Proxy Error

/***************************************************************************** * $Id: proxydemo.c * * Example application source code using the libcurl multi socket interface * with a glib event loop to create a basic http proxy server. * * Written by Jeff Pohlmeyer * * Tested with libcurl-7.16.0 and glib-2.12.4 on SuSE-10.1 * * This demo implements a very crude local-proxy server, it supports only * http GET and simple form POST (NOT multipart/formdata or chunked!). * It also does NOT support https, ftp, content-encoded data, etc... * * NOTE: The request-header parser is fairly primitive, it is NOT intended * to be used as a public proxy for untrusted clients! * * Compile with: * gcc -g -Wall `pkg-config glib-2.0 libcurl --libs --cflags` \ * proxydemo.c -o proxydemo * * To test, start the application with the desired [port] or [address:port], * and point your browser's http-proxy setting to it. * For instance: * proxydemo 127.0.0.1:8080 */ #include #include #include #include #include #include #include #ifdef __WIN32__ # define IO_CHANNEL_NEW g_io_channel_win32_new_socket #else # include # include # define IO_CHANNEL_NEW g_io_channel_unix_new #endif #define MAX_PENDING_CONNECTIONS 256 /* Global information, common to all connections */ typedef struct _GlobalInfo { CURLM *multi; guint timer_event; int prev_running; int still_running; } GlobalInfo; /* Information associated with a specific easy handle */ typedef struct _ConnInfo { CURL *easy; char *url; GlobalInfo *global; char error[CURL_ERROR_SIZE]; int client_fd; GIOChannel *client_ch; struct curl_slist* request_hdr; gsize post_len; gsize post_left; } ConnInfo; /* Information associated with a specific socket */ typedef struct _SockInfo { GIOChannel *ch; guint watch_id; gboolean watching; GlobalInfo *global; } SockInfo; /* Sends data to the client */ guint write_client(int sock, char *buf, guint size) { int rv; guint rem=size; guint Result=0; char *p=buf; do { rv=send(sock, p, rem, 0); if ( rv >= 0 ) { Result+=rv; if (Result>=size) { return Result; } p += rv; rem -= rv; } else { g_printerr("write_client(): error on socket #%d:%s\n", sock, strerror(errno)); return Result; } } while(1); } /* Sends a null-terminated string to client */ static gboolean write_client_str(int sock, char *str) { size_t len; if (!str) { return FALSE;} len = strlen(str); return (write_client(sock,str,len) == len)?TRUE:FALSE; } /* Sends a brief error page to the client */ static gboolean send_error_page(int sock, char *url, char *err){ return ( write_client_str(sock, "Proxy Error\

Proxy Error

\ While attempting to retrieve: ") && write_client_str(sock, url) && write_client_str(sock, "
The following error was encountered:
") && write_client_str(sock, err) && write_client_str(sock, "

libcurl proxy demo program\n") ); } /* g_slist_foreach callback to free element data */ static void free_header_cb(gpointer data, gpointer user_data) { if (data) g_free(data); } /* Shutdown the channel, report any error, and close the socket */ static void shutdown_channel(GIOChannel*ch) { GError *err=NULL; int fd; if (!ch) return; fd=g_io_channel_unix_get_fd(ch); g_io_channel_shutdown(ch, TRUE, &err); if ( (err) && (err->message) ) { g_critical("Error on channel shutdown:%s\n", err->message); } g_io_channel_unref(ch); if (fd >= 0) close(fd); } /* Free all data in a ConnInfo struct */ static void conn_info_free(ConnInfo *conn) { if (!conn) return; shutdown_channel(conn->client_ch); if (conn->url) { g_free(conn->url);} g_slist_foreach((GSList*)(conn->request_hdr), free_header_cb, NULL); g_slist_free((GSList*)(conn->request_hdr)); if (conn->easy) { curl_easy_cleanup(conn->easy); } g_free(conn); } /* Check for completed transfers, and remove their easy handles */ static void check_run_count(GlobalInfo *gi) { if ((gi->prev_running > gi->still_running)||(0==gi->still_running)){ char *eff_url=NULL; CURLMsg *msg; int msgs_left; ConnInfo *conn=NULL; CURL*easy; CURLcode res; do { easy=NULL; while ((msg = curl_multi_info_read(gi->multi, &msgs_left))) { if (msg->msg == CURLMSG_DONE) { easy=msg->easy_handle; res=msg->data.result; break; } } if (easy) { curl_easy_getinfo(easy, CURLINFO_PRIVATE, &conn); curl_easy_getinfo(easy, CURLINFO_EFFECTIVE_URL, &eff_url); g_print("DONE: %s => (%d) %s\n", eff_url, res, conn->error); curl_multi_remove_handle(gi->multi, easy); switch (res) { case CURLE_OK: break; case CURLE_WRITE_ERROR: break; /* Pipe broke, can't talk to client */ case CURLE_ABORTED_BY_CALLBACK: break;/* Probably also broken pipe */ case CURLE_COULDNT_RESOLVE_PROXY: case CURLE_COULDNT_RESOLVE_HOST: case CURLE_COULDNT_CONNECT: /* Upstream connection failed */ write_client_str(conn->client_fd, "HTTP/1.1 502 Bad Gateway\r\n\r\n"); default: send_error_page(conn->client_fd, conn->url, conn->error); } conn_info_free(conn); } } while (easy); g_print( "Remaining:%d\n", gi->still_running ); } gi->prev_running = gi->still_running; } /* Die if we get a bad CURLMcode somewhere */ void mcode_or_die(CURLMcode code, char *where) { if ( CURLM_OK != code ) { char *s; switch (code) { case CURLM_CALL_MULTI_PERFORM: s="CURLM_CALL_MULTI_PERFORM"; break; case CURLM_OK: s="CURLM_OK"; break; case CURLM_BAD_HANDLE: s="CURLM_BAD_HANDLE"; break; case CURLM_BAD_EASY_HANDLE: s="CURLM_BAD_EASY_HANDLE"; break; case CURLM_OUT_OF_MEMORY: s="CURLM_OUT_OF_MEMORY"; break; case CURLM_INTERNAL_ERROR: s="CURLM_INTERNAL_ERROR"; break; case CURLM_BAD_SOCKET: s="CURLM_BAD_SOCKET"; break; case CURLM_UNKNOWN_OPTION: s="CURLM_UNKNOWN_OPTION"; break; case CURLM_LAST: s="CURLM_LAST"; break; default: s="CURLM_unknown"; } g_printerr("ERROR: %s returns %s\n", where, s); exit(code); } } /* Called by glib when our timeout expires */ static gboolean timer_cb(gpointer data) { GlobalInfo *gi = (GlobalInfo *)data; CURLMcode rc; do { rc = curl_multi_socket(gi->multi, CURL_SOCKET_TIMEOUT, &gi->still_running); } while (rc == CURLM_CALL_MULTI_PERFORM); mcode_or_die(rc, "timer_cb"); check_run_count(gi); return FALSE; } /* CURLMOPT_TIMERFUNCTION */ static int update_timeout_cb(CURLM *multi, long timeout_ms, void *userp) { GlobalInfo *gi=(GlobalInfo *)userp; gi->timer_event = g_timeout_add(timeout_ms, timer_cb, gi); return 0; } /* Called by glib when we get action on a multi socket */ static gboolean event_cb(GIOChannel *ch, GIOCondition cond, gpointer data) { GlobalInfo *gi = (GlobalInfo*) data; CURLMcode rc; int fd=g_io_channel_unix_get_fd(ch); (void) cond; do { rc = curl_multi_socket(gi->multi, fd, &gi->still_running); } while (rc == CURLM_CALL_MULTI_PERFORM); mcode_or_die(rc, "event_cb"); check_run_count(gi); if(gi->still_running) { return TRUE; } else { g_print("Last transfer done, kill timeout\n"); if (gi->timer_event) { g_source_remove(gi->timer_event); } return FALSE; } } /* Assign information to a SockInfo structure */ static void setsock(SockInfo*si,curl_socket_t s,CURL*e,int act,GlobalInfo*gi) { GIOCondition kind = (act&CURL_POLL_IN?G_IO_IN:0)|(act&CURL_POLL_OUT?G_IO_OUT:0); if (si->watching) { g_source_remove(si->watch_id); } si->watch_id=g_io_add_watch(si->ch, kind, event_cb, gi); si->watching=TRUE; } /* Initialize a new SockInfo structure */ static void addsock(curl_socket_t s, CURL *easy, int action, GlobalInfo *gi) { SockInfo *si = g_malloc0(sizeof(SockInfo)); si->global = gi; si->ch=IO_CHANNEL_NEW(s); setsock(si, s, easy, action, gi); curl_multi_assign(gi->multi, s, si); } /* CURLMOPT_SOCKETFUNCTION */ static int sock_cb(CURL*e, curl_socket_t s, int what, void*cbp, void*sockp) { GlobalInfo *gi = (GlobalInfo*) cbp; SockInfo *si = (SockInfo*) sockp; if (CURL_POLL_REMOVE == what) { if (si) { if (si->watching) { g_source_remove(si->watch_id); } g_free(si); } } else { if (!si) { addsock(s, e, what, gi); } else { setsock(si, s, e, what, gi); } } return 0; } /* CURLOPT_WRITEFUNCTION */ static size_t write_cb(void *ptr, size_t size, size_t nmemb, void *user_data) { size_t Result = size * nmemb; ConnInfo *conn = (ConnInfo*) user_data; return write_client(conn->client_fd, ptr, Result); } #define MatchHeader(s1,s2,n)((strncasecmp(s1,s2,n)==0)&&(s1[n]==':')) /* CURLOPT_HEADERFUNCTION */ size_t header_cb(char *hdr, size_t size, size_t nmemb, void *data) { size_t Result = size * nmemb; ConnInfo *conn = (ConnInfo*) data; /* Curl handles the encodings, so don't report them to the client... */ if ( MatchHeader(hdr, "Content-Encoding", 16) || MatchHeader(hdr, "Transfer-Encoding", 17) ) { return Result; } return write_client(conn->client_fd, hdr, Result); } /* CURLOPT_READFUNCTION (for POST data only) */ static size_t read_cb(void*outbuf, size_t size, size_t nmemb, void *userp){ ConnInfo *conn = (ConnInfo*)userp; GError *err=NULL; size_t buf_avail=size*nmemb; size_t ask_for=(conn->post_left>buf_avail)?buf_avail:conn->post_left; size_t got_from_client=0; if (ask_for) { GIOStatus rv; rv=g_io_channel_read_chars( conn->client_ch, outbuf, ask_for, &got_from_client, &err); if (G_IO_STATUS_NORMAL != rv) { if (err && err->message) { g_printerr("*** Warning: Reading POST data: %s\n", err->message); return CURL_READFUNC_ABORT; } } conn->post_left -= got_from_client; } return got_from_client; } /* Create a new easy handle, and add it to the global curl_multi */ void new_conn( char*url, GSList*hdr, gsize postlen, char meth, GIOChannel*ch,GlobalInfo*gi) { ConnInfo *conn = g_malloc0(sizeof(ConnInfo)); CURLMcode rc; conn->post_len=postlen; conn->post_left=postlen; conn->client_ch=ch; conn->client_fd=g_io_channel_unix_get_fd(ch); conn->error[0]='\0'; conn->global = gi; conn->url = url; conn->request_hdr = (struct curl_slist *)hdr; conn->easy = curl_easy_init(); g_assert(conn->easy); curl_easy_setopt(conn->easy, CURLOPT_VERBOSE, 0); curl_easy_setopt(conn->easy, CURLOPT_URL, conn->url); curl_easy_setopt(conn->easy, CURLOPT_FOLLOWLOCATION, 0); curl_easy_setopt(conn->easy, CURLOPT_HTTPHEADER, conn->request_hdr); curl_easy_setopt(conn->easy, CURLOPT_ERRORBUFFER, conn->error); curl_easy_setopt(conn->easy, CURLOPT_PRIVATE, conn); curl_easy_setopt(conn->easy, CURLOPT_HEADERFUNCTION, header_cb); curl_easy_setopt(conn->easy, CURLOPT_HEADERDATA, conn); if ('H'==meth) { curl_easy_setopt(conn->easy, CURLOPT_NOBODY, TRUE); } else { curl_easy_setopt(conn->easy, CURLOPT_WRITEFUNCTION, write_cb); curl_easy_setopt(conn->easy, CURLOPT_WRITEDATA, conn); if ('P'==meth) { curl_easy_setopt(conn->easy, CURLOPT_POST, 1); curl_easy_setopt(conn->easy, CURLOPT_POSTFIELDSIZE, conn->post_len); curl_easy_setopt(conn->easy, CURLOPT_READFUNCTION, read_cb); curl_easy_setopt(conn->easy, CURLOPT_READDATA, conn); g_print("POST: len=%d\n",postlen); } } curl_easy_setopt(conn->easy, CURLOPT_CONNECTTIMEOUT, 120); curl_easy_setopt(conn->easy, CURLOPT_LOW_SPEED_LIMIT, 1); curl_easy_setopt(conn->easy, CURLOPT_LOW_SPEED_TIME, 120); g_print("START: %s\n", url); rc =curl_multi_add_handle(gi->multi, conn->easy); mcode_or_die(rc, "new_conn::add_handle"); do { rc = curl_multi_socket_all(gi->multi, &gi->still_running); } while (CURLM_CALL_MULTI_PERFORM == rc); mcode_or_die(rc, "new_conn::socket_all"); check_run_count(gi); } /* g_slist_find_custom() callback to find matching header name */ gint find_header_cb(char *list_data, char *user_data){ if (list_data && user_data){ return MatchHeader(list_data, user_data, strlen(user_data))?0:1; } else { return -1; } } /* Search header list for the given name and return a pointer to the value on the right of the colon and white space. Returns NULL if empty or not found */ static char*get_header_value(GSList *HeaderList, char*name) { char *value=NULL; GSList*hdr=g_slist_find_custom( HeaderList, name, (GCompareFunc)find_header_cb ); if (hdr && hdr->data) { value=strchr(hdr->data, ':'); if (value) { value++; while (' '==*value) { value++; } if (!*value) { value=NULL; } } } return value; } /* Clean up after bad client request headers.*/ static gboolean request_failed(GIOChannel *ch, GSList *hdr) { shutdown_channel(ch); if (hdr) { g_slist_foreach(hdr, free_header_cb, NULL); g_slist_free(hdr); } return TRUE; } /* This gets called by glib when a client tries to connect. Note that this creates a copy of the headers, and it will keep on allocating until it finds the expected double CRLF or runs completely out of memory, so a DoS would probably be trivial. You have been warned! */ static gboolean listen_cb(GIOChannel*ch, GIOCondition condition, gpointer data) { struct sockaddr_in ClientAddr; size_t size = sizeof(ClientAddr); int ClientSocket; GIOChannel *ClientChannel; GIOStatus rv; GError *err=NULL; GSList *HeaderList=NULL, *ThisHeader; gsize ReadLen, tp, PostLength=0; char *ReadBuf, *MethodLine, *Url, *HeaderValue, *EndPtr; char MethodID; ClientSocket = accept( g_io_channel_unix_get_fd(ch), (struct sockaddr*)&ClientAddr, &size); ClientChannel = IO_CHANNEL_NEW(ClientSocket); do { rv = g_io_channel_read_line(ClientChannel,&ReadBuf,&ReadLen,&tp,&err); if (ReadBuf) { if (&ReadBuf[tp]>ReadBuf) { ReadBuf[tp]='\0'; HeaderList=g_slist_append(HeaderList, ReadBuf); } else { break; } } if (err) { g_printerr("listen_cb: %s\n", err->message); g_free(err); break; } } while ( (ReadLen&&(G_IO_STATUS_NORMAL==rv))||(G_IO_STATUS_AGAIN==rv) ); if ( (!HeaderList) || (!HeaderList->data) ) { write_client_str(ClientSocket, "HTTP/1.1 400 Bad Request\r\n\r\n"); send_error_page(ClientSocket, "[Unknown]", "400: Empty request."); return request_failed(ClientChannel,HeaderList); } MethodLine=(char*)HeaderList->data; /* Save first line of request and */ HeaderList = g_slist_remove(HeaderList, MethodLine); /* remove it from list */ if ( (strncmp(MethodLine,"GET " , 4) != 0) && (strncmp(MethodLine,"POST ", 5) != 0) && (strncmp(MethodLine,"HEAD ", 5) != 0) ) { write_client_str(ClientSocket,"HTTP/1.1 501 Method Not Implemented\r\n"); write_client_str(ClientSocket,"Allow: GET, HEAD, POST\r\n\r\n"); send_error_page(ClientSocket, MethodLine, "501: Request method not supported."); g_free(MethodLine); return request_failed(ClientChannel,HeaderList); } /* Uppercased first char of method is our "nmemonic" (G|P|H) */ MethodID=(MethodLine[0]<='Z')?MethodLine[0]:MethodLine[0]+0x20; Url=strchr(MethodLine, ' '); if (!Url) { write_client_str(ClientSocket, "HTTP/1.1 400 Bad Request\r\n\r\n"); send_error_page(ClientSocket, "[Unknown]", "400: Unable to determine the URL."); g_free(MethodLine); return request_failed(ClientChannel,HeaderList); } while ( ' ' == *Url ) { Url++; } EndPtr=strchr(Url, ' '); if (EndPtr){ *EndPtr='\0'; } /* We hope the client specifies a complete URL when talking to a proxy. */ if ( 0 == strncasecmp(Url, "http://", 7) ) { Url=g_strdup(Url); } else { /* Our resource didn't start with "http://", so we try a little harder */ char *ProtoSep=strstr(Url,"://"); if (ProtoSep && (ProtoSepdata); g_slist_free(ThisHeader); } /* If we made it this far, go get it! */ new_conn(Url, HeaderList, PostLength, MethodID, ClientChannel, data); return TRUE; } #ifndef __WIN32__ /* Unix apps get a SIGPIPE if the client closes a connection unexpectedly, so we need to trap it here... */ static void trap_sigpipe() { struct sigaction sa; sa.sa_handler = SIG_IGN; sigemptyset (&sa.sa_mask); sa.sa_flags = 0; sigaction (SIGPIPE, &sa, NULL); } #endif /* Check all curl multi sockets ocassionally, to avoid stalling. */ #define UGLY_STALLING_HACK 0 #if UGLY_STALLING_HACK static gboolean check_timer_cb(void *user_data) { GlobalInfo*gi = (GlobalInfo*)user_data; CURLMcode rc; if (gi->still_running>0) { do { rc = curl_multi_socket_all(gi->multi, &gi->still_running); } while (CURLM_CALL_MULTI_PERFORM == rc); mcode_or_die(rc, "check_timer_cb"); check_run_count(gi); } return TRUE; } #else #define check_timer_cb NULL #endif /* Show usage syntax and example and exit */ static void usage(char *AppName){ g_printerr("Usage:\n %s [address:]\n", AppName ); g_printerr("Examples:\n"); g_printerr(" %s 127.0.0.1:8080 <= specify interface\n", AppName ); g_printerr(" %s 3128 <= use any interface\n", AppName ); exit(1); } /**** MAIN ****/ int main(int argc, char **argv) { GlobalInfo *gi; GMainLoop*gmain; char *AppName, *PortStr, *EndPtr, *ListenIntf = NULL; int ListenPort = 0; int ListenSocket; struct sockaddr_in ListenAddr; GIOChannel* ListenChannel; gi=g_malloc0(sizeof(GlobalInfo)); AppName=(char *)g_basename(argv[0]); curl_global_init(CURL_GLOBAL_ALL); /* Needed for winsock init */ #ifndef __WIN32__ trap_sigpipe(); /* Don't let a SIGPIPE from the client kill us */ #endif if ((argc!=2) || (argv[1] && ('-'==argv[1][0])) ) { usage(AppName); } PortStr=strchr(argv[1], ':'); if (PortStr) { if (PortStr>argv[1]){ListenIntf=g_strndup(argv[1], PortStr-argv[1]);} PortStr++; } else {PortStr=argv[1];} ListenPort = g_ascii_strtoll(PortStr, &EndPtr, 0); if ( (!EndPtr) || (*EndPtr !='\0') ) { g_printerr("%s: PORT must be a numeric value, not \"%s\"\n", AppName, PortStr); exit(1); } if ( ( ListenPort < 1 ) || ( ListenPort > 65535 ) ) { g_printerr("%s: Error: PORT must be between 1 and 65535, got %u\n", AppName, ListenPort); exit(1); } ListenSocket=socket(AF_INET, SOCK_STREAM, 0); if (ListenSocket < 0) { g_printerr("%s: socket() failed: %s.\n", AppName, strerror(errno)); exit(1); } ListenAddr.sin_family= AF_INET; ListenAddr.sin_port=htons(ListenPort); if (ListenIntf) { ListenAddr.sin_addr.s_addr=inet_addr(ListenIntf); if (strcmp(ListenIntf, "255.255.255.255") != 0 ) { if ( INADDR_NONE == ListenAddr.sin_addr.s_addr ) { g_print( "%s: failed to convert \"%s\" to a valid address.\n", AppName, ListenIntf); exit(1); } } } else { ListenAddr.sin_addr.s_addr = htonl(INADDR_ANY); } if (bind(ListenSocket, (struct sockaddr*)&ListenAddr, sizeof(ListenAddr))<0) { g_printerr("%s: Can't bind to port %d on %s (%s)\n", AppName, ListenPort, ListenIntf?ListenIntf:"", strerror(errno)); exit(1); } if ( listen(ListenSocket,MAX_PENDING_CONNECTIONS) < 0 ) { g_printerr("%s: Unable to listen on socket #%d (%s)\n", AppName, ListenSocket, strerror(errno) ); exit(1); } ListenChannel=IO_CHANNEL_NEW(ListenSocket); if ( !ListenChannel ) { g_printerr("%s: Failed to create listener channel.\n", AppName); exit(1); } g_io_add_watch(ListenChannel,G_IO_IN,listen_cb,gi); if ( ListenIntf && ListenIntf[0] ) { g_print("%s: Listening on %s port %d\n", AppName, ListenIntf, ListenPort); } else { g_print("%s: Listening on port %d (promiscuous mode)\n", AppName, ListenPort); } gmain=g_main_loop_new(NULL,FALSE); gi->multi = curl_multi_init(); curl_multi_setopt(gi->multi, CURLMOPT_SOCKETFUNCTION, sock_cb); curl_multi_setopt(gi->multi, CURLMOPT_SOCKETDATA, gi); curl_multi_setopt(gi->multi, CURLMOPT_TIMERFUNCTION, update_timeout_cb); curl_multi_setopt(gi->multi, CURLMOPT_TIMERDATA, gi); if (check_timer_cb) g_timeout_add(5000, check_timer_cb, gi); g_main_loop_run(gmain); return 0; }