diff options
Diffstat (limited to 'lib/dhcp.c')
| -rw-r--r-- | lib/dhcp.c | 825 |
1 files changed, 825 insertions, 0 deletions
diff --git a/lib/dhcp.c b/lib/dhcp.c new file mode 100644 index 000000000..b7a1f1f0a --- /dev/null +++ b/lib/dhcp.c @@ -0,0 +1,825 @@ +/* + * Copyright (c) 2008 Nicira Networks. + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#include <config.h> +#include "dhcp.h" +#include <arpa/inet.h> +#include <assert.h> +#include <ctype.h> +#include <errno.h> +#include <inttypes.h> +#include <stdlib.h> +#include "dynamic-string.h" +#include "ofpbuf.h" + +#define THIS_MODULE VLM_dhcp +#include "vlog.h" + +/* Information about a DHCP argument type. */ +struct arg_type { + const char *name; /* Name. */ + size_t size; /* Number of bytes per argument. */ +}; + +static struct arg_type types[] = { +#define DHCP_ARG(NAME, SIZE) [DHCP_ARG_##NAME] = {#NAME, SIZE}, + DHCP_ARGS +#undef DHCP_ARG +}; + +/* Information about a DHCP option. */ +struct option_class { + const char *name; /* Name. */ + enum dhcp_arg_type type; /* Argument type. */ + size_t min_args; /* Minimum number of arguments. */ + size_t max_args; /* Maximum number of arguments. */ +}; + +static const struct option_class * +get_option_class(int code) +{ + static struct option_class classes[DHCP_N_OPTIONS]; + static bool init = false; + if (!init) { + int i; + + init = true; +#define DHCP_OPT(NAME, CODE, TYPE, MIN, MAX) \ + classes[CODE].name = #NAME; \ + classes[CODE].type = DHCP_ARG_##TYPE; \ + classes[CODE].min_args = MIN; \ + classes[CODE].max_args = MAX; + DHCP_OPTS +#undef DHCP_OPT + + for (i = 0; i < DHCP_N_OPTIONS; i++) { + if (!classes[i].name) { + classes[i].name = xasprintf("option-%d", i); + classes[i].type = DHCP_ARG_UINT8; + classes[i].min_args = 0; + classes[i].max_args = SIZE_MAX; + } + } + } + assert(code >= 0 && code < DHCP_N_OPTIONS); + return &classes[code]; +} + +/* A single (bad) DHCP message can in theory dump out many, many log messages, + * especially at high logging levels, so the burst size is set quite high + * here to avoid missing useful information. */ +struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 600); + +static void copy_data(struct dhcp_msg *); + +const char * +dhcp_type_name(enum dhcp_msg_type type) +{ + switch (type) { +#define DHCP_MSG(NAME, VALUE) case NAME: return #NAME; + DHCP_MSGS +#undef DHCP_MSG + } + return "<<unknown DHCP message type>>"; +} + +/* Initializes 'msg' as a DHCP message. The message should be freed with + * dhcp_msg_uninit() when it is no longer needed. */ +void +dhcp_msg_init(struct dhcp_msg *msg) +{ + memset(msg, 0, sizeof *msg); +} + +/* Frees the contents of 'msg'. The caller is responsible for freeing 'msg', + * if necessary. */ +void +dhcp_msg_uninit(struct dhcp_msg *msg) +{ + if (msg) { + free(msg->data); + } +} + +/* Initializes 'dst' as a copy of 'src'. 'dst' (and 'src') should be freed + * with dhcp_msg_uninit() when it is no longer needed. */ +void +dhcp_msg_copy(struct dhcp_msg *dst, const struct dhcp_msg *src) +{ + *dst = *src; + dst->data_allocated = src->data_used; + dst->data_used = 0; + dst->data = xmalloc(dst->data_allocated); + copy_data(dst); +} + +static void +prealloc_data(struct dhcp_msg *msg, size_t n) +{ + size_t needed = msg->data_used + n; + if (needed > msg->data_allocated) { + uint8_t *old_data = msg->data; + msg->data_allocated = MAX(needed * 2, 64); + msg->data = xmalloc(msg->data_allocated); + if (old_data) { + copy_data(msg); + free(old_data); + } + } +} + +static void * +append_data(struct dhcp_msg *msg, const void *data, size_t n) +{ + uint8_t *p = &msg->data[msg->data_used]; + memcpy(p, data, n); + msg->data_used += n; + return p; +} + +static void +copy_data(struct dhcp_msg *msg) +{ + int code; + + msg->data_used = 0; + for (code = 0; code < DHCP_N_OPTIONS; code++) { + struct dhcp_option *opt = &msg->options[code]; + if (opt->data) { + assert(msg->data_used + opt->n <= msg->data_allocated); + opt->data = append_data(msg, opt->data, opt->n); + } + } +} + +/* Appends the 'n' bytes in 'data' to the DHCP option in 'msg' represented by + * 'code' (which must be in the range 0...DHCP_N_OPTIONS). */ +void +dhcp_msg_put(struct dhcp_msg *msg, int code, + const void *data, size_t n) +{ + struct dhcp_option *opt; + if (code == DHCP_CODE_PAD || code == DHCP_CODE_END) { + return; + } + + opt = &msg->options[code]; + prealloc_data(msg, n + opt->n); + if (opt->n) { + if (&msg->data[msg->data_used - opt->n] != opt->data) { + opt->data = append_data(msg, opt->data, opt->n); + } + append_data(msg, data, n); + } else { + opt->data = append_data(msg, data, n); + } + opt->n += n; +} + +/* Appends the boolean value 'b', as a octet with value 0 (false) or 1 (true), + * to the DHCP option in 'msg' represented by 'code' (which must be in the + * range 0...DHCP_N_OPTIONS). */ +void +dhcp_msg_put_bool(struct dhcp_msg *msg, int code, bool b_) +{ + char b = !!b_; + dhcp_msg_put(msg, code, &b, 1); +} + +/* Appends the number of seconds 'secs', as a 32-bit number in network byte + * order, to the DHCP option in 'msg' represented by 'code' (which must be in + * the range 0...DHCP_N_OPTIONS). */ +void +dhcp_msg_put_secs(struct dhcp_msg *msg, int code, uint32_t secs_) +{ + uint32_t secs = htonl(secs_); + dhcp_msg_put(msg, code, &secs, sizeof secs); +} + +/* Appends the IP address 'ip', as a 32-bit number in network byte order, to + * the DHCP option in 'msg' represented by 'code' (which must be in the range + * 0...DHCP_N_OPTIONS). */ +void +dhcp_msg_put_ip(struct dhcp_msg *msg, int code, uint32_t ip) +{ + dhcp_msg_put(msg, code, &ip, sizeof ip); +} + +/* Appends the ASCII string 'string', to the DHCP option in 'msg' represented + * by 'code' (which must be in the range 0...DHCP_N_OPTIONS). */ +void +dhcp_msg_put_string(struct dhcp_msg *msg, int code, const char *string) +{ + dhcp_msg_put(msg, code, string, strlen(string)); +} + +/* Appends octet 'x' to DHCP option in 'msg' represented by 'code' (which must + * be in the range 0...DHCP_N_OPTIONS). */ +void +dhcp_msg_put_uint8(struct dhcp_msg *msg, int code, uint8_t x) +{ + dhcp_msg_put(msg, code, &x, sizeof x); +} + +/* Appends the 'n' octets in 'data' to DHCP option in 'msg' represented by + * 'code' (which must be in the range 0...DHCP_N_OPTIONS). */ +void dhcp_msg_put_uint8_array(struct dhcp_msg *msg, int code, + const uint8_t data[], size_t n) +{ + dhcp_msg_put(msg, code, data, n); +} + +/* Appends the 16-bit value in 'x', in network byte order, to DHCP option in + * 'msg' represented by 'code' (which must be in the range + * 0...DHCP_N_OPTIONS). */ +void +dhcp_msg_put_uint16(struct dhcp_msg *msg, int code, uint16_t x_) +{ + uint16_t x = htons(x_); + dhcp_msg_put(msg, code, &x, sizeof x); +} + + +/* Appends the 'n' 16-bit values in 'data', in network byte order, to DHCP + * option in 'msg' represented by 'code' (which must be in the range + * 0...DHCP_N_OPTIONS). */ +void +dhcp_msg_put_uint16_array(struct dhcp_msg *msg, int code, + const uint16_t data[], size_t n) +{ + size_t i; + + for (i = 0; i < n; i++) { + dhcp_msg_put_uint16(msg, code, data[i]); + } +} + +/* Returns a pointer to the 'size' bytes starting at byte offset 'offset' in + * the DHCP option in 'msg' represented by 'code' (which must be in the range + * 0...DHCP_N_OPTIONS). If the option has fewer than 'offset + size' bytes, + * returns a null pointer. */ +const void * +dhcp_msg_get(const struct dhcp_msg *msg, int code, + size_t offset, size_t size) +{ + const struct dhcp_option *opt = &msg->options[code]; + return offset + size <= opt->n ? (const char *) opt->data + offset : NULL; +} + +/* Stores in '*out' the boolean value at byte offset 'offset' in the DHCP + * option in 'msg' represented by 'code' (which must be in the range + * 0...DHCP_N_OPTIONS). Returns true if successful, false if the option has + * fewer than 'offset + 1' bytes. */ +bool +dhcp_msg_get_bool(const struct dhcp_msg *msg, int code, size_t offset, + bool *out) +{ + const uint8_t *uint8 = dhcp_msg_get(msg, code, offset, sizeof *uint8); + if (uint8) { + *out = *uint8 != 0; + return true; + } else { + return false; + } +} + +/* Stores in '*out' the 32-bit count of seconds at offset 'offset' (in + * 4-byte increments) in the DHCP option in 'msg' represented by 'code' + * (which must be in the range 0...DHCP_N_OPTIONS). The value is converted to + * native byte order. Returns true if successful, false if the option has + * fewer than '4 * (offset + 1)' bytes. */ +bool +dhcp_msg_get_secs(const struct dhcp_msg *msg, int code, size_t offset, + uint32_t *out) +{ + const uint32_t *uint32 = dhcp_msg_get(msg, code, offset * sizeof *uint32, + sizeof *uint32); + if (uint32) { + *out = ntohl(*uint32); + return true; + } else { + return false; + } +} + +/* Stores in '*out' the IP address at offset 'offset' (in 4-byte increments) in + * the DHCP option in 'msg' represented by 'code' (which must be in the range + * 0...DHCP_N_OPTIONS). The IP address is stored in network byte order. + * Returns true if successful, false if the option has fewer than '4 * (offset + * + 1)' bytes. */ +bool +dhcp_msg_get_ip(const struct dhcp_msg *msg, int code, + size_t offset, uint32_t *out) +{ + const uint32_t *uint32 = dhcp_msg_get(msg, code, offset * sizeof *uint32, + sizeof *uint32); + if (uint32) { + *out = *uint32; + return true; + } else { + return false; + } +} + +/* Returns the string in the DHCP option in 'msg' represented by 'code' (which + * must be in the range 0...DHCP_N_OPTIONS). The caller is responsible for + * freeing the string with free(). + * + * If 'msg' has no option represented by 'code', returns a null pointer. (If + * the option was specified but had no content, then an empty string is + * returned, not a null pointer.) */ +char * +dhcp_msg_get_string(const struct dhcp_msg *msg, int code) +{ + const struct dhcp_option *opt = &msg->options[code]; + return opt->data ? xmemdup0(opt->data, opt->n) : NULL; +} + +/* Stores in '*out' the octet at byte offset 'offset' in the DHCP option in + * 'msg' represented by 'code' (which must be in the range 0...DHCP_N_OPTIONS). + * Returns true if successful, false if the option has fewer than 'offset + 1' + * bytes. */ +bool +dhcp_msg_get_uint8(const struct dhcp_msg *msg, int code, + size_t offset, uint8_t *out) +{ + const uint8_t *uint8 = dhcp_msg_get(msg, code, offset, sizeof *uint8); + if (uint8) { + *out = *uint8; + return true; + } else { + return false; + } +} + +/* Stores in '*out' the 16-bit value at offset 'offset' (in 2-byte units) in + * the DHCP option in 'msg' represented by 'code' (which must be in the range + * 0...DHCP_N_OPTIONS). The value is converted to native byte order. Returns + * true if successful, false if the option has fewer than '2 * (offset + 1)' + * bytes. */ +bool +dhcp_msg_get_uint16(const struct dhcp_msg *msg, int code, + size_t offset, uint16_t *out) +{ + const uint16_t *uint16 = dhcp_msg_get(msg, code, offset * sizeof *uint16, + sizeof *uint16); + if (uint16) { + *out = ntohs(*uint16); + return true; + } else { + return false; + } +} + +/* Appends a string representing 'duration' seconds to 'ds'. */ +static void +put_duration(struct ds *ds, unsigned int duration) +{ + if (duration) { + if (duration >= 86400) { + ds_put_format(ds, "%ud", duration / 86400); + duration %= 86400; + } + if (duration >= 3600) { + ds_put_format(ds, "%uh", duration / 3600); + duration %= 3600; + } + if (duration >= 60) { + ds_put_format(ds, "%umin", duration / 60); + duration %= 60; + } + if (duration > 0) { + ds_put_format(ds, "%us", duration); + } + } else { + ds_put_cstr(ds, "0s"); + } +} + +/* Appends a string representation of 'opt', which has the given 'code', to + * 'ds'. */ +const char * +dhcp_option_to_string(const struct dhcp_option *opt, int code, struct ds *ds) +{ + const struct option_class *class = get_option_class(code); + const struct arg_type *type = &types[class->type]; + size_t offset; + const char *cp; + + for (cp = class->name; *cp; cp++) { + unsigned char c = *cp; + ds_put_char(ds, c == '_' ? '-' : tolower(c)); + } + ds_put_char(ds, '='); + + if (!opt->data || !opt->n) { + ds_put_cstr(ds, opt->data ? "empty" : "null"); + return ds_cstr(ds); + } + + if (class->type == DHCP_ARG_STRING) { + ds_put_char(ds, '"'); + ds_put_printable(ds, opt->data, opt->n); + ds_put_char(ds, '"'); + return ds_cstr(ds); + } + for (offset = 0; offset + type->size <= opt->n; offset += type->size) { + const void *p = (const char *) opt->data + offset; + const uint8_t *uint8 = p; + const uint32_t *uint32 = p; + const uint16_t *uint16 = p; + + if (offset && class->type != DHCP_ARG_STRING) { + ds_put_cstr(ds, class->type == DHCP_ARG_UINT8 ? ":" : ", "); + } + switch (class->type) { + case DHCP_ARG_FIXED: + NOT_REACHED(); + case DHCP_ARG_IP: + ds_put_format(ds, IP_FMT, IP_ARGS(uint32)); + break; + case DHCP_ARG_UINT8: + ds_put_format(ds, "%02"PRIx8, *uint8); + break; + case DHCP_ARG_UINT16: + ds_put_format(ds, "%"PRIu16, ntohs(*uint16)); + break; + case DHCP_ARG_UINT32: + ds_put_format(ds, "%"PRIu32, ntohl(*uint32)); + break; + case DHCP_ARG_SECS: + put_duration(ds, ntohl(*uint32)); + break; + case DHCP_ARG_STRING: + NOT_REACHED(); + case DHCP_ARG_BOOLEAN: + if (*uint8 == 0) { + ds_put_cstr(ds, "false"); + } else if (*uint8 == 1) { + ds_put_cstr(ds, "true"); + } else { + ds_put_format(ds, "**%"PRIu8"**", *uint8); + } + break; + } + } + if (offset != opt->n) { + if (offset) { + ds_put_cstr(ds, ", "); + } + ds_put_cstr(ds, "**leftovers:"); + for (; offset < opt->n; offset++) { + const void *p = (const char *) opt->data + offset; + const uint8_t *uint8 = p; + ds_put_format(ds, " %"PRIu8, *uint8); + } + ds_put_cstr(ds, "**"); + } + return ds_cstr(ds); +} + +/* Returns true if 'a' and 'b' have the same content, false otherwise. */ +bool +dhcp_option_equals(const struct dhcp_option *a, const struct dhcp_option *b) +{ + return ((a->data != NULL) == (b->data != NULL) + && a->n == b->n + && !memcmp(a->data, b->data, a->n)); +} + +/* Replaces 'ds' by a string representation of 'msg'. If 'multiline' is + * false, 'ds' receives a single-line representation of 'msg', otherwise a + * multiline representation. */ +const char * +dhcp_msg_to_string(const struct dhcp_msg *msg, bool multiline, struct ds *ds) +{ + char separator = multiline ? '\n' : ' '; + int code; + + ds_clear(ds); + ds_put_format(ds, "op=%s", + (msg->op == DHCP_BOOTREQUEST ? "request" + : msg->op == DHCP_BOOTREPLY ? "reply" + : "error")); + ds_put_format(ds, "%ctype=%s", separator, dhcp_type_name(msg->type)); + ds_put_format(ds, "%cxid=0x%08"PRIx32, separator, msg->xid); + ds_put_format(ds, "%csecs=", separator); + put_duration(ds, msg->secs); + if (msg->flags) { + ds_put_format(ds, "%cflags=", separator); + if (msg->flags & DHCP_FLAGS_BROADCAST) { + ds_put_cstr(ds, "[BROADCAST]"); + } + if (msg->flags & DHCP_FLAGS_MBZ) { + ds_put_format(ds, "[0x%04"PRIx16"]", msg->flags & DHCP_FLAGS_MBZ); + } + } + if (msg->ciaddr) { + ds_put_format(ds, "%cciaddr="IP_FMT, separator, IP_ARGS(&msg->ciaddr)); + } + if (msg->yiaddr) { + ds_put_format(ds, "%cyiaddr="IP_FMT, separator, IP_ARGS(&msg->yiaddr)); + } + if (msg->siaddr) { + ds_put_format(ds, "%csiaddr="IP_FMT, separator, IP_ARGS(&msg->siaddr)); + } + if (msg->giaddr) { + ds_put_format(ds, "%cgiaddr="IP_FMT, separator, IP_ARGS(&msg->giaddr)); + } + ds_put_format(ds, "%cchaddr="ETH_ADDR_FMT, + separator, ETH_ADDR_ARGS(msg->chaddr)); + + for (code = 0; code < DHCP_N_OPTIONS; code++) { + const struct dhcp_option *opt = &msg->options[code]; + if (opt->data) { + ds_put_char(ds, separator); + dhcp_option_to_string(opt, code, ds); + } + } + if (multiline) { + ds_put_char(ds, separator); + } + return ds_cstr(ds); +} + +static void +parse_options(struct dhcp_msg *msg, const char *name, void *data, size_t size, + int option_offset) +{ + struct ofpbuf b; + + b.data = data; + b.size = size; + for (;;) { + uint8_t *code, *len; + void *payload; + + code = ofpbuf_try_pull(&b, 1); + if (!code || *code == DHCP_CODE_END) { + break; + } else if (*code == DHCP_CODE_PAD) { + continue; + } + + len = ofpbuf_try_pull(&b, 1); + if (!len) { + VLOG_DBG_RL(&rl, "reached end of %s expecting length byte", name); + break; + } + + payload = ofpbuf_try_pull(&b, *len); + if (!payload) { + VLOG_DBG_RL(&rl, "expected %"PRIu8" bytes of option-%"PRIu8" " + "payload with only %zu bytes of %s left", + *len, *code, b.size, name); + break; + } + dhcp_msg_put(msg, *code + option_offset, payload, *len); + } +} + +static void +validate_options(struct dhcp_msg *msg) +{ + int code; + + for (code = 0; code < DHCP_N_OPTIONS; code++) { + struct dhcp_option *opt = &msg->options[code]; + const struct option_class *class = get_option_class(code); + struct arg_type *type = &types[class->type]; + if (opt->data) { + size_t n_elems = opt->n / type->size; + size_t remainder = opt->n % type->size; + bool ok = true; + if (remainder) { + VLOG_DBG_RL(&rl, "%s option has %zu %zu-byte %s arguments " + "with %zu bytes left over", + class->name, n_elems, type->size, + type->name, remainder); + ok = false; + } + if (n_elems < class->min_args || n_elems > class->max_args) { + VLOG_DBG_RL(&rl, "%s option has %zu %zu-byte %s arguments but " + "between %zu and %zu are required", + class->name, n_elems, type->size, type->name, + class->min_args, class->max_args); + ok = false; + } + if (!ok) { + struct ds ds = DS_EMPTY_INITIALIZER; + VLOG_DBG_RL(&rl, "%s option contains: %s", class->name, + dhcp_option_to_string(opt, code, &ds)); + ds_destroy(&ds); + + opt->n = 0; + opt->data = NULL; + } + } + } +} + +/* Attempts to parse 'b' as a DHCP message. If successful, initializes '*msg' + * to the parsed message and returns 0. Otherwise, returns a positive errno + * value and '*msg' is indeterminate. */ +int +dhcp_parse(struct dhcp_msg *msg, const struct ofpbuf *b_) +{ + struct ofpbuf b = *b_; + struct dhcp_header *dhcp; + uint32_t *cookie; + uint8_t type; + char *vendor_class; + + dhcp = ofpbuf_try_pull(&b, sizeof *dhcp); + if (!dhcp) { + VLOG_DBG_RL(&rl, "buffer too small for DHCP header (%zu bytes)", + b.size); + goto error; + } + + if (dhcp->op != DHCP_BOOTREPLY && dhcp->op != DHCP_BOOTREQUEST) { + VLOG_DBG_RL(&rl, "invalid DHCP op (%"PRIu8")", dhcp->op); + goto error; + } + if (dhcp->htype != ARP_HRD_ETHERNET) { + VLOG_DBG_RL(&rl, "invalid DHCP htype (%"PRIu8")", dhcp->htype); + goto error; + } + if (dhcp->hlen != ETH_ADDR_LEN) { + VLOG_DBG_RL(&rl, "invalid DHCP hlen (%"PRIu8")", dhcp->hlen); + goto error; + } + + dhcp_msg_init(msg); + msg->op = dhcp->op; + msg->xid = ntohl(dhcp->xid); + msg->secs = ntohs(dhcp->secs); + msg->flags = ntohs(dhcp->flags); + msg->ciaddr = dhcp->ciaddr; + msg->yiaddr = dhcp->yiaddr; + msg->siaddr = dhcp->siaddr; + msg->giaddr = dhcp->giaddr; + memcpy(msg->chaddr, dhcp->chaddr, ETH_ADDR_LEN); + + cookie = ofpbuf_try_pull(&b, sizeof cookie); + if (cookie) { + if (ntohl(*cookie) == DHCP_OPTS_COOKIE) { + uint8_t overload; + + parse_options(msg, "options", b.data, b.size, 0); + if (dhcp_msg_get_uint8(msg, DHCP_CODE_OPTION_OVERLOAD, + 0, &overload)) { + if (overload & 1) { + parse_options(msg, "file", dhcp->file, sizeof dhcp->file, + 0); + } + if (overload & 2) { + parse_options(msg, "sname", + dhcp->sname, sizeof dhcp->sname, 0); + } + } + } else { + VLOG_DBG_RL(&rl, "bad DHCP options cookie: %08"PRIx32, + ntohl(*cookie)); + } + } else { + VLOG_DBG_RL(&rl, "DHCP packet has no options"); + } + + vendor_class = dhcp_msg_get_string(msg, DHCP_CODE_VENDOR_CLASS); + if (vendor_class && !strcmp(vendor_class, "OpenFlow")) { + parse_options(msg, "vendor-specific", + msg->options[DHCP_CODE_VENDOR_SPECIFIC].data, + msg->options[DHCP_CODE_VENDOR_SPECIFIC].n, + DHCP_VENDOR_OFS); + } + free(vendor_class); + + validate_options(msg); + if (!dhcp_msg_get_uint8(msg, DHCP_CODE_DHCP_MSG_TYPE, 0, &type)) { + VLOG_DBG_RL(&rl, "missing DHCP message type"); + dhcp_msg_uninit(msg); + goto error; + } + msg->type = type; + return 0; + +error: + if (VLOG_IS_DBG_ENABLED()) { + struct ds ds; + + ds_init(&ds); + ds_put_hex_dump(&ds, b_->data, b_->size, 0, true); + VLOG_DBG_RL(&rl, "invalid DHCP message dump:\n%s", ds_cstr(&ds)); + + ds_clear(&ds); + dhcp_msg_to_string(msg, false, &ds); + VLOG_DBG_RL(&rl, "partially dissected DHCP message: %s", ds_cstr(&ds)); + + ds_destroy(&ds); + } + return EPROTO; +} + +static void +put_option_chunk(struct ofpbuf *b, uint8_t code, void *data, size_t n) +{ + uint8_t header[2]; + + assert(n < 256); + header[0] = code; + header[1] = n; + ofpbuf_put(b, header, sizeof header); + ofpbuf_put(b, data, n); +} + +static void +put_option(struct ofpbuf *b, uint8_t code, void *data, size_t n) +{ + if (data) { + if (n) { + /* Divide the data into chunks of 255 bytes or less. Make + * intermediate chunks multiples of 8 bytes in case the + * recipient validates a chunk at a time instead of the + * concatenated value. */ + uint8_t *p = data; + while (n) { + size_t chunk = n > 255 ? 248 : n; + put_option_chunk(b, code, p, chunk); + p += chunk; + n -= chunk; + } + } else { + /* Option should be present but carry no data. */ + put_option_chunk(b, code, NULL, 0); + } + } +} + +/* Appends to 'b' the DHCP message represented by 'msg'. */ +void +dhcp_assemble(const struct dhcp_msg *msg, struct ofpbuf *b) +{ + const uint8_t end = DHCP_CODE_END; + uint32_t cookie = htonl(DHCP_OPTS_COOKIE); + struct ofpbuf vnd_data; + struct dhcp_header dhcp; + int i; + + memset(&dhcp, 0, sizeof dhcp); + dhcp.op = msg->op; + dhcp.htype = ARP_HRD_ETHERNET; + dhcp.hlen = ETH_ADDR_LEN; + dhcp.hops = 0; + dhcp.xid = htonl(msg->xid); + dhcp.secs = htons(msg->secs); + dhcp.flags = htons(msg->flags); + dhcp.ciaddr = msg->ciaddr; + dhcp.yiaddr = msg->yiaddr; + dhcp.siaddr = msg->siaddr; + dhcp.giaddr = msg->giaddr; + memcpy(dhcp.chaddr, msg->chaddr, ETH_ADDR_LEN); + ofpbuf_put(b, &dhcp, sizeof dhcp); + ofpbuf_put(b, &cookie, sizeof cookie); + + /* Put DHCP message type first. (The ordering is not required but it + * seems polite.) */ + if (msg->type) { + uint8_t type = msg->type; + put_option(b, DHCP_CODE_DHCP_MSG_TYPE, &type, 1); + } + + /* Put the standard options. */ + for (i = 0; i < DHCP_VENDOR_OFS; i++) { + const struct dhcp_option *option = &msg->options[i]; + put_option(b, i, option->data, option->n); + } + + /* Assemble vendor specific option and put it. */ + ofpbuf_init(&vnd_data, 0); + for (i = DHCP_VENDOR_OFS; i < DHCP_N_OPTIONS; i++) { + const struct dhcp_option *option = &msg->options[i]; + put_option(&vnd_data, i - DHCP_VENDOR_OFS, option->data, option->n); + } + if (vnd_data.size) { + put_option(b, DHCP_CODE_VENDOR_SPECIFIC, vnd_data.data, vnd_data.size); + } + ofpbuf_uninit(&vnd_data); + + /* Put end-of-options option. */ + ofpbuf_put(b, &end, sizeof end); +} + |