443 lines
10 KiB
C
443 lines
10 KiB
C
/*
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* tftp.c - a simple, read-only tftp server for qemu
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*
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* Copyright (c) 2004 Magnus Damm <damm@opensource.se>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <slirp.h>
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#include "qemu-common.h"
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static inline int tftp_session_in_use(struct tftp_session *spt)
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{
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return (spt->slirp != NULL);
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}
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static inline void tftp_session_update(struct tftp_session *spt)
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{
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spt->timestamp = curtime;
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}
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static void tftp_session_terminate(struct tftp_session *spt)
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{
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if (spt->fd >= 0) {
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close(spt->fd);
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spt->fd = -1;
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}
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g_free(spt->filename);
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spt->slirp = NULL;
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}
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static int tftp_session_allocate(Slirp *slirp, struct tftp_t *tp)
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{
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struct tftp_session *spt;
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int k;
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for (k = 0; k < TFTP_SESSIONS_MAX; k++) {
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spt = &slirp->tftp_sessions[k];
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if (!tftp_session_in_use(spt))
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goto found;
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/* sessions time out after 5 inactive seconds */
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if ((int)(curtime - spt->timestamp) > 5000) {
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tftp_session_terminate(spt);
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goto found;
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}
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}
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return -1;
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found:
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memset(spt, 0, sizeof(*spt));
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memcpy(&spt->client_ip, &tp->ip.ip_src, sizeof(spt->client_ip));
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spt->fd = -1;
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spt->client_port = tp->udp.uh_sport;
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spt->slirp = slirp;
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tftp_session_update(spt);
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return k;
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}
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static int tftp_session_find(Slirp *slirp, struct tftp_t *tp)
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{
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struct tftp_session *spt;
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int k;
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for (k = 0; k < TFTP_SESSIONS_MAX; k++) {
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spt = &slirp->tftp_sessions[k];
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if (tftp_session_in_use(spt)) {
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if (!memcmp(&spt->client_ip, &tp->ip.ip_src, sizeof(spt->client_ip))) {
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if (spt->client_port == tp->udp.uh_sport) {
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return k;
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}
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}
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}
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}
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return -1;
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}
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static int tftp_read_data(struct tftp_session *spt, uint32_t block_nr,
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uint8_t *buf, int len)
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{
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int bytes_read = 0;
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if (spt->fd < 0) {
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spt->fd = open(spt->filename, O_RDONLY | O_BINARY);
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}
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if (spt->fd < 0) {
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return -1;
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}
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if (len) {
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lseek(spt->fd, block_nr * 512, SEEK_SET);
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bytes_read = read(spt->fd, buf, len);
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}
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return bytes_read;
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}
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static int tftp_send_oack(struct tftp_session *spt,
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const char *keys[], uint32_t values[], int nb,
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struct tftp_t *recv_tp)
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{
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struct sockaddr_in saddr, daddr;
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struct mbuf *m;
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struct tftp_t *tp;
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int i, n = 0;
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m = m_get(spt->slirp);
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if (!m)
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return -1;
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memset(m->m_data, 0, m->m_size);
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m->m_data += IF_MAXLINKHDR;
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tp = (void *)m->m_data;
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m->m_data += sizeof(struct udpiphdr);
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tp->tp_op = htons(TFTP_OACK);
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for (i = 0; i < nb; i++) {
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n += snprintf(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%s",
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keys[i]) + 1;
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n += snprintf(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%u",
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values[i]) + 1;
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}
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saddr.sin_addr = recv_tp->ip.ip_dst;
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saddr.sin_port = recv_tp->udp.uh_dport;
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daddr.sin_addr = spt->client_ip;
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daddr.sin_port = spt->client_port;
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m->m_len = sizeof(struct tftp_t) - 514 + n -
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sizeof(struct ip) - sizeof(struct udphdr);
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udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
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return 0;
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}
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static void tftp_send_error(struct tftp_session *spt,
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uint16_t errorcode, const char *msg,
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struct tftp_t *recv_tp)
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{
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struct sockaddr_in saddr, daddr;
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struct mbuf *m;
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struct tftp_t *tp;
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m = m_get(spt->slirp);
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if (!m) {
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goto out;
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}
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memset(m->m_data, 0, m->m_size);
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m->m_data += IF_MAXLINKHDR;
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tp = (void *)m->m_data;
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m->m_data += sizeof(struct udpiphdr);
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tp->tp_op = htons(TFTP_ERROR);
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tp->x.tp_error.tp_error_code = htons(errorcode);
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pstrcpy((char *)tp->x.tp_error.tp_msg, sizeof(tp->x.tp_error.tp_msg), msg);
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saddr.sin_addr = recv_tp->ip.ip_dst;
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saddr.sin_port = recv_tp->udp.uh_dport;
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daddr.sin_addr = spt->client_ip;
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daddr.sin_port = spt->client_port;
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m->m_len = sizeof(struct tftp_t) - 514 + 3 + strlen(msg) -
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sizeof(struct ip) - sizeof(struct udphdr);
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udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
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out:
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tftp_session_terminate(spt);
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}
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static void tftp_send_next_block(struct tftp_session *spt,
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struct tftp_t *recv_tp)
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{
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struct sockaddr_in saddr, daddr;
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struct mbuf *m;
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struct tftp_t *tp;
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int nobytes;
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m = m_get(spt->slirp);
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if (!m) {
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return;
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}
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memset(m->m_data, 0, m->m_size);
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m->m_data += IF_MAXLINKHDR;
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tp = (void *)m->m_data;
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m->m_data += sizeof(struct udpiphdr);
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tp->tp_op = htons(TFTP_DATA);
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tp->x.tp_data.tp_block_nr = htons((spt->block_nr + 1) & 0xffff);
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saddr.sin_addr = recv_tp->ip.ip_dst;
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saddr.sin_port = recv_tp->udp.uh_dport;
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daddr.sin_addr = spt->client_ip;
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daddr.sin_port = spt->client_port;
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nobytes = tftp_read_data(spt, spt->block_nr, tp->x.tp_data.tp_buf, 512);
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if (nobytes < 0) {
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m_free(m);
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/* send "file not found" error back */
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tftp_send_error(spt, 1, "File not found", tp);
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return;
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}
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m->m_len = sizeof(struct tftp_t) - (512 - nobytes) -
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sizeof(struct ip) - sizeof(struct udphdr);
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udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
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if (nobytes == 512) {
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tftp_session_update(spt);
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}
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else {
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tftp_session_terminate(spt);
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}
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spt->block_nr++;
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}
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static void tftp_handle_rrq(Slirp *slirp, struct tftp_t *tp, int pktlen)
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{
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struct tftp_session *spt;
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int s, k;
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size_t prefix_len;
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char *req_fname;
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const char *option_name[2];
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uint32_t option_value[2];
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int nb_options = 0;
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/* check if a session already exists and if so terminate it */
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s = tftp_session_find(slirp, tp);
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if (s >= 0) {
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tftp_session_terminate(&slirp->tftp_sessions[s]);
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}
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s = tftp_session_allocate(slirp, tp);
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if (s < 0) {
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return;
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}
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spt = &slirp->tftp_sessions[s];
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/* unspecified prefix means service disabled */
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if (!slirp->tftp_prefix) {
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tftp_send_error(spt, 2, "Access violation", tp);
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return;
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}
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/* skip header fields */
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k = 0;
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pktlen -= offsetof(struct tftp_t, x.tp_buf);
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/* prepend tftp_prefix */
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prefix_len = strlen(slirp->tftp_prefix);
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spt->filename = g_malloc(prefix_len + TFTP_FILENAME_MAX + 2);
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memcpy(spt->filename, slirp->tftp_prefix, prefix_len);
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spt->filename[prefix_len] = '/';
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/* get name */
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req_fname = spt->filename + prefix_len + 1;
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while (1) {
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if (k >= TFTP_FILENAME_MAX || k >= pktlen) {
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tftp_send_error(spt, 2, "Access violation", tp);
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return;
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}
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req_fname[k] = tp->x.tp_buf[k];
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if (req_fname[k++] == '\0') {
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break;
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}
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}
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/* check mode */
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if ((pktlen - k) < 6) {
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tftp_send_error(spt, 2, "Access violation", tp);
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return;
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}
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if (strcasecmp(&tp->x.tp_buf[k], "octet") != 0) {
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tftp_send_error(spt, 4, "Unsupported transfer mode", tp);
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return;
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}
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k += 6; /* skipping octet */
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/* do sanity checks on the filename */
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if (!strncmp(req_fname, "../", 3) ||
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req_fname[strlen(req_fname) - 1] == '/' ||
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strstr(req_fname, "/../")) {
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tftp_send_error(spt, 2, "Access violation", tp);
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return;
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}
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/* check if the file exists */
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if (tftp_read_data(spt, 0, NULL, 0) < 0) {
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tftp_send_error(spt, 1, "File not found", tp);
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return;
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}
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if (tp->x.tp_buf[pktlen - 1] != 0) {
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tftp_send_error(spt, 2, "Access violation", tp);
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return;
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}
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while (k < pktlen && nb_options < ARRAY_SIZE(option_name)) {
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const char *key, *value;
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key = &tp->x.tp_buf[k];
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k += strlen(key) + 1;
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if (k >= pktlen) {
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tftp_send_error(spt, 2, "Access violation", tp);
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return;
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}
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value = &tp->x.tp_buf[k];
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k += strlen(value) + 1;
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if (strcasecmp(key, "tsize") == 0) {
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int tsize = atoi(value);
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struct stat stat_p;
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if (tsize == 0) {
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if (stat(spt->filename, &stat_p) == 0)
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tsize = stat_p.st_size;
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else {
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tftp_send_error(spt, 1, "File not found", tp);
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return;
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}
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}
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option_name[nb_options] = "tsize";
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option_value[nb_options] = tsize;
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nb_options++;
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} else if (strcasecmp(key, "blksize") == 0) {
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int blksize = atoi(value);
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/* If blksize option is bigger than what we will
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* emit, accept the option with our packet size.
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* Otherwise, simply do as we didn't see the option.
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*/
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if (blksize >= 512) {
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option_name[nb_options] = "blksize";
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option_value[nb_options] = 512;
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nb_options++;
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}
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}
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}
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if (nb_options > 0) {
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assert(nb_options <= ARRAY_SIZE(option_name));
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tftp_send_oack(spt, option_name, option_value, nb_options, tp);
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return;
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}
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spt->block_nr = 0;
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tftp_send_next_block(spt, tp);
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}
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static void tftp_handle_ack(Slirp *slirp, struct tftp_t *tp, int pktlen)
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{
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int s;
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s = tftp_session_find(slirp, tp);
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if (s < 0) {
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return;
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}
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tftp_send_next_block(&slirp->tftp_sessions[s], tp);
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}
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static void tftp_handle_error(Slirp *slirp, struct tftp_t *tp, int pktlen)
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{
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int s;
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s = tftp_session_find(slirp, tp);
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if (s < 0) {
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return;
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}
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tftp_session_terminate(&slirp->tftp_sessions[s]);
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}
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void tftp_input(struct mbuf *m)
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{
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struct tftp_t *tp = (struct tftp_t *)m->m_data;
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switch(ntohs(tp->tp_op)) {
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case TFTP_RRQ:
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tftp_handle_rrq(m->slirp, tp, m->m_len);
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break;
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case TFTP_ACK:
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tftp_handle_ack(m->slirp, tp, m->m_len);
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break;
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case TFTP_ERROR:
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tftp_handle_error(m->slirp, tp, m->m_len);
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break;
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}
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}
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