net: add async operation helpers.
authorRusty Russell <rusty@rustcorp.com.au>
Wed, 2 Oct 2013 08:23:37 +0000 (17:53 +0930)
committerRusty Russell <rusty@rustcorp.com.au>
Wed, 2 Oct 2013 08:23:37 +0000 (17:53 +0930)
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
ccan/net/_info
ccan/net/net.c
ccan/net/net.h

index 9ce0e150dfe3b53f26bc2c293497b6cf4e10e20d..b4b219fd3599094a7195e9c1a83c24bc79a8c28f 100644 (file)
@@ -66,6 +66,7 @@ int main(int argc, char *argv[])
                return 1;
 
        if (strcmp(argv[1], "depends") == 0) {
+               printf("ccan/noerr\n");
                return 0;
        }
 
index e84380fff96f27a885d05618a46b6d1d2d46cc2c..d2eaa9ecb45e58660fb80ea607210226d3385a7f 100644 (file)
@@ -1,5 +1,6 @@
 /* Licensed under BSD-MIT - see LICENSE file for details */
 #include <ccan/net/net.h>
+#include <ccan/noerr/noerr.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <poll.h>
@@ -11,6 +12,7 @@
 #include <errno.h>
 #include <stdbool.h>
 #include <netinet/in.h>
+#include <assert.h>
 
 struct addrinfo *net_client_lookup(const char *hostname,
                                   const char *service,
@@ -48,107 +50,145 @@ static bool set_nonblock(int fd, bool nonblock)
        return (fcntl(fd, F_SETFL, flags) == 0);
 }
 
-/* We only handle IPv4 and IPv6 */
-#define MAX_PROTOS 2
-
-static void remove_fd(struct pollfd pfd[],
-                     const struct addrinfo *addr[],
-                     socklen_t slen[],
-                     unsigned int *num,
-                     unsigned int i)
+static int start_connect(const struct addrinfo *addr, bool *immediate)
 {
-       memmove(pfd + i, pfd + i + 1, (*num - i - 1) * sizeof(pfd[0]));
-       memmove(addr + i, addr + i + 1, (*num - i - 1) * sizeof(addr[0]));
-       memmove(slen + i, slen + i + 1, (*num - i - 1) * sizeof(slen[0]));
-       (*num)--;
+       int fd;
+
+       *immediate = false;
+
+       fd = socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);
+       if (fd == -1)
+               return fd;
+
+       if (!set_nonblock(fd, true))
+               goto close;
+
+       if (connect(fd, addr->ai_addr, addr->ai_addrlen) == 0) {
+               /* Immediate connect. */
+               *immediate = true;
+               return fd;
+       }
+
+       if (errno == EINPROGRESS)
+               return fd;
+
+close:
+       close_noerr(fd);
+       return -1;
 }
 
-int net_connect(const struct addrinfo *addrinfo)
+
+int net_connect_async(const struct addrinfo *addrinfo, struct pollfd pfds[2])
 {
-       int sockfd = -1, saved_errno;
-       unsigned int i, num;
-       const struct addrinfo *ipv4 = NULL, *ipv6 = NULL;
-       const struct addrinfo *addr[MAX_PROTOS];
-       socklen_t slen[MAX_PROTOS];
-       struct pollfd pfd[MAX_PROTOS];
+       const struct addrinfo *addr[2] = { NULL, NULL };
+       unsigned int i;
 
+       pfds[0].fd = pfds[1].fd = -1;
+       pfds[0].events = pfds[1].events = POLLOUT;
+
+       /* Give IPv6 a slight advantage, by trying it first. */
        for (; addrinfo; addrinfo = addrinfo->ai_next) {
                switch (addrinfo->ai_family) {
                case AF_INET:
-                       if (!ipv4)
-                               ipv4 = addrinfo;
+                       addr[1] = addrinfo;
                        break;
                case AF_INET6:
-                       if (!ipv6)
-                               ipv6 = addrinfo;
+                       addr[0] = addrinfo;
                        break;
+               default:
+                       continue;
                }
        }
 
-       num = 0;
-       /* We give IPv6 a slight edge by connecting it first. */
-       if (ipv6) {
-               addr[num] = ipv6;
-               slen[num] = sizeof(struct sockaddr_in6);
-               pfd[num].fd = socket(AF_INET6, ipv6->ai_socktype,
-                                    ipv6->ai_protocol);
-               if (pfd[num].fd != -1)
-                       num++;
+       /* In case we found nothing. */
+       errno = ENOENT;
+       for (i = 0; i < 2; i++) {
+               bool immediate;
+
+               if (!addr[i])
+                       continue;
+
+               pfds[i].fd = start_connect(addr[i], &immediate);
+               if (immediate) {
+                       if (pfds[!i].fd != -1)
+                               close(pfds[!i].fd);
+                       if (!set_nonblock(pfds[i].fd, false)) {
+                               close_noerr(pfds[i].fd);
+                               return -1;
+                       }
+                       return pfds[0].fd;
+               }
        }
-       if (ipv4) {
-               addr[num] = ipv4;
-               slen[num] = sizeof(struct sockaddr_in);
-               pfd[num].fd = socket(AF_INET, ipv4->ai_socktype,
-                                    ipv4->ai_protocol);
-               if (pfd[num].fd != -1)
-                       num++;
+
+       if (pfds[0].fd != -1 || pfds[1].fd != -1)
+               errno = EINPROGRESS;
+       return -1;
+}
+
+void net_connect_abort(struct pollfd pfds[2])
+{
+       unsigned int i;
+
+       for (i = 0; i < 2; i++) {
+               if (pfds[i].fd != -1)
+                       close_noerr(pfds[i].fd);
+               pfds[i].fd = -1;
        }
+}
+
+int net_connect_complete(struct pollfd pfds[2])
+{
+       unsigned int i;
+
+       assert(pfds[0].fd != -1 || pfds[1].fd != -1);
+
+       for (i = 0; i < 2; i++) {
+               int err;
+               socklen_t errlen = sizeof(err);
 
-       for (i = 0; i < num; i++) {
-               if (!set_nonblock(pfd[i].fd, true)) {
-                       remove_fd(pfd, addr, slen, &num, i--);
+               if (pfds[i].fd == -1)
                        continue;
+               if (getsockopt(pfds[i].fd, SOL_SOCKET, SO_ERROR, &err,
+                              &errlen) != 0) {
+                       net_connect_abort(pfds);
+                       return -1;
                }
-               /* Connect *can* be instant. */
-               if (connect(pfd[i].fd, addr[i]->ai_addr, slen[i]) == 0)
-                       goto got_one;
-               if (errno != EINPROGRESS) {
-                       /* Remove dead one. */
-                       remove_fd(pfd, addr, slen, &num, i--);
+               if (err == 0) {
+                       /* Don't hand them non-blocking fd! */
+                       if (!set_nonblock(pfds[i].fd, false)) {
+                               net_connect_abort(pfds);
+                               return -1;
+                       }
+                       /* Close other one. */
+                       if (pfds[!i].fd != -1)
+                               close(pfds[!i].fd);
+                       return pfds[i].fd;
                }
-               pfd[i].events = POLLOUT;
        }
 
-       while (num && poll(pfd, num, -1) != -1) {
-               for (i = 0; i < num; i++) {
-                       int err;
-                       socklen_t errlen = sizeof(err);
-                       if (!pfd[i].revents)
-                               continue;
-                       if (getsockopt(pfd[i].fd, SOL_SOCKET, SO_ERROR, &err,
-                                      &errlen) != 0)
-                               goto out;
-                       if (err == 0)
-                               goto got_one;
-
-                       /* Remove dead one. */
-                       errno = err;
-                       remove_fd(pfd, addr, slen, &num, i--);
-               }
-       }
+       /* Still going... */
+       errno = EINPROGRESS;
+       return -1;
+}
 
-got_one:
-       /* We don't want to hand them a non-blocking socket! */
-       if (set_nonblock(pfd[i].fd, false))
-               sockfd = pfd[i].fd;
+int net_connect(const struct addrinfo *addrinfo)
+{
+       struct pollfd pfds[2];
+       int sockfd;
+
+       sockfd = net_connect_async(addrinfo, pfds);
+       /* Immediate connect or error is easy. */
+       if (sockfd >= 0 || errno != EINPROGRESS)
+               return sockfd;
+
+       while (poll(pfds, 2, -1) != -1) {
+               sockfd = net_connect_complete(pfds);
+               if (sockfd >= 0 || errno != EINPROGRESS)
+                       return sockfd;
+       }
 
-out:
-       saved_errno = errno;
-       for (i = 0; i < num; i++)
-               if (pfd[i].fd != sockfd)
-                       close(pfd[i].fd);
-       errno = saved_errno;
-       return sockfd;
+       net_connect_abort(pfds);
+       return -1;
 }
 
 struct addrinfo *net_server_lookup(const char *service,
index 9ad6de56a498b12aab9a5372c9114b5def47b505..5e02fc36e7d09a329484ac5bfebf582c8c400cf3 100644 (file)
@@ -1,6 +1,10 @@
 /* Licensed under BSD-MIT - see LICENSE file for details */
 #ifndef CCAN_NET_H
 #define CCAN_NET_H
+#include <stdbool.h>
+
+struct pollfd;
+
 /**
  * net_client_lookup - look up a network name to connect to.
  * @hostname: the name to look up
@@ -16,6 +20,7 @@
  *     #include <sys/socket.h>
  *     #include <stdio.h>
  *     #include <netdb.h>
+ *     #include <poll.h>
  *     #include <err.h>
  *     ...
  *     struct addrinfo *addr;
@@ -48,6 +53,67 @@ struct addrinfo *net_client_lookup(const char *hostname,
  */
 int net_connect(const struct addrinfo *addrinfo);
 
+/**
+ * net_connect_async - initiate connect to a server
+ * @addrinfo: linked list struct addrinfo (usually from net_client_lookup).
+ * @pfds: array of two struct pollfd.
+ *
+ * This begins connecting to a server described by @addrinfo,
+ * and places the one or two file descriptors into pfds[0] and pfds[1].
+ * It returns a valid file descriptor if connect() returned immediately.
+ *
+ * Otherwise it returns -1 and sets errno, most likely EINPROGRESS.
+ * In this case, poll() on pfds and call net_connect_complete().
+ *
+ * Example:
+ *     struct pollfd pfds[2];
+ *     ...
+ *     fd = net_connect_async(addr, pfds);
+ *     if (fd < 0 && errno != EINPROGRESS)
+ *             err(1, "Failed to connect to ccan.ozlabs.org");
+ */
+int net_connect_async(const struct addrinfo *addrinfo, struct pollfd *pfds);
+
+/**
+ * net_connect_complete - complete net_connect_async call.
+ * @pfds: array of two struct pollfd handed to net_connect_async.
+ *
+ * When poll() reports some activity, this determines whether a connection
+ * has completed.  If so, it cleans up and returns the connected fd.
+ * Otherwise, it returns -1, and sets errno (usually EINPROGRESS).
+ *
+ * Example:
+ *     // After net_connect_async.
+ *     while (fd < 0 && errno == EINPROGRESS) {
+ *             // Wait for activity...
+ *             poll(pfds, 2, -1);
+ *             fd = net_connect_complete(pfds);
+ *     }
+ *     if (fd < 0)
+ *             err(1, "connecting");
+ *     printf("Connected on fd %i!\n", fd);
+ */
+int net_connect_complete(struct pollfd *pfds);
+
+/**
+ * net_connect_abort - abort a net_connect_async call.
+ * @pfds: array of two struct pollfd handed to net_connect_async.
+ *
+ * Closes the file descriptors.
+ *
+ * Example:
+ *     // After net_connect_async.
+ *     if (poll(pfds, 2, 1000) == 0) { // Timeout.
+ *             net_connect_abort(pfds);
+ *             fd = -1;
+ *     } else {
+ *             fd = net_connect_complete(pfds);
+ *             if (fd < 0)
+ *                     err(1, "connecting");
+ *     }
+ */
+void net_connect_abort(struct pollfd *pfds);
+
 /**
  * net_server_lookup - look up a service name to bind to.
  * @service: the service to look up