Implement if_nameindex(3)/if_freenameindex(3).
This is just a subset of the recently-implemented getifaddrs(3), though if
we want to handle interfaces (such as "rmnet_*") that don't have an address,
we need to either expose ifaddrs_storage and keep track of which interfaces
we've already seen (which is pretty messy), or refactor the netlink code so
we can reuse it and just extract the information we need for if_nameindex(3).
This patch goes the latter route.
Also clean up if_nametoindex(3) and if_indextoname(3).
Change-Id: I5ffc5df0bab62286cdda2e7af06f032c767119a8
diff --git a/libc/bionic/bionic_netlink.cpp b/libc/bionic/bionic_netlink.cpp
new file mode 100644
index 0000000..19ca88d
--- /dev/null
+++ b/libc/bionic/bionic_netlink.cpp
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "bionic_netlink.h"
+
+#include <errno.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <string.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include "private/ErrnoRestorer.h"
+
+NetlinkConnection::NetlinkConnection() {
+ fd_ = -1;
+
+ // The kernel keeps packets under 8KiB (NLMSG_GOODSIZE),
+ // but that's a bit too large to go on the stack.
+ size_ = 8192;
+ data_ = new char[size_];
+}
+
+NetlinkConnection::~NetlinkConnection() {
+ ErrnoRestorer errno_restorer;
+ if (fd_ != -1) close(fd_);
+ delete[] data_;
+}
+
+bool NetlinkConnection::SendRequest(int type) {
+ // Rather than force all callers to check for the unlikely event of being
+ // unable to allocate 8KiB, check here.
+ if (data_ == nullptr) return false;
+
+ // Did we open a netlink socket yet?
+ if (fd_ == -1) {
+ fd_ = socket(PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
+ }
+
+ // Construct and send the message.
+ struct NetlinkMessage {
+ nlmsghdr hdr;
+ rtgenmsg msg;
+ } request;
+ memset(&request, 0, sizeof(request));
+ request.hdr.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
+ request.hdr.nlmsg_type = type;
+ request.hdr.nlmsg_len = sizeof(request);
+ request.msg.rtgen_family = AF_UNSPEC; // All families.
+ return (TEMP_FAILURE_RETRY(send(fd_, &request, sizeof(request), 0)) == sizeof(request));
+}
+
+bool NetlinkConnection::ReadResponses(void callback(void*, nlmsghdr*), void* context) {
+ // Read through all the responses, handing interesting ones to the callback.
+ ssize_t bytes_read;
+ while ((bytes_read = TEMP_FAILURE_RETRY(recv(fd_, data_, size_, 0))) > 0) {
+ nlmsghdr* hdr = reinterpret_cast<nlmsghdr*>(data_);
+ for (; NLMSG_OK(hdr, static_cast<size_t>(bytes_read)); hdr = NLMSG_NEXT(hdr, bytes_read)) {
+ if (hdr->nlmsg_type == NLMSG_DONE) return true;
+ if (hdr->nlmsg_type == NLMSG_ERROR) return false;
+ callback(context, hdr);
+ }
+ }
+
+ // We only get here if recv fails before we see a NLMSG_DONE.
+ return false;
+}
diff --git a/libc/bionic/if_nametoindex.c b/libc/bionic/bionic_netlink.h
similarity index 63%
rename from libc/bionic/if_nametoindex.c
rename to libc/bionic/bionic_netlink.h
index d670e43..4b103f3 100644
--- a/libc/bionic/if_nametoindex.c
+++ b/libc/bionic/bionic_netlink.h
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2008 The Android Open Source Project
+ * Copyright (C) 2016 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -26,33 +26,34 @@
* SUCH DAMAGE.
*/
-#include <string.h>
-#include <unistd.h>
-#include <linux/sockios.h>
-#include <net/if.h>
-#include <sys/socket.h>
-#include <sys/ioctl.h>
+#ifndef BIONIC_NETLINK_H
+#define BIONIC_NETLINK_H
-/*
- * Map an interface name into its corresponding index.
- * Returns 0 on error, as 0 is not a valid index.
- */
-unsigned int if_nametoindex(const char *ifname)
-{
- int index;
- int ctl_sock;
- struct ifreq ifr;
+#include <sys/types.h>
- memset(&ifr, 0, sizeof(struct ifreq));
- strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
- ifr.ifr_name[IFNAMSIZ - 1] = 0;
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
- index = 0;
- if ((ctl_sock = socket(AF_INET, SOCK_DGRAM, 0)) >= 0) {
- if (ioctl(ctl_sock, SIOCGIFINDEX, &ifr) >= 0) {
- index = ifr.ifr_ifindex;
- }
- close(ctl_sock);
- }
- return index;
-}
+struct nlmsghdr;
+
+class NetlinkConnection {
+ public:
+ NetlinkConnection();
+ ~NetlinkConnection();
+
+ bool SendRequest(int type);
+ bool ReadResponses(void callback(void*, nlmsghdr*), void* context);
+
+ private:
+ int fd_;
+ char* data_;
+ size_t size_;
+};
+
+#if !defined(__clang__)
+// GCC gets confused by NLMSG_DATA and doesn't realize that the old-style
+// cast is from a system header and should be ignored.
+#pragma GCC diagnostic ignored "-Wold-style-cast"
+#endif
+
+#endif
diff --git a/libc/bionic/if_indextoname.c b/libc/bionic/if_indextoname.c
deleted file mode 100644
index f0db512..0000000
--- a/libc/bionic/if_indextoname.c
+++ /dev/null
@@ -1,62 +0,0 @@
-/*
- * Copyright (C) 2008 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * * Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#include <string.h>
-#include <unistd.h>
-#include <linux/sockios.h>
-#include <net/if.h>
-#include <sys/socket.h>
-#include <sys/ioctl.h>
-#include <errno.h>
-
-/*
- * Map an interface index into its name.
- * Returns NULL on error.
- */
-char*
-if_indextoname(unsigned ifindex, char *ifname)
-{
- int ctl_sock;
- struct ifreq ifr;
- char* ret = NULL;
-
- memset(&ifr, 0, sizeof(struct ifreq));
- ifr.ifr_ifindex = ifindex;
-
- if ((ctl_sock = socket(AF_INET, SOCK_DGRAM, 0)) >= 0) {
- if (ioctl(ctl_sock, SIOCGIFNAME, &ifr) >= 0) {
- ret = strncpy (ifname, ifr.ifr_name, IFNAMSIZ);
- } else {
- /* Posix requires ENXIO */
- if (errno == ENODEV)
- errno = ENXIO;
- }
- close(ctl_sock);
- }
- return ret;
-}
diff --git a/libc/bionic/ifaddrs.cpp b/libc/bionic/ifaddrs.cpp
index b66883e..d03d76f 100644
--- a/libc/bionic/ifaddrs.cpp
+++ b/libc/bionic/ifaddrs.cpp
@@ -30,8 +30,6 @@
#include <errno.h>
#include <linux/if_packet.h>
-#include <linux/netlink.h>
-#include <linux/rtnetlink.h>
#include <net/if.h>
#include <netinet/in.h>
#include <stdint.h>
@@ -40,6 +38,10 @@
#include <string.h>
#include <unistd.h>
+#include "private/ErrnoRestorer.h"
+
+#include "bionic_netlink.h"
+
// The public ifaddrs struct is full of pointers. Rather than track several
// different allocations, we use a maximally-sized structure with the public
// part at offset 0, and pointers into its hidden tail.
@@ -119,13 +121,9 @@
}
};
-#if !defined(__clang__)
-// GCC gets confused by NLMSG_DATA and doesn't realize that the old-style
-// cast is from a system header and should be ignored.
-#pragma GCC diagnostic ignored "-Wold-style-cast"
-#endif
+static void __getifaddrs_callback(void* context, nlmsghdr* hdr) {
+ ifaddrs** out = reinterpret_cast<ifaddrs**>(context);
-static void __handle_netlink_response(ifaddrs** out, nlmsghdr* hdr) {
if (hdr->nlmsg_type == RTM_NEWLINK) {
ifinfomsg* ifi = reinterpret_cast<ifinfomsg*>(NLMSG_DATA(hdr));
@@ -195,62 +193,22 @@
}
}
-static bool __send_netlink_request(int fd, int type) {
- struct NetlinkMessage {
- nlmsghdr hdr;
- rtgenmsg msg;
- } request;
- memset(&request, 0, sizeof(request));
- request.hdr.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
- request.hdr.nlmsg_type = type;
- request.hdr.nlmsg_len = sizeof(request);
- request.msg.rtgen_family = AF_UNSPEC; // All families.
- return (TEMP_FAILURE_RETRY(send(fd, &request, sizeof(request), 0)) == sizeof(request));
-}
-
-static bool __read_netlink_responses(int fd, ifaddrs** out, char* buf, size_t buf_len) {
- ssize_t bytes_read;
- // Read through all the responses, handing interesting ones to __handle_netlink_response.
- while ((bytes_read = TEMP_FAILURE_RETRY(recv(fd, buf, buf_len, 0))) > 0) {
- nlmsghdr* hdr = reinterpret_cast<nlmsghdr*>(buf);
- for (; NLMSG_OK(hdr, static_cast<size_t>(bytes_read)); hdr = NLMSG_NEXT(hdr, bytes_read)) {
- if (hdr->nlmsg_type == NLMSG_DONE) return true;
- if (hdr->nlmsg_type == NLMSG_ERROR) return false;
- __handle_netlink_response(out, hdr);
- }
- }
- // We only get here if recv fails before we see a NLMSG_DONE.
- return false;
-}
-
int getifaddrs(ifaddrs** out) {
- // Make cleanup easy.
+ // We construct the result directly into `out`, so terminate the list.
*out = nullptr;
- // The kernel keeps packets under 8KiB (NLMSG_GOODSIZE),
- // but that's a bit too large to go on the stack.
- size_t buf_len = 8192;
- char* buf = new char[buf_len];
- if (buf == nullptr) return -1;
-
// Open the netlink socket and ask for all the links and addresses.
- int fd = socket(PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
- bool okay = fd != -1 &&
- __send_netlink_request(fd, RTM_GETLINK) && __read_netlink_responses(fd, out, buf, buf_len) &&
- __send_netlink_request(fd, RTM_GETADDR) && __read_netlink_responses(fd, out, buf, buf_len);
-
+ NetlinkConnection nc;
+ bool okay = nc.SendRequest(RTM_GETLINK) && nc.ReadResponses(__getifaddrs_callback, out) &&
+ nc.SendRequest(RTM_GETADDR) && nc.ReadResponses(__getifaddrs_callback, out);
if (!okay) {
freeifaddrs(*out);
// Ensure that callers crash if they forget to check for success.
*out = nullptr;
+ return -1;
}
- {
- int saved_errno = errno;
- close(fd);
- delete[] buf;
- errno = saved_errno;
- }
- return okay ? 0 : -1;
+
+ return 0;
}
void freeifaddrs(ifaddrs* list) {
diff --git a/libc/bionic/net_if.cpp b/libc/bionic/net_if.cpp
new file mode 100644
index 0000000..a6b896e
--- /dev/null
+++ b/libc/bionic/net_if.cpp
@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <net/if.h>
+
+#include <errno.h>
+#include <ifaddrs.h>
+#include <linux/if_packet.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <linux/sockios.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include "private/ErrnoRestorer.h"
+
+#include "bionic_netlink.h"
+
+char* if_indextoname(unsigned ifindex, char* ifname) {
+ int s = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, 0);
+ if (s == -1) return nullptr;
+
+ struct ifreq ifr = {};
+ ifr.ifr_ifindex = ifindex;
+
+ int rc = ioctl(s, SIOCGIFNAME, &ifr);
+ ErrnoRestorer errno_restorer;
+ close(s);
+ return (rc == -1) ? nullptr : strncpy(ifname, ifr.ifr_name, IFNAMSIZ);
+}
+
+unsigned if_nametoindex(const char* ifname) {
+ int s = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, 0);
+ if (s == -1) return 0;
+
+ struct ifreq ifr = {};
+ strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+ ifr.ifr_name[IFNAMSIZ - 1] = 0;
+
+ int rc = ioctl(s, SIOCGIFINDEX, &ifr);
+ ErrnoRestorer errno_restorer;
+ close(s);
+ return (rc == -1) ? 0 : ifr.ifr_ifindex;
+}
+
+struct if_list {
+ if_list* next;
+ struct if_nameindex data;
+
+ if_list(if_list** list) {
+ // push_front onto `list`.
+ next = *list;
+ *list = this;
+ }
+
+ static void Free(if_list* list, bool names_too) {
+ while (list) {
+ if_list* it = list;
+ list = it->next;
+ if (names_too) free(it->data.if_name);
+ free(it);
+ }
+ }
+};
+
+static void __if_nameindex_callback(void* context, nlmsghdr* hdr) {
+ if_list** list = reinterpret_cast<if_list**>(context);
+ if (hdr->nlmsg_type == RTM_NEWLINK) {
+ ifinfomsg* ifi = reinterpret_cast<ifinfomsg*>(NLMSG_DATA(hdr));
+
+ // Create a new entry and set the interface index.
+ if_list* new_link = new if_list(list);
+ new_link->data.if_index = ifi->ifi_index;
+
+ // Go through the various bits of information and find the name.
+ rtattr* rta = IFLA_RTA(ifi);
+ size_t rta_len = IFLA_PAYLOAD(hdr);
+ while (RTA_OK(rta, rta_len)) {
+ if (rta->rta_type == IFLA_IFNAME) {
+ new_link->data.if_name = strndup(reinterpret_cast<char*>(RTA_DATA(rta)), RTA_PAYLOAD(rta));
+ }
+ rta = RTA_NEXT(rta, rta_len);
+ }
+ }
+}
+
+struct if_nameindex* if_nameindex() {
+ if_list* list = nullptr;
+
+ // Open the netlink socket and ask for all the links;
+ NetlinkConnection nc;
+ bool okay = nc.SendRequest(RTM_GETLINK) && nc.ReadResponses(__if_nameindex_callback, &list);
+ if (!okay) {
+ if_list::Free(list, true);
+ return nullptr;
+ }
+
+ // Count the interfaces.
+ size_t interface_count = 0;
+ for (if_list* it = list; it != nullptr; it = it->next) {
+ ++interface_count;
+ }
+
+ // Build the array POSIX requires us to return.
+ struct if_nameindex* result = new struct if_nameindex[interface_count + 1];
+ if (result) {
+ struct if_nameindex* out = result;
+ for (if_list* it = list; it != nullptr; it = it->next) {
+ out->if_index = it->data.if_index;
+ out->if_name = it->data.if_name;
+ ++out;
+ }
+ out->if_index = 0;
+ out->if_name = nullptr;
+ }
+
+ // Free temporary storage.
+ if_list::Free(list, false);
+
+ return result;
+}
+
+void if_freenameindex(struct if_nameindex* array) {
+ if (array == nullptr) return;
+
+ struct if_nameindex* ptr = array;
+ while (ptr->if_index != 0 || ptr->if_name != nullptr) {
+ free(ptr->if_name);
+ ++ptr;
+ }
+
+ delete[] array;
+}