Imported Upstream version 1.3.0+dfsgupstream/1.3.0+dfsg

1 files changed, 567 insertions, 236 deletions

diff --git a/src/web_server.c b/src/web_server.c
index 0da72b5be..cf3687f3e 100644
--- a/src/web_server.c
+++ b/src/web_server.c
@@ -1,270 +1,601 @@
-#ifdef HAVE_CONFIG_H
-#include <config.h>
-#endif
-#include <unistd.h>
-#include <stdlib.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <arpa/inet.h>
-#include <errno.h>
-#include <pthread.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <netinet/tcp.h>
-#include <malloc.h>
-
 #include "common.h"
-#include "log.h"
-#include "appconfig.h"
-#include "url.h"
-#include "web_buffer.h"
-#include "web_client.h"
-#include "web_server.h"
-#include "global_statistics.h"
-#include "rrd.h"
-#include "rrd2json.h"
-#include "../config.h"
 
 int listen_backlog = LISTEN_BACKLOG;
-
-int listen_fd = -1;
+size_t listen_fds_count = 0;
+int listen_fds[MAX_LISTEN_FDS] = { [0 ... 99] = -1 };
+char *listen_fds_names[MAX_LISTEN_FDS] = { [0 ... 99] = NULL };
 int listen_port = LISTEN_PORT;
+int web_server_mode = WEB_SERVER_MODE_MULTI_THREADED;
 
 #ifdef NETDATA_INTERNAL_CHECKS
 static void log_allocations(void)
 {
-	static int mem = 0;
+    static int mem = 0;
 
-	struct mallinfo mi;
+    struct mallinfo mi;
 
-	mi = mallinfo();
-	if(mi.uordblks > mem) {
-		int clients = 0;
-		struct web_client *w;
-		for(w = web_clients; w ; w = w->next) clients++;
+    mi = mallinfo();
+    if(mi.uordblks > mem) {
+        int clients = 0;
+        struct web_client *w;
+        for(w = web_clients; w ; w = w->next) clients++;
 
-		info("Allocated memory increased from %d to %d (increased by %d bytes). There are %d web clients connected.", mem, mi.uordblks, mi.uordblks - mem, clients);
-		mem = mi.uordblks;
-	}
+        info("Allocated memory increased from %d to %d (increased by %d bytes). There are %d web clients connected.", mem, mi.uordblks, mi.uordblks - mem, clients);
+        mem = mi.uordblks;
+    }
 }
 #endif
 
-static int is_ip_anything(const char *ip)
-{
-	if(!ip || !*ip
-			|| !strcmp(ip, "any")
-			|| !strcmp(ip, "all")
-			|| !strcmp(ip, "*")
-			|| !strcmp(ip, "::")
-			|| !strcmp(ip, "0.0.0.0")
-			) return 1;
-
-	return 0;
+#ifndef HAVE_ACCEPT4
+int accept4(int sock, struct sockaddr *addr, socklen_t *addrlen, int flags) {
+    int fd = accept(sock, addr, addrlen);
+    int newflags = 0;
+
+    if (fd < 0) return fd;
+
+    if (flags & SOCK_NONBLOCK) {
+        newflags |= O_NONBLOCK;
+        flags &= ~SOCK_NONBLOCK;
+    }
+
+    if (flags & SOCK_CLOEXEC) {
+        newflags |= O_CLOEXEC;
+        flags &= ~SOCK_CLOEXEC;
+    }
+
+    if (flags) {
+        errno = -EINVAL;
+        return -1;
+    }
+
+    if (fcntl(fd, F_SETFL, newflags) < 0) {
+        int saved_errno = errno;
+        close(fd);
+        errno = saved_errno;
+        return -1;
+    }
+
+    return fd;
 }
+#endif
 
-int create_listen_socket4(const char *ip, int port, int listen_backlog)
-{
-	int sock;
-	int sockopt = 1;
-
-	debug(D_LISTENER, "IPv4 creating new listening socket on port %d", port);
-
-	sock = socket(AF_INET, SOCK_STREAM, 0);
-	if(sock < 0) {
-		error("IPv4 socket() failed.");
-		return -1;
-	}
-
-	/* avoid "address already in use" */
-	setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void*)&sockopt, sizeof(sockopt));
-
-	struct sockaddr_in name;
-	memset(&name, 0, sizeof(struct sockaddr_in));
-	name.sin_family = AF_INET;
-	name.sin_port = htons (port);
-
-	if(is_ip_anything(ip)) {
-		name.sin_addr.s_addr = htonl(INADDR_ANY);
-		info("Listening on any IPs (IPv4).");
-	}
-	else {
-		int ret = inet_pton(AF_INET, ip, (void *)&name.sin_addr.s_addr);
-		if(ret != 1) {
-			error("Failed to convert IP '%s' to a valid IPv4 address.", ip);
-			close(sock);
-			return -1;
-		}
-		info("Listening on IP '%s' (IPv4).", ip);
-	}
-
-	if(bind (sock, (struct sockaddr *) &name, sizeof (name)) < 0) {
-		close(sock);
-		error("IPv4 bind() failed.");
-		return -1;
-	}
-
-	if(listen(sock, listen_backlog) < 0) {
-		close(sock);
-		fatal("IPv4 listen() failed.");
-		return -1;
-	}
-
-	debug(D_LISTENER, "IPv4 listening port %d created", port);
-	return sock;
+int create_listen_socket4(const char *ip, int port, int listen_backlog) {
+    int sock;
+    int sockopt = 1;
+
+    debug(D_LISTENER, "IPv4 creating new listening socket on ip '%s' port %d", ip, port);
+
+    sock = socket(AF_INET, SOCK_STREAM, 0);
+    if(sock < 0) {
+        error("IPv4 socket() on ip '%s' port %d failed.", ip, port);
+        return -1;
+    }
+
+    /* avoid "address already in use" */
+    if(setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void*)&sockopt, sizeof(sockopt)) != 0)
+        error("Cannot set SO_REUSEADDR on ip '%s' port's %d.", ip, port);
+
+    struct sockaddr_in name;
+    memset(&name, 0, sizeof(struct sockaddr_in));
+    name.sin_family = AF_INET;
+    name.sin_port = htons (port);
+
+    int ret = inet_pton(AF_INET, ip, (void *)&name.sin_addr.s_addr);
+    if(ret != 1) {
+        error("Failed to convert IP '%s' to a valid IPv4 address.", ip);
+        close(sock);
+        return -1;
+    }
+
+    if(bind (sock, (struct sockaddr *) &name, sizeof (name)) < 0) {
+        close(sock);
+        error("IPv4 bind() on ip '%s' port %d failed.", ip, port);
+        return -1;
+    }
+
+    if(listen(sock, listen_backlog) < 0) {
+        close(sock);
+        fatal("IPv4 listen() on ip '%s' port %d failed.", ip, port);
+        return -1;
+    }
+
+    debug(D_LISTENER, "Listening on IPv4 ip '%s' port %d", ip, port);
+    return sock;
 }
 
-int create_listen_socket6(const char *ip, int port, int listen_backlog)
-{
-	int sock = -1;
-	int sockopt = 1;
-
-	debug(D_LISTENER, "IPv6 creating new listening socket on port %d", port);
-
-	sock = socket(AF_INET6, SOCK_STREAM, 0);
-	if (sock < 0) {
-		error("IPv6 socket() failed. Disabling IPv6.");
-		return -1;
-	}
-
-	/* avoid "address already in use" */
-	setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void*)&sockopt, sizeof(sockopt));
-
-	struct sockaddr_in6 name;
-	memset(&name, 0, sizeof(struct sockaddr_in6));
-	name.sin6_family = AF_INET6;
-	name.sin6_port = htons ((uint16_t) port);
-
-	if(is_ip_anything(ip)) {
-		name.sin6_addr = in6addr_any;
-		info("Listening on all IPs (IPv6 and IPv4)");
-	}
-	else {
-		int ret = inet_pton(AF_INET6, ip, (void *)&name.sin6_addr.s6_addr);
-		if(ret != 1) {
-			error("Failed to convert IP '%s' to a valid IPv6 address. Disabling IPv6.", ip);
-			close(sock);
-			return -1;
-		}
-		info("Listening on IP '%s' (IPv6)", ip);
-	}
-
-	name.sin6_scope_id = 0;
-
-	if (bind (sock, (struct sockaddr *) &name, sizeof (name)) < 0) {
-		close(sock);
-		error("IPv6 bind() failed. Disabling IPv6.");
-		return -1;
-	}
-
-	if (listen(sock, listen_backlog) < 0) {
-		close(sock);
-		error("IPv6 listen() failed. Disabling IPv6.");
-		return -1;
-	}
-
-	debug(D_LISTENER, "IPv6 listening port %d created", port);
-	return sock;
+int create_listen_socket6(const char *ip, int port, int listen_backlog) {
+    int sock = -1;
+    int sockopt = 1;
+    int ipv6only = 1;
+
+    debug(D_LISTENER, "IPv6 creating new listening socket on ip '%s' port %d", ip, port);
+
+    sock = socket(AF_INET6, SOCK_STREAM, 0);
+    if (sock < 0) {
+        error("IPv6 socket() on ip '%s' port %d failed.", ip, port);
+        return -1;
+    }
+
+    /* avoid "address already in use" */
+    if(setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void*)&sockopt, sizeof(sockopt)) != 0)
+        error("Cannot set SO_REUSEADDR on ip '%s' port's %d.", ip, port);
+
+    /* IPv6 only */
+    if(setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, (void*)&ipv6only, sizeof(ipv6only)) != 0)
+        error("Cannot set IPV6_V6ONLY on ip '%s' port's %d.", ip, port);
+
+    struct sockaddr_in6 name;
+    memset(&name, 0, sizeof(struct sockaddr_in6));
+    name.sin6_family = AF_INET6;
+    name.sin6_port = htons ((uint16_t) port);
+
+    int ret = inet_pton(AF_INET6, ip, (void *)&name.sin6_addr.s6_addr);
+    if(ret != 1) {
+        error("Failed to convert IP '%s' to a valid IPv6 address.", ip);
+        close(sock);
+        return -1;
+    }
+
+    name.sin6_scope_id = 0;
+
+    if (bind (sock, (struct sockaddr *) &name, sizeof (name)) < 0) {
+        close(sock);
+        error("IPv6 bind() on ip '%s' port %d failed.", ip, port);
+        return -1;
+    }
+
+    if (listen(sock, listen_backlog) < 0) {
+        close(sock);
+        error("IPv6 listen() on ip '%s' port %d failed.", ip, port);
+        return -1;
+    }
+
+    debug(D_LISTENER, "Listening on IPv6 ip '%s' port %d", ip, port);
+    return sock;
+}
+
+static inline int add_listen_socket(int fd, const char *ip, int port) {
+    if(listen_fds_count >= MAX_LISTEN_FDS) {
+        error("Too many listening sockets. Failed to add listening socket at ip '%s' port %d", ip, port);
+        close(fd);
+        return -1;
+    }
+
+    listen_fds[listen_fds_count] = fd;
+
+    char buffer[100 + 1];
+    snprintfz(buffer, 100, "[%s]:%d", ip, port);
+    listen_fds_names[listen_fds_count] = strdupz(buffer);
+
+    listen_fds_count++;
+    return 0;
+}
+
+int is_listen_socket(int fd) {
+    size_t i;
+    for(i = 0; i < listen_fds_count ;i++)
+        if(listen_fds[i] == fd) return 1;
+
+    return 0;
+}
+
+static inline void close_listen_sockets(void) {
+    size_t i;
+    for(i = 0; i < listen_fds_count ;i++) {
+        close(listen_fds[i]);
+        listen_fds[i] = -1;
+
+        freez(listen_fds_names[i]);
+        listen_fds_names[i] = NULL;
+    }
+
+    listen_fds_count = 0;
+}
+
+static inline int bind_to_one(const char *definition, int default_port, int listen_backlog) {
+    int added = 0;
+    struct addrinfo hints;
+    struct addrinfo *result = NULL, *rp = NULL;
+
+    char buffer[strlen(definition) + 1];
+    strcpy(buffer, definition);
+
+    char buffer2[10 + 1];
+    snprintfz(buffer2, 10, "%d", default_port);
+
+    char *ip = buffer, *port = buffer2;
+
+    char *e = ip;
+    if(*e == '[') {
+        e = ++ip;
+        while(*e && *e != ']') e++;
+        if(*e == ']') {
+            *e = '\0';
+            e++;
+        }
+    }
+    else {
+        while(*e && *e != ':') e++;
+    }
+
+    if(*e == ':') {
+        port = e + 1;
+        *e = '\0';
+    }
+
+    if(!*ip || *ip == '*' || !strcmp(ip, "any") || !strcmp(ip, "all"))
+        ip = NULL;
+    if(!*port)
+        port = buffer2;
+
+    memset(&hints, 0, sizeof(struct addrinfo));
+    hints.ai_family = AF_UNSPEC;    /* Allow IPv4 or IPv6 */
+    hints.ai_socktype = SOCK_DGRAM; /* Datagram socket */
+    hints.ai_flags = AI_PASSIVE;    /* For wildcard IP address */
+    hints.ai_protocol = 0;          /* Any protocol */
+    hints.ai_canonname = NULL;
+    hints.ai_addr = NULL;
+    hints.ai_next = NULL;
+
+    int r = getaddrinfo(ip, port, &hints, &result);
+    if (r != 0) {
+        error("getaddrinfo('%s', '%s'): %s\n", ip, port, gai_strerror(r));
+        return -1;
+    }
+
+    for (rp = result; rp != NULL; rp = rp->ai_next) {
+        int fd = -1;
+
+        char rip[INET_ADDRSTRLEN + INET6_ADDRSTRLEN] = "INVALID";
+        int rport = default_port;
+
+        switch (rp->ai_addr->sa_family) {
+            case AF_INET: {
+                struct sockaddr_in *sin = (struct sockaddr_in *) rp->ai_addr;
+                inet_ntop(AF_INET, &sin->sin_addr, rip, INET_ADDRSTRLEN);
+                rport = ntohs(sin->sin_port);
+                fd = create_listen_socket4(rip, rport, listen_backlog);
+                break;
+            }
+
+            case AF_INET6: {
+                struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) rp->ai_addr;
+                inet_ntop(AF_INET6, &sin6->sin6_addr, rip, INET6_ADDRSTRLEN);
+                rport = ntohs(sin6->sin6_port);
+                fd = create_listen_socket6(rip, rport, listen_backlog);
+                break;
+            }
+        }
+
+        if (fd == -1)
+            error("Cannot bind to ip '%s', port %d", rip, default_port);
+        else {
+            add_listen_socket(fd, rip, rport);
+            added++;
+        }
+    }
+
+    freeaddrinfo(result);
+
+    return added;
 }
 
+int create_listen_sockets(void) {
+    listen_backlog = (int) config_get_number("global", "http port listen backlog", LISTEN_BACKLOG);
+
+    if(config_exists("global", "bind socket to IP") && !config_exists("global", "bind to"))
+        config_rename("global", "bind socket to IP", "bind to");
+
+    if(config_exists("global", "port") && !config_exists("global", "default port"))
+        config_rename("global", "port", "default port");
+
+    listen_port = (int) config_get_number("global", "default port", LISTEN_PORT);
+    if(listen_port < 1 || listen_port > 65535) {
+        error("Invalid listen port %d given. Defaulting to %d.", listen_port, LISTEN_PORT);
+        listen_port = (int) config_set_number("global", "default port", LISTEN_PORT);
+    }
+    debug(D_OPTIONS, "Default listen port set to %d.", listen_port);
+
+    char *s = config_get("global", "bind to", "*");
+    while(*s) {
+        char *e = s;
+
+        // skip separators, moving both s(tart) and e(nd)
+        while(isspace(*e) || *e == ',') s = ++e;
+
+        // move e(nd) to the first separator
+        while(*e && !isspace(*e) && *e != ',') e++;
+
+        // is there anything?
+        if(!*s || s == e) break;
+
+        char buf[e - s + 1];
+        strncpyz(buf, s, e - s);
+        bind_to_one(buf, listen_port, listen_backlog);
+
+        s = e;
+    }
+
+    if(!listen_fds_count)
+        fatal("Cannot listen on any socket. Exiting...");
+
+    return (int)listen_fds_count;
+}
 
 // --------------------------------------------------------------------------------------
 // the main socket listener
 
+static inline void cleanup_web_clients(void) {
+    struct web_client *w;
+
+    for (w = web_clients; w;) {
+        if (w->obsolete) {
+            debug(D_WEB_CLIENT, "%llu: Removing client.", w->id);
+            // pthread_cancel(w->thread);
+            // pthread_join(w->thread, NULL);
+            w = web_client_free(w);
+#ifdef NETDATA_INTERNAL_CHECKS
+            log_allocations();
+#endif
+        }
+        else w = w->next;
+    }
+}
+
 // 1. it accepts new incoming requests on our port
 // 2. creates a new web_client for each connection received
 // 3. spawns a new pthread to serve the client (this is optimal for keep-alive clients)
 // 4. cleans up old web_clients that their pthreads have been exited
 
-void *socket_listen_main(void *ptr)
-{
-	if(ptr) { ; }
-
-	info("WEB SERVER thread created with task id %d", gettid());
-
-	struct web_client *w;
-	struct timeval tv;
-	int retval;
-
-	if(ptr) { ; }
-
-	if(pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL) != 0)
-		error("Cannot set pthread cancel type to DEFERRED.");
-
-	if(pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL) != 0)
-		error("Cannot set pthread cancel state to ENABLE.");
-
-	web_client_timeout = (int) config_get_number("global", "disconnect idle web clients after seconds", DEFAULT_DISCONNECT_IDLE_WEB_CLIENTS_AFTER_SECONDS);
-	web_enable_gzip = config_get_boolean("global", "enable web responses gzip compression", web_enable_gzip);
-
-	if(listen_fd < 0) fatal("LISTENER: Listen socket is not ready.");
-
-	fd_set ifds, ofds, efds;
-	int fdmax = listen_fd;
-
-	FD_ZERO (&ifds);
-	FD_ZERO (&ofds);
-	FD_ZERO (&efds);
-
-	for(;;) {
-		tv.tv_sec = 0;
-		tv.tv_usec = 200000;
-
-		if(listen_fd >= 0) {
-			FD_SET(listen_fd, &ifds);
-			FD_SET(listen_fd, &efds);
-		}
-
-		// debug(D_WEB_CLIENT, "LISTENER: Waiting...");
-		retval = select(fdmax+1, &ifds, &ofds, &efds, &tv);
-
-		if(retval == -1) {
-			error("LISTENER: select() failed.");
-			continue;
-		}
-		else if(retval) {
-			// check for new incoming connections
-			if(FD_ISSET(listen_fd, &ifds)) {
-				w = web_client_create(listen_fd);
-				if(unlikely(!w)) {
-					// no need for error log - web_client_create already logged the error
-					continue;
-				}
-
-				if(pthread_create(&w->thread, NULL, web_client_main, w) != 0) {
-					error("%llu: failed to create new thread for web client.");
-					w->obsolete = 1;
-				}
-				else if(pthread_detach(w->thread) != 0) {
-					error("%llu: Cannot request detach of newly created web client thread.", w->id);
-					w->obsolete = 1;
-				}
-			}
-			else debug(D_WEB_CLIENT, "LISTENER: select() didn't do anything.");
-
-		}
-		//else {
-		//	debug(D_WEB_CLIENT, "LISTENER: select() timeout.");
-		//}
-
-		// cleanup unused clients
-		for(w = web_clients; w ; w = w?w->next:NULL) {
-			if(w->obsolete) {
-				debug(D_WEB_CLIENT, "%llu: Removing client.", w->id);
-				// pthread_join(w->thread,  NULL);
-				w = web_client_free(w);
-#ifdef NETDATA_INTERNAL_CHECKS
-				log_allocations();
-#endif
-			}
-		}
-	}
+#define CLEANUP_EVERY_EVENTS 100
+
+void *socket_listen_main_multi_threaded(void *ptr) {
+    (void)ptr;
+
+    web_server_mode = WEB_SERVER_MODE_MULTI_THREADED;
+    info("Multi-threaded WEB SERVER thread created with task id %d", gettid());
+
+    struct web_client *w;
+    int retval, counter = 0;
+
+    if(pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL) != 0)
+        error("Cannot set pthread cancel type to DEFERRED.");
+
+    if(pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL) != 0)
+        error("Cannot set pthread cancel state to ENABLE.");
+
+    if(!listen_fds_count)
+        fatal("LISTENER: No sockets to listen to.");
+
+    struct pollfd *fds = callocz(sizeof(struct pollfd), listen_fds_count);
+
+    size_t i;
+    for(i = 0; i < listen_fds_count ;i++) {
+        fds[i].fd = listen_fds[i];
+        fds[i].events = POLLIN;
+        fds[i].revents = 0;
+
+        info("Listening on '%s'", (listen_fds_names[i])?listen_fds_names[i]:"UNKNOWN");
+    }
+
+    int timeout = 10 * 1000;
+
+    for(;;) {
+        // debug(D_WEB_CLIENT, "LISTENER: Waiting...");
+        retval = poll(fds, listen_fds_count, timeout);
+
+        if(unlikely(retval == -1)) {
+            error("LISTENER: poll() failed.");
+            continue;
+        }
+        else if(unlikely(!retval)) {
+            debug(D_WEB_CLIENT, "LISTENER: select() timeout.");
+            counter = 0;
+            cleanup_web_clients();
+            continue;
+        }
+
+        for(i = 0 ; i < listen_fds_count ; i++) {
+            short int revents = fds[i].revents;
+
+            // check for new incoming connections
+            if(revents & POLLIN || revents & POLLPRI) {
+                fds[i].revents = 0;
+
+                w = web_client_create(fds[i].fd);
+                if(unlikely(!w)) {
+                    // no need for error log - web_client_create already logged the error
+                    continue;
+                }
+
+                if(pthread_create(&w->thread, NULL, web_client_main, w) != 0) {
+                    error("%llu: failed to create new thread for web client.", w->id);
+                    w->obsolete = 1;
+                }
+                else if(pthread_detach(w->thread) != 0) {
+                    error("%llu: Cannot request detach of newly created web client thread.", w->id);
+                    w->obsolete = 1;
+                }
+            }
+        }
+
+        // cleanup unused clients
+        counter++;
+        if(counter >= CLEANUP_EVERY_EVENTS) {
+            counter = 0;
+            cleanup_web_clients();
+        }
+    }
+
+    debug(D_WEB_CLIENT, "LISTENER: exit!");
+    close_listen_sockets();
+
+    return NULL;
+}
 
-	error("LISTENER: exit!");
+struct web_client *single_threaded_clients[FD_SETSIZE];
 
-	if(listen_fd >= 0) close(listen_fd);
-	exit(2);
+static inline int single_threaded_link_client(struct web_client *w, fd_set *ifds, fd_set *ofds, fd_set *efds, int *max) {
+    if(unlikely(w->obsolete || w->dead || (!w->wait_receive && !w->wait_send)))
+        return 1;
 
-	return NULL;
+    if(unlikely(w->ifd < 0 || w->ifd >= FD_SETSIZE || w->ofd < 0 || w->ofd >= FD_SETSIZE)) {
+        error("%llu: invalid file descriptor, ifd = %d, ofd = %d (required 0 <= fd < FD_SETSIZE (%d)", w->id, w->ifd, w->ofd, FD_SETSIZE);
+        return 1;
+    }
+
+    FD_SET(w->ifd, efds);
+    if(unlikely(*max < w->ifd)) *max = w->ifd;
+
+    if(unlikely(w->ifd != w->ofd)) {
+        if(*max < w->ofd) *max = w->ofd;
+        FD_SET(w->ofd, efds);
+    }
+
+    if(w->wait_receive) FD_SET(w->ifd, ifds);
+    if(w->wait_send)    FD_SET(w->ofd, ofds);
+
+    single_threaded_clients[w->ifd] = w;
+    single_threaded_clients[w->ofd] = w;
+
+    return 0;
 }
 
+static inline int single_threaded_unlink_client(struct web_client *w, fd_set *ifds, fd_set *ofds, fd_set *efds) {
+    FD_CLR(w->ifd, efds);
+    if(unlikely(w->ifd != w->ofd)) FD_CLR(w->ofd, efds);
+
+    if(w->wait_receive) FD_CLR(w->ifd, ifds);
+    if(w->wait_send)    FD_CLR(w->ofd, ofds);
+
+    single_threaded_clients[w->ifd] = NULL;
+    single_threaded_clients[w->ofd] = NULL;
+
+    if(unlikely(w->obsolete || w->dead || (!w->wait_receive && !w->wait_send)))
+        return 1;
+
+    return 0;
+}
+
+void *socket_listen_main_single_threaded(void *ptr) {
+    (void)ptr;
+
+    web_server_mode = WEB_SERVER_MODE_SINGLE_THREADED;
+
+    info("Single-threaded WEB SERVER thread created with task id %d", gettid());
+
+    struct web_client *w;
+    int retval;
+
+    if(pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL) != 0)
+        error("Cannot set pthread cancel type to DEFERRED.");
+
+    if(pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL) != 0)
+        error("Cannot set pthread cancel state to ENABLE.");
+
+    if(!listen_fds_count)
+        fatal("LISTENER: no listen sockets available.");
+
+    size_t i;
+    for(i = 0; i < FD_SETSIZE ; i++)
+        single_threaded_clients[i] = NULL;
+
+    fd_set ifds, ofds, efds, rifds, rofds, refds;
+    FD_ZERO (&ifds);
+    FD_ZERO (&ofds);
+    FD_ZERO (&efds);
+    int fdmax = 0;
+
+    for(i = 0; i < listen_fds_count ; i++) {
+        if (listen_fds[i] < 0 || listen_fds[i] >= FD_SETSIZE)
+            fatal("LISTENER: Listen socket %d is not ready, or invalid.", listen_fds[i]);
+
+        info("Listening on '%s'", (listen_fds_names[i])?listen_fds_names[i]:"UNKNOWN");
+
+        FD_SET(listen_fds[i], &ifds);
+        FD_SET(listen_fds[i], &efds);
+        if(fdmax < listen_fds[i])
+            fdmax = listen_fds[i];
+    }
+
+    for(;;) {
+        debug(D_WEB_CLIENT_ACCESS, "LISTENER: single threaded web server waiting (fdmax = %d)...", fdmax);
+
+        struct timeval tv = { .tv_sec = 1, .tv_usec = 0 };
+        rifds = ifds;
+        rofds = ofds;
+        refds = efds;
+        retval = select(fdmax+1, &rifds, &rofds, &refds, &tv);
+
+        if(unlikely(retval == -1)) {
+            error("LISTENER: select() failed.");
+            continue;
+        }
+        else if(likely(retval)) {
+            debug(D_WEB_CLIENT_ACCESS, "LISTENER: got something.");
+
+            for(i = 0; i < listen_fds_count ; i++) {
+                if (FD_ISSET(listen_fds[i], &rifds)) {
+                    debug(D_WEB_CLIENT_ACCESS, "LISTENER: new connection.");
+                    w = web_client_create(listen_fds[i]);
+                    if (single_threaded_link_client(w, &ifds, &ofds, &ifds, &fdmax) != 0) {
+                        web_client_free(w);
+                    }
+                }
+            }
+
+            for(i = 0 ; i <= (size_t)fdmax ; i++) {
+                if(likely(!FD_ISSET(i, &rifds) && !FD_ISSET(i, &rofds) && !FD_ISSET(i, &refds)))
+                    continue;
+
+                w = single_threaded_clients[i];
+                if(unlikely(!w))
+                    continue;
+
+                if(unlikely(single_threaded_unlink_client(w, &ifds, &ofds, &efds) != 0)) {
+                    web_client_free(w);
+                    continue;
+                }
+
+                if (unlikely(FD_ISSET(w->ifd, &refds) || FD_ISSET(w->ofd, &refds))) {
+                    web_client_free(w);
+                    continue;
+                }
+
+                if (unlikely(w->wait_receive && FD_ISSET(w->ifd, &rifds))) {
+                    if (unlikely(web_client_receive(w) < 0)) {
+                        web_client_free(w);
+                        continue;
+                    }
+
+                    if (w->mode != WEB_CLIENT_MODE_FILECOPY) {
+                        debug(D_WEB_CLIENT, "%llu: Processing received data.", w->id);
+                        web_client_process(w);
+                    }
+                }
+
+                if (unlikely(w->wait_send && FD_ISSET(w->ofd, &rofds))) {
+                    if (unlikely(web_client_send(w) < 0)) {
+                        debug(D_WEB_CLIENT, "%llu: Cannot send data to client. Closing client.", w->id);
+                        web_client_free(w);
+                        continue;
+                    }
+                }
+
+                if(unlikely(single_threaded_link_client(w, &ifds, &ofds, &efds, &fdmax) != 0)) {
+                    web_client_free(w);
+                }
+            }
+        }
+        else {
+            debug(D_WEB_CLIENT_ACCESS, "LISTENER: single threaded web server timeout.");
+#ifdef NETDATA_INTERNAL_CHECKS
+            log_allocations();
+#endif
+        }
+    }
+
+    debug(D_WEB_CLIENT, "LISTENER: exit!");
+    close_listen_sockets();
+    return NULL;
+}