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/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) {