/* * tftp.c - a simple, read-only tftp server for qemu * * Copyright (c) 2004 Magnus Damm * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include static void tftp_session_update(PNATState pData, struct tftp_session *spt) { spt->timestamp = curtime; spt->in_use = 1; } static void tftp_session_terminate(struct tftp_session *spt) { spt->in_use = 0; } static int tftp_session_allocate(PNATState pData, struct tftp_t *tp) { struct tftp_session *spt; int k; for (k = 0; k < TFTP_SESSIONS_MAX; k++) { spt = &tftp_sessions[k]; if (!spt->in_use) goto found; /* sessions time out after 5 inactive seconds */ if ((int)(curtime - spt->timestamp) > 5000) goto found; } return -1; found: memset(spt, 0, sizeof(*spt)); memcpy(&spt->client_ip, &tp->ip.ip_src, sizeof(spt->client_ip)); spt->client_port = tp->udp.uh_sport; tftp_session_update(pData, spt); return k; } static int tftp_session_find(PNATState pData, struct tftp_t *tp) { struct tftp_session *spt; int k; for (k = 0; k < TFTP_SESSIONS_MAX; k++) { spt = &tftp_sessions[k]; if (spt->in_use) { if (!memcmp(&spt->client_ip, &tp->ip.ip_src, sizeof(spt->client_ip))) { if (spt->client_port == tp->udp.uh_sport) return k; } } } return -1; } static int tftp_read_data(PNATState pData, struct tftp_session *spt, u_int16_t block_nr, u_int8_t *buf, int len) { int fd; int bytes_read = 0; char buffer[1024]; int n; n = RTStrPrintf(buffer, sizeof(buffer), "%s/%s", tftp_prefix, spt->filename); if (n >= sizeof(buffer)) return -1; fd = open(buffer, O_RDONLY | O_BINARY); if (fd < 0) return -1; if (len) { lseek(fd, block_nr * 512, SEEK_SET); bytes_read = read(fd, buf, len); } close(fd); return bytes_read; } static int tftp_send_oack(PNATState pData, struct tftp_session *spt, const char *key, uint32_t value, struct tftp_t *recv_tp) { struct sockaddr_in saddr, daddr; struct mbuf *m; struct tftp_t *tp; int n = 0; m = m_get(pData); if (!m) return -1; 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_OACK); n += sprintf((char *)tp->x.tp_buf + n, "%s", key) + 1; n += sprintf((char *)tp->x.tp_buf + n, "%u", value) + 1; 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 + n - sizeof(struct ip) - sizeof(struct udphdr); udp_output2(pData, NULL, m, &saddr, &daddr, IPTOS_LOWDELAY); return 0; } static int tftp_send_error(PNATState pData, struct tftp_session *spt, u_int16_t errorcode, const char *msg, struct tftp_t *recv_tp) { struct sockaddr_in saddr, daddr; struct mbuf *m; struct tftp_t *tp; int nobytes; m = m_get(pData); if (!m) return -1; 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); strcpy((char *)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; nobytes = 2; m->m_len = sizeof(struct tftp_t) - 514 + 3 + strlen(msg) - sizeof(struct ip) - sizeof(struct udphdr); udp_output2(pData, NULL, m, &saddr, &daddr, IPTOS_LOWDELAY); tftp_session_terminate(spt); return 0; } static int tftp_send_data(PNATState pData, struct tftp_session *spt, u_int16_t block_nr, struct tftp_t *recv_tp) { struct sockaddr_in saddr, daddr; struct mbuf *m; struct tftp_t *tp; int nobytes; if (block_nr < 1) return -1; m = m_get(pData); if (!m) return -1; 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_DATA); tp->x.tp_data.tp_block_nr = htons(block_nr); 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; nobytes = tftp_read_data(pData, spt, block_nr - 1, tp->x.tp_data.tp_buf, 512); if (nobytes < 0) { m_free(pData, m); /* send "file not found" error back */ tftp_send_error(pData, spt, 1, "File not found", tp); return -1; } m->m_len = sizeof(struct tftp_t) - (512 - nobytes) - sizeof(struct ip) - sizeof(struct udphdr); udp_output2(pData, NULL, m, &saddr, &daddr, IPTOS_LOWDELAY); if (nobytes == 512) tftp_session_update(pData, spt); else tftp_session_terminate(spt); return 0; } static void tftp_handle_rrq(PNATState pData, struct tftp_t *tp, int pktlen) { struct tftp_session *spt; int s, k, n; u_int8_t *src, *dst; s = tftp_session_allocate(pData, tp); if (s < 0) return; spt = &tftp_sessions[s]; src = tp->x.tp_buf; dst = spt->filename; n = pktlen - ((uint8_t *)&tp->x.tp_buf[0] - (uint8_t *)tp); /* get name */ for (k = 0; k < n; k++) { if (k < TFTP_FILENAME_MAX) dst[k] = src[k]; else return; if (src[k] == '\0') break; } if (k >= n) return; k++; /* check mode */ if ((n - k) < 6) return; if (memcmp(&src[k], "octet\0", 6) != 0) { tftp_send_error(pData, spt, 4, "Unsupported transfer mode", tp); return; } k += 6; /* skipping octet */ /* do sanity checks on the filename */ if ( !strncmp((const char*)spt->filename, "../", 3) || (spt->filename[strlen((const char *)spt->filename) - 1] == '/') || strstr((const char *)spt->filename, "/../")) { tftp_send_error(pData, spt, 2, "Access violation", tp); return; } /* only allow exported prefixes */ if (!tftp_prefix) { tftp_send_error(pData, spt, 2, "Access violation", tp); return; } /* check if the file exists */ if (tftp_read_data(pData, spt, 0, spt->filename, 0) < 0) { tftp_send_error(pData, spt, 1, "File not found", tp); return; } if (src[n - 1] != 0) { tftp_send_error(pData, spt, 2, "Access violation", tp); return; } while (k < n) { const char *key, *value; key = (const char *)src + k; k += strlen(key) + 1; if (k >= n) { tftp_send_error(pData, spt, 2, "Access violation", tp); return; } value = (const char *)src + k; k += strlen(value) + 1; if (strcmp(key, "tsize") == 0) { int tsize = atoi(value); struct stat stat_p; if (tsize == 0 && tftp_prefix) { char buffer[1024]; int len; len = RTStrPrintf(buffer, sizeof(buffer), "%s/%s", tftp_prefix, spt->filename); if (stat(buffer, &stat_p) == 0) tsize = stat_p.st_size; else { tftp_send_error(pData, spt, 1, "File not found", tp); return; } } tftp_send_oack(pData, spt, "tsize", tsize, tp); return; } } tftp_send_data(pData, spt, 1, tp); } static void tftp_handle_ack(PNATState pData, struct tftp_t *tp, int pktlen) { int s; s = tftp_session_find(pData, tp); if (s < 0) return; if (tftp_send_data(pData, &tftp_sessions[s], ntohs(tp->x.tp_data.tp_block_nr) + 1, tp) < 0) { /* XXX */ } } void tftp_input(PNATState pData, struct mbuf *m) { struct tftp_t *tp = (struct tftp_t *)m->m_data; switch(ntohs(tp->tp_op)) { case TFTP_RRQ: tftp_handle_rrq(pData, tp, m->m_len); break; case TFTP_ACK: tftp_handle_ack(pData, tp, m->m_len); break; } }