Hi Felix, list, Thanks for your comments. I have incorporated your comments into the tftpd.c, attached is the modified file.
regards, Ashwini On Sat, Oct 26, 2013 at 7:04 PM, Felix Janda <[email protected]> wrote: > Ashwini Sharma wrote: > > Hi Rob, All, > > > > Attached is the TFTPD implementation. > > Add it to hg, if you find it fine. > > > > Let me know for any comments/improvements. > > > > -Ashwini > > Thanks for your submission. Some comments sprinkled into the code below. > > Felix > > > /* tftpd.c - TFTP server. > > * > > * Copyright 2013 Ranjan Kumar <[email protected]> > > * Copyright 2013 Kyungwan Han <[email protected]> > > * > > * No Standard. > > > > USE_TFTPD(NEWTOY(tftpd, "rcu:", TOYFLAG_BIN)) > > > > config TFTPD > > bool "tftpd" > > default y > > help > > usage: tftpd [-cr] [-u USER] [DIR] > > > > Transfer file from/to tftp server. > > > > -r Prohibit upload > > -c Allow file creation via upload > > -u Access files as USER > > */ > > #define FOR_tftpd > > #include "toys.h" > > #include "toynet.h" > > > > GLOBALS( > > char *user; > > long sfd; > > struct passwd *pw; > > ) > > > > #define TFTPD_BLKSIZE 512 // as per RFC 1350. > > > > // opcodes > > #define TFTPD_OP_RRQ 1 // Read Request RFC 1350, RFC 2090 > > #define TFTPD_OP_WRQ 2 // Write Request RFC 1350 > > #define TFTPD_OP_DATA 3 // Data chunk RFC 1350 > > #define TFTPD_OP_ACK 4 // Acknowledgement RFC 1350 > > #define TFTPD_OP_ERR 5 // Error Message RFC 1350 > > #define TFTPD_OP_OACK 6 // Option acknowledgment RFC 2347 > > > > // Error Codes: > > #define TFTPD_ER_NOSUCHFILE 1 // File not found > > #define TFTPD_ER_ACCESS 2 // Access violation > > #define TFTPD_ER_FULL 3 // Disk full or allocation exceeded > > #define TFTPD_ER_ILLEGALOP 4 // Illegal TFTP operation > > #define TFTPD_ER_UNKID 5 // Unknown transfer ID > > #define TFTPD_ER_EXISTS 6 // File already exists > > #define TFTPD_ER_UNKUSER 7 // No such user > > #define TFTPD_ER_NEGOTIATE 8 // Terminate transfer due to option > negotiation > > > > /* TFTP Packet Formats > > * Type Op # Format without header > > * 2 bytes string 1 byte string 1 byte > > * ----------------------------------------------- > > * RRQ/ | 01/02 | Filename | 0 | Mode | 0 | > > * WRQ ----------------------------------------------- > > * 2 bytes 2 bytes n bytes > > * --------------------------------- > > * DATA | 03 | Block # | Data | > > * --------------------------------- > > * 2 bytes 2 bytes > > * ------------------- > > * ACK | 04 | Block # | > > * -------------------- > > * 2 bytes 2 bytes string 1 byte > > * ---------------------------------------- > > * ERROR | 05 | ErrorCode | ErrMsg | 0 | > > * ---------------------------------------- > > */ > > Thanks for the useful comments. > > > static char g_buff[TFTPD_BLKSIZE]; > > static char g_errpkt[TFTPD_BLKSIZE]; > > How about using toybuf and toybuf + TFTP_BLKSIZE for this? > Modified code as per your suggestion. > > > static void bind_and_connect(struct sockaddr *srcaddr, > > struct sockaddr *dstaddr, socklen_t socklen) > > { > > int set = 1; > > > > TT.sfd = xsocket(dstaddr->sa_family, SOCK_DGRAM, 0); > > if (setsockopt(TT.sfd, SOL_SOCKET, SO_REUSEADDR, (const void *)&set, > > sizeof(set)) < 0) perror_exit("setsockopt failed"); > > if (bind(TT.sfd, srcaddr, socklen)) perror_exit("bind"); > > if (connect(TT.sfd, dstaddr, socklen) < 0) > > perror_exit("can't connect to remote host"); > > } > > This can be inlined into tftpd_main(). > inlined the function > > > // Create and send error packet. > > static void send_errpkt(struct sockaddr *dstaddr, > > socklen_t socklen, char *errmsg) > > { > > error_msg(errmsg); > > g_errpkt[1] = TFTPD_OP_ERR; > > strcpy(g_errpkt + 4, errmsg); > > if (sendto(TT.sfd, g_errpkt, strlen(errmsg)+5, 0, dstaddr, socklen) < > 0) > > perror_exit("sendto failed"); > > } > > Why does this function not set g_errpkt[3] (the error code)? In some cases > before send_errpkt is called it is set up, in some cases not. In the second > type of case I guess the error code of the previous packet would be used. > Is that intentional? > > On an error, the server sends the error packet and shuts down. In places where the error code is not set, it is intentional to set it as ZERO. which happens due the _static_ global declaration of the __g_errpkt__ variable. > > // Used to send / receive packets. > > static void do_action(struct sockaddr *srcaddr, struct sockaddr *dstaddr, > > socklen_t socklen, char *file, int opcode, int tsize, int blksize) > > This is also only used once in tftpd_main() and can be inlined. That would > however require quite some work. > This is not done intentionaly, as this will result into one function being very big, of around 300 lines. > > > { > > int fd, done = 0, retry_count = 12, timeout = 100, len; > > uint16_t blockno = 1, pktopcode, rblockno; > > char *ptr, *spkt, *rpkt; > > struct pollfd pollfds[1]; > > > > spkt = xzalloc(blksize + 4); > > rpkt = xzalloc(blksize + 4); > > ptr = spkt+2; //point after opcode. > > > > pollfds[0].fd = TT.sfd; > > // initialize groups, setgid and setuid > > if (TT.pw) { > > if (change_identity(TT.pw)) perror_exit("Failed to change identity"); > > endgrent(); > > } > > > > if (opcode == TFTPD_OP_RRQ) fd = open(file, O_RDONLY, 0666); > > else fd = open(file, ((toys.optflags & FLAG_c) ? > > (O_WRONLY|O_TRUNC|O_CREAT) : (O_WRONLY|O_TRUNC)) , 0666); > > if (fd < 0) { > > g_errpkt[3] = TFTPD_ER_NOSUCHFILE; > > send_errpkt(dstaddr, socklen, "can't open file"); > > goto CLEAN_APP; > > } > > // For download -> blockno will be 1. > > // 1st ACK will be from dst,which will have blockno-=1 > > // Create and send ACK packet. > > if (blksize != TFTPD_BLKSIZE || tsize) { > > pktopcode = TFTPD_OP_OACK; > > // add "blksize\000blksize_val\000" in send buffer. > > if (blksize != TFTPD_BLKSIZE) { > > strcpy(ptr, "blksize"); > > ptr += strlen("blksize") + 1; > > ptr += snprintf(ptr, 6, "%d", blksize) + 1; > > } > > if (tsize) {// add "tsize\000tsize_val\000" in send buffer. > > struct stat sb; > > > > sb.st_size = 0; > > fstat(fd, &sb); > > strcpy(ptr, "tsize"); > > ptr += strlen("tsize") + 1; > > ptr += sprintf(ptr, "%lu", (unsigned long)sb.st_size)+1; > > } > > goto SEND_PKT; > > } > > // upload -> ACK 1st packet with filename, as it has blockno 0. > > if (opcode == TFTPD_OP_WRQ) blockno = 0; > > > > // Prepare DATA and/or ACK pkt and send it. > > for (;;) { > > int poll_ret; > > > > retry_count = 12, timeout = 100, pktopcode = TFTPD_OP_ACK; > > ptr = spkt+2; > > *((uint16_t*)ptr) = htons(blockno); > > blockno++; > > ptr += 2; > > if (opcode == TFTPD_OP_RRQ) { > > pktopcode = TFTPD_OP_DATA; > > len = readall(fd, ptr, blksize); > > if (len < 0) { > > send_errpkt(dstaddr, socklen, "read-error"); > > break; > > } > > if (len != blksize) done = 1; //last pkt. > > ptr += len; > > } > > SEND_PKT: > > // 1st ACK will be from dst, which will have blockno-=1 > > *((uint16_t*)spkt) = htons(pktopcode); //append send pkt's opcode. > > RETRY_SEND: > > if (sendto(TT.sfd, spkt, (ptr - spkt), 0, dstaddr, socklen) <0) > > perror_exit("sendto failed"); > > // if "block size < 512", send ACK and exit. > > if ((pktopcode == TFTPD_OP_ACK) && done) break; > > > > POLL_IN: > > pollfds[0].events = POLLIN; > > pollfds[0].fd = TT.sfd; > > poll_ret = poll(pollfds, 1, timeout); > > if (poll_ret < 0 && (errno == EINTR || errno == ENOMEM)) goto > POLL_IN; > > if (!poll_ret) { > > if (!--retry_count) { > > error_msg("timeout"); > > break; > > } > > timeout += 150; > > goto RETRY_SEND; > > } else if (poll_ret == 1) { > > len = read(pollfds[0].fd, rpkt, blksize + 4); > > if (len < 0) { > > send_errpkt(dstaddr, socklen, "read-error"); > > break; > > } > > if (len < 4) goto POLL_IN; > > } else { > > perror_msg("poll"); > > break; > > } > > // Validate receive packet. > > pktopcode = ntohs(((uint16_t*)rpkt)[0]); > > rblockno = ntohs(((uint16_t*)rpkt)[1]); > > if (pktopcode == TFTPD_OP_ERR) { > > switch(rblockno) { > > case TFTPD_ER_NOSUCHFILE: error_msg("File not found"); break; > > case TFTPD_ER_ACCESS: error_msg("Access violation"); break; > > case TFTPD_ER_FULL: error_msg("Disk full or allocation > exceeded"); > > break; > > case TFTPD_ER_ILLEGALOP: error_msg("Illegal TFTP operation"); > break; > > case TFTPD_ER_UNKID: error_msg("Unknown transfer ID"); break; > > case TFTPD_ER_EXISTS: error_msg("File already exists"); break; > > case TFTPD_ER_UNKUSER: error_msg("No such user"); break; > > case TFTPD_ER_NEGOTIATE: > > error_msg("Terminate transfer due to option negotiation"); > break; > > default: error_msg("DATA Check failure."); break; > > } > > How about > > char *message = "DATA Check failure."; > > if (rblockno && (rblockno < 9)) message = > ((char **){"File not found", "Access violation", > "Disk full or allocation exceeded", "Illegal TFTP operation", > "Unknown transfer ID", "File already exists", > "No such user", "Terminate transfer due to option > negotiation"})[rblockno - 1]; > error_msg(message); > this is a good suggestion, modified the code with a little modification. As for this snippet, compiler shouts of excess initialization for message. > > > break; // Break the for loop. > > } > > > > // if download requested by client, > > // server will send data pkt and will receive ACK pkt from client. > > if ((opcode == TFTPD_OP_RRQ) && (pktopcode == TFTPD_OP_ACK)) { > > if (rblockno == (uint16_t) (blockno - 1)) { > > if (!done) continue; // Send next chunk of data. > > break; > > } > > } > > > > // server will receive DATA pkt and write the data. > > if ((opcode == TFTPD_OP_WRQ) && (pktopcode == TFTPD_OP_DATA)) { > > if (rblockno == blockno) { > > int nw = writeall(fd, &rpkt[4], len-4); > > if (nw != len-4) { > > g_errpkt[3] = TFTPD_ER_FULL; > > send_errpkt(dstaddr, socklen, "write error"); > > break; > > } > > > > if (nw != blksize) done = 1; > > } > > continue; > > } > > goto POLL_IN; > > } // end of loop > > > > CLEAN_APP: > > if (CFG_TOYBOX_FREE) { > > free(spkt); > > free(rpkt); > > close(fd); > > } > > } > > > > void tftpd_main(void) > > { > > int recvmsg_len, rbuflen, opcode, blksize = TFTPD_BLKSIZE, tsize = 0; > > struct sockaddr_storage srcaddr, dstaddr; > > static socklen_t socklen = sizeof(struct sockaddr_storage); > > Leave out the "static". > Done. > > > char *buf = g_buff; > > > > TT.pw = NULL; > > memset(&srcaddr, 0, sizeof(srcaddr)); > > if (getsockname(STDIN_FILENO, (struct sockaddr*)&srcaddr, &socklen)) { > > toys.exithelp = 1; > > error_exit(NULL); > > } > > > > if (toys.optflags & FLAG_u) { > > struct passwd *pw = getpwnam(TT.user); > > if (!pw) error_exit("unknown user %s", TT.user); > > TT.pw = pw; > > } > > if (*toys.optargs) { > > if (chroot(*toys.optargs)) > > perror_exit("can't change root directory to '%s'", *toys.optargs); > > if (chdir("/")) perror_exit("can't change directory to '/'"); > > } > > > > recvmsg_len = recvfrom(STDIN_FILENO, g_buff, TFTPD_BLKSIZE, 0, > > (struct sockaddr*)&dstaddr, &socklen); > > bind_and_connect((struct sockaddr*)&srcaddr, (struct > sockaddr*)&dstaddr, socklen); > > // Error condition. > > if (recvmsg_len < 4 || recvmsg_len > TFTPD_BLKSIZE > > || g_buff[recvmsg_len-1] != '\0') { > > send_errpkt((struct sockaddr*)&dstaddr, socklen, "packet format > error"); > > return; > > } > > > > // request is either upload or Download. > > opcode = ntohs(*(uint16_t*)buf); > > if (((opcode != TFTPD_OP_RRQ) && (opcode != TFTPD_OP_WRQ)) > > || ((opcode == TFTPD_OP_WRQ) && (toys.optflags & FLAG_r))) { > > send_errpkt((struct sockaddr*)&dstaddr, socklen, > > ((opcode == TFTPD_OP_WRQ) ? "write error" : "packet format > error")); > > return; > > } > > > > buf += 2; > > if (*buf == '.' || strstr(buf, "/.")) { > > send_errpkt((struct sockaddr*)&dstaddr, socklen, "dot in filename"); > > return; > > } > > > > buf += strlen(buf) + 1; //1 '\0'. > > // As per RFC 1350, mode is case in-sensitive. > > if ((buf >= (g_buff + recvmsg_len)) || (strcasecmp(buf, "octet"))) { > > send_errpkt((struct sockaddr*)&dstaddr, socklen, "packet format > error"); > > return; > > } > > > > //RFC2348. e.g. of size type: > "ttype1\0ttype1_val\0...ttypeN\0ttypeN_val\0" > > buf += strlen(buf) + 1; > > rbuflen = g_buff + recvmsg_len - buf; > > if (rbuflen) { > > int jump = 0, bflag = 0; > > > > for (; rbuflen; rbuflen -= jump, buf += jump) { > > if (!bflag && !strcasecmp(buf, "blksize")) { //get blksize > > errno = 0; > > blksize = strtoul(buf, NULL, 10); > > if (errno || blksize > 65564 || blksize < 8) blksize = > TFTPD_BLKSIZE; > > bflag ^= 1; > > } else if (!tsize && !strcasecmp(buf, "tsize")) tsize ^= 1; > > > > jump += strlen(buf) + 1; > > } > > tsize &= (opcode == TFTPD_OP_RRQ); > > } > > > > //do send / receive file. > > do_action((struct sockaddr*)&srcaddr, (struct sockaddr*)&dstaddr, > > socklen, g_buff + 2, opcode, tsize, blksize); > > if (CFG_TOYBOX_FREE) close(STDIN_FILENO); > > } >
/* tftpd.c - TFTP server. * * Copyright 2013 Ranjan Kumar <[email protected]> * Copyright 2013 Kyungwan Han <[email protected]> * * No Standard. USE_TFTPD(NEWTOY(tftpd, "rcu:l", TOYFLAG_BIN)) config TFTPD bool "tftpd" default y help usage: tftpd [-cr] [-u USER] [DIR] Transfer file from/to tftp server. -r Prohibit upload -c Allow file creation via upload -u Access files as USER -l Log to syslog (inetd mode requires this) */ #define FOR_tftpd #include "toys.h" #include "toynet.h" GLOBALS( char *user; long sfd; struct passwd *pw; ) #define TFTPD_BLKSIZE 512 // as per RFC 1350. // opcodes #define TFTPD_OP_RRQ 1 // Read Request RFC 1350, RFC 2090 #define TFTPD_OP_WRQ 2 // Write Request RFC 1350 #define TFTPD_OP_DATA 3 // Data chunk RFC 1350 #define TFTPD_OP_ACK 4 // Acknowledgement RFC 1350 #define TFTPD_OP_ERR 5 // Error Message RFC 1350 #define TFTPD_OP_OACK 6 // Option acknowledgment RFC 2347 // Error Codes: #define TFTPD_ER_NOSUCHFILE 1 // File not found #define TFTPD_ER_ACCESS 2 // Access violation #define TFTPD_ER_FULL 3 // Disk full or allocation exceeded #define TFTPD_ER_ILLEGALOP 4 // Illegal TFTP operation #define TFTPD_ER_UNKID 5 // Unknown transfer ID #define TFTPD_ER_EXISTS 6 // File already exists #define TFTPD_ER_UNKUSER 7 // No such user #define TFTPD_ER_NEGOTIATE 8 // Terminate transfer due to option negotiation /* TFTP Packet Formats * Type Op # Format without header * 2 bytes string 1 byte string 1 byte * ----------------------------------------------- * RRQ/ | 01/02 | Filename | 0 | Mode | 0 | * WRQ ----------------------------------------------- * 2 bytes 2 bytes n bytes * --------------------------------- * DATA | 03 | Block # | Data | * --------------------------------- * 2 bytes 2 bytes * ------------------- * ACK | 04 | Block # | * -------------------- * 2 bytes 2 bytes string 1 byte * ---------------------------------------- * ERROR | 05 | ErrorCode | ErrMsg | 0 | * ---------------------------------------- */ static char *g_errpkt = toybuf + TFTPD_BLKSIZE; // Create and send error packet. static void send_errpkt(struct sockaddr *dstaddr, socklen_t socklen, char *errmsg) { error_msg(errmsg); g_errpkt[1] = TFTPD_OP_ERR; strcpy(g_errpkt + 4, errmsg); if (sendto(TT.sfd, g_errpkt, strlen(errmsg)+5, 0, dstaddr, socklen) < 0) perror_exit("sendto failed"); } // Used to send / receive packets. static void do_action(struct sockaddr *srcaddr, struct sockaddr *dstaddr, socklen_t socklen, char *file, int opcode, int tsize, int blksize) { int fd, done = 0, retry_count = 12, timeout = 100, len; uint16_t blockno = 1, pktopcode, rblockno; char *ptr, *spkt, *rpkt; struct pollfd pollfds[1]; spkt = xzalloc(blksize + 4); rpkt = xzalloc(blksize + 4); ptr = spkt+2; //point after opcode. pollfds[0].fd = TT.sfd; // initialize groups, setgid and setuid if (TT.pw) { if (change_identity(TT.pw)) perror_exit("Failed to change identity"); endgrent(); } if (opcode == TFTPD_OP_RRQ) fd = open(file, O_RDONLY, 0666); else fd = open(file, ((toys.optflags & FLAG_c) ? (O_WRONLY|O_TRUNC|O_CREAT) : (O_WRONLY|O_TRUNC)) , 0666); if (fd < 0) { g_errpkt[3] = TFTPD_ER_NOSUCHFILE; send_errpkt(dstaddr, socklen, "can't open file"); goto CLEAN_APP; } // For download -> blockno will be 1. // 1st ACK will be from dst,which will have blockno-=1 // Create and send ACK packet. if (blksize != TFTPD_BLKSIZE || tsize) { pktopcode = TFTPD_OP_OACK; // add "blksize\000blksize_val\000" in send buffer. if (blksize != TFTPD_BLKSIZE) { strcpy(ptr, "blksize"); ptr += strlen("blksize") + 1; ptr += snprintf(ptr, 6, "%d", blksize) + 1; } if (tsize) {// add "tsize\000tsize_val\000" in send buffer. struct stat sb; sb.st_size = 0; fstat(fd, &sb); strcpy(ptr, "tsize"); ptr += strlen("tsize") + 1; ptr += sprintf(ptr, "%lu", (unsigned long)sb.st_size)+1; } goto SEND_PKT; } // upload -> ACK 1st packet with filename, as it has blockno 0. if (opcode == TFTPD_OP_WRQ) blockno = 0; // Prepare DATA and/or ACK pkt and send it. for (;;) { int poll_ret; retry_count = 12, timeout = 100, pktopcode = TFTPD_OP_ACK; ptr = spkt+2; *((uint16_t*)ptr) = htons(blockno); blockno++; ptr += 2; if (opcode == TFTPD_OP_RRQ) { pktopcode = TFTPD_OP_DATA; len = readall(fd, ptr, blksize); if (len < 0) { send_errpkt(dstaddr, socklen, "read-error"); break; } if (len != blksize) done = 1; //last pkt. ptr += len; } SEND_PKT: // 1st ACK will be from dst, which will have blockno-=1 *((uint16_t*)spkt) = htons(pktopcode); //append send pkt's opcode. RETRY_SEND: if (sendto(TT.sfd, spkt, (ptr - spkt), 0, dstaddr, socklen) <0) perror_exit("sendto failed"); // if "block size < 512", send ACK and exit. if ((pktopcode == TFTPD_OP_ACK) && done) break; POLL_IN: pollfds[0].events = POLLIN; pollfds[0].fd = TT.sfd; poll_ret = poll(pollfds, 1, timeout); if (poll_ret < 0 && (errno == EINTR || errno == ENOMEM)) goto POLL_IN; if (!poll_ret) { if (!--retry_count) { error_msg("timeout"); break; } timeout += 150; goto RETRY_SEND; } else if (poll_ret == 1) { len = read(pollfds[0].fd, rpkt, blksize + 4); if (len < 0) { send_errpkt(dstaddr, socklen, "read-error"); break; } if (len < 4) goto POLL_IN; } else { perror_msg("poll"); break; } // Validate receive packet. pktopcode = ntohs(((uint16_t*)rpkt)[0]); rblockno = ntohs(((uint16_t*)rpkt)[1]); if (pktopcode == TFTPD_OP_ERR) { char *message = "DATA Check failure."; char *arr[] = {"File not found", "Access violation", "Disk full or allocation exceeded", "Illegal TFTP operation", "Unknown transfer ID", "File already exists", "No such user", "Terminate transfer due to option negotiation"}; if (rblockno && (rblockno < 9)) message = arr[rblockno - 1]; error_msg(message); break; // Break the for loop. } // if download requested by client, // server will send data pkt and will receive ACK pkt from client. if ((opcode == TFTPD_OP_RRQ) && (pktopcode == TFTPD_OP_ACK)) { if (rblockno == (uint16_t) (blockno - 1)) { if (!done) continue; // Send next chunk of data. break; } } // server will receive DATA pkt and write the data. if ((opcode == TFTPD_OP_WRQ) && (pktopcode == TFTPD_OP_DATA)) { if (rblockno == blockno) { int nw = writeall(fd, &rpkt[4], len-4); if (nw != len-4) { g_errpkt[3] = TFTPD_ER_FULL; send_errpkt(dstaddr, socklen, "write error"); break; } if (nw != blksize) done = 1; } continue; } goto POLL_IN; } // end of loop CLEAN_APP: if (CFG_TOYBOX_FREE) { free(spkt); free(rpkt); close(fd); } } void tftpd_main(void) { int recvmsg_len, rbuflen, opcode, blksize = TFTPD_BLKSIZE, tsize = 0, set =1; struct sockaddr_storage srcaddr, dstaddr; socklen_t socklen = sizeof(struct sockaddr_storage); char *buf = toybuf; TT.pw = NULL; memset(&srcaddr, 0, sizeof(srcaddr)); if (getsockname(STDIN_FILENO, (struct sockaddr*)&srcaddr, &socklen)) { toys.exithelp = 1; error_exit(NULL); } if (toys.optflags & FLAG_u) { struct passwd *pw = getpwnam(TT.user); if (!pw) error_exit("unknown user %s", TT.user); TT.pw = pw; } if (*toys.optargs) { if (chroot(*toys.optargs)) perror_exit("can't change root directory to '%s'", *toys.optargs); if (chdir("/")) perror_exit("can't change directory to '/'"); } recvmsg_len = recvfrom(STDIN_FILENO, toybuf, TFTPD_BLKSIZE, 0, (struct sockaddr*)&dstaddr, &socklen); TT.sfd = xsocket(((struct sockaddr*)&dstaddr)->sa_family, SOCK_DGRAM, 0); if (setsockopt(TT.sfd, SOL_SOCKET, SO_REUSEADDR, (const void *)&set, sizeof(set)) < 0) perror_exit("setsockopt failed"); if (bind(TT.sfd, (struct sockaddr*)&srcaddr, socklen)) perror_exit("bind"); if (connect(TT.sfd, (struct sockaddr*)&dstaddr, socklen) < 0) perror_exit("can't connect to remote host"); // Error condition. if (recvmsg_len < 4 || recvmsg_len > TFTPD_BLKSIZE || toybuf[recvmsg_len-1] != '\0') { send_errpkt((struct sockaddr*)&dstaddr, socklen, "packet format error"); return; } // request is either upload or Download. opcode = ntohs(*(uint16_t*)buf); if (((opcode != TFTPD_OP_RRQ) && (opcode != TFTPD_OP_WRQ)) || ((opcode == TFTPD_OP_WRQ) && (toys.optflags & FLAG_r))) { send_errpkt((struct sockaddr*)&dstaddr, socklen, ((opcode == TFTPD_OP_WRQ) ? "write error" : "packet format error")); return; } buf += 2; if (*buf == '.' || strstr(buf, "/.")) { send_errpkt((struct sockaddr*)&dstaddr, socklen, "dot in filename"); return; } buf += strlen(buf) + 1; //1 '\0'. // As per RFC 1350, mode is case in-sensitive. if ((buf >= (toybuf + recvmsg_len)) || (strcasecmp(buf, "octet"))) { send_errpkt((struct sockaddr*)&dstaddr, socklen, "packet format error"); return; } //RFC2348. e.g. of size type: "ttype1\0ttype1_val\0...ttypeN\0ttypeN_val\0" buf += strlen(buf) + 1; rbuflen = toybuf + recvmsg_len - buf; if (rbuflen) { int jump = 0, bflag = 0; for (; rbuflen; rbuflen -= jump, buf += jump) { if (!bflag && !strcasecmp(buf, "blksize")) { //get blksize errno = 0; blksize = strtoul(buf, NULL, 10); if (errno || blksize > 65564 || blksize < 8) blksize = TFTPD_BLKSIZE; bflag ^= 1; } else if (!tsize && !strcasecmp(buf, "tsize")) tsize ^= 1; jump += strlen(buf) + 1; } tsize &= (opcode == TFTPD_OP_RRQ); } //do send / receive file. do_action((struct sockaddr*)&srcaddr, (struct sockaddr*)&dstaddr, socklen, toybuf + 2, opcode, tsize, blksize); if (CFG_TOYBOX_FREE) close(STDIN_FILENO); }
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