Add an RFC 2132 type lookup table mapping DHCP option codes to their
expected value formats, and a dhcp_opt_parse() function that converts
CLI string values into their binary wire representation.
Wire dhcp_opt_parse() into the --dhcp-opt handler so that values are
validated and encoded at configuration time.
Link: https://bugs.passt.top/show_bug.cgi?id=192
Signed-off-by: Anshu Kumari
---
v2:
- Replaced struct lookup table + dhcp_opt_type_lookup() function with flat dhcp_opt_types[256] array indexed by code.
- Consolidated DHCP_OPT_UINT8/UINT16/UINT32 into single DHCP_OPT_INTEGER with dhcp_opt_int_width[256] table.
- Dropped DHCP_OPT_ROUTES / option 121 entirely.
- Added kerneldoc for enum dhcp_opt_type values.
- Removed curly braces from switch cases, declarations before switch.
- Added newlines before return statements.
- Changed IP list delimiter from space to comma (--dhcp-opt 6,1.1.1.1,8.8.8.8).
- Defined DHCP_OPT_PARSE_BUF constant for bare 1024.
- Added len and val[255] fields to struct here (moved from patch 1).
- Added kerneldoc for @custom_opts.len and @custom_opts.val.
- Wired dhcp_opt_parse() into case 32 (--dhcp-boot) to populate val/len.
---
conf.c | 16 ++++++
dhcp.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
dhcp.h | 17 +++++++
passt.h | 4 ++
4 files changed, 185 insertions(+)
diff --git a/conf.c b/conf.c
index ae8ee26..3a5f45d 100644
--- a/conf.c
+++ b/conf.c
@@ -1266,6 +1266,7 @@ void conf(struct ctx *c, int argc, char **argv)
char *end;
uid_t uid;
gid_t gid;
+ int len;
if (c->mode == MODE_PASTA)
@@ -1482,7 +1483,14 @@ void conf(struct ctx *c, int argc, char **argv)
die("Too many DHCP options (max %d)",
MAX_CUSTOM_DHCP_OPTS);
+ ret = dhcp_opt_parse(67, optarg,
+ c->custom_opts[c->custom_opts_count].val,
+ sizeof(c->custom_opts[0].val));
+ if (ret < 0)
+ die("Invalid boot file value: %s", optarg);
+
c->custom_opts[c->custom_opts_count].code = 67;
+ c->custom_opts[c->custom_opts_count].len = ret;
if (snprintf_check(c->custom_opts[c->custom_opts_count].str,
sizeof(c->custom_opts[0].str),
"%s", optarg))
@@ -1503,7 +1511,15 @@ void conf(struct ctx *c, int argc, char **argv)
die("Too many --dhcp-opt entries (max %d)",
MAX_CUSTOM_DHCP_OPTS);
+ len = dhcp_opt_parse(optcode, comma + 1,
+ c->custom_opts[c->custom_opts_count].val,
+ sizeof(c->custom_opts[0].val));
+ if (len < 0)
+ die("Invalid value for DHCP option %lu: %s",
+ optcode, comma + 1);
+
c->custom_opts[c->custom_opts_count].code = optcode;
+ c->custom_opts[c->custom_opts_count].len = len;
if (snprintf_check(c->custom_opts[c->custom_opts_count].str,
sizeof(c->custom_opts[0].str),
"%s", comma + 1))
diff --git a/dhcp.c b/dhcp.c
index 1ff8cba..e1c95ad 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -33,6 +33,154 @@
#include "log.h"
#include "dhcp.h"
+/**
+ * dhcp_opt_types - Maps option code to RFC 2132 value type, indexed by code
+ */
+static const enum dhcp_opt_type dhcp_opt_types[256] = {
+ [1] = DHCP_OPT_IPV4, /* Subnet Mask */
+ [2] = DHCP_OPT_INTEGER, /* Time Offset */
+ [3] = DHCP_OPT_IPV4_LIST, /* Router */
+ [4] = DHCP_OPT_IPV4_LIST, /* Time Server */
+ [5] = DHCP_OPT_IPV4_LIST, /* Name Server */
+ [6] = DHCP_OPT_IPV4_LIST, /* Domain Name Server */
+ [7] = DHCP_OPT_IPV4_LIST, /* Log Server */
+ [8] = DHCP_OPT_IPV4_LIST, /* Cookie Server */
+ [9] = DHCP_OPT_IPV4_LIST, /* LPR Server */
+ [10] = DHCP_OPT_IPV4_LIST, /* Impress Server */
+ [11] = DHCP_OPT_IPV4_LIST, /* Resource Location Server */
+ [12] = DHCP_OPT_STR, /* Host Name */
+ [13] = DHCP_OPT_INTEGER, /* Boot File Size */
+ [15] = DHCP_OPT_STR, /* Domain Name */
+ [16] = DHCP_OPT_IPV4, /* Swap Server */
+ [17] = DHCP_OPT_STR, /* Root Path */
+ [19] = DHCP_OPT_INTEGER, /* IP Forwarding */
+ [23] = DHCP_OPT_INTEGER, /* Default IP TTL */
+ [26] = DHCP_OPT_INTEGER, /* Interface MTU */
+ [28] = DHCP_OPT_IPV4, /* Broadcast Address */
+ [33] = DHCP_OPT_IPV4_LIST, /* Static Routes */
+ [37] = DHCP_OPT_INTEGER, /* TCP Default TTL */
+ [38] = DHCP_OPT_INTEGER, /* TCP Keepalive Interval */
+ [40] = DHCP_OPT_STR, /* NIS Domain Name */
+ [41] = DHCP_OPT_IPV4_LIST, /* NIS Servers */
+ [42] = DHCP_OPT_IPV4_LIST, /* NTP Servers */
+ [44] = DHCP_OPT_IPV4_LIST, /* NetBIOS Name Server */
+ [50] = DHCP_OPT_IPV4, /* Requested IP Address */
+ [51] = DHCP_OPT_INTEGER, /* IP Address Lease Time */
+ [53] = DHCP_OPT_INTEGER, /* DHCP Message Type */
+ [54] = DHCP_OPT_IPV4, /* Server Identifier */
+ [55] = DHCP_OPT_STR, /* Parameter Request List */
+ [57] = DHCP_OPT_INTEGER, /* Max DHCP Message Size */
+ [58] = DHCP_OPT_INTEGER, /* Renewal (T1) Time */
+ [59] = DHCP_OPT_INTEGER, /* Rebinding (T2) Time */
+ [60] = DHCP_OPT_STR, /* Vendor Class Identifier */
+ [61] = DHCP_OPT_STR, /* Client Identifier */
+ [66] = DHCP_OPT_STR, /* TFTP Server Name */
+ [67] = DHCP_OPT_STR, /* Bootfile Name */
+ [119] = DHCP_OPT_STR, /* Domain Search List */
+ [252] = DHCP_OPT_STR, /* WPAD URL */
+};
+
+/**
+ * dhcp_opt_int_width - Integer width in bytes for INTEGER-typed options
+ */
+static const uint8_t dhcp_opt_int_width[256] = {
+ [2] = 4, /* Time Offset */
+ [13] = 2, /* Boot File Size */
+ [19] = 1, /* IP Forwarding */
+ [23] = 1, /* Default IP TTL */
+ [26] = 2, /* Interface MTU */
+ [37] = 1, /* TCP Default TTL */
+ [38] = 4, /* TCP Keepalive Interval */
+ [51] = 4, /* IP Address Lease Time */
+ [53] = 1, /* DHCP Message Type */
+ [57] = 2, /* Max DHCP Message Size */
+ [58] = 4, /* Renewal (T1) Time */
+ [59] = 4, /* Rebinding (T2) Time */
+};
+
+#define DHCP_OPT_PARSE_BUF 1024
+
+/**
+ * dhcp_opt_parse() - Parse a DHCP option value
+ * @code: DHCP option code
+ * @str: DHCP Value string from command line
+ * @buf: Output buffer
+ * @buf_len: Size of output buffer
+ *
+ * Return: number of bytes written to @buf, or -1 on error
+ */
+int dhcp_opt_parse(uint8_t code, const char *str, uint8_t *buf, size_t buf_len)
+{
+ enum dhcp_opt_type type = dhcp_opt_types[code];
+ char tmp[DHCP_OPT_PARSE_BUF];
+ char *tok, *saveptr, *end;
+ struct in_addr addr;
+ unsigned long val;
+ unsigned int i;
+ uint8_t width;
+ size_t slen;
+ int len;
+
+ switch (type) {
+ case DHCP_OPT_NONE:
+ die("Unsupported DHCP option: %u,"
+ " see passt(1) for supported codes", code);
+ case DHCP_OPT_IPV4:
+ if (inet_pton(AF_INET, str, &addr) != 1)
+ return -1;
+
+ if (buf_len < sizeof(addr))
+ return -1;
+
+ memcpy(buf, &addr, sizeof(addr));
+
+ return sizeof(addr);
+ case DHCP_OPT_IPV4_LIST:
+ len = 0;
+
+ if (snprintf_check(tmp, sizeof(tmp), "%s", str))
+ return -1;
+
+ for (tok = strtok_r(tmp, ",", &saveptr); tok;
+ tok = strtok_r(NULL, ",", &saveptr)) {
+ if (inet_pton(AF_INET, tok, &addr) != 1)
+ return -1;
+
+ if (len + (int)sizeof(addr) > (int)buf_len)
+ return -1;
+
+ memcpy(buf + len, &addr, sizeof(addr));
+ len += sizeof(addr);
+ }
+ return len;
+ case DHCP_OPT_INTEGER:
+ width = dhcp_opt_int_width[code];
+ val = strtoul(str, &end, 0);
+
+ if (*end || buf_len < width)
+ return -1;
+
+ if (width < 4 && val >= (1UL << (width * 8)))
+ return -1;
+
+ for (i = 0; i < width; i++)
+ buf[i] = (val >> ((width - 1 - i) * 8)) & 0xff;
+
+ return width;
+ case DHCP_OPT_STR:
+ slen = strlen(str);
+
+ if (!slen || slen >= buf_len)
+ return -1;
+
+ strncpy((char *)buf, str, buf_len);
+
+ return slen;
+ }
+
+ return -1;
+}
+
/**
* struct opt - DHCP option
* @sent: Convenience flag, set while filling replies
diff --git a/dhcp.h b/dhcp.h
index cd50c99..3da571c 100644
--- a/dhcp.h
+++ b/dhcp.h
@@ -6,7 +6,24 @@
#ifndef DHCP_H
#define DHCP_H
+/**
+ * enum dhcp_opt_type - DHCP option value types per RFC 2132
+ * @DHCP_OPT_NONE: Unsupported or unknown option
+ * @DHCP_OPT_STR: Variable-length string
+ * @DHCP_OPT_IPV4: Single IPv4 address
+ * @DHCP_OPT_IPV4_LIST:Multiple IPv4 addresses, comma-separated
+ * @DHCP_OPT_INTEGER: Unsigned integer (1, 2, or 4 bytes)
+ */
+enum dhcp_opt_type {
+ DHCP_OPT_NONE,
+ DHCP_OPT_STR,
+ DHCP_OPT_IPV4,
+ DHCP_OPT_IPV4_LIST,
+ DHCP_OPT_INTEGER,
+};
+
int dhcp(const struct ctx *c, struct iov_tail *data);
void dhcp_init(void);
+int dhcp_opt_parse(uint8_t code, const char *str, uint8_t *buf, size_t buf_len);
#endif /* DHCP_H */
diff --git a/passt.h b/passt.h
index 3a0816f..751fee3 100644
--- a/passt.h
+++ b/passt.h
@@ -184,6 +184,8 @@ struct ip6_ctx {
* @fqdn: Guest FQDN
* @custom_opts: User-specified DHCP options from --dhcp-opt
* @custom_opts.code: DHCP option code
+ * @custom_opts.len: Length of binary value in @val
+ * @custom_opts.val: Binary-encoded option value
* @custom_opts.str: Original string value from command line
* @custom_opts_count: Number of entries in @custom_opts
* @ifi6: Template interface for IPv6, -1: none, 0: IPv6 disabled
@@ -271,6 +273,8 @@ struct ctx {
struct {
uint8_t code;
+ uint8_t len;
+ uint8_t val[255];
char str[256];
} custom_opts[MAX_CUSTOM_DHCP_OPTS];
int custom_opts_count;
--
2.54.0