/* * tftp.c - a simple, read-only tftp server for qemu * * Copyright (c) 2004 Magnus Damm <damm@opensource.se> * * 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 <slirp.h> #include "qemu-common.h" static inline int tftp_session_in_use(struct tftp_session *spt) { return (spt->slirp != NULL); } static inline void tftp_session_update(struct tftp_session *spt) { spt->timestamp = curtime; } static void tftp_session_terminate(struct tftp_session *spt) { if (spt->fd >= 0) { close(spt->fd); spt->fd = -1; } g_free(spt->filename); spt->slirp = NULL; } static int tftp_session_allocate(Slirp *slirp, struct tftp_t *tp) { struct tftp_session *spt; int k; for (k = 0; k < TFTP_SESSIONS_MAX; k++) { spt = &slirp->tftp_sessions[k]; if (!tftp_session_in_use(spt)) goto found; /* sessions time out after 5 inactive seconds */ if ((int)(curtime - spt->timestamp) > 5000) { tftp_session_terminate(spt); goto found; } } return -1; found: memset(spt, 0, sizeof(*spt)); memcpy(&spt->client_ip, &tp->ip.ip_src, sizeof(spt->client_ip)); spt->fd = -1; spt->client_port = tp->udp.uh_sport; spt->slirp = slirp; tftp_session_update(spt); return k; } static int tftp_session_find(Slirp *slirp, struct tftp_t *tp) { struct tftp_session *spt; int k; for (k = 0; k < TFTP_SESSIONS_MAX; k++) { spt = &slirp->tftp_sessions[k]; if (tftp_session_in_use(spt)) { 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(struct tftp_session *spt, uint32_t block_nr, uint8_t *buf, int len) { int bytes_read = 0; if (spt->fd < 0) { spt->fd = open(spt->filename, O_RDONLY | O_BINARY); } if (spt->fd < 0) { return -1; } if (len) { lseek(spt->fd, block_nr * 512, SEEK_SET); bytes_read = read(spt->fd, buf, len); } return bytes_read; } static int tftp_send_oack(struct tftp_session *spt, const char *keys[], uint32_t values[], int nb, struct tftp_t *recv_tp) { struct sockaddr_in saddr, daddr; struct mbuf *m; struct tftp_t *tp; int i, n = 0; m = m_get(spt->slirp); 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); for (i = 0; i < nb; i++) { n += snprintf(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%s", keys[i]) + 1; n += snprintf(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%u", values[i]) + 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(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY); return 0; } 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); } static void tftp_send_next_block(struct tftp_session *spt, struct tftp_t *recv_tp) { struct sockaddr_in saddr, daddr; struct mbuf *m; struct tftp_t *tp; int nobytes; m = m_get(spt->slirp); if (!m) { return; } 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((spt->block_nr + 1) & 0xffff); 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(spt, spt->block_nr, tp->x.tp_data.tp_buf, 512); if (nobytes < 0) { m_free(m); /* send "file not found" error back */ tftp_send_error(spt, 1, "File not found", tp); return; } m->m_len = sizeof(struct tftp_t) - (512 - nobytes) - sizeof(struct ip) - sizeof(struct udphdr); udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY); if (nobytes == 512) { tftp_session_update(spt); } else { tftp_session_terminate(spt); } spt->block_nr++; } static void tftp_handle_rrq(Slirp *slirp, struct tftp_t *tp, int pktlen) { struct tftp_session *spt; int s, k; size_t prefix_len; char *req_fname; const char *option_name[2]; uint32_t option_value[2]; int nb_options = 0; /* check if a session already exists and if so terminate it */ s = tftp_session_find(slirp, tp); if (s >= 0) { tftp_session_terminate(&slirp->tftp_sessions[s]); } s = tftp_session_allocate(slirp, tp); if (s < 0) { return; } spt = &slirp->tftp_sessions[s]; /* unspecifed prefix means service disabled */ if (!slirp->tftp_prefix) { tftp_send_error(spt, 2, "Access violation", tp); return; } /* skip header fields */ k = 0; pktlen -= offsetof(struct tftp_t, x.tp_buf); /* prepend tftp_prefix */ prefix_len = strlen(slirp->tftp_prefix); spt->filename = g_malloc(prefix_len + TFTP_FILENAME_MAX + 2); memcpy(spt->filename, slirp->tftp_prefix, prefix_len); spt->filename[prefix_len] = '/'; /* get name */ req_fname = spt->filename + prefix_len + 1; while (1) { if (k >= TFTP_FILENAME_MAX || k >= pktlen) { tftp_send_error(spt, 2, "Access violation", tp); return; } req_fname[k] = tp->x.tp_buf[k]; if (req_fname[k++] == '\0') { break; } } /* check mode */ if ((pktlen - k) < 6) { tftp_send_error(spt, 2, "Access violation", tp); return; } if (strcasecmp(&tp->x.tp_buf[k], "octet") != 0) { tftp_send_error(spt, 4, "Unsupported transfer mode", tp); return; } k += 6; /* skipping octet */ /* do sanity checks on the filename */ if (!strncmp(req_fname, "../", 3) || req_fname[strlen(req_fname) - 1] == '/' || strstr(req_fname, "/../")) { tftp_send_error(spt, 2, "Access violation", tp); return; } /* check if the file exists */ if (tftp_read_data(spt, 0, NULL, 0) < 0) { tftp_send_error(spt, 1, "File not found", tp); return; } if (tp->x.tp_buf[pktlen - 1] != 0) { tftp_send_error(spt, 2, "Access violation", tp); return; } while (k < pktlen && nb_options < ARRAY_SIZE(option_name)) { const char *key, *value; key = &tp->x.tp_buf[k]; k += strlen(key) + 1; if (k >= pktlen) { tftp_send_error(spt, 2, "Access violation", tp); return; } value = &tp->x.tp_buf[k]; k += strlen(value) + 1; if (strcasecmp(key, "tsize") == 0) { int tsize = atoi(value); struct stat stat_p; if (tsize == 0) { if (stat(spt->filename, &stat_p) == 0) tsize = stat_p.st_size; else { tftp_send_error(spt, 1, "File not found", tp); return; } } option_name[nb_options] = "tsize"; option_value[nb_options] = tsize; nb_options++; } else if (strcasecmp(key, "blksize") == 0) { int blksize = atoi(value); /* If blksize option is bigger than what we will * emit, accept the option with our packet size. * Otherwise, simply do as we didn't see the option. */ if (blksize >= 512) { option_name[nb_options] = "blksize"; option_value[nb_options] = 512; nb_options++; } } } if (nb_options > 0) { assert(nb_options <= ARRAY_SIZE(option_name)); tftp_send_oack(spt, option_name, option_value, nb_options, tp); return; } spt->block_nr = 0; tftp_send_next_block(spt, tp); } static void tftp_handle_ack(Slirp *slirp, struct tftp_t *tp, int pktlen) { int s; s = tftp_session_find(slirp, tp); if (s < 0) { return; } tftp_send_next_block(&slirp->tftp_sessions[s], tp); } static void tftp_handle_error(Slirp *slirp, struct tftp_t *tp, int pktlen) { int s; s = tftp_session_find(slirp, tp); if (s < 0) { return; } tftp_session_terminate(&slirp->tftp_sessions[s]); } void tftp_input(struct mbuf *m) { struct tftp_t *tp = (struct tftp_t *)m->m_data; switch(ntohs(tp->tp_op)) { case TFTP_RRQ: tftp_handle_rrq(m->slirp, tp, m->m_len); break; case TFTP_ACK: tftp_handle_ack(m->slirp, tp, m->m_len); break; case TFTP_ERROR: tftp_handle_error(m->slirp, tp, m->m_len); break; } }