static void tftp_send_error(struct tftp_session *spt, uint16_t errorcode, const char *msg, struct tftp_t *recv_tp) { struct sockaddr_in saddr, daddr; struct mbuf *m; struct tftp_t *tp; m = m_get(spt->slirp); if (!m) { goto out; } memset(m->m_data, 0, m->m_size); m->m_data += IF_MAXLINKHDR; tp = (void *)m->m_data; m->m_data += sizeof(struct udpiphdr); tp->tp_op = htons(TFTP_ERROR); tp->x.tp_error.tp_error_code = htons(errorcode); pstrcpy((char *)tp->x.tp_error.tp_msg, sizeof(tp->x.tp_error.tp_msg), msg); saddr.sin_addr = recv_tp->ip.ip_dst; saddr.sin_port = recv_tp->udp.uh_dport; daddr.sin_addr = spt->client_ip; daddr.sin_port = spt->client_port; m->m_len = sizeof(struct tftp_t) - 514 + 3 + strlen(msg) - sizeof(struct ip) - sizeof(struct udphdr); udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY); out: tftp_session_terminate(spt); }