[app][inetsrv] add tftp server.

lib/tftp/tftp.c

+/*
+ * Copyright (c) 2015 Carlos Pizano-Uribe <cpu@chromium.org>
+ *
+ * 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 <err.h>
+#include <trace.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <list.h>
+#include <compiler.h>
+#include <endian.h>
+#include <lib/minip.h>
+#include <lib/cksum.h>
+#include <platform.h>
+
+#include <lib/tftp.h>
+
+#define LOCAL_TRACE 0
+
+// TFTP Opcodes:
+#define TFTP_OPCODE_RRQ   1UL
+#define TFTP_OPCODE_WRQ   2UL
+#define TFTP_OPCODE_DATA  3UL
+#define TFTP_OPCODE_ACK   4UL
+#define TFTP_OPCODE_ERROR 5UL
+
+// TFTP Errors:
+#define TFTP_ERROR_UNDEF        0UL
+#define TFTP_ERROR_NOT_FOUND    1UL
+#define TFTP_ERROR_ACCESS       2UL
+#define TFTP_ERROR_FULL         3UL
+#define TFTP_ERROR_ILLEGAL_OP   4UL
+#define TFTP_ERROR_UNKNOWN_XFER 4UL
+#define TFTP_ERROR_EXISTS       6UL
+#define TFTP_ERROR_NO_SUCH_USER 7UL
+
+#define TFTP_PORT 69
+
+#define RD_U16(ptr)     \
+    (uint16_t)(((uint16_t)*((uint8_t*)(ptr)+1)<<8)|(uint16_t)*(uint8_t*)(ptr))
+
+static struct list_node tftp_list = LIST_INITIAL_VALUE(tftp_list);
+
+// Represents tftp jobs and clients of them. If |socket| is not null the
+// job is in progress and members below it are valid.
+typedef struct {
+    struct list_node list;
+    // Registration info.
+    const char* file_name;
+    tftp_callback_t callback;
+    void *arg;
+    // Current job info.
+    udp_socket_t* socket;
+    uint32_t src_addr;
+    uint16_t src_port;
+    uint16_t pkt_count;
+} tftp_job_t;
+
+uint16_t next_port = 2224;
+
+static void send_ack(udp_socket_t* socket, uint16_t count) 
+{
+    // Packet is [4][count].
+    status_t st;
+    uint16_t ack[] = {htons(TFTP_OPCODE_ACK), htons(count)};
+    st = udp_send(ack, sizeof(ack), socket);
+    if (st < 0) {
+        LTRACEF("send_ack failed: %d\n", st);
+    }
+}
+
+static void send_error(udp_socket_t* socket, uint16_t code)
+{
+    // Packet is [5][error code][error in ascii-string][0].
+    status_t st;
+    uint16_t ncode = htons(code);
+    uint16_t err[] = {htons(TFTP_OPCODE_ERROR), ncode,
+                      0x7245, 0x2072, 0x3030 + ncode, 0 };
+    st = udp_send(err, sizeof(err), socket);
+    if (st < 0) {
+        LTRACEF("send_err failed: %d\n", st);
+    }
+}
+
+static void end_transfer(tftp_job_t* job)
+{
+    udp_close(job->socket);
+    job->socket = NULL;
+    job->src_addr = 0UL;
+    job->callback(NULL, 0UL, job->arg);
+}
+
+static void udp_wrq_callback(void *data, size_t len,
+                             uint32_t srcaddr, uint16_t srcport,
+                             void *arg)
+{ 
+    // Packet is [3][count][data]. All packets but the last have 512
+    // bytes of data, including zero data.
+    char* data_c = data;
+    tftp_job_t* job = arg;
+    job->pkt_count++;
+
+    if (len < 4) {
+        // Not to spec. Ignore.
+        return;
+    }
+
+    if (!job->socket) {
+        // It is possible to have the client sent another packet
+        // after we called end_transfer().
+        return;
+    }
+
+    if ((srcaddr != job->src_addr) || (srcport != job->src_port)) {
+        LTRACEF("invalid source\n");
+        send_error(job->socket, TFTP_ERROR_UNKNOWN_XFER);
+        end_transfer(job);
+        return;
+    }
+
+    if (RD_U16(data_c) != htons(TFTP_OPCODE_DATA)) {
+        LTRACEF("invalid opcode\n");
+        send_error(job->socket, TFTP_ERROR_ILLEGAL_OP);
+        end_transfer(job);
+        return;
+    }
+
+    send_ack(job->socket, job->pkt_count);
+
+    if (job->callback(&data_c[4], len - 4, job->arg) < 0) {
+      // The client wants to abort.
+      send_error(job->socket, TFTP_ERROR_FULL);
+      end_transfer(job);      
+    }
+    
+    // 512 bytes payload plus 4 of fixed header. The last packet.
+    // has always less than 512 bytes of payload.
+    if (len != 516) {
+        end_transfer(job);
+    }
+}
+
+static tftp_job_t* get_job_by_name(const char* file_name) 
+{
+    DEBUG_ASSERT(file_name);    
+    tftp_job_t *entry;
+    list_for_every_entry(&tftp_list, entry, tftp_job_t, list) {
+        if (strcmp(entry->file_name, file_name) == 0) {
+            return entry;
+        }
+    }
+    return NULL;
+}
+
+static void udp_svc_callback(void *data, size_t len,
+                             uint32_t srcaddr, uint16_t srcport,
+                             void *arg)
+{
+    status_t st;
+    uint16_t opcode;
+    udp_socket_t* socket;
+    tftp_job_t* job;
+
+    st = udp_open(srcaddr, next_port, srcport, &socket);
+    if (st < 0) {
+        LTRACEF("error opening send socket %d\n", st);
+        return;
+    }
+
+    opcode = ntohs(RD_U16(data));
+
+    if (opcode != TFTP_OPCODE_WRQ)
+    {
+        // Operation not suported.
+        LTRACEF("op not supported, opcode: %d\n", opcode);
+        send_error(socket, TFTP_ERROR_ACCESS);
+        udp_close(socket);
+        return;
+    }
+
+    // Look for a client that can hadle the file. TODO: |data|
+    // needs to be null terminated. A malicious client can crash us.
+    job = get_job_by_name(((char*)data) + 2);
+
+    if (!job) {
+        // Nobody claims to handle that file.
+        LTRACEF("no client registered for file\n");
+        send_error(socket, TFTP_ERROR_UNKNOWN_XFER);
+        udp_close(socket);
+        return;      
+    }
+
+    if (job->socket) {
+      // There is already an ongoing job.
+      // TODO: garbage collect the existing one if too long since the
+      // last packet was processed.
+      LTRACEF("existing job in progress\n");
+      send_error(socket, TFTP_ERROR_EXISTS);
+      udp_close(socket);
+      return;      
+    }
+
+    LTRACEF("write op accepted, port %d\n", srcport);
+    // Request accepted. The rest of the transfer happens between
+    // next_port <----> srcport via udp_wrq_callback().
+
+    job->socket = socket;
+    job->src_addr = srcaddr;
+    job->src_port = srcport;
+    job->pkt_count = 0UL;
+
+    st = udp_listen(next_port, &udp_wrq_callback, job);
+    if (st < 0) {
+        LTRACEF("error listening on port\n");
+        return;
+    }
+
+    send_ack(socket, 0UL);
+    next_port++;
+}
+
+int tftp_set_write_client(const char* file_name, tftp_callback_t cb, void* arg)
+{
+    DEBUG_ASSERT(file_name);
+    DEBUG_ASSERT(cb);
+
+    tftp_job_t *job;
+
+    list_for_every_entry(&tftp_list, job, tftp_job_t, list) {
+        if (strcmp(file_name, job->file_name) == 0) {
+            // TODO: un-registration.
+            return -1;
+        }
+    }
+
+    if ((job = malloc(sizeof(tftp_job_t))) == NULL) {
+        return -1;
+    }
+
+    memset(job, 0, sizeof(tftp_job_t));
+    job->file_name = file_name;
+    job->callback = cb;
+    job->arg = arg;
+
+    list_add_tail(&tftp_list, &job->list);
+    return 0;
+}
+
+static unsigned long test_crc = 0UL;
+
+int test_tftp_client(void* data, size_t len, void* arg) {
+    if (!data) {
+        printf("--test transfer done-- crc32 = %lu\n", test_crc);
+        test_crc = 0UL;
+    }
+
+    test_crc = crc32(test_crc, data,len);
+    return 0;
+}
+
+int tftp_server_init(void *arg)
+{
+    tftp_set_write_client("tftp_test.txt", &test_tftp_client, NULL);
+
+    status_t st = udp_listen(TFTP_PORT, &udp_svc_callback, 0);
+    return st;
+}
+