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Race parallel connects

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This commit is contained in:
Curtis McEnroe 2018-09-16 13:00:49 -04:00
parent 6aecd7a712
commit e3e2b36ecf
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GPG Key ID: CEA2F97ADCFCD77C
1 changed files with 57 additions and 22 deletions
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79
irc.c
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@ -15,9 +15,11 @@
*/ */
#include <err.h> #include <err.h>
#include <errno.h>
#include <fcntl.h> #include <fcntl.h>
#include <netdb.h> #include <netdb.h>
#include <netinet/in.h> #include <netinet/in.h>
#include <poll.h>
#include <stdarg.h> #include <stdarg.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
@ -29,6 +31,60 @@
#include "chat.h" #include "chat.h"
static int connectRace(const char *host, const char *port) {
int error;
struct addrinfo *head;
struct addrinfo hints = {
.ai_family = AF_UNSPEC,
.ai_socktype = SOCK_STREAM,
.ai_protocol = IPPROTO_TCP,
};
error = getaddrinfo(host, port, &hints, &head);
if (error) errx(EX_NOHOST, "getaddrinfo: %s", gai_strerror(error));
nfds_t len = 0;
enum { SocksLen = 16 };
struct pollfd socks[SocksLen];
for (struct addrinfo *ai = head; ai; ai = ai->ai_next) {
if (len == SocksLen) break;
socks[len].events = POLLOUT;
socks[len].fd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
if (socks[len].fd < 0) err(EX_OSERR, "socket");
error = fcntl(socks[len].fd, F_SETFL, O_NONBLOCK);
if (error) err(EX_OSERR, "fcntl");
error = connect(socks[len].fd, ai->ai_addr, ai->ai_addrlen);
if (error && errno != EINPROGRESS && errno != EINTR) {
close(socks[len].fd);
continue;
}
len++;
}
if (!len) err(EX_UNAVAILABLE, "connect");
freeaddrinfo(head);
int ready = poll(socks, len, -1);
if (ready < 0) err(EX_IOERR, "poll");
int sock = -1;
for (nfds_t i = 0; i < len; ++i) {
if ((socks[i].revents & POLLOUT) && sock < 0) {
sock = socks[i].fd;
} else {
close(socks[i].fd);
}
}
if (sock < 0) errx(EX_UNAVAILABLE, "no socket became writable");
error = fcntl(sock, F_SETFL, 0);
if (error) err(EX_IOERR, "fcntl");
return sock;
}
static struct tls *client; static struct tls *client;
static void webirc(const char *pass) { static void webirc(const char *pass) {
@ -59,28 +115,7 @@ int ircConnect(
if (error) errx(EX_SOFTWARE, "tls_configure"); if (error) errx(EX_SOFTWARE, "tls_configure");
tls_config_free(config); tls_config_free(config);
struct addrinfo *head; int sock = connectRace(host, port);
struct addrinfo hints = {
.ai_family = AF_UNSPEC,
.ai_socktype = SOCK_STREAM,
.ai_protocol = IPPROTO_TCP,
};
error = getaddrinfo(host, port, &hints, &head);
if (error) errx(EX_NOHOST, "getaddrinfo: %s", gai_strerror(error));
int sock = -1;
for (struct addrinfo *ai = head; ai; ai = ai->ai_next) {
sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
if (sock < 0) err(EX_OSERR, "socket");
error = connect(sock, ai->ai_addr, ai->ai_addrlen);
if (!error) break;
close(sock);
sock = -1;
}
if (sock < 0) err(EX_UNAVAILABLE, "connect");
freeaddrinfo(head);
error = fcntl(sock, F_SETFD, FD_CLOEXEC); error = fcntl(sock, F_SETFD, FD_CLOEXEC);
if (error) err(EX_IOERR, "fcntl"); if (error) err(EX_IOERR, "fcntl");