlen(header)) < 0) { safefree(header); return -1; } } safefree(header); /* * Spin here pulling the data from the client. */ if (content_length >= 0) return pull_client_data(connptr, (unsigned long int) content_length); else return 0; } /* * Loop through all the headers (including the response code) from the * server. */ static int process_server_headers(struct conn_s *connptr) { char *header; for (;;) { if (readline(connptr->server_fd, &header) <= 0) { DEBUG2("Server (file descriptor %d) closed connection.", connptr->server_fd); return -1; } if (header[0] == '\n' || (header[0] == '\r' && header[1] == '\n')) { break; } if (safe_write(connptr->client_fd, header, strlen(header)) < 0) { safefree(header); return -1; } } if (safe_write(connptr->client_fd, header, strlen(header)) < 0) { safefree(header); return -1; } safefree(header); return 0; } /* * Switch the sockets into nonblocking mode and begin relaying the bytes * between the two connections. We continue to use the buffering code * since we want to be able to buffer a certain amount for slower * connections (as this was the reason why I originally modified * tinyproxy oh so long ago...) * - rjkaes */ static void relay_connection(struct conn_s *connptr) { fd_set rset, wset; struct timeval tv; time_t last_access; int ret; double tdiff; int maxfd = max(connptr->client_fd, connptr->server_fd) + 1; socket_nonblocking(connptr->client_fd); socket_nonblocking(connptr->server_fd); last_access = time(NULL); for (;;) { FD_ZERO(&rset); FD_ZERO(&wset); tv.tv_sec = config.idletimeout - difftime(time(NULL), last_access); tv.tv_usec = 0; if (BUFFER_SIZE(connptr->sbuffer) > 0) FD_SET(connptr->client_fd, &wset); if (BUFFER_SIZE(connptr->cbuffer) > 0) FD_SET(connptr->server_fd, &wset); if (BUFFER_SIZE(connptr->sbuffer) < MAXBUFFSIZE) FD_SET(connptr->server_fd, &rset); if (BUFFER_SIZE(connptr->cbuffer) < MAXBUFFSIZE) FD_SET(connptr->client_fd, &rset); ret = select(maxfd, &rset, &wset, NULL, &tv); if (ret == 0) { tdiff = difftime(time(NULL), last_access); if (tdiff > config.idletimeout) { log_message(LOG_INFO, "Idle Timeout (after select) as %g > %u.", tdiff, config.idletimeout); return; } else { continue; } } else if (ret < 0) { log_message(LOG_ERR, "relay_connection: select() error \"%s\". Closing connection (client_fd:%d, server_fd:%d)", strerror(errno), connptr->client_fd, connptr->server_fd); return; } else { /* * Okay, something was actually selected so mark it. */ last_access = time(NULL); } if (FD_ISSET(connptr->server_fd, &rset) && read_buffer(connptr->server_fd, connptr->sbuffer) < 0) { break; } if (FD_ISSET(connptr->client_fd, &rset) && read_buffer(connptr->client_fd, connptr->cbuffer) < 0) { break; } if (FD_ISSET(connptr->server_fd, &wset) && write_buffer(connptr->server_fd, connptr->cbuffer) < 0) { break; } if (FD_ISSET(connptr->client_fd, &wset) && write_buffer(connptr->client_fd, connptr->sbuffer) < 0) { break; } } /* * Here the server has closed the connection... write the * remainder to the client and then exit. */ socket_blocking(connptr->client_fd); while (BUFFER_SIZE(connptr->sbuffer) > 0) { if (write_buffer(connptr->client_fd, connptr->sbuffer) < 0) break; } /* * Try to send any remaining data to the server if we can. */ socket_blocking(connptr->server_fd); while (BUFFER_SIZE(connptr->cbuffer) > 0) { if (write_buffer(connptr->client_fd, connptr->cbuffer) < 0) break; } return; } #ifdef UPSTREAM_SUPPORT /* * Establish a connection to the upstream proxy server. */ static int connect_to_upstream(struct conn_s *connptr, struct request_s *request) { char *combined_string; int len; connptr->server_fd = opensock(config.upstream_name, config.upstream_port); if (connptr->server_fd < 0) { log_message(LOG_WARNING, "Could not connect to upstream proxy."); httperr(connptr, 404, "Unable to connect to upstream proxy."); return -1; } log_message(LOG_CONN, "Established connection to upstream proxy \"%s\" using file descriptor %d.", config.upstream_name, connptr->server_fd); /* * We need to re-write the "path" part of the request so that we * can reuse the establish_http_connection() function. It expects a * method and path. */ if (connptr->connect_method) { len = strlen(request->host) + 6; combined_string = safemalloc(len + 1); if (!combined_string) { return -1; } snprintf(combined_string, len, "%s:%d", request->host, request->port); } else { len = strlen(request->host) + strlen(request->path) + 14; combined_string = safemalloc(len + 1); if (!combined_string) { return -1; } snprintf(combined_string, len, "http://%s:%d%s", request->host, request->port, request->path); } safefree(request->path); request->path = combined_string; return establish_http_connection(connptr, request); } #endif /* * This is the main drive for each connection. As you can tell, for the * first few steps we are using a blocking socket. If you remember the * older tinyproxy code, this use to be a very confusing state machine. * Well, no more! :) The sockets are only switched into nonblocking mode * when we start the relay portion. This makes most of the original * tinyproxy code, which was confusing, redundant. Hail progress. * - rjkaes */ void handle_connection(int fd) { struct conn_s *connptr; struct request_s *request = NULL; char peer_ipaddr[PEER_IP_LENGTH]; char peer_string[PEER_STRING_LENGTH]; char *request_line = NULL; log_message(LOG_CONN, "Connect (file descriptor %d): %s [%s]", fd, getpeer_string(fd, peer_string), getpeer_ip(fd, peer_ipaddr)); connptr = safemalloc(sizeof(struct conn_s)); if (!connptr) return; initialize_conn(connptr); connptr->client_fd = fd; if (check_acl(fd) <= 0) { update_stats(STAT_DENIED); httperr(connptr, 403, "You do not have authorization for using this service."); goto send_error; } #ifdef TUNNEL_SUPPORT /* * If tunnel has been configured then redirect any connections to * it. I know I used GOTOs, but it seems to me to be the best way * of handling this situations. So sue me. :) * - rjkaes */ if (config.tunnel_name && config.tunnel_port != -1) { char *request_buf; size_t len; int pos; request_buf = safemalloc(HTTP_LINE_LENGTH); if (request_buf) { len = recv(connptr->client_fd, request_buf, HTTP_LINE_LENGTH - 1, MSG_PEEK); for (pos = 0; pos < len && request_buf[pos] != '\n'; pos++) ; request_buf[pos] = '\0'; log_message(LOG_CONN, "Request: %s", request_buf); safefree(request_buf); } log_message(LOG_INFO, "Redirecting to %s:%d", config.tunnel_name, config.tunnel_port); connptr->server_fd = opensock(config.tunnel_name, config.tunnel_port); if (connptr->server_fd < 0) { log_message(LOG_WARNING, "Could not connect to tunnel."); httperr(connptr, 404, "Unable to connect to tunnel."); goto internal_proxy; } log_message(LOG_INFO, "Established a connection to the tunnel \"%s\" using file descriptor %d.", config.tunnel_name, connptr->server_fd); /* * I know GOTOs are evil, but duplicating the code is even * more evil. * - rjkaes */ goto relay_proxy; } #endif /* TUNNEL_SUPPORT */ internal_proxy: request_line = read_request_line(connptr); if (!request_line) { update_stats(STAT_BADCONN); destroy_conn(connptr); return; } request = process_request(connptr, request_line); safefree(request_line); if (!request) { if (!connptr->send_response_message) { update_stats(STAT_BADCONN); destroy_conn(connptr); return; } goto send_error; } if (UPSTREAM_CONFIGURED()) { if (connect_to_upstream(connptr, request) < 0) goto send_error; } else { connptr->server_fd = opensock(request->host, request->port); if (connptr->server_fd < 0) { httperr(connptr, 500, HTTP500ERROR); goto send_error; } log_message(LOG_CONN, "Established connection to host \"%s\" using file descriptor %d.", request->host, connptr->server_fd); if (!connptr->connect_method) establish_http_connection(connptr, request); } send_error: free_request_struct(request); if (process_client_headers(connptr) < 0) { update_stats(STAT_BADCONN); if (!connptr->send_response_message) { destroy_conn(connptr); return; } } if (connptr->send_response_message) { destroy_conn(connptr); return; } if (!connptr->connect_method || UPSTREAM_CONFIGURED()) { if (process_server_headers(connptr) < 0) { update_stats(STAT_BADCONN); destroy_conn(connptr); return; } } else { if (send_ssl_response(connptr) < 0) { log_message(LOG_ERR, "handle_connection: Could not send SSL greeting to client."); update_stats(STAT_BADCONN); destroy_conn(connptr); return; } } relay_proxy: relay_connection(connptr); /* * All done... close everything and go home... :) */ destroy_conn(connptr); return; }