Ensure that stack layers above transport manager never get chained packet buffers.

[bzbarsky-apple]

None of our upper-layer core really deals with chained packet buffers, starting with the way we do in-place decryption that assumes that we have a contiguous buffer.

The changes here:

1. Flatten out possibly-chained buffers in the LwIP case in the UDP
   and raw endpoints.
2. Ensure that we don't have a chained buffer in BTP. There was
   already a check for this in the "in progress" case; this change just
   adds the same check in the "idle" case.

Problem

Want to ensure that upper layers never have to deal with chained buffers.

Change overview

See above.

Testing

Not sure how to test LwIP, unfortunately, especially how to inject chained buffers into the receive path there.

[todo]

add support for BtpEngine messages longer than 1 pbuf

connectedhomeip/src/ble/BtpEngine.cpp

Lines 326 to 330 in 100b18c

	// TODO add support for BtpEngine messages longer than 1 pbuf
	VerifyOrExit(!mRxBuf->HasChainedBuffer(), err = CHIP_ERROR_INBOUND_MESSAGE_TOO_BIG);
	}
	else if (mRxState == kState_InProgress)
	{

---

This comment was generated by todo based on a TODO comment in 100b18c in #9599. cc @bzbarsky-apple.

[github-actions]

Size increase report for "gn_qpg-example-build" from eda07d5

File	Section	File	VM
chip-qpg6100-lighting-example.out	.text	352	352

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-qpg6100-lighting-example.out.map and ./pull_artifact/chip-qpg6100-lighting-example.out.map:

BLOAT EXECUTION FAILED WITH CODE 1:
bloaty: unknown file type for file './pull_artifact/chip-qpg6100-lighting-example.out.map'

Comparing ./master_artifact/chip-qpg6100-lighting-example.out and ./pull_artifact/chip-qpg6100-lighting-example.out:

sections,vmsize,filesize
.debug_info,0,1067
.debug_line,0,467
.text,352,352
.debug_loc,0,309
.debug_ranges,0,168
.symtab,0,96
.strtab,0,86
.debug_frame,0,76
.debug_abbrev,0,71
.debug_aranges,0,16
.debug_str,0,10
.shstrtab,0,2
[Unmapped],0,-352

[github-actions]

Size increase report for "nrfconnect-example-build" from eda07d5

File	Section	File	VM
chip-lock.elf	rodata	80	80
chip-lock.elf	text	40	40
chip-lock.elf	device_handles	-8	-8
chip-shell.elf	rodata	80	80
chip-shell.elf	text	40	40
chip-shell.elf	device_handles	-8	-8

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-lock.elf and ./pull_artifact/chip-lock.elf:

sections,vmsize,filesize
.debug_info,0,215
.debug_loc,0,120
rodata,80,80
.debug_line,0,69
.debug_ranges,0,56
.debug_frame,0,52
.symtab,0,48
.strtab,0,46
.debug_abbrev,0,40
text,40,40
.debug_aranges,0,8
.shstrtab,0,2
device_handles,-8,-8

Comparing ./master_artifact/chip-shell.elf and ./pull_artifact/chip-shell.elf:

sections,vmsize,filesize
.debug_info,0,215
.debug_loc,0,120
rodata,80,80
.debug_line,0,69
.debug_ranges,0,56
.debug_frame,0,52
.symtab,0,48
.strtab,0,46
.debug_abbrev,0,40
text,40,40
.debug_aranges,0,8
.shstrtab,0,-2
device_handles,-8,-8

[github-actions]

Size increase report for "esp32-example-build" from eda07d5

File	Section	File	VM
chip-ipv6only-app.elf	.flash.text	172	172
chip-all-clusters-app.elf	.flash.text	276	276
chip-all-clusters-app.elf	.flash.rodata	144	144
chip-lock-app.elf	.flash.text	216	216
chip-lock-app.elf	.flash.rodata	144	144
chip-shell.elf	.flash.rodata	144	144
chip-shell.elf	.flash.text	92	92
chip-bridge-app.elf	.flash.text	216	216
chip-bridge-app.elf	.flash.rodata	144	144
chip-temperature-measurement-app.elf	.flash.text	268	268
chip-temperature-measurement-app.elf	.flash.rodata	144	144

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-persistent-storage.elf and ./pull_artifact/chip-persistent-storage.elf:

sections,vmsize,filesize

Comparing ./master_artifact/chip-ipv6only-app.elf and ./pull_artifact/chip-ipv6only-app.elf:

sections,vmsize,filesize
[Unmapped],0,3924
.flash.text,172,172

Comparing ./master_artifact/chip-all-clusters-app.elf and ./pull_artifact/chip-all-clusters-app.elf:

sections,vmsize,filesize
.debug_info,0,752
.debug_line,0,661
.debug_loc,0,553
.flash.text,276,276
.flash.rodata,144,144
.debug_ranges,0,120
.strtab,0,86
.debug_frame,0,80
.symtab,0,48
.debug_abbrev,0,31
.debug_aranges,0,16
.debug_str,0,12
.riscv.attributes,0,3
.shstrtab,0,-2
[Unmapped],0,-420

Comparing ./master_artifact/chip-pigweed-app.elf and ./pull_artifact/chip-pigweed-app.elf:

sections,vmsize,filesize

Comparing ./master_artifact/chip-lock-app.elf and ./pull_artifact/chip-lock-app.elf:

sections,vmsize,filesize
.debug_line,0,844
.debug_info,0,817
.debug_loc,0,339
.flash.text,216,216
.xt.prop._ZNK4chip9Transport11PeerAddress8ToStringEPcj,0,168
.flash.rodata,144,144
.debug_ranges,0,128
.shstrtab,0,110
.strtab,0,86
.symtab,0,80
[ELF Section Headers],0,80
.debug_frame,0,48
.debug_abbrev,0,28
.debug_aranges,0,16
.debug_str,0,12
.xt.lit._ZNK4chip9Transport11PeerAddress8ToStringEPcj,0,8
[Unmapped],0,-360

Comparing ./master_artifact/chip-shell.elf and ./pull_artifact/chip-shell.elf:

sections,vmsize,filesize
.debug_line,0,844
.debug_info,0,814
.debug_loc,0,342
.xt.prop._ZNK4chip9Transport11PeerAddress8ToStringEPcj,0,168
.flash.rodata,144,144
.debug_ranges,0,128
.shstrtab,0,110
.flash.text,92,92
[ELF Section Headers],0,80
.symtab,0,64
.debug_frame,0,48
.strtab,0,46
.debug_abbrev,0,28
.debug_aranges,0,16
.xt.lit._ZNK4chip9Transport11PeerAddress8ToStringEPcj,0,8
[Unmapped],0,-236

Comparing ./master_artifact/chip-bridge-app.elf and ./pull_artifact/chip-bridge-app.elf:

sections,vmsize,filesize
.debug_line,0,844
.debug_info,0,814
.debug_loc,0,334
.flash.text,216,216
.xt.prop._ZNK4chip9Transport11PeerAddress8ToStringEPcj,0,168
.flash.rodata,144,144
.debug_ranges,0,128
.shstrtab,0,110
.strtab,0,86
.symtab,0,80
[ELF Section Headers],0,80
.debug_frame,0,48
.debug_abbrev,0,28
.debug_aranges,0,16
.debug_str,0,12
.xt.lit._ZNK4chip9Transport11PeerAddress8ToStringEPcj,0,8
[Unmapped],0,-360

Comparing ./master_artifact/chip-temperature-measurement-app.elf and ./pull_artifact/chip-temperature-measurement-app.elf:

sections,vmsize,filesize
[Unmapped],0,3684
.debug_line,0,863
.debug_info,0,824
.debug_loc,0,321
.flash.text,268,268
.flash.rodata,144,144
.xt.prop._ZNK4chip9Transport11PeerAddress8ToStringEPcj,0,144
.shstrtab,0,110
.debug_ranges,0,104
.strtab,0,86
.symtab,0,80
[ELF Section Headers],0,80
.debug_frame,0,48
.debug_aranges,0,16
.debug_str,0,13
.xt.lit._ZNK4chip9Transport11PeerAddress8ToStringEPcj,0,8
.debug_abbrev,0,-1

[bzbarsky-apple]

@LuDuda @jepenven-silabs @jmartinez-silabs @Damian-Nordic Please take a look?