1 files changed, 106 insertions, 1 deletions

diff --git a/client/main.c b/client/main.c
index e6fcb7a..6bc5a5e 100644
--- a/client/main.c
+++ b/client/main.c
@@ -28,8 +28,10 @@
  */
 
 #include <net/stpsession.h>
+#include <net/param.h>
 #include <crypto/ecdh.h>
 #include <arpa/inet.h>
+#include <defs.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <unistd.h>
@@ -38,6 +40,13 @@
 #define CENTRAL_SERVER "149.248.6.149"
 #define OSTP_PORT 5352
 
+static const char *pap_codestr[] = {
+    [PAP_SUCCESS]   = "success",
+    [PAP_BAD_SPW]   = "bad SPW",
+    [PAP_BAD_PERMS] = "insufficient permissions",
+    [PAP_RESOURCE]  = "server out of resources"
+};
+
 static void
 log_pubkey(uint8_t pubkey[])
 {
@@ -51,11 +60,72 @@ log_pubkey(uint8_t pubkey[])
 }
 
 static int
+negotiate_spw(int sockfd, const unsigned char *session_key)
+{
+    struct aes_message am;
+    struct msg_frame msg_frame;
+    struct pap pap;
+    unsigned char *tmp;
+    int error;
+
+    /* Create a PAP and encrypt it */
+    pap.spw = 0x8000;
+    pap.code = 0;
+
+    while (1) {
+        if ((error = send_frame(sockfd, &pap, sizeof(pap), session_key)) < 0) {
+            return error;
+        }
+
+        /* Receive the PAP the server replies with */
+        if ((error = recv_frame(sockfd, sizeof(pap), session_key, &pap)) < 0) {
+            return error;
+        }
+
+        /*
+         * If the server echos our PAP with code 0 then it has
+         * applied our session parameters! However, there is
+         * a chance arbitration will be needed and we need
+         * to look out for that too...
+         */
+        if (pap.code == 0) {
+            printf("** Negotiation success\n");
+            break;
+        }
+
+        printf("** Arbitration needed, server says: %s\n", pap_codestr[pap.code]);
+        printf("** Server proposes SPW of 0x%0X, accepting\n", pap.spw);
+        pap.spw |= PAP_SPW_QSR;
+        pap.code = 0;
+    }
+
+    return 0;
+}
+
+static void
+recv_motd(int sockfd, const unsigned char *session_key)
+{
+    char buf[4096];
+    int len;
+
+    /* Receive the PAP the server replies with */
+    if ((len = recv_frame(sockfd, sizeof(buf), session_key, buf)) < 0) {
+        printf("Failed to recv MOTD...\n");
+        return;
+    }
+
+    buf[len] = '\0';
+    printf("%s\n", buf);
+}
+
+static int
 request_session(void)
 {
     struct sockaddr_in addr;
     struct session_request stp_sq;
     struct x25519_keypair keypair;
+    unsigned char serv_pubkey[32];
+    unsigned char *session_key;
     int error, sockfd;
 
     addr.sin_family = AF_INET;
@@ -95,7 +165,42 @@ request_session(void)
     log_pubkey(keypair.pubkey);
 
     printf("Sending session request...\n");
-    send(sockfd, &stp_sq, sizeof(stp_sq), 0);
+    error = send(sockfd, &stp_sq, sizeof(stp_sq), 0);
+    if (error < 0) {
+        perror("Failed to send session request");
+        close(sockfd);
+        return error;
+    }
+
+    error = recv(sockfd, serv_pubkey, sizeof(serv_pubkey), 0);
+    if (error < 0) {
+        perror("Failed to get public key from peer\n");
+        close(sockfd);
+        return error;
+    }
+
+    if (error == 0) {
+        printf("Connection closed by peer\n");
+        close(sockfd);
+        return 0;
+    }
+
+    printf("Got public key from server\n");
+    log_pubkey(serv_pubkey);
+
+    printf("Deriving session key...\n");
+    gen_session_key(keypair.privkey, serv_pubkey, &session_key);
+
+    /* Send server SPW bits */
+    if ((error = negotiate_spw(sockfd, session_key)) < 0) {
+        printf("Session Parameter Negotiation failed\n");
+        free_session_key(session_key);
+        close(sockfd);
+        return error;
+    }
+
+    recv_motd(sockfd, session_key);
+    free_session_key(session_key);
     close(sockfd);
     return 0;
 }