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echosrv.c
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echosrv.c
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/* echosrv: a simple line echo server with optional prefix adding.
*
* echosrv --listen localhost6:1234 --prefix "ssl: "
*
* This will bind to 1234, and echo every line pre-pending "ssl: ". This is
* used for testing: we create several such servers with different prefixes,
* then we connect test clients that can then check they get the proper data
* back (thus testing that shoveling works both ways) with the correct prefix
* (thus testing it connected to the expected service).
* **/
#define _GNU_SOURCE
#include <sys/types.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <signal.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <pwd.h>
#include <syslog.h>
#include <libgen.h>
#include <getopt.h>
#include <errno.h>
#define cfg sslhcfg
#include "common.h"
#undef cfg
#include "echosrv-conf.h"
/* Added to make the code compilable under CYGWIN
* */
#ifndef SA_NOCLDWAIT
#define SA_NOCLDWAIT 0
#endif
struct echocfg_item cfg;
void check_res_dump(int res, struct addrinfo *addr, char* syscall)
{
char buf[NI_MAXHOST];
if (res == -1) {
if (addr)
fprintf(stderr, "error %s:%s: %s\n",
sprintaddr(buf, sizeof(buf), addr),
syscall,
strerror(errno));
else
fprintf(stderr, "Dying just because\n");
exit(1);
}
}
void start_echo(int fd)
{
ssize_t res;
char buffer[1 << 20];
ssize_t ret;
size_t prefix_len;
int first = 1;
prefix_len = strlen(cfg.prefix);
memset(buffer, 0, sizeof(buffer));
strcpy(buffer, cfg.prefix);
while (1) {
ret = read(fd, buffer + prefix_len, sizeof(buffer) - prefix_len);
if (ret <= 0) {
fprintf(stderr, "%s", strerror(errno));
return;
}
if (first) {
res = write(fd, buffer, ret + prefix_len);
first = 0;
if (write(1, buffer, ret + prefix_len) < 0) {
fprintf(stderr, "%s", strerror(errno));
}
} else {
res = write(fd, buffer + prefix_len, ret);
}
if (res < 0) {
fprintf(stderr, "%s", strerror(errno));
return;
}
}
}
/* TCP echo server: accepts connections to an endpoint, forks an echo for each
* connection, forever. Prefix is added at start of response stream */
void tcp_echo(struct listen_endpoint* listen_socket)
{
while (1) {
int in_socket = accept(listen_socket->socketfd, 0, 0);
if (in_socket == -1) {
perror("tcp_echo:accept");
exit(1);
}
if (!fork())
{
close(listen_socket->socketfd);
start_echo(in_socket);
exit(0);
}
close(in_socket);
waitpid(-1, NULL, WNOHANG);
}
}
void print_udp_xchange(int sockfd, struct sockaddr* addr, socklen_t addrlen)
{
struct addrinfo src_addrinfo, to_addrinfo;
char str_addr[NI_MAXHOST+1+NI_MAXSERV+1];
char str_addr2[NI_MAXHOST+1+NI_MAXSERV+1];
struct sockaddr_storage ss;
src_addrinfo.ai_addr = (struct sockaddr*)&ss;
src_addrinfo.ai_addrlen = sizeof(ss);
getsockname(sockfd, src_addrinfo.ai_addr, &src_addrinfo.ai_addrlen);
to_addrinfo.ai_addr = addr;
to_addrinfo.ai_addrlen = sizeof(*addr);
fprintf(stderr, "UDP local %s remote %s\n",
sprintaddr(str_addr, sizeof(str_addr), &src_addrinfo),
sprintaddr(str_addr2, sizeof(str_addr2), &to_addrinfo)
);
}
/* UDP echo server: receive packets, return them, forever.
* Prefix is added at each packet */
void udp_echo(struct listen_endpoint* listen_socket)
{
char data[65536];
struct sockaddr src_addr;
socklen_t addrlen;
memset(data, 0, sizeof(data));
size_t prefix_len = strlen(cfg.prefix);
memcpy(data, cfg.prefix, prefix_len);
while (1) {
addrlen = sizeof(src_addr);
ssize_t len = recvfrom(listen_socket->socketfd,
data + prefix_len,
sizeof(data) - prefix_len,
0,
&src_addr,
&addrlen);
if (len < 0) {
perror("recvfrom");
}
*(data + prefix_len + len) = 0;
fprintf(stderr, "%zd %s\n", len, data + prefix_len);
print_udp_xchange(listen_socket->socketfd, &src_addr, addrlen);
ssize_t res = sendto(listen_socket->socketfd,
data,
len + prefix_len,
0,
&src_addr,
addrlen);
if (res < 0) {
perror("sendto");
}
}
}
void main_loop(struct listen_endpoint listen_sockets[], int num_addr_listen)
{
int i;
for (i = 0; i < num_addr_listen; i++) {
if (!fork()) {
if (cfg.udp) {
udp_echo(&listen_sockets[i]);
} else {
tcp_echo(&listen_sockets[i]);
}
}
}
wait(NULL);
}
/* Following is a number of utility functions copied from common.c: linking
* against common.o directly means echosrv has to work with sslh config struct,
* which makes it all too awkward */
/* simplified from common.c */
char* sprintaddr(char* buf, size_t size, struct addrinfo *a)
{
char host[NI_MAXHOST], serv[NI_MAXSERV];
int res;
res = getnameinfo(a->ai_addr, a->ai_addrlen,
host, sizeof(host),
serv, sizeof(serv),
0 );
if (res) {
/* Name resolution failed: do it numerically instead */
res = getnameinfo(a->ai_addr, a->ai_addrlen,
host, sizeof(host),
serv, sizeof(serv),
NI_NUMERICHOST | NI_NUMERICSERV);
/* should not fail but... */
if (res) {
strcpy(host, "?");
strcpy(serv, "?");
}
}
snprintf(buf, size, "%s:%s", host, serv);
return buf;
}
/* simplified from common.c */
int listen_single_addr(struct addrinfo* addr, int keepalive, int udp)
{
struct sockaddr_storage *saddr;
int sockfd, one, res;
saddr = (struct sockaddr_storage*)addr->ai_addr;
sockfd = socket(saddr->ss_family, udp ? SOCK_DGRAM : SOCK_STREAM, 0);
check_res_dump(sockfd, addr, "socket");
one = 1;
res = setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (char*)&one, sizeof(one));
check_res_dump(res, addr, "setsockopt(SO_REUSEADDR)");
if (addr->ai_addr->sa_family == AF_INET6) {
res = setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY, (char*)&one, sizeof(one));
check_res_dump(res, addr, "setsockopt(IPV6_V6ONLY)");
}
res = bind(sockfd, addr->ai_addr, addr->ai_addrlen);
check_res_dump(res, addr, "bind");
if (!udp) {
res = listen (sockfd, 50);
check_res_dump(res, addr, "listen");
}
return sockfd;
}
/* simplified from common.c */
int resolve_split_name(struct addrinfo **out, char* host, char* serv)
{
struct addrinfo hint;
char *end;
int res;
memset(&hint, 0, sizeof(hint));
hint.ai_family = PF_UNSPEC;
hint.ai_socktype = SOCK_STREAM;
/* If it is a RFC-Compliant IPv6 address ("[1234::12]:443"), remove brackets
* around IP address */
if (host[0] == '[') {
end = strrchr(host, ']');
if (!end) {
fprintf(stderr, "%s: no closing bracket in IPv6 address?\n", host);
return -1;
}
host++; /* skip first bracket */
*end = 0; /* remove last bracket */
}
res = getaddrinfo(host, serv, &hint, out);
if (res)
fprintf(stderr, "%s `%s:%s'\n", gai_strerror(res), host, serv);
return res;
}
int start_listen_sockets(struct listen_endpoint *sockfd[])
{
struct addrinfo *addr, *start_addr;
char buf[NI_MAXHOST];
int i, res;
int num_addr = 0, keepalive = 0, udp = 0;
*sockfd = NULL;
fprintf(stderr, "Listening to:\n");
for (i = 0; i < cfg.listen_len; i++) {
udp = cfg.udp;
res = resolve_split_name(&start_addr, cfg.listen[i].host, cfg.listen[i].port);
if (res) exit(4);
for (addr = start_addr; addr; addr = addr->ai_next) {
num_addr++;
*sockfd = realloc(*sockfd, num_addr * sizeof(*sockfd));
(*sockfd)[num_addr-1].socketfd = listen_single_addr(addr, keepalive, udp);
(*sockfd)[num_addr-1].type = udp ? SOCK_DGRAM : SOCK_STREAM;
fprintf(stderr, "%d:\t%s\n", (*sockfd)[num_addr-1].socketfd, sprintaddr(buf, sizeof(buf), addr));
}
freeaddrinfo(start_addr);
}
return num_addr;
}
int main(int argc, char *argv[])
{
extern char *optarg;
extern int optind;
int num_addr_listen;
struct listen_endpoint *listen_sockets;
memset(&cfg, 0, sizeof(cfg));
if (echocfg_cl_parse(argc, argv, &cfg))
exit(1);
echocfg_fprint(stdout, &cfg, 0);
num_addr_listen = start_listen_sockets(&listen_sockets);
main_loop(listen_sockets, num_addr_listen);
return 0;
}