/* tcpsvd.c - TCP(UDP)/IP service daemon
*
* Copyright 2013 Ashwini Kumar <ak.ashwini@gmail.com>
* Copyright 2013 Sandeep Sharma <sandeep.jack2756@gmail.com>
* Copyright 2013 Kyungwan Han <asura321@gmail.com>
*
* No Standard.
USE_TCPSVD(NEWTOY(tcpsvd, "^<3c#=30<1C:b#=20<0u:l:hEv", TOYFLAG_USR|TOYFLAG_BIN))
USE_TCPSVD(OLDTOY(udpsvd, tcpsvd, TOYFLAG_USR|TOYFLAG_BIN))
config TCPSVD
bool "tcpsvd"
default n
help
usage: tcpsvd [-hEv] [-c N] [-C N[:MSG]] [-b N] [-u User] [-l Name] IP Port Prog
usage: udpsvd [-hEv] [-c N] [-u User] [-l Name] IP Port Prog
Create TCP/UDP socket, bind to IP:PORT and listen for incoming connection.
Run PROG for each connection.
IP IP to listen on, 0 = all
PORT Port to listen on
PROG ARGS Program to run
-l NAME Local hostname (else looks up local hostname in DNS)
-u USER[:GRP] Change to user/group after bind
-c N Handle up to N (> 0) connections simultaneously
-b N (TCP Only) Allow a backlog of approximately N TCP SYNs
-C N[:MSG] (TCP Only) Allow only up to N (> 0) connections from the same IP
New connections from this IP address are closed
immediately. MSG is written to the peer before close
-h Look up peer's hostname
-E Don't set up environment variables
-v Verbose
*/
#define FOR_tcpsvd
#include "toys.h"
GLOBALS(
char *name;
char *user;
long bn;
char *nmsg;
long cn;
int maxc;
int count_all;
int udp;
)
struct list_pid {
struct list_pid *next;
char *ip;
int pid;
};
struct list {
struct list* next;
char *d;
int count;
};
struct hashed {
struct list *head;
};
#define HASH_NR 256
struct hashed h[HASH_NR];
struct list_pid *pids = NULL;
// convert IP address to string.
static char *sock_to_address(struct sockaddr *sock, int flags)
{
char hbuf[NI_MAXHOST] = {0,};
char sbuf[NI_MAXSERV] = {0,};
int status = 0;
socklen_t len = sizeof(struct sockaddr_in6);
if (!(status = getnameinfo(sock, len, hbuf, sizeof(hbuf), sbuf,
sizeof(sbuf), flags))) {
if (flags & NI_NUMERICSERV) return xmprintf("%s:%s",hbuf, sbuf);
return xmprintf("%s",hbuf);
}
error_exit("getnameinfo: %s", gai_strerror(status));
}
// Insert pid, ip and fd in the list.
static void insert(struct list_pid **l, int pid, char *addr)
{
struct list_pid *newnode = xmalloc(sizeof(struct list_pid));
newnode->pid = pid;
newnode->ip = addr;
newnode->next = NULL;
if (!*l) *l = newnode;
else {
newnode->next = (*l);
*l = newnode;
}
}
// Hashing of IP address.
static int haship( char *addr)
{
uint32_t ip[8] = {0,};
int count = 0, i = 0;
if (!addr) error_exit("NULL ip");
while (i < strlen(addr)) {
while (addr[i] && (addr[i] != ':') && (addr[i] != '.')) {
ip[count] = ip[count]*10 + (addr[i]-'0');
i++;
}
if (i >= strlen(addr)) break;
count++;
i++;
}
return (ip[0]^ip[1]^ip[2]^ip[3]^ip[4]^ip[5]^ip[6]^ip[7])%HASH_NR;
}
// Remove a node from the list.
static char *delete(struct list_pid **pids, int pid)
{
struct list_pid *prev, *free_node, *head = *pids;
char *ip = NULL;
if (!head) return NULL;
prev = free_node = NULL;
while (head) {
if (head->pid == pid) {
ip = head->ip;
free_node = head;
if (!prev) *pids = head->next;
else prev->next = head->next;
free(free_node);
return ip;
}
prev = head;
head = head->next;
}
return NULL;
}
// decrement the ref count fora connection, if count reches ZERO then remove the node
static void remove_connection(char *ip)
{
struct list *head, *prev = NULL, *free_node = NULL;
int hash = haship(ip);
head = h[hash].head;
while (head) {
if (!strcmp(ip, head->d)) {
head->count--;
free_node = head;
if (!head->count) {
if (!prev) h[hash].head = head->next;
else prev->next = head->next;
free(free_node);
}
break;
}
prev = head;
head = head->next;
}
free(ip);
}
// Handler function.
static void handle_exit(int sig)
{
int status;
pid_t pid_n = wait(&status);
if (pid_n <= 0) return;
char *ip = delete(&pids, pid_n);
if (!ip) return;
remove_connection(ip);
TT.count_all--;
if (toys.optflags & FLAG_v) {
if (WIFEXITED(status))
xprintf("%s: end %d exit %d\n",toys.which->name, pid_n, WEXITSTATUS(status));
else if (WIFSIGNALED(status))
xprintf("%s: end %d signaled %d\n",toys.which->name, pid_n, WTERMSIG(status));
if (TT.cn > 1) xprintf("%s: status %d/%d\n",toys.which->name, TT.count_all, TT.cn);
}
}
// Grab uid and gid
static void get_uidgid(uid_t *uid, gid_t *gid, char *ug)
{
struct passwd *pass = NULL;
struct group *grp = NULL;
char *user = NULL, *group = NULL;
unsigned int n;
user = ug;
group = strchr(ug,':');
if (group) {
*group = '\0';
group++;
}
if (!(pass = getpwnam(user))) {
n = atolx_range(user, 0, INT_MAX);
if (!(pass = getpwuid(n))) perror_exit("Invalid user '%s'", user);
}
*uid = pass->pw_uid;
*gid = pass->pw_gid;
if (group) {
if (!(grp = getgrnam(group))) {
n = atolx_range(group, 0, INT_MAX);
if (!(grp = getgrgid(n))) perror_exit("Invalid group '%s'",group);
}
}
if (grp) *gid = grp->gr_gid;
}
// Bind socket.
static int create_bind_sock(char *host, struct sockaddr *haddr)
{
struct addrinfo hints, *res = NULL, *rp;
int sockfd, ret, set = 1;
char *ptr;
unsigned long port;
errno = 0;
port = strtoul(toys.optargs[1], &ptr, 10);
if (errno || port > 65535)
error_exit("Invalid port, Range is [0-65535]");
if (*ptr) ptr = toys.optargs[1];
else {
sprintf(toybuf, "%lu", port);
ptr = toybuf;
}
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = ((TT.udp) ?SOCK_DGRAM : SOCK_STREAM);
if ((ret = getaddrinfo(host, ptr, &hints, &res)))
perror_exit("%s", gai_strerror(ret));
for (rp = res; rp; rp = rp->ai_next)
if ( (rp->ai_family == AF_INET) || (rp->ai_family == AF_INET6)) break;
if (!rp) error_exit("Invalid IP %s", host);
sockfd = xsocket(rp->ai_family, TT.udp ?SOCK_DGRAM :SOCK_STREAM, 0);
setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &set, sizeof(set));
if (TT.udp) setsockopt(sockfd, IPPROTO_IP, IP_PKTINFO, &set, sizeof(set));
if ((bind(sockfd, rp->ai_addr, rp->ai_addrlen)) < 0) perror_exit("Bind failed");
if(haddr) memcpy(haddr, rp->ai_addr, rp->ai_addrlen);
freeaddrinfo(res);
return sockfd;
}
static void handle_signal(int sig)
{
if (toys.optflags & FLAG_v) xprintf("got signal %d, exit\n", sig);
raise(sig);
_exit(sig + 128); //should not reach here
}
void tcpsvd_main(void)
{
uid_t uid = 0;
gid_t gid = 0;
pid_t pid;
char haddr[sizeof(struct sockaddr_in6)];
struct list *head, *newnode;
int hash, fd, newfd, j;
char *ptr = NULL, *addr, *server, buf[sizeof(struct sockaddr_in6)];
socklen_t len = sizeof(buf);
TT.udp = (*toys.which->name == 'u');
if (TT.udp) toys.optflags &= ~FLAG_C;
memset(buf, 0, len);
if (toys.optflags & FLAG_C) {
if ((ptr = strchr(TT.nmsg, ':'))) {
*ptr = '\0';
ptr++;
}
TT.maxc = atolx_range(TT.nmsg, 1, INT_MAX);
}
fd = create_bind_sock(toys.optargs[0], (struct sockaddr*)&haddr);
if(toys.optflags & FLAG_u) {
get_uidgid(&uid, &gid, TT.user);
setuid(uid);
setgid(gid);
}
if (!TT.udp && (listen(fd, TT.bn) < 0)) perror_exit("Listen failed");
server = sock_to_address((struct sockaddr*)&haddr, NI_NUMERICHOST|NI_NUMERICSERV);
if (toys.optflags & FLAG_v) {
if (toys.optflags & FLAG_u)
xprintf("%s: listening on %s, starting, uid %u, gid %u\n"
,toys.which->name, server, uid, gid);
else
xprintf("%s: listening on %s, starting\n", toys.which->name, server);
}
for (j = 0; j < HASH_NR; j++) h[j].head = NULL;
sigatexit(handle_signal);
signal(SIGCHLD, handle_exit);
while (1) {
if (TT.count_all < TT.cn) {
if (TT.udp) {
if(recvfrom(fd, NULL, 0, MSG_PEEK, (struct sockaddr *)buf, &len) < 0)
perror_exit("recvfrom");
newfd = fd;
} else {
newfd = accept(fd, (struct sockaddr *)buf, &len);
if (newfd < 0) perror_exit("Error on accept");
}
} else {
sigset_t ss;
sigemptyset(&ss);
sigsuspend(&ss);
continue;
}
TT.count_all++;
addr = sock_to_address((struct sockaddr*)buf, NI_NUMERICHOST);
hash = haship(addr);
if (toys.optflags & FLAG_C) {
for (head = h[hash].head; head; head = head->next)
if (!strcmp(head->d, addr)) break;
if (head && head->count >= TT.maxc) {
if (ptr) write(newfd, ptr, strlen(ptr)+1);
close(newfd);
TT.count_all--;
continue;
}
}
newnode = (struct list*)xzalloc(sizeof(struct list));
newnode->d = addr;
for (head = h[hash].head; head; head = head->next) {
if (!strcmp(addr, head->d)) {
head->count++;
free(newnode);
break;
}
}
if (!head) {
newnode->next = h[hash].head;
h[hash].head = newnode;
h[hash].head->count++;
}
if (!(pid = xfork())) {
char *serv = NULL, *clie = NULL;
char *client = sock_to_address((struct sockaddr*)buf, NI_NUMERICHOST | NI_NUMERICSERV);
if (toys.optflags & FLAG_h) { //lookup name
if (toys.optflags & FLAG_l) serv = xstrdup(TT.name);
else serv = sock_to_address((struct sockaddr*)&haddr, 0);
clie = sock_to_address((struct sockaddr*)buf, 0);
}
if (!(toys.optflags & FLAG_E)) {
setenv("PROTO", TT.udp ?"UDP" :"TCP", 1);
setenv("PROTOLOCALADDR", server, 1);
setenv("PROTOREMOTEADDR", client, 1);
if (toys.optflags & FLAG_h) {
setenv("PROTOLOCALHOST", serv, 1);
setenv("PROTOREMOTEHOST", clie, 1);
}
if (!TT.udp) {
char max_c[32];
sprintf(max_c, "%d", TT.maxc);
setenv("TCPCONCURRENCY", max_c, 1); //Not valid for udp
}
}
if (toys.optflags & FLAG_v) {
xprintf("%s: start %d %s-%s",toys.which->name, getpid(), server, client);
if (toys.optflags & FLAG_h) xprintf(" (%s-%s)", serv, clie);
xputc('\n');
if (TT.cn > 1)
xprintf("%s: status %d/%d\n",toys.which->name, TT.count_all, TT.cn);
}
free(client);
if (toys.optflags & FLAG_h) {
free(serv);
free(clie);
}
if (TT.udp && (connect(newfd, (struct sockaddr *)buf, sizeof(buf)) < 0))
perror_exit("connect");
close(0);
close(1);
dup2(newfd, 0);
dup2(newfd, 1);
xexec(toys.optargs+2); //skip IP PORT
} else {
insert(&pids, pid, addr);
xclose(newfd); //close and reopen for next client.
if (TT.udp) fd = create_bind_sock(toys.optargs[0],
(struct sockaddr*)&haddr);
}
} //while(1)
}