TFTP support (Magnus Damm)

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@1050 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 335 insertions, 0 deletions

diff --git a/tftp.c b/tftp.c
new file mode 100644
index 0000000..9607efd
--- /dev/null
+++ b/tftp.c
@@ -0,0 +1,335 @@
+/*
+ * 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>
+
+struct tftp_session {
+    int in_use;
+    unsigned char filename[TFTP_FILENAME_MAX];
+
+    struct in_addr client_ip;
+    u_int16_t client_port;
+
+    struct timeval timestamp;
+};
+
+struct tftp_session tftp_sessions[TFTP_SESSIONS_MAX];
+
+char *tftp_prefix;
+
+static void tftp_session_update(struct tftp_session *spt)
+{
+    gettimeofday(&spt->timestamp, 0);
+    spt->in_use = 1;
+}
+
+static void tftp_session_terminate(struct tftp_session *spt)
+{
+    spt->in_use = 0;
+}
+
+static int tftp_session_allocate(struct tftp_t *tp)
+{
+    struct tftp_session *spt;
+    struct timeval tv;
+    int k;
+
+    gettimeofday(&tv, 0);
+
+    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 (tv.tv_sec > (spt->timestamp.tv_sec + 5)) {
+            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(spt);
+
+    return k;
+}
+
+static int tftp_session_find(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(struct tftp_session *spt, u_int16_t block_nr,
+                          u_int8_t *buf, int len)
+{
+    int fd;
+    int bytes_read = 0;
+
+    fd = open(spt->filename, O_RDONLY);
+
+    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_error(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();
+
+    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(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(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
+
+    tftp_session_terminate(spt);
+
+    return 0;
+}
+
+static int tftp_send_data(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();
+
+    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(spt, block_nr - 1, 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 -1;
+    }
+
+    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);
+    }
+
+    return 0;
+}
+
+static void tftp_handle_rrq(struct tftp_t *tp, int pktlen)
+{
+    struct tftp_session *spt;
+    int s, k, n;
+    u_int8_t *src, *dst;
+
+    s = tftp_session_allocate(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(spt, 4, "Unsupported transfer mode", tp);
+        return;
+    }
+
+    /* do sanity checks on the filename */
+
+    if ((spt->filename[0] != '/') ||
+        (spt->filename[strlen(spt->filename) - 1] == '/') ||
+        strstr(spt->filename, "/../")) {
+        tftp_send_error(spt, 2, "Access violation", tp);
+        return;
+    }
+
+    /* only allow exported prefixes */
+
+    if (!tftp_prefix ||
+        (strncmp(spt->filename, tftp_prefix, strlen(tftp_prefix)) != 0)) {
+        tftp_send_error(spt, 2, "Access violation", tp);
+        return;
+    }
+
+    /* check if the file exists */
+
+    if (tftp_read_data(spt, 0, spt->filename, 0) < 0) {
+        tftp_send_error(spt, 1, "File not found", tp);
+        return;
+    }
+
+    tftp_send_data(spt, 1, tp);
+}
+
+static void tftp_handle_ack(struct tftp_t *tp, int pktlen)
+{
+    int s;
+
+    s = tftp_session_find(tp);
+
+    if (s < 0) {
+        return;
+    }
+
+    if (tftp_send_data(&tftp_sessions[s], ntohs(tp->x.tp_data.tp_block_nr) + 1,
+                       tp) < 0) {
+        return;
+    }
+}
+
+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(tp, m->m_len);
+        break;
+
+    case TFTP_ACK:
+        tftp_handle_ack(tp, m->m_len);
+        break;
+    }
+}