[sr-dev] git:pd/outbound: modules_k/outbound: Filled in functions to encode and decode flow tokens

Module: sip-router Branch: pd/outbound Commit: 1db38af24d8808a9a2045c7bac25581199717a2b URL: http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commit;h=1db38af… Author: Peter Dunkley &lt;peter.dunkley(a)crocodile-rcs.com&gt; Committer: Peter Dunkley &lt;peter.dunkley(a)crocodile-rcs.com&gt; Date: Sat Dec 22 13:07:58 2012 +0000 modules_k/outbound: Filled in functions to encode and decode flow tokens --- modules_k/outbound/Makefile | 2 +- modules_k/outbound/ob_mod.c | 108 ++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 108 insertions(+), 2 deletions(-) diff --git a/modules_k/outbound/Makefile b/modules_k/outbound/Makefile index 148a900..e877c04 100644 --- a/modules_k/outbound/Makefile +++ b/modules_k/outbound/Makefile @@ -18,7 +18,7 @@ else LIBS= $(shell pkg-config --libs libssl) endif -DEFS+=-DOPENSER_MOD_INTERFACE +DEFS+=-DKAMAILIO_MOD_INTERFACE SERLIBPATH=../../lib SER_LIBS+=$(SERLIBPATH)/kcore/kcore diff --git a/modules_k/outbound/ob_mod.c b/modules_k/outbound/ob_mod.c index fbbee03..63e922f 100644 --- a/modules_k/outbound/ob_mod.c +++ b/modules_k/outbound/ob_mod.c @@ -20,7 +20,9 @@ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * */ +#include <openssl/hmac.h> +#include "../../basex.h" #include "../../dprint.h" #include "../../dset.h" #include "../../ip_addr.h" @@ -90,14 +92,118 @@ static int mod_init(void) return 0; } +/* Structure of flow token + + <HMAC-SHA1-80><protocol><dst_ip><dst_port><src_ip><src_port> + 10 + 1 + 16 + 2 + 16 + 2 + = 47 bytes + + IP addresses will always be 16 bytes. When an IPv4 address is used the + address will be encoded in the first four bytes and the last four bytes will + be ignored. + + base64 encoded size: ceiling((47+2)/3)*4 = 68 bytes +*/ + +#define UNENC_FLOW_TOKEN_LENGTH 47 +#define SHA1_LENGTH 20 +#define SHA1_80_LENGTH 10 +#define FLOW_TOKEN_START_POS (SHA1_80_LENGTH) +static unsigned char unenc_flow_token[UNENC_FLOW_TOKEN_LENGTH]; +static unsigned char hmac_sha1[EVP_MAX_MD_SIZE]; + int encode_flow_token(str *flow_token, struct receive_info rcv) { - + int pos = FLOW_TOKEN_START_POS, i; + + if (flow_token == NULL) + { + LM_ERR("bad string pointer\n"); + return -1; + } + + /* Encode protocol information */ + unenc_flow_token[pos++] = rcv.proto; + + /* Encode destination address */ + for (i = 0; i < 16; i++) + unenc_flow_token[pos++] = rcv.dst_ip.u.addr[i]; + unenc_flow_token[pos++] = (rcv.dst_port >> 8) & 0xff; + unenc_flow_token[pos++] = rcv.dst_port & 0xff; + + /* Encode source address */ + for (i = 0; i < 16; i++) + unenc_flow_token[pos++] = rcv.src_ip.u.addr[i]; + unenc_flow_token[pos++] = (rcv.dst_port >> 8) & 0xff; + unenc_flow_token[pos++] = rcv.dst_port & 0xff; + + /* HMAC-SHA1 the calculated flow token, truncate to 80 bits, and + prepend onto the flow token */ + HMAC(EVP_sha1(), ob_key.s, ob_key.len, + &unenc_flow_token[FLOW_TOKEN_START_POS], + UNENC_FLOW_TOKEN_LENGTH - FLOW_TOKEN_START_POS, + hmac_sha1, NULL); + memcpy(unenc_flow_token, &hmac_sha1[SHA1_LENGTH - SHA1_80_LENGTH], + SHA1_80_LENGTH); + + /* base64 encode the entire flow token and store for the caller to + use */ + flow_token->s = pkg_malloc(base64_enc_len(UNENC_FLOW_TOKEN_LENGTH)); + if (flow_token->s == NULL) + { + LM_ERR("allocating package memory\n"); + return -1; + } + flow_token->len = base64_enc(unenc_flow_token, UNENC_FLOW_TOKEN_LENGTH, + (unsigned char *) flow_token->s, + base64_enc_len(UNENC_FLOW_TOKEN_LENGTH)); + return 0; } int decode_flow_token(struct receive_info *rcv, str flow_token) { + int pos = FLOW_TOKEN_START_POS, i; + + if (flow_token.len != base64_enc_len(UNENC_FLOW_TOKEN_LENGTH)) + { + LM_ERR("bad flow token length. Length is %d, expected %d\n", + flow_token.len, UNENC_FLOW_TOKEN_LENGTH); + return -1; + } + + /* base64 decode the flow token */ + base64_dec((unsigned char *) flow_token.s, flow_token.len, + unenc_flow_token, UNENC_FLOW_TOKEN_LENGTH); + + /* HMAC-SHA1 the flow token (after the hash) and compare with the + truncated hash at the start of the flow token. */ + HMAC(EVP_sha1(), ob_key.s, ob_key.len, + &unenc_flow_token[FLOW_TOKEN_START_POS], + UNENC_FLOW_TOKEN_LENGTH - FLOW_TOKEN_START_POS, + hmac_sha1, NULL); + if (memcmp(unenc_flow_token, &hmac_sha1[SHA1_LENGTH - SHA1_80_LENGTH], + SHA1_80_LENGTH) != 0) + { + LM_ERR("flow token failed validation\n"); + return -1; + } + + /* Decode protocol information */ + rcv->proto = unenc_flow_token[pos++]; + + /* Decode destination address */ + for (i = 0; i < 16; i++) + rcv->dst_ip.u.addr[i] = unenc_flow_token[pos++]; + rcv->dst_port = ((unenc_flow_token[pos++] << 8) & 0xff) + | (unenc_flow_token[pos++] & 0xff); + + /* Decode source address */ + for (i = 0; i < 16; i++) + rcv->src_ip.u.addr[i] = unenc_flow_token[pos++]; + rcv->src_port = ((unenc_flow_token[pos++] << 8) & 0xff) + | (unenc_flow_token[pos++] & 0xff); + return 0; }