[pacman-dev] [PATCH 1/2] lib/dload: enforce usage of TCP keepalives

[Dave Reisner]

This is particularly important in the case of FTP control connections,
which may be closed by rogue NAT/firewall devices detecting idle
connections on larger transfers which may take 5-10+ minutes.

Signed-off-by: Dave Reisner <dreisner at archlinux.org>
---
This is basically on the advice of Daniel Stenberg, who mentions that it's a
common problem that he's aware of. I have no idea if this is actually the fix
we're looking for and I'm still unable to reproduce, but it seems plausible
solution.

Also, fuck FTP.

 configure.ac        |    7 +++--
 lib/libalpm/dload.c |   59 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 3 deletions(-)

diff --git a/configure.ac b/configure.ac
index 6941054..c8ba03f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -174,9 +174,10 @@ AM_CONDITIONAL([HAVE_LIBGPGME], [test "x$with_gpgme" = "xyes"])
 
 # Checks for header files.
 AC_CHECK_HEADERS([fcntl.h float.h glob.h libintl.h limits.h locale.h \
-                  mntent.h stddef.h string.h sys/ioctl.h sys/mount.h \
-                  sys/param.h sys/statvfs.h sys/time.h sys/types.h \
-                  sys/ucred.h syslog.h termios.h wchar.h])
+                  mntent.h netinet/in.h netinet/tcp.h stddef.h string.h \
+                  sys/ioctl.h sys/mount.h sys/param.h sys/statvfs.h \
+                  sys/time.h sys/types.h sys/ucred.h syslog.h termios.h \
+                  wchar.h])
 
 # Checks for typedefs, structures, and compiler characteristics.
 AC_C_INLINE
diff --git a/lib/libalpm/dload.c b/lib/libalpm/dload.c
index a3980d6..790080c 100644
--- a/lib/libalpm/dload.c
+++ b/lib/libalpm/dload.c
@@ -23,11 +23,19 @@
 #include <errno.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/socket.h> /* setsockopt, SO_KEEPALIVE */
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <signal.h>
 
+#ifdef _HAVE_NETINET_IN_H
+#include <netinet/in.h> /* IPPROTO_TCP */
+#endif
+#ifdef _HAVE_NETINET_TCP_H
+#include <netinet/tcp.h> /* TCP_KEEPINTVL, TCP_KEEPIDLE */
+#endif
+
 #ifdef HAVE_LIBCURL
 #include <curl/curl.h>
 #endif
@@ -215,6 +223,53 @@ static size_t parse_headers(void *ptr, size_t size, size_t nmemb, void *user)
 	return realsize;
 }
 
+static int curl_sockopt_cb(void *userdata, curl_socket_t curlfd,
+		curlsocktype purpose)
+{
+	alpm_handle_t *handle = userdata;
+
+	int onoff = 1;
+
+#ifdef TCP_KEEPIDLE
+	int keepidle = TCP_KEEPIDLE;
+#endif
+#ifdef TCP_KEEPINTVL
+	int keepintvl = TCP_KEEPINTVL;
+#endif
+
+	switch(purpose) {
+		case CURLSOCKTYPE_IPCXN:
+			if(setsockopt(curlfd, SOL_SOCKET, SO_KEEPALIVE, (void *)&onoff,
+										sizeof(onoff)) < 0) {
+				/* don't abort operation, just log to debug */
+				_alpm_log(handle, ALPM_LOG_DEBUG, "Failed to set SO_KEEPALIVE on fd %d\n",
+						curlfd);
+			}
+			else {
+#ifdef TCP_KEEPIDLE
+				if(setsockopt(curlfd, IPPROTO_TCP, TCP_KEEPIDLE, (void *)&keepidle,
+											sizeof(keepidle)) < 0) {
+					/* don't abort operation, just log to debug */
+					_alpm_log(handle, ALPM_LOG_DEBUG, "Failed to set TCP_KEEPIDLE on fd %d\n",
+							curlfd);
+				}
+#endif
+#ifdef TCP_KEEPINTVL
+				if(setsockopt(curlfd, IPPROTO_TCP, TCP_KEEPINTVL, (void *)&keepintvl,
+											sizeof(keepintvl)) < 0) {
+					/* don't abort operation, just log to debug */
+					_alpm_log(handle, ALPM_LOG_DEBUG, "Failed to set TCP_KEEPINTVL on fd %d\n",
+							curlfd);
+				}
+#endif
+			}
+		default:
+			break;
+	}
+
+	return 0;
+}
+
 static void curl_set_handle_opts(struct dload_payload *payload,
 		CURL *curl, char *error_buffer)
 {
@@ -239,6 +294,8 @@ static void curl_set_handle_opts(struct dload_payload *payload,
 	curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, parse_headers);
 	curl_easy_setopt(curl, CURLOPT_WRITEHEADER, (void *)payload);
 	curl_easy_setopt(curl, CURLOPT_NETRC, CURL_NETRC_OPTIONAL);
+	curl_easy_setopt(curl, CURLOPT_SOCKOPTFUNCTION, curl_sockopt_cb);
+	curl_easy_setopt(curl, CURLOPT_SOCKOPTDATA, (void *)handle);
 
 	_alpm_log(handle, ALPM_LOG_DEBUG, "url: %s\n", payload->fileurl);
 
@@ -388,6 +445,8 @@ static int curl_download_internal(struct dload_payload *payload,
 
 	/* perform transfer */
 	payload->curlerr = curl_easy_perform(curl);
+	_alpm_log(handle, ALPM_LOG_DEBUG, "curl returned error %d from transfer\n",
+			payload->curlerr);
 
 	/* disconnect relationships from the curl handle for things that might go out
 	 * of scope, but could still be touched on connection teardown.  This really
-- 
1.7.8.4