2 * tftp.c - a simple, read-only tftp server for qemu
4 * Copyright (c) 2004 Magnus Damm <damm@opensource.se>
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
29 unsigned char filename[TFTP_FILENAME_MAX];
31 struct in_addr client_ip;
32 u_int16_t client_port;
37 struct tftp_session tftp_sessions[TFTP_SESSIONS_MAX];
39 const char *tftp_prefix;
41 static void tftp_session_update(struct tftp_session *spt)
43 spt->timestamp = curtime;
47 static void tftp_session_terminate(struct tftp_session *spt)
52 static int tftp_session_allocate(struct tftp_t *tp)
54 struct tftp_session *spt;
57 for (k = 0; k < TFTP_SESSIONS_MAX; k++) {
58 spt = &tftp_sessions[k];
63 /* sessions time out after 5 inactive seconds */
64 if ((int)(curtime - spt->timestamp) > 5000)
71 memset(spt, 0, sizeof(*spt));
72 memcpy(&spt->client_ip, &tp->ip.ip_src, sizeof(spt->client_ip));
73 spt->client_port = tp->udp.uh_sport;
75 tftp_session_update(spt);
80 static int tftp_session_find(struct tftp_t *tp)
82 struct tftp_session *spt;
85 for (k = 0; k < TFTP_SESSIONS_MAX; k++) {
86 spt = &tftp_sessions[k];
89 if (!memcmp(&spt->client_ip, &tp->ip.ip_src, sizeof(spt->client_ip))) {
90 if (spt->client_port == tp->udp.uh_sport) {
100 static int tftp_read_data(struct tftp_session *spt, u_int16_t block_nr,
101 u_int8_t *buf, int len)
106 fd = open(spt->filename, O_RDONLY | O_BINARY);
113 lseek(fd, block_nr * 512, SEEK_SET);
115 bytes_read = read(fd, buf, len);
123 static int tftp_send_error(struct tftp_session *spt,
124 u_int16_t errorcode, const char *msg,
125 struct tftp_t *recv_tp)
127 struct sockaddr_in saddr, daddr;
138 memset(m->m_data, 0, m->m_size);
140 m->m_data += if_maxlinkhdr;
141 tp = (void *)m->m_data;
142 m->m_data += sizeof(struct udpiphdr);
144 tp->tp_op = htons(TFTP_ERROR);
145 tp->x.tp_error.tp_error_code = htons(errorcode);
146 strcpy(tp->x.tp_error.tp_msg, msg);
148 saddr.sin_addr = recv_tp->ip.ip_dst;
149 saddr.sin_port = recv_tp->udp.uh_dport;
151 daddr.sin_addr = spt->client_ip;
152 daddr.sin_port = spt->client_port;
156 m->m_len = sizeof(struct tftp_t) - 514 + 3 + strlen(msg) -
157 sizeof(struct ip) - sizeof(struct udphdr);
159 udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
161 tftp_session_terminate(spt);
166 static int tftp_send_data(struct tftp_session *spt,
168 struct tftp_t *recv_tp)
170 struct sockaddr_in saddr, daddr;
185 memset(m->m_data, 0, m->m_size);
187 m->m_data += if_maxlinkhdr;
188 tp = (void *)m->m_data;
189 m->m_data += sizeof(struct udpiphdr);
191 tp->tp_op = htons(TFTP_DATA);
192 tp->x.tp_data.tp_block_nr = htons(block_nr);
194 saddr.sin_addr = recv_tp->ip.ip_dst;
195 saddr.sin_port = recv_tp->udp.uh_dport;
197 daddr.sin_addr = spt->client_ip;
198 daddr.sin_port = spt->client_port;
200 nobytes = tftp_read_data(spt, block_nr - 1, tp->x.tp_data.tp_buf, 512);
205 /* send "file not found" error back */
207 tftp_send_error(spt, 1, "File not found", tp);
212 m->m_len = sizeof(struct tftp_t) - (512 - nobytes) -
213 sizeof(struct ip) - sizeof(struct udphdr);
215 udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
217 if (nobytes == 512) {
218 tftp_session_update(spt);
221 tftp_session_terminate(spt);
227 static void tftp_handle_rrq(struct tftp_t *tp, int pktlen)
229 struct tftp_session *spt;
233 s = tftp_session_allocate(tp);
239 spt = &tftp_sessions[s];
243 n = pktlen - ((uint8_t *)&tp->x.tp_buf[0] - (uint8_t *)tp);
247 for (k = 0; k < n; k++) {
248 if (k < TFTP_FILENAME_MAX) {
255 if (src[k] == '\0') {
271 if (memcmp(&src[k], "octet\0", 6) != 0) {
272 tftp_send_error(spt, 4, "Unsupported transfer mode", tp);
276 /* do sanity checks on the filename */
278 if ((spt->filename[0] != '/')
279 || (spt->filename[strlen(spt->filename) - 1] == '/')
280 || strstr(spt->filename, "/../")) {
281 tftp_send_error(spt, 2, "Access violation", tp);
285 /* only allow exported prefixes */
288 || (strncmp(spt->filename, tftp_prefix, strlen(tftp_prefix)) != 0)) {
289 tftp_send_error(spt, 2, "Access violation", tp);
293 /* check if the file exists */
295 if (tftp_read_data(spt, 0, spt->filename, 0) < 0) {
296 tftp_send_error(spt, 1, "File not found", tp);
300 tftp_send_data(spt, 1, tp);
303 static void tftp_handle_ack(struct tftp_t *tp, int pktlen)
307 s = tftp_session_find(tp);
313 if (tftp_send_data(&tftp_sessions[s],
314 ntohs(tp->x.tp_data.tp_block_nr) + 1,
320 void tftp_input(struct mbuf *m)
322 struct tftp_t *tp = (struct tftp_t *)m->m_data;
324 switch(ntohs(tp->tp_op)) {
326 tftp_handle_rrq(tp, m->m_len);
330 tftp_handle_ack(tp, m->m_len);