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fpm_stub.c
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fpm_stub.c
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/*
* Copyright (C) 2012 Internet Systems Consortium, Inc. ("ISC")
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#include <stdint.h>
#include <memory.h>
#include <stdio.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <errno.h>
#include <stdlib.h>
#include <assert.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include "fpm/fpm.h"
typedef struct glob_t_
{
int server_sock;
int sock;
} glob_t;
glob_t glob_space;
glob_t *glob = &glob_space;
int log_level = 1;
#define log(level, format...) \
do { \
if (level <= log_level) { \
fprintf(stderr, format); \
fprintf(stderr, "\n"); \
} \
} while (0);
#define NUM_OF(x) (sizeof(x) / sizeof(x[0]))
#define warn_msg(format...) log(0, format)
#define err_msg(format...) log(-1, format)
#define trace log
/*
* get_print_buf
*/
static char *
get_print_buf (size_t *buf_len)
{
static char print_bufs[16][128];
static int counter;
counter++;
if (counter >= 16) {
counter = 0;
}
*buf_len = 128;
return &print_bufs[counter][0];
}
/*
* create_listen_sock
*/
int
create_listen_sock (int port, int *sock_p)
{
int sock;
struct sockaddr_in addr;
int reuse;
sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
if (sock < 0) {
err_msg(0, "Failed to create socket: %s", strerror(errno));
return 0;
}
reuse = 1;
if (setsockopt (sock, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) < 0)
{
warn_msg("Failed to set reuse addr option: %s", strerror(errno));
}
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_ANY);
addr.sin_port = htons(port);
if (bind(sock, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
err_msg("Failed to bind to port %d: %s", port, strerror(errno));
close(sock);
return 0;
}
if (listen(sock, 5)) {
err_msg("Failed to listen on socket: %s", strerror(errno));
close(sock);
return 0;
}
*sock_p = sock;
return 1;
}
/*
* accept_conn
*/
int
accept_conn (int listen_sock)
{
int sock;
struct sockaddr_in client_addr;
unsigned int client_len;
while (1) {
trace(1, "Waiting for client connection...");
client_len = sizeof(client_addr);
sock = accept(listen_sock, (struct sockaddr *) &client_addr,
&client_len);
if (sock >= 0) {
trace(1, "Accepted client %s", inet_ntoa(client_addr.sin_addr));
return sock;
}
err_msg("Failed to accept socket: %s", strerror(errno));
}
}
/*
* read_fpm_msg
*/
fpm_msg_hdr_t *
read_fpm_msg (char *buf, size_t buf_len)
{
char *cur, *end;
int need_len, bytes_read, have_len;
fpm_msg_hdr_t *hdr;
int reading_full_msg;
end = buf + buf_len;
cur = buf;
hdr = (fpm_msg_hdr_t *) buf;
while (1) {
reading_full_msg = 0;
have_len = cur - buf;
if (have_len < FPM_MSG_HDR_LEN) {
need_len = FPM_MSG_HDR_LEN - have_len;
} else {
need_len = fpm_msg_len(hdr) - have_len;
assert(need_len >= 0 && need_len < (end - cur));
if (!need_len)
return hdr;
reading_full_msg = 1;
}
trace(3, "Looking to read %d bytes", need_len);
bytes_read = read(glob->sock, cur, need_len);
if (bytes_read <= 0) {
err_msg("Error reading from socket: %s", strerror(errno));
return NULL;
}
trace(3, "Read %d bytes", bytes_read);
cur += bytes_read;
if (bytes_read < need_len) {
continue;
}
assert(bytes_read == need_len);
if (reading_full_msg)
return hdr;
if (!fpm_msg_ok(hdr, buf_len))
{
assert(0);
err_msg("Malformed fpm message");
return NULL;
}
}
}
/*
* netlink_msg_type_to_s
*/
const char *
netlink_msg_type_to_s (uint16_t type)
{
switch (type) {
case RTM_NEWROUTE:
return "New route";
case RTM_DELROUTE:
return "Del route";
default:
return "Unknown";
}
}
/*
* netlink_prot_to_s
*/
const char *
netlink_prot_to_s (unsigned char prot)
{
switch (prot) {
case RTPROT_KERNEL:
return "Kernel";
case RTPROT_BOOT:
return "Boot";
case RTPROT_STATIC:
return "Static";
case RTPROT_ZEBRA:
return "Zebra";
case RTPROT_DHCP:
return "Dhcp";
default:
return "Unknown";
}
}
#define MAX_NHS 16
typedef struct netlink_nh_t {
struct rtattr *gateway;
int if_index;
} netlink_nh_t;
typedef struct netlink_msg_ctx_t_ {
struct nlmsghdr *hdr;
/*
* Stuff pertaining to route messages.
*/
struct rtmsg *rtmsg;
struct rtattr *rtattrs[RTA_MAX + 1];
/*
* Nexthops.
*/
struct netlink_nh_t nhs[MAX_NHS];
int num_nhs;
struct rtattr *dest;
struct rtattr *src;
int *metric;
const char *err_msg;
} netlink_msg_ctx_t;
/*
* netlink_msg_ctx_init
*/
static inline void
netlink_msg_ctx_init (netlink_msg_ctx_t *ctx)
{
memset(ctx, 0, sizeof(*ctx));
}
/*
* netlink_msg_ctx_set_err
*/
static inline void
netlink_msg_ctx_set_err (netlink_msg_ctx_t *ctx, const char *err_msg)
{
if (ctx->err_msg) {
return;
}
ctx->err_msg = err_msg;
}
/*
* netlink_msg_ctx_cleanup
*/
static inline void
netlink_msg_ctx_cleanup (netlink_msg_ctx_t *ctx)
{
return;
}
/*
* parse_rtattrs_
*/
int
parse_rtattrs_ (struct rtattr *rta, size_t len, struct rtattr**rtas,
int num_rtas, const char **err_msg)
{
memset(rtas, 0, num_rtas * sizeof(rtas[0]));
for (; len > 0; rta = RTA_NEXT(rta, len)) {
if (!RTA_OK(rta, len)) {
*err_msg = "Malformed rta";
return 0;
}
if (rta->rta_type >= num_rtas) {
warn("Unknown rtattr type %d", rta->rta_type);
continue;
}
rtas[rta->rta_type] = rta;
}
}
/*
* parse_rtattrs
*/
int
parse_rtattrs (netlink_msg_ctx_t *ctx, struct rtattr *rta, size_t len)
{
const char *err_msg;
err_msg = NULL;
if (!parse_rtattrs_(rta, len, ctx->rtattrs, NUM_OF(ctx->rtattrs),
&err_msg)) {
netlink_msg_ctx_set_err(ctx, err_msg);
return 0;
}
return 1;
}
/*
* netlink_msg_ctx_add_nh
*/
static int
netlink_msg_ctx_add_nh (netlink_msg_ctx_t *ctx, int if_index,
struct rtattr *gateway)
{
netlink_nh_t *nh;
if (ctx->num_nhs + 1 >= NUM_OF(ctx->nhs)) {
warn("Too many next hops");
return 0;
}
nh = &ctx->nhs[ctx->num_nhs];
ctx->num_nhs++;
nh->gateway = gateway;
nh->if_index = if_index;
return 1;
}
/*
* parse_multipath_attr
*/
int
parse_multipath_attr (netlink_msg_ctx_t *ctx, struct rtattr *mpath_rtattr)
{
size_t len, attr_len;
struct rtnexthop *rtnh;
struct rtattr *rtattrs[RTA_MAX + 1];
struct rtattr *rtattr, *gateway;
int if_index;
const char *err_msg;
rtnh = RTA_DATA(mpath_rtattr);
len = RTA_PAYLOAD(mpath_rtattr);
for (; len > 0;
len -= NLMSG_ALIGN(rtnh->rtnh_len), rtnh = RTNH_NEXT(rtnh)) {
if (!RTNH_OK(rtnh, len)) {
netlink_msg_ctx_set_err(ctx, "Malformed nh");
return 0;
}
if (rtnh->rtnh_len <= sizeof(*rtnh)) {
netlink_msg_ctx_set_err(ctx, "NH len too small");
return 0;
}
/*
* Parse attributes included in the nexthop.
*/
err_msg = NULL;
if (!parse_rtattrs_(RTNH_DATA(rtnh), rtnh->rtnh_len - sizeof(*rtnh),
rtattrs, NUM_OF(rtattrs), &err_msg)) {
netlink_msg_ctx_set_err(ctx, err_msg);
return 0;
}
gateway = rtattrs[RTA_GATEWAY];
netlink_msg_ctx_add_nh(ctx, rtnh->rtnh_ifindex, gateway);
}
return 1;
}
/*
* parse_route_msg
*/
int
parse_route_msg (netlink_msg_ctx_t *ctx)
{
int len;
struct rtattr **rtattrs, *rtattr, *gateway, *oif;
int if_index;
ctx->rtmsg = NLMSG_DATA(ctx->hdr);
len = ctx->hdr->nlmsg_len - NLMSG_LENGTH(sizeof(struct rtmsg));
if (len < 0) {
netlink_msg_ctx_set_err(ctx, "Bad message length");
return 0;
}
if (!parse_rtattrs(ctx, RTM_RTA(ctx->rtmsg), len)) {
return 0;
}
rtattrs = ctx->rtattrs;
ctx->dest = rtattrs[RTA_DST];
ctx->src = rtattrs[RTA_PREFSRC];
rtattr = rtattrs[RTA_PRIORITY];
if (rtattr) {
ctx->metric = (int *) RTA_DATA(rtattr);
}
gateway = rtattrs[RTA_GATEWAY];
oif = rtattrs[RTA_OIF];
if (gateway || oif) {
if_index = 0;
if (oif) {
if_index = *((int *) RTA_DATA(oif));
}
netlink_msg_ctx_add_nh(ctx, if_index, gateway);
}
rtattr = rtattrs[RTA_MULTIPATH];
if (rtattr) {
parse_multipath_attr(ctx, rtattr);
}
return 1;
}
/*
* addr_to_s
*/
const char *
addr_to_s (unsigned char family, void *addr)
{
size_t buf_len;
char *buf;
buf = get_print_buf(&buf_len);
return inet_ntop(family, addr, buf, buf_len);
}
/*
* netlink_msg_ctx_print
*/
int
netlink_msg_ctx_snprint (netlink_msg_ctx_t *ctx, char *buf, size_t buf_len)
{
struct nlmsghdr *hdr;
struct rtmsg *rtmsg;
netlink_nh_t *nh;
char *cur, *end;
int i;
hdr = ctx->hdr;
rtmsg = ctx->rtmsg;
cur = buf;
end = buf + buf_len;
cur += snprintf(cur, end - cur, "%s %s/%d, Prot: %s",
netlink_msg_type_to_s(hdr->nlmsg_type),
addr_to_s(rtmsg->rtm_family, RTA_DATA(ctx->dest)),
rtmsg->rtm_dst_len,
netlink_prot_to_s(rtmsg->rtm_protocol));
if (ctx->metric) {
cur += snprintf(cur, end - cur, ", Metric: %d", *ctx->metric);
}
for (i = 0; i < ctx->num_nhs; i++) {
cur += snprintf(cur, end - cur, "\n ");
nh = &ctx->nhs[i];
if (nh->gateway) {
cur += snprintf(cur, end - cur, " %s",
addr_to_s(rtmsg->rtm_family, RTA_DATA(nh->gateway)));
}
if (nh->if_index) {
cur += snprintf(cur, end - cur, " via interface %d", nh->if_index);
}
}
return cur - buf;
}
/*
* print_netlink_msg_ctx
*/
void
print_netlink_msg_ctx (netlink_msg_ctx_t *ctx)
{
char buf[1024];
netlink_msg_ctx_snprint(ctx, buf, sizeof(buf));
printf("%s\n", buf);
}
/*
* parse_netlink_msg
*/
void
parse_netlink_msg (char *buf, size_t buf_len)
{
netlink_msg_ctx_t ctx_space, *ctx;
struct nlmsghdr *hdr;
int status;
int len;
ctx = &ctx_space;
hdr = (struct nlmsghdr *) buf;
len = buf_len;
for (; NLMSG_OK (hdr, len); hdr = NLMSG_NEXT(hdr, len)) {
netlink_msg_ctx_init(ctx);
ctx->hdr = (struct nlmsghdr *) buf;
switch (hdr->nlmsg_type) {
case RTM_DELROUTE:
case RTM_NEWROUTE:
parse_route_msg(ctx);
if (ctx->err_msg) {
err_msg("Error parsing route message: %s", ctx->err_msg);
}
print_netlink_msg_ctx(ctx);
break;
default:
trace(1, "Ignoring unknown netlink message - Type: %d", hdr->nlmsg_type);
}
netlink_msg_ctx_cleanup(ctx);
}
}
/*
* process_fpm_msg
*/
void
process_fpm_msg (fpm_msg_hdr_t *hdr)
{
trace(1, "FPM message - Type: %d, Length %d", hdr->msg_type,
ntohs(hdr->msg_len));
if (hdr->msg_type != FPM_MSG_TYPE_NETLINK) {
warn("Unknown fpm message type %u", hdr->msg_type);
return;
}
parse_netlink_msg (fpm_msg_data (hdr), fpm_msg_data_len (hdr));
}
/*
* fpm_serve
*/
void
fpm_serve ()
{
char buf[FPM_MAX_MSG_LEN];
fpm_msg_hdr_t *hdr;
while (1) {
hdr = read_fpm_msg(buf, sizeof(buf));
if (!hdr) {
return;
}
process_fpm_msg(hdr);
}
}
int main (void)
{
int sock;
memset(glob, 0, sizeof(*glob));
if (!create_listen_sock(FPM_DEFAULT_PORT, &glob->server_sock)) {
exit(1);
}
/*
* Server forever.
*/
while (1) {
glob->sock = accept_conn(glob->server_sock);
fpm_serve();
trace(1, "Done serving client");
}
}