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Using poll() instead of select() to prevent FD_SETSIZE overflows, for programs that open large number of descriptors

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This commit is contained in:
Sergey Lyubka 2013-01-16 23:45:03 +00:00
parent c7e5573d08
commit 5646caa572
1 changed files with 76 additions and 68 deletions
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144
mongoose.c
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@ -176,13 +176,23 @@ typedef struct DIR {
struct dirent result;
} DIR;
#ifndef HAS_POLL
struct pollfd {
int fd;
short events;
short revents;
};
#define POLLIN 1
#endif
// Mark required libraries
#pragma comment(lib, "Ws2_32.lib")
#else // UNIX specific
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <sys/poll.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h>
@ -435,7 +445,6 @@ struct file {
// Describes listening socket, or socket which was accept()-ed by the master
// thread and queued for future handling by the worker thread.
struct socket {
struct socket *next; // Linkage
SOCKET sock; // Listening socket
union usa lsa; // Local socket address
union usa rsa; // Remote socket address
@ -490,6 +499,7 @@ struct mg_context {
void *user_data; // User-defined data
struct socket *listening_sockets;
int num_listening_sockets;
volatile int num_threads; // Number of threads
pthread_mutex_t mutex; // Protects (max|num)_threads
@ -1231,6 +1241,33 @@ static struct dirent *readdir(DIR *dir) {
return result;
}
#ifndef HAVE_POLL
static int poll(struct pollfd *pfd, int n, int milliseconds) {
struct timeval tv;
fd_set set;
int i, result;
tv.tv_sec = milliseconds / 1000;
tv.tv_usec = (milliseconds % 1000) * 1000;
FD_ZERO(&set);
for (i = 0; i < n; i++) {
FD_SET((SOCKET) pfd[i].fd, &set);
pfd[i].revents = 0;
}
if ((result = select(0, &set, NULL, NULL, &tv)) > 0) {
for (i = 0; i < n; i++) {
if (FD_ISSET(pfd[i].fd, &set)) {
pfd[i].revents = POLLIN;
}
}
}
return result;
}
#endif // HAVE_POLL
#define set_close_on_exec(x) // No FD_CLOEXEC on Windows
int mg_start_thread(mg_thread_func_t f, void *p) {
@ -1470,17 +1507,14 @@ static int64_t push(FILE *fp, SOCKET sock, SSL *ssl, const char *buf,
// reading, must give up and close the connection and exit serving thread.
static int wait_until_socket_is_readable(struct mg_connection *conn) {
int result;
struct timeval tv;
fd_set set;
struct pollfd pfd;
do {
tv.tv_sec = 0;
tv.tv_usec = 300 * 1000;
FD_ZERO(&set);
FD_SET(conn->client.sock, &set);
result = select(conn->client.sock + 1, &set, NULL, NULL, &tv);
if(result == 0 && conn->ssl != NULL) {
result = SSL_pending(conn->ssl);
pfd.fd = conn->client.sock;
pfd.events = POLLIN;
result = poll(&pfd, 1, 200);
if (result == 0 && conn->ssl != NULL) {
result = SSL_pending(conn->ssl);
}
} while ((result == 0 || (result < 0 && ERRNO == EINTR)) &&
conn->ctx->stop_flag == 0);
@ -1609,7 +1643,8 @@ int mg_printf(struct mg_connection *conn, const char *fmt, ...) {
// vsnprintf() error, give up
len = -1;
cry(conn, "%s(%s, ...): vsnprintf() error", __func__, fmt);
} else if (len > (int) sizeof(mem) && (buf = (char *) malloc(len + 1)) != NULL) {
} else if (len > (int) sizeof(mem) &&
(buf = (char *) malloc(len + 1)) != NULL) {
// Local buffer is not large enough, allocate big buffer on heap
va_start(ap, fmt);
vsnprintf(buf, len + 1, fmt, ap);
@ -4272,12 +4307,11 @@ static void handle_request(struct mg_connection *conn) {
}
static void close_all_listening_sockets(struct mg_context *ctx) {
struct socket *sp, *tmp;
for (sp = ctx->listening_sockets; sp != NULL; sp = tmp) {
tmp = sp->next;
(void) closesocket(sp->sock);
free(sp);
int i;
for (i = 0; i < ctx->num_listening_sockets; i++) {
closesocket(ctx->listening_sockets[i].sock);
}
free(ctx->listening_sockets);
}
// Valid listening port specification is: [ip_address:]port[s]
@ -4316,9 +4350,8 @@ static int parse_port_string(const struct vec *vec, struct socket *so) {
static int set_ports_option(struct mg_context *ctx) {
const char *list = ctx->config[LISTENING_PORTS];
int on = 1, success = 1;
SOCKET sock;
struct vec vec;
struct socket so, *listener;
struct socket so;
while (success && (list = next_option(list, &vec, NULL)) != NULL) {
if (!parse_port_string(&vec, &so)) {
@ -4329,11 +4362,11 @@ static int set_ports_option(struct mg_context *ctx) {
(ctx->ssl_ctx == NULL || ctx->config[SSL_CERTIFICATE] == NULL)) {
cry(fc(ctx), "Cannot add SSL socket, is -ssl_certificate option set?");
success = 0;
} else if ((sock = socket(so.lsa.sa.sa_family, SOCK_STREAM, 6)) ==
} else if ((so.sock = socket(so.lsa.sa.sa_family, SOCK_STREAM, 6)) ==
INVALID_SOCKET ||
// On Windows, SO_REUSEADDR is recommended only for
// broadcast UDP sockets
setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (const char *) &on,
setsockopt(so.sock, SOL_SOCKET, SO_REUSEADDR, (const char *) &on,
sizeof(on)) != 0 ||
// Set TCP keep-alive. This is needed because if HTTP-level
// keep-alive is enabled, and client resets the connection,
@ -4342,27 +4375,22 @@ static int set_ports_option(struct mg_context *ctx) {
// handshake will figure out that the client is down and
// will close the server end.
// Thanks to Igor Klopov who suggested the patch.
setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (char *) &on,
setsockopt(so.sock, SOL_SOCKET, SO_KEEPALIVE, (char *) &on,
sizeof(on)) != 0 ||
bind(sock, &so.lsa.sa, sizeof(so.lsa)) != 0 ||
listen(sock, SOMAXCONN) != 0) {
closesocket(sock);
bind(so.sock, &so.lsa.sa, sizeof(so.lsa)) != 0 ||
listen(so.sock, SOMAXCONN) != 0) {
closesocket(so.sock);
cry(fc(ctx), "%s: cannot bind to %.*s: %s", __func__,
(int) vec.len, vec.ptr, strerror(ERRNO));
success = 0;
} else if ((listener = (struct socket *)
calloc(1, sizeof(*listener))) == NULL) {
// NOTE(lsm): order is important: call cry before closesocket(),
// cause closesocket() alters the errno.
cry(fc(ctx), "%s: %s", __func__, strerror(ERRNO));
closesocket(sock);
success = 0;
} else {
*listener = so;
listener->sock = sock;
set_close_on_exec(listener->sock);
listener->next = ctx->listening_sockets;
ctx->listening_sockets = listener;
set_close_on_exec(so.sock);
// TODO: handle realloc failure
ctx->listening_sockets = realloc(ctx->listening_sockets,
(ctx->num_listening_sockets + 1) *
sizeof(ctx->listening_sockets[0]));
ctx->listening_sockets[ctx->num_listening_sockets] = so;
ctx->num_listening_sockets++;
}
}
@ -4443,13 +4471,6 @@ static int check_acl(struct mg_context *ctx, uint32_t remote_ip) {
return allowed == '+';
}
static void add_to_set(SOCKET fd, fd_set *set, int *max_fd) {
FD_SET(fd, set);
if (fd > (SOCKET) *max_fd) {
*max_fd = (int) fd;
}
}
#if !defined(_WIN32)
static int set_uid_option(struct mg_context *ctx) {
struct passwd *pw;
@ -4982,10 +5003,8 @@ static void accept_new_connection(const struct socket *listener,
static void *master_thread(void *thread_func_param) {
struct mg_context *ctx = thread_func_param;
fd_set read_set;
struct timeval tv;
struct socket *sp;
int max_fd;
struct pollfd *pfd;
int i;
// Increase priority of the master thread
#if defined(_WIN32)
@ -4998,33 +5017,22 @@ static void *master_thread(void *thread_func_param) {
pthread_setschedparam(pthread_self(), SCHED_RR, &sched_param);
#endif
pfd = calloc(ctx->num_listening_sockets, sizeof(pfd[0]));
while (ctx->stop_flag == 0) {
FD_ZERO(&read_set);
max_fd = -1;
// Add listening sockets to the read set
for (sp = ctx->listening_sockets; sp != NULL; sp = sp->next) {
add_to_set(sp->sock, &read_set, &max_fd);
for (i = 0; i < ctx->num_listening_sockets; i++) {
pfd[i].fd = ctx->listening_sockets[i].sock;
pfd[i].events = POLLIN;
}
tv.tv_sec = 0;
tv.tv_usec = 200 * 1000;
if (select(max_fd + 1, &read_set, NULL, NULL, &tv) < 0) {
#ifdef _WIN32
// On windows, if read_set and write_set are empty,
// select() returns "Invalid parameter" error
// (at least on my Windows XP Pro). So in this case, we sleep here.
mg_sleep(1000);
#endif // _WIN32
} else {
for (sp = ctx->listening_sockets; sp != NULL; sp = sp->next) {
if (ctx->stop_flag == 0 && FD_ISSET(sp->sock, &read_set)) {
accept_new_connection(sp, ctx);
if (poll(pfd, ctx->num_listening_sockets, 200) > 0) {
for (i = 0; i < ctx->num_listening_sockets; i++) {
if (ctx->stop_flag == 0 && pfd[i].revents == POLLIN) {
accept_new_connection(&ctx->listening_sockets[i], ctx);
}
}
}
}
free(pfd);
DEBUG_TRACE(("stopping workers"));
// Stop signal received: somebody called mg_stop. Quit.