ssize_t py_recv(int fd, void *buf, size_t len, int *cdata) { struct msghdr msg = {0}; struct iovec iov = {0}; size_t cmsglen = CMSG_SPACE(sizeof(int)); char control[CMSG_SPACE(sizeof(int))]; struct cmsghdr *cmsg; ssize_t ret; iov.iov_base = buf; iov.iov_len = len; msg.msg_iov = &iov; msg.msg_iovlen = 1; if (cdata != NULL) { msg.msg_control = control; msg.msg_controllen = cmsglen; } ret = recvmsg(fd, &msg, 0); if (ret == -1 || cdata == NULL) { return ret; } cmsg = CMSG_FIRSTHDR(&msg); if (cmsg == NULL || cmsg->cmsg_len != CMSG_LEN(sizeof(int)) || cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) { *cdata = -1; } else { *cdata = get_unaligned_int(CMSG_DATA(cmsg)); } return ret; }
/* receives a fd and data_len data * params: unix_socket * data * data_len * fd - will be set to the passed fd value or -1 if no fd * was passed * flags - 0, MSG_DONTWAIT, MSG_WAITALL; same as recv_all flags * returns: bytes read on success, -1 on error (and sets errno) */ int receive_fd(int unix_socket, void* data, int data_len, int* fd, int flags) { struct msghdr msg; struct iovec iov[1]; int new_fd; int ret; int n; #ifdef HAVE_MSGHDR_MSG_CONTROL struct cmsghdr* cmsg; union{ struct cmsghdr cm; char control[CMSG_SPACE(sizeof(new_fd))]; }control_un; msg.msg_control=control_un.control; msg.msg_controllen=sizeof(control_un.control); #else msg.msg_accrights=(caddr_t) &new_fd; msg.msg_accrightslen=sizeof(int); #endif msg.msg_name=0; msg.msg_namelen=0; iov[0].iov_base=data; iov[0].iov_len=data_len; msg.msg_iov=iov; msg.msg_iovlen=1; again: ret=recvmsg(unix_socket, &msg, flags); if (ret<0){ if (errno==EINTR) goto again; if ((errno==EAGAIN)||(errno==EWOULDBLOCK)) goto error; LM_CRIT("recvmsg on %d failed: %s\n", unix_socket, strerror(errno)); goto error; } if (ret==0){ /* EOF */ LM_CRIT("EOF on %d\n", unix_socket); goto error; } if (ret<data_len){ LM_WARN("too few bytes read (%d from %d) trying to fix...\n", ret, data_len); /* blocking recv_all */ n=recv_all(unix_socket, (char*)data+ret, data_len-ret, MSG_WAITALL); if (n>=0) ret+=n; else{ ret=n; goto error; } } #ifdef HAVE_MSGHDR_MSG_CONTROL cmsg=CMSG_FIRSTHDR(&msg); if ((cmsg!=0) && (cmsg->cmsg_len==CMSG_LEN(sizeof(new_fd)))){ if (cmsg->cmsg_type!= SCM_RIGHTS){ LM_ERR("msg control type != SCM_RIGHTS\n"); ret=-1; goto error; } if (cmsg->cmsg_level!= SOL_SOCKET){ LM_ERR("msg level != SOL_SOCKET\n"); ret=-1; goto error; } *fd = get_unaligned_int(CMSG_DATA(cmsg)); }else{ /* LM_ERR("no descriptor passed, cmsg=%p,len=%d\n", cmsg, (unsigned)cmsg->cmsg_len); */ *fd=-1; /* it's not really an error */ } #else if (msg.msg_accrightslen==sizeof(int)){ *fd=new_fd; }else{ /*LM_ERR("no descriptor passed, accrightslen=%d\n", msg.msg_accrightslen); */ *fd=-1; } #endif error: return ret; }