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
---
conf.c | 9 +++
dhcp.c | 227 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
dhcp.h | 15 ++++
3 files changed, 251 insertions(+)
diff --git a/conf.c b/conf.c
index 61a393f..3ec10ac 100644
--- a/conf.c
+++ b/conf.c
@@ -1485,6 +1485,7 @@ void conf(struct ctx *c, int argc, char **argv)
unsigned long code;
const char *comma;
char *end;
+ int len;
comma = strchr(optarg, ',');
if (!comma)
@@ -1499,7 +1500,15 @@ 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(code, 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",
+ code, comma + 1);
+
c->custom_opts[c->custom_opts_count].code = code;
+ 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..9220516 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -33,6 +33,233 @@
#include "log.h"
#include "dhcp.h"
+/**
+ * struct dhcp_opt_type_entry - Maps option code to RFC 2132 value type
+ * @code: DHCP option code
+ * @type: Expected value format
+ */
+static const struct dhcp_opt_type_entry {
+ uint8_t code;
+ enum dhcp_opt_type type;
+} dhcp_opt_types[] = {
+ { 1, DHCP_OPT_IPV4 }, /* Subnet Mask */
+ { 2, DHCP_OPT_UINT32 }, /* 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_UINT16 }, /* Boot File Size */
+ { 15, DHCP_OPT_STR }, /* Domain Name */
+ { 16, DHCP_OPT_IPV4 }, /* Swap Server */
+
+ { 17, DHCP_OPT_STR }, /* Root Path */
+ { 19, DHCP_OPT_UINT8 }, /* IP Forwarding */
+ { 23, DHCP_OPT_UINT8 }, /* Default IP TTL */
+ { 26, DHCP_OPT_UINT16 }, /* Interface MTU */
+ { 28, DHCP_OPT_IPV4 }, /* Broadcast Address */
+
+ { 33, DHCP_OPT_IPV4_LIST }, /* Static Routes (dest+router pairs) */
+ { 37, DHCP_OPT_UINT8 }, /* TCP Default TTL */
+ { 38, DHCP_OPT_UINT32 }, /* 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_UINT32 }, /* IP Address Lease Time */
+ { 53, DHCP_OPT_UINT8 }, /* DHCP Message Type */
+
+ { 54, DHCP_OPT_IPV4 }, /* Server Identifier */
+ { 57, DHCP_OPT_UINT16 }, /* Max DHCP Message Size */
+ { 58, DHCP_OPT_UINT32 }, /* Renewal (T1) Time */
+ { 59, DHCP_OPT_UINT32 }, /* 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 (RFC 3397) */
+ { 121, DHCP_OPT_ROUTES }, /* Classless Static Routes */
+
+ { 252, DHCP_OPT_STR }, /* WPAD URL */
+};
+
+/**
+ * dhcp_opt_type_lookup() - Look up the value type for a DHCP option code
+ * @code: DHCP option code
+ *
+ * Return: type from table
+ */
+static enum dhcp_opt_type dhcp_opt_type_lookup(uint8_t code)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(dhcp_opt_types); i++) {
+ if (dhcp_opt_types[i].code == code)
+ return dhcp_opt_types[i].type;
+ }
+
+ return DHCP_OPT_NONE;
+}
+
+/**
+ * dhcp_opt_parse() - Parse a DHCP option value
+ * @code: DHCP option code (determines value type via lookup table)
+ * @str: Value string from command line
+ * @buf: Output buffer for binary value
+ * @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_type_lookup(code);
+
+ switch (type) {
+ case DHCP_OPT_NONE: {
+ die("Unsupported DHCP option: %u,"
+ " see passt(1) for supported codes",
+ code);
+ }
+ case DHCP_OPT_IPV4: {
+ struct in_addr addr;
+
+ 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: {
+ char *tok, *saveptr;
+ char tmp[1024];
+ int len = 0;
+
+ if (snprintf_check(tmp, sizeof(tmp), "%s", str))
+ return -1;
+
+ for (tok = strtok_r(tmp, " ", &saveptr); tok;
+ tok = strtok_r(NULL, " ", &saveptr)) {
+ struct in_addr addr;
+
+ 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_UINT8: {
+ unsigned long val;
+ char *end;
+
+ val = strtoul(str, &end, 0);
+ if (*end || val > 255 || buf_len < 1)
+ return -1;
+ buf[0] = val;
+ return 1;
+ }
+ case DHCP_OPT_UINT16: {
+ unsigned long val;
+ char *end;
+
+ val = strtoul(str, &end, 0);
+ if (*end || val > 65535 || buf_len < 2)
+ return -1;
+ buf[0] = (val >> 8) & 0xff;
+ buf[1] = val & 0xff;
+ return 2;
+ }
+ case DHCP_OPT_UINT32: {
+ unsigned long val;
+ char *end;
+
+ val = strtoul(str, &end, 0);
+ if (*end || buf_len < 4)
+ return -1;
+ buf[0] = (val >> 24) & 0xff;
+ buf[1] = (val >> 16) & 0xff;
+ buf[2] = (val >> 8) & 0xff;
+ buf[3] = val & 0xff;
+ return 4;
+ }
+ case DHCP_OPT_ROUTES: {
+ /* RFC 3442: "CIDR/mask,gateway" entries, space-separated
+ * Encodes as: mask-width + significant-octets + router
+ * e.g. "192.168.1.0/24,10.0.0.1 0.0.0.0/0,10.0.0.1"
+ */
+ char *tok, *saveptr;
+ char tmp[1024];
+ int len = 0;
+
+ if (snprintf_check(tmp, sizeof(tmp), "%s", str))
+ return -1;
+
+ for (tok = strtok_r(tmp, " ", &saveptr); tok;
+ tok = strtok_r(NULL, " ", &saveptr)) {
+ struct in_addr dest, gw;
+ char *slash, *comma;
+ unsigned long mask;
+ int sig_octets;
+
+ slash = strchr(tok, '/');
+ if (!slash)
+ return -1;
+ *slash = '\0';
+
+ if (inet_pton(AF_INET, tok, &dest) != 1)
+ return -1;
+
+ comma = strchr(slash + 1, ',');
+ if (!comma)
+ return -1;
+ *comma = '\0';
+
+ mask = strtoul(slash + 1, NULL, 10);
+ if (mask > 32)
+ return -1;
+
+ if (inet_pton(AF_INET, comma + 1, &gw) != 1)
+ return -1;
+
+ sig_octets = (mask + 7) / 8;
+
+ if (len + 1 + sig_octets + 4 > (int)buf_len)
+ return -1;
+
+ buf[len++] = mask;
+ memcpy(buf + len, &dest, sig_octets);
+ len += sig_octets;
+ memcpy(buf + len, &gw, 4);
+ len += 4;
+ }
+ return len;
+ }
+ case DHCP_OPT_STR: {
+ size_t len = strlen(str);
+
+ if (!len || len >= buf_len)
+ return -1;
+ strncpy((char *)buf, str, buf_len);
+ return len;
+ }
+ }
+
+ return -1;
+}
+
/**
* struct opt - DHCP option
* @sent: Convenience flag, set while filling replies
diff --git a/dhcp.h b/dhcp.h
index cd50c99..01b2290 100644
--- a/dhcp.h
+++ b/dhcp.h
@@ -6,7 +6,22 @@
#ifndef DHCP_H
#define DHCP_H
+/**
+ * enum dhcp_opt_type - DHCP option value types per RFC 2132
+ */
+enum dhcp_opt_type {
+ DHCP_OPT_NONE,
+ DHCP_OPT_STR,
+ DHCP_OPT_IPV4,
+ DHCP_OPT_IPV4_LIST,
+ DHCP_OPT_UINT8,
+ DHCP_OPT_UINT16,
+ DHCP_OPT_UINT32,
+ DHCP_OPT_ROUTES,
+};
+
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 */
--
2.54.0