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#define _GNU_SOURCE
#include <dlfcn.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
/* Wrapper around connect(2) to explicitly set TCP_NODELAY. */
static int nodelay_connect(
int (*real_connect)(int, const struct sockaddr *, socklen_t),
int sock, const struct sockaddr *addr, socklen_t addrlen)
{
int res = real_connect(sock, addr, addrlen);
if (!res && addr->sa_family == AF_INET) {
int opt = 1;
setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &opt, sizeof(opt));
}
return res;
}
#if __APPLE__
/* OS X does not have LD_PRELOAD but has DYLD_INSERT_LIBRARIES. The right
* environment variable is set by sshfs.c when attempting to load the
* sshnodelay workaround.
*
* However, things are not that simple: DYLD_INSERT_LIBRARIES does not
* behave exactly like LD_PRELOAD. Instead, the dyld dynamic linker will
* look for __DATA __interpose sections on the libraries given via the
* DYLD_INSERT_LIBRARIES variable. The contents of this section are pairs
* of replacement functions and functions to be replaced, respectively.
* Prepare such section here. */
int custom_connect(int sock, const struct sockaddr *addr, socklen_t addrlen);
typedef struct interpose_s {
void *new_func;
void *orig_func;
} interpose_t;
static const interpose_t interposers[] \
__attribute__ ((section("__DATA, __interpose"))) = {
{ (void *)custom_connect, (void *)connect },
};
int custom_connect(int sock, const struct sockaddr *addr, socklen_t addrlen)
{
return nodelay_connect(connect, sock, addr, addrlen);
}
#else /* !__APPLE__ */
int connect(int sock, const struct sockaddr *addr, socklen_t addrlen)
{
return nodelay_connect(dlsym(RTLD_NEXT, "connect"),
sock, addr, addrlen);
}
#endif /* !__APPLE__ */
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