// if the caller attempted to bind to 0.0.0.0 or ::, then change it to
// this node's public IP address
int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen) {
errno = 0;
// save the original bind() call
void *handle = dlopen( LIBC_PATH, RTLD_LAZY );
if (!handle) {
handle = dlopen( LIBC_PATH_DEBIAN, RTLD_LAZY );
if( !handle ) {
fprintf( stderr, "Error loading libc.so.6\n" );
fflush( stderr );
return -1;
}
}
bind_original = dlsym(handle, "bind");
if( bind_original == NULL ) {
fprintf( stderr, "Error loading bind symbol\n" );
fflush( stderr );
return -1;
}
int tried_normal_bind = 0;
int rc = is_addr_any( addr );
fprintf( stderr, "bind(%d, %p, %ld)\n", sockfd, addr, addrlen);
if( rc > 0 ) {
rc = 0;
// rewrite this address
struct sockaddr_storage new_addr;
memset( &new_addr, 0, sizeof(struct sockaddr_storage));
memcpy( &new_addr, addr, addrlen );
rc = get_public_ip( (struct sockaddr*)&new_addr );
if( rc == -EINVAL ) {
// this will happen for DHCP, so bind the normal way
fprintf(stderr, "WARNING: could not get IP address; attempting normal bind.");
rc = bind_original( sockfd, (struct sockaddr*)&new_addr, addrlen );
fprintf(stderr, "normal bind rc = %d, errno = %d\n", rc, errno );
tried_normal_bind = 1;
}
else if( rc != 0 ) {
rc = -1;
}
if( rc == 0 && tried_normal_bind == 0 ) {
debug( addr, (struct sockaddr*)&new_addr );
rc = bind_original( sockfd, (struct sockaddr*)&new_addr, addrlen );
fprintf( stderr, "re-addressed bind rc = %d, errno = %d\n", rc, errno);
// save this result
if( rc == 0 ) {
cache_public_ip( (struct sockaddr*)&new_addr);
}
}
}
else {
rc = bind_original( sockfd, (struct sockaddr*)addr, addrlen );
fprintf( stderr, "bind rc = %d, errno = %d\n", rc, errno);
}
return rc;
}
int main() {
char public_ip[16] = {0};
int ret = get_public_ip(16, public_ip);
return 0;
}