diff options
| -rw-r--r-- | conf.c | 15 | ||||
| -rw-r--r-- | dhcp.c | 3 | ||||
| -rw-r--r-- | ndp.c | 2 |
3 files changed, 16 insertions, 4 deletions
@@ -617,7 +617,9 @@ static void usage(const char *name) info(" /tmp/passt_ISO8601-TIMESTAMP_INSTANCE-NUMBER.pcap"); info( " -m, --mtu MTU Assign MTU via DHCP/NDP"); - info( " default: no MTU assigned via DHCP/NDP options"); + info( " a zero value disables assignment"); + info( " default: 65520: maximum 802.3 MTU minus 802.3 header"); + info( " length, rounded to 32 bits (IPv4 words)"); info( " -a, --address ADDR Assign IPv4 or IPv6 address ADDR"); info( " can be specified zero to two times (for IPv4 and IPv6)"); info( " default: use addresses from interface with default route"); @@ -954,6 +956,12 @@ void conf(struct ctx *c, int argc, char **argv) errno = 0; c->mtu = strtol(optarg, NULL, 0); + + if (!c->mtu) { + c->mtu = -1; + break; + } + if (c->mtu < ETH_MIN_MTU || c->mtu > (int)ETH_MAX_MTU || errno) { err("Invalid MTU: %s", optarg); @@ -1132,6 +1140,11 @@ void conf(struct ctx *c, int argc, char **argv) } } + if (!c->mtu) { + c->mtu = (ETH_MAX_MTU - ETH_HLEN) / + sizeof(uint32_t) * sizeof(uint32_t); + } + get_routes(c); get_addrs(c); @@ -49,7 +49,6 @@ struct opt { static struct opt opts[255] = { [1] = { 0, 4, { 0 }, 0, { 0 }, }, /* Mask */ [3] = { 0, 4, { 0 }, 0, { 0 }, }, /* Router */ - [26] = { 0, 2, { 0xff, 0xf0 }, 0, { 0 }, }, /* MTU */ [51] = { 0, 4, { 0xff, 0xff, 0xff, 0xff }, 0, { 0 }, }, /* Lease time */ [53] = { 0, 1, { 0 }, 0, { 0 }, }, /* Type */ #define DHCPDISCOVER 1 @@ -319,7 +318,7 @@ int dhcp(struct ctx *c, struct ethhdr *eh, size_t len) *(unsigned long *)&opts[121].s[10] = c->gw4; } - if (c->mtu) { + if (c->mtu != -1) { opts[26].slen = 2; opts[26].s[0] = c->mtu / 256; opts[26].s[1] = c->mtu % 256; @@ -116,7 +116,7 @@ int ndp(struct ctx *c, struct ethhdr *eh, size_t len) memcpy(p, &c->addr6, 8); /* prefix */ p += 16; - if (c->mtu) { + if (c->mtu != -1) { *p++ = 5; /* type */ *p++ = 1; /* length */ p += 2; /* reserved */ |