1 files changed, 438 insertions, 0 deletions

diff --git a/src/libsystemd-network/dhcp-option.c b/src/libsystemd-network/dhcp-option.c
new file mode 100644
index 0000000..7f49da7
--- /dev/null
+++ b/src/libsystemd-network/dhcp-option.c
@@ -0,0 +1,438 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+  Copyright © 2013 Intel Corporation. All rights reserved.
+***/
+
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#include "alloc-util.h"
+#include "dhcp-internal.h"
+#include "dhcp-server-internal.h"
+#include "memory-util.h"
+#include "strv.h"
+#include "utf8.h"
+
+/* Append type-length value structure to the options buffer */
+static int dhcp_option_append_tlv(uint8_t options[], size_t size, size_t *offset, uint8_t code, size_t optlen, const void *optval) {
+        assert(options);
+        assert(size > 0);
+        assert(offset);
+        assert(optlen <= UINT8_MAX);
+        assert(*offset < size);
+
+        if (*offset + 2 + optlen > size)
+                return -ENOBUFS;
+
+        options[*offset] = code;
+        options[*offset + 1] = optlen;
+
+        memcpy_safe(&options[*offset + 2], optval, optlen);
+        *offset += 2 + optlen;
+        return 0;
+}
+
+static int option_append(uint8_t options[], size_t size, size_t *offset,
+                         uint8_t code, size_t optlen, const void *optval) {
+        assert(options);
+        assert(size > 0);
+        assert(offset);
+
+        int r;
+
+        if (code != SD_DHCP_OPTION_END)
+                /* always make sure there is space for an END option */
+                size--;
+
+        switch (code) {
+
+        case SD_DHCP_OPTION_PAD:
+        case SD_DHCP_OPTION_END:
+                if (*offset + 1 > size)
+                        return -ENOBUFS;
+
+                options[*offset] = code;
+                *offset += 1;
+                break;
+
+        case SD_DHCP_OPTION_USER_CLASS: {
+                size_t total = 0;
+
+                if (strv_isempty((char **) optval))
+                        return -EINVAL;
+
+                STRV_FOREACH(s, (const char* const*) optval) {
+                        size_t len = strlen(*s);
+
+                        if (len > 255 || len == 0)
+                                return -EINVAL;
+
+                        total += 1 + len;
+                }
+
+                if (*offset + 2 + total > size)
+                        return -ENOBUFS;
+
+                options[*offset] = code;
+                options[*offset + 1] = total;
+                *offset += 2;
+
+                STRV_FOREACH(s, (const char* const*) optval) {
+                        size_t len = strlen(*s);
+
+                        options[*offset] = len;
+                        memcpy(&options[*offset + 1], *s, len);
+                        *offset += 1 + len;
+                }
+
+                break;
+        }
+        case SD_DHCP_OPTION_SIP_SERVER:
+                if (*offset + 3 + optlen > size)
+                        return -ENOBUFS;
+
+                options[*offset] = code;
+                options[*offset + 1] = optlen + 1;
+                options[*offset + 2] = 1;
+
+                memcpy_safe(&options[*offset + 3], optval, optlen);
+                *offset += 3 + optlen;
+
+                break;
+        case SD_DHCP_OPTION_VENDOR_SPECIFIC: {
+                OrderedSet *s = (OrderedSet *) optval;
+                struct sd_dhcp_option *p;
+                size_t l = 0;
+
+                ORDERED_SET_FOREACH(p, s)
+                        l += p->length + 2;
+
+                if (*offset + l + 2 > size)
+                        return -ENOBUFS;
+
+                options[*offset] = code;
+                options[*offset + 1] = l;
+                *offset += 2;
+
+                ORDERED_SET_FOREACH(p, s) {
+                        r = dhcp_option_append_tlv(options, size, offset, p->option, p->length, p->data);
+                        if (r < 0)
+                                return r;
+                }
+                break;
+        }
+        case SD_DHCP_OPTION_RELAY_AGENT_INFORMATION: {
+                sd_dhcp_server *server = (sd_dhcp_server *) optval;
+                size_t current_offset = *offset + 2;
+
+                if (server->agent_circuit_id) {
+                        r = dhcp_option_append_tlv(options, size, &current_offset, SD_DHCP_RELAY_AGENT_CIRCUIT_ID,
+                                                   strlen(server->agent_circuit_id), server->agent_circuit_id);
+                        if (r < 0)
+                                return r;
+                }
+                if (server->agent_remote_id) {
+                        r = dhcp_option_append_tlv(options, size, &current_offset, SD_DHCP_RELAY_AGENT_REMOTE_ID,
+                                                   strlen(server->agent_remote_id), server->agent_remote_id);
+                        if (r < 0)
+                                return r;
+                }
+
+                options[*offset] = code;
+                options[*offset + 1] = current_offset - *offset - 2;
+                assert(current_offset - *offset - 2 <= UINT8_MAX);
+                *offset = current_offset;
+                break;
+        }
+        default:
+                return dhcp_option_append_tlv(options, size, offset, code, optlen, optval);
+        }
+        return 0;
+}
+
+static int option_length(uint8_t *options, size_t length, size_t offset) {
+        assert(options);
+        assert(offset < length);
+
+        if (IN_SET(options[offset], SD_DHCP_OPTION_PAD, SD_DHCP_OPTION_END))
+                return 1;
+        if (length < offset + 2)
+                return -ENOBUFS;
+
+        /* validating that buffer is long enough */
+        if (length < offset + 2 + options[offset + 1])
+                return -ENOBUFS;
+
+        return options[offset + 1] + 2;
+}
+
+int dhcp_option_find_option(uint8_t *options, size_t length, uint8_t code, size_t *ret_offset) {
+        int r;
+
+        assert(options);
+        assert(ret_offset);
+
+        for (size_t offset = 0; offset < length; offset += r) {
+                r = option_length(options, length, offset);
+                if (r < 0)
+                        return r;
+
+                if (code == options[offset]) {
+                        *ret_offset = offset;
+                        return r;
+                }
+        }
+        return -ENOENT;
+}
+
+int dhcp_option_remove_option(uint8_t *options, size_t length, uint8_t option_code) {
+        int r;
+        size_t offset;
+
+        assert(options);
+
+        r = dhcp_option_find_option(options, length, option_code, &offset);
+        if (r < 0)
+                return r;
+
+        memmove(options + offset, options + offset + r, length - offset - r);
+        return length - r;
+}
+
+int dhcp_option_append(DHCPMessage *message, size_t size, size_t *offset,
+                       uint8_t overload,
+                       uint8_t code, size_t optlen, const void *optval) {
+        const bool use_file = overload & DHCP_OVERLOAD_FILE;
+        const bool use_sname = overload & DHCP_OVERLOAD_SNAME;
+        int r;
+
+        assert(message);
+        assert(offset);
+
+        /* If *offset is in range [0, size), we are writing to ->options,
+         * if *offset is in range [size, size + sizeof(message->file)) and use_file, we are writing to ->file,
+         * if *offset is in range [size + use_file*sizeof(message->file), size + use_file*sizeof(message->file) + sizeof(message->sname))
+         * and use_sname, we are writing to ->sname.
+         */
+
+        if (*offset < size) {
+                /* still space in the options array */
+                r = option_append(message->options, size, offset, code, optlen, optval);
+                if (r >= 0)
+                        return 0;
+                else if (r == -ENOBUFS && (use_file || use_sname)) {
+                        /* did not fit, but we have more buffers to try
+                           close the options array and move the offset to its end */
+                        r = option_append(message->options, size, offset, SD_DHCP_OPTION_END, 0, NULL);
+                        if (r < 0)
+                                return r;
+
+                        *offset = size;
+                } else
+                        return r;
+        }
+
+        if (use_file) {
+                size_t file_offset = *offset - size;
+
+                if (file_offset < sizeof(message->file)) {
+                        /* still space in the 'file' array */
+                        r = option_append(message->file, sizeof(message->file), &file_offset, code, optlen, optval);
+                        if (r >= 0) {
+                                *offset = size + file_offset;
+                                return 0;
+                        } else if (r == -ENOBUFS && use_sname) {
+                                /* did not fit, but we have more buffers to try
+                                   close the file array and move the offset to its end */
+                                r = option_append(message->file, sizeof(message->file), &file_offset, SD_DHCP_OPTION_END, 0, NULL);
+                                if (r < 0)
+                                        return r;
+
+                                *offset = size + sizeof(message->file);
+                        } else
+                                return r;
+                }
+        }
+
+        if (use_sname) {
+                size_t sname_offset = *offset - size - use_file*sizeof(message->file);
+
+                if (sname_offset < sizeof(message->sname)) {
+                        /* still space in the 'sname' array */
+                        r = option_append(message->sname, sizeof(message->sname), &sname_offset, code, optlen, optval);
+                        if (r >= 0) {
+                                *offset = size + use_file*sizeof(message->file) + sname_offset;
+                                return 0;
+                        } else
+                                /* no space, or other error, give up */
+                                return r;
+                }
+        }
+
+        return -ENOBUFS;
+}
+
+static int parse_options(const uint8_t options[], size_t buflen, uint8_t *overload,
+                         uint8_t *message_type, char **error_message, dhcp_option_callback_t cb,
+                         void *userdata) {
+        uint8_t code, len;
+        const uint8_t *option;
+        size_t offset = 0;
+
+        while (offset < buflen) {
+                code = options[offset ++];
+
+                switch (code) {
+                case SD_DHCP_OPTION_PAD:
+                        continue;
+
+                case SD_DHCP_OPTION_END:
+                        return 0;
+                }
+
+                if (buflen < offset + 1)
+                        return -ENOBUFS;
+
+                len = options[offset ++];
+
+                if (buflen < offset + len)
+                        return -EINVAL;
+
+                option = &options[offset];
+
+                switch (code) {
+                case SD_DHCP_OPTION_MESSAGE_TYPE:
+                        if (len != 1)
+                                return -EINVAL;
+
+                        if (message_type)
+                                *message_type = *option;
+
+                        break;
+
+                case SD_DHCP_OPTION_ERROR_MESSAGE:
+                        if (len == 0)
+                                return -EINVAL;
+
+                        if (error_message) {
+                                _cleanup_free_ char *string = NULL;
+
+                                /* Accept a trailing NUL byte */
+                                if (memchr(option, 0, len - 1))
+                                        return -EINVAL;
+
+                                string = memdup_suffix0((const char *) option, len);
+                                if (!string)
+                                        return -ENOMEM;
+
+                                if (!ascii_is_valid(string))
+                                        return -EINVAL;
+
+                                free_and_replace(*error_message, string);
+                        }
+
+                        break;
+                case SD_DHCP_OPTION_OVERLOAD:
+                        if (len != 1)
+                                return -EINVAL;
+
+                        if (overload)
+                                *overload = *option;
+
+                        break;
+
+                default:
+                        if (cb)
+                                cb(code, len, option, userdata);
+
+                        break;
+                }
+
+                offset += len;
+        }
+
+        if (offset < buflen)
+                return -EINVAL;
+
+        return 0;
+}
+
+int dhcp_option_parse(DHCPMessage *message, size_t len, dhcp_option_callback_t cb, void *userdata, char **_error_message) {
+        _cleanup_free_ char *error_message = NULL;
+        uint8_t overload = 0;
+        uint8_t message_type = 0;
+        int r;
+
+        if (!message)
+                return -EINVAL;
+
+        if (len < sizeof(DHCPMessage))
+                return -EINVAL;
+
+        len -= sizeof(DHCPMessage);
+
+        r = parse_options(message->options, len, &overload, &message_type, &error_message, cb, userdata);
+        if (r < 0)
+                return r;
+
+        if (overload & DHCP_OVERLOAD_FILE) {
+                r = parse_options(message->file, sizeof(message->file), NULL, &message_type, &error_message, cb, userdata);
+                if (r < 0)
+                        return r;
+        }
+
+        if (overload & DHCP_OVERLOAD_SNAME) {
+                r = parse_options(message->sname, sizeof(message->sname), NULL, &message_type, &error_message, cb, userdata);
+                if (r < 0)
+                        return r;
+        }
+
+        if (message_type == 0)
+                return -ENOMSG;
+
+        if (_error_message && IN_SET(message_type, DHCP_NAK, DHCP_DECLINE))
+                *_error_message = TAKE_PTR(error_message);
+
+        return message_type;
+}
+
+static sd_dhcp_option* dhcp_option_free(sd_dhcp_option *i) {
+        if (!i)
+                return NULL;
+
+        free(i->data);
+        return mfree(i);
+}
+
+int sd_dhcp_option_new(uint8_t option, const void *data, size_t length, sd_dhcp_option **ret) {
+        assert_return(ret, -EINVAL);
+        assert_return(length == 0 || data, -EINVAL);
+
+        _cleanup_free_ void *q = memdup(data, length);
+        if (!q)
+                return -ENOMEM;
+
+        sd_dhcp_option *p = new(sd_dhcp_option, 1);
+        if (!p)
+                return -ENOMEM;
+
+        *p = (sd_dhcp_option) {
+                .n_ref = 1,
+                .option = option,
+                .length = length,
+                .data = TAKE_PTR(q),
+        };
+
+        *ret = TAKE_PTR(p);
+        return 0;
+}
+
+DEFINE_TRIVIAL_REF_UNREF_FUNC(sd_dhcp_option, sd_dhcp_option, dhcp_option_free);
+DEFINE_HASH_OPS_WITH_VALUE_DESTRUCTOR(
+                dhcp_option_hash_ops,
+                void,
+                trivial_hash_func,
+                trivial_compare_func,
+                sd_dhcp_option,
+                sd_dhcp_option_unref);